Vertebrate Biology Chapter 34.

Vertebrate Biology Chapter 34

Classification Phylum Chordata Subphylum Urochordata Subphylum
Cephalochordata Subphylum Vertebrata lancets Agnathans Fish Sharks tetrapods tunicates

Chordate Characteristics

Burgess Shale Fauna (540 MYBP)
Pikaia- earliest known chordate

Possible evolution of 1st fish
lancelet Proto-vertebrate Tunicate larvae Adult tunicate

Adult tunicate Larval tunicate Amphioxus

Geologic Time Scale end of dinosaurs 1st dinosaur 1st reptiles
Millions of Years end of dinosaurs 1st dinosaur 1st reptiles 1st amphibians 1st land plants 1st fish 1st invertebrates

Class Agnatha, the jawless fishes
Class Agnatha, the jawless fishes Subclass (or order) Cyclostomata, the lampreys and hagfishes. Class Chondrichthyes, the cartilaginous-skeleton fishes Subclass Holocephali, the chimaeras, or ratfishes Subclass Elasmobranchii, the sharks, skates, and rays Class Placodermi Class Acanthodii Class Osteichthyes, the bony fishes Subclass Actinopterygii, the ray-finned fishes Superorder Chondrostei, the primitive ray-finned bony fishes: sturgeons, paddlefish, and bichirs Superorder Holostei or Neopterygii, the intermediate ray-finned fishes: gars and the bowfin Superorder Teleostei or Neopterygii, the advanced bony fishes: herring, salmon, perch. Subclass Crossopterygii, the coelacanth Subclass Dipnoi or Dipneusti, the lungfishes

Evolution of Jaws in fish
chondocranium palatoquadrate Hyomandibular arch Meckel’s cartilage all gill arches derived from neural crest ectoderm all other cartilage in the body is derived from mesoderm ossifymoves gills forward and add teeth epibranchialbecomes upper jaw = palatoquadrate ceratobranchiallower jaw = mandibular bone epibranchial and ceratobranchial fused to form hyomandibular arch (which ossified) and supports lower jaw recent evidence suggests that the 3rd gill arch became the jaw and the 4th arch became the hyomandibular the 1st two gill arches became part of the cranium (the 1st may have disappeared, the 2nd definitely became part of the cranium agnathostome gnathostome 1st appeared 400 mya

Class Agnatha Lack jaws, paired fins, scales
Possess medial nostril, medial fins, notocord rather than vertebral column Heterostracans are represented by nearly 300 species. They were marine but lived in sandy lagoons or deltas. Some species, however, are regarded as fresh water. They are known exclusively from North America, Europe and Siberia. They probably fed by scraping the bottom with their fan-shaped oral plates that armed their lower lip. They were poor swimmers and probably bottom-dewellers. It has been suggested that their posteriorly placed common gill opening could serve as a jet propulsion device and that made them moved like Cousteau''s diving saucer. Although most heterostracans are relatively small (5 to 30 cm in total length), some of them, the Psammosteidae, could grow to a very large size (up to 1.5 m in length) and developed steer-like branchial plates. The heterostracan head armor comprises large ventral and dorsal shields and a variable number of separate plates, laterally (cornual, branchial plates) and around the mouth (oral, postoral, orogonal plates). In some taxa (Pteraspidiformes, Traquairaspidiformes), the dorsal shield can be compound of several distinct plates (orbital, pineal, rostral), but there always remains a large median dorsal "disk". Since heterostracans have no calcified endoskeleton, their internal anatomy is only known from the impressions of the internal organs on the internal surface of the dermal armor. One may trace the impressions of the brain, gills, eyeballs, paired olfactory organ, and two distinct vertical semicircular canals of the labyrinth. Although paired, the olfactory organs seem to have opened ventrally into a large, median inhalent duct, as in extant hagfishes (see Hyperotreti). Ostracoderm 400 mya heterostracan

Hagfish Class Agnatha Subphylum Vertebrata What do they do?
For a long time, people thought of hagfish as scavengers and parasites, probably due to their habit or burrowing into dead or dying animals and eating them from the inside out. In fact, most of their diet is made up of marine worms and other invertebrates. Scientists used to think the hagfish looked primitive as a result of the loss of characteristics often associated with being a parasite. Now common belief is that hagfish just haven't needed to change for the last couple of hundred million years. Now that's a successful body plan and lifestyle! Another ability that had won fame for hagfish is the mass amounts of slime almost instantly secreted as a defense mechanism. Where are they found? Hagfish can be found in the chilly waters of the antitropical north and south. They tend to live on and in muddy sea floors in very dense groups (up to 15,000 in an area). Because females tend to produce large eggs in small numbers, their population sizes suggest a low death rate. One very useful trick hagfish have developed is the ability to tie themselves in knots, and be able to slide in and out of this knot. This can be used to escape predators, to clean themselves of slime, and to work their way into a carcass. This picture shows: A) knotting; this movement is used to clean slime off the body; B) escaping from capture using knotting, a very powerful motion; C) pulling on food by knotting They can also sneeze to unclog their nostrils of their own slime. Hagfish don't really have jaws. Instead they have two pairs of rasps on top of a tongue. They pull meat into their mouths with the tongue, then tear it off the prey with the rasps. Newly hatched hagfish look just like the adults, but have both male and female sex organs. When they mature, they will be either male or female, but have the ability to change from one to the other if the population structure demands it. Although hagfish have a partial skull, they have no back bone, so are not true vertebrates. What skeleton they do have is made of cartilage. How are they used by people? Yes, humans will find a way to exploit even these seemingly useless and repulsive animals. In Korea, almost 5 million pounds of hagfish meat are consumed each year. Hagfish skin is processed into "eelskin" boots, bags, wallets, purses, and other products. Overfishing in Asia has decimated their local hagfish stocks, so the Asian hagfish fishery has turned its eyes towards North America, where these "slime eels" are considered a worthless bycatch. It could mean a boost of over $2 million to the local fisheries, but care must be taken not to damage these stocks as well. Hagfish may not be pretty in most people's eyes, but they serve a purpose and are slow to reproduce. It would take them a long time to recover from over-harvesting. Who can tell what removing them from the local food web would do? Phylogenetics amongst species (for hard core scientists): There are about 20 species of hagfish divided into four genera (Myxine, Neomyxine, Paramyxine, and Eptatretus). These four groups make a sort of evolutionary continuum with regards to external traits. For example, the Myxine and Neomyxine are considered more advanced than the latter two for several reasons: They have a single pair of common external gill openings. The latter two have two minute separate gill openings (considered primitive). Paramyxine's openings are closer together than Eptatretus' so Paramyxine is considered more closely related to the first two. The eyes in Myxine and Neomyxine are smaller than those of the other two, suggesting a less primitive condition by an adaptation to the dark environment favoured my hagfish. Hagfish

Hagfish characteristics
Strictly marine No bone Rasping tongue Eyes degenerate, covered by skin; no pineal; single pair of semicircular canals No lateral line organs 5-15 pair gills Partial open circulatory system Holonephros and neotenic pronephros Numerous slime glands in skin, secrete copious amounts of mucus; Separate sexes, but all individuals have ovitestis, Eggs deposited at sea; direct development; totally marine

Subphylum Vertebrata Class Agnatha lamprey

Lamprey Characteristics
Oral disc/buccal funnel, with epidermal denticles and rasping tongue; active "predatory parasites” No bone Nostril on top of head Well-developed vertebrate eyes Well-developed Lateral Line system Best developed pineal “eye” of any aquatic vertebrate; 2 pairs of semicircular canals; Uniformly 7 pairs of gills Cranium cartilaginous, open on top Opisthonephros Eggs deposited in freshwater; freshwater larva; many species have freshwater adult, but most migrate to sea and have marine adult stage (anadromous).

Class Chondrichthyes Characteristics Sharks, skates, rays, chimera
Posses jaws with teeth, cartilaginous skeleton, paired fins Scales (denticles) have same origin and composition as teeth Possesses 5-7 gills Spiral valve intestine Ureoosmotic strategy Lateral line No swim bladder Heterocercal tail Relatively unchanged (480 mybp)

Subphylum Vertebrata Sharks, skates, rays Class Chondrichthyes

Basic Shark Anatomy

Modern Sharks Feeding Types Planktivores Carnivores Parasites

planktivores Gill arch from basking shark

carnivores

Parasites Cookie cutter shark

Ampullae of Lorenzeni pores
The ampullae of Lorenzini are small vesicles that form part of an extensive subcutaneous sensory network system. These vesicles are found around the head of the shark. They detect weak magnetic fields at short ranges that are produced by other fishes. This enables the shark to locate prey that are buried in the sand or orient to nearby movement. Each ampulla is a bundle of sensory cells that are enervated by several nerve fibers. These fibers are enclosed in a jelly filled tubule which has a direct opening to the surface through a pore. These pores on the head of the shark are visible to the naked eye, and appear as dark spots in the photo of a porbeagle shark head below. Detects weak magnetic fields produced by other fish

Ampullae of Lorenzeni

Development Ovipary- eggs enclosed in capsule; eggs are laid and hatched outside the mother Ovovipary- give birth to young, eggs develop in uterus Vivipary- give birth to young, placental connection

Class Placodermi Totally fossil, early jawed fishes;
Bony armor usually present around head-trunk, generally flattened body, tend to be bottom-adapted with eyes rather dorsal (other various designs); No true teeth Notochord persistent, un-constricted.

Class Placodermi

Class Osteichthyes Posses jaws with teeth bony skeleton paired fins
4 paired gill arches covered by operculum Intestine- simple, no spiral valve Swim bladder Lateral line Homocercal tail Scales- cycloid, ctenoid, ganoid

Basic Fish Structure

Superorder Chondrostei
sturgeon paddlefish ganoid scales (don’t form rings as they grow) heterocercal tail persistent notochord; centra absent or cartilage rings large mouth, long maxilla attached at rear open spiracle

Superorder Holostei gar L.Permian-Recent, but mostly Juras. & Cretac.;
Abbreviated heterocercal tail, often symmetric caudal fin; Ganoid or cycloid scales Single dorsal swim bladder, hydrostatic & respiratory; physostomous; No open spiracle Vertebral centra often at least partly ossified, constricting persistent notochord; More modernized jaws (than Chondrosteans) - maxilla shorter, free at rear; shorter mouth

Superorder Holostei bowfin

Superorder Teleostei

Fish Diversity 680 species of fish in the islands' waters. About 30% of these fish are endemic to the area .

White mouthed morey Achilles tang trumpetfish Domino damsel
Trigger (Humu) White mouthed morey Porcupine Dwarf moray Achilles tang trumpetfish

Subclass Crossopterygii
Latimeria Swim bladder modified to lungs Paired appendages May have given rise to terrestrial tetrapods Bony head Scales and teeth

Coelacanth Thought to be extinct 80 million years ago Found in 1938 off the coast of the Comoro Islands

Who found it first? 1938 Marjorie Courtenay-Latimer
How the coelacanth became known to science Marjorie Courtenay-Latimer Marjorie Courtenay-Latimer was born in East London on 24th February From the childhood she was interested in birds and mammals, and fossil collecting was also a hobby of hers. In 1930 she was appointed Curator of the newly established East London Museum which had at that time a very small collection of bird specimens. She worked hard to create a display of natural history of the Eastern Cape. Since fishing was a major local industry, she decided to concentrate on marine life. She interviewed fishing clubs and managers of fishing trawlers; specimens were enthusiastically donated and she made mounts of the small fish. She first met JLB Smith, then a Lecture in Chemistry at Rhodes University College, in December 1933 when he visited the museum during a camping trip at Igoda. He had been advised by doctors to spend his vacations in the open air because of ill health, and his love of angling soon turned into scientific interest .He was very impressed with the work she was doing, and offered to help her with any specimens which might want to classified, because she had on books on fish at the museum. In November 1936 she and her parents visited Bird Island where she spent weeks amassing a huge collection of sponges, seaweeds, sea shells and bird eggs. She also went out to sea in the Irvin & Johnson trawler, Nerine, and made friends with the Captain, Hendrik Goosen, who took her crates of specimens back to East London and thereafter saved interesting fishes from the trawl nests for her attention. Miss Courtenay-Latimer's sketch of the first coelacanth which she posted to JLB Smith On December 22, 1938, Captain Goosen and the Nerine put into East London harbour with the usual catch of sharks, rays, starfish and rat-tail fish. But there was one unusual fish amongst the catch that had been caught in about 70 meters, near the mouth of the Chalumna River. Once ashore Captain Goosen left word at the Museum that there were several specimens at the ship for Miss Latimer. At first she said that she was too busy because she was hard at work cleaning and articulating the fossil reptile bones collected from Tarkastad. But as it was so near Christmas time she decided to go and wish the crew a “Happy Christmas” and took a taxi to the docks. There, attracted by a blue fin amid the pile of sharks, she found a magnificent fish. She and her assistant put it in a bag and persuaded a reluctant taxi driver to take it to the museum in the boot of the car .It measured 150 cm and weighed 57.5 kg. From its hard bony scales with sharp, prickly spines and paired fins looking rather like legs, she knew that it must be some kind of primitive fish. But her greatest problem was to preserve it until it could be identified. It was extremely hot, the fish was too big to go into a bath and she could not find any organization willing to store it in a freezer. Although she was told by experts that it was only a type of rock cod and that she was making a fuss about nothing, she persisted in her attempts to save the fish for science. At first it was wrapped in cloths soaked in formalin but eventually, on the 26th, Mr. Center, a taxidermist, skinned it. Unfortunately the internal organs were thrown away. Marjorie went home disappointed and worried that she had not saved all the soft parts. What she had done, however, was to write immediately to her friend, JLB Smith, and send him her famous sketch of the strange fish. James Leonard Brierley Smith The next part of the story concerns JLB Smith, at that time enjoying a working holiday in Knysna. The next fourteen years of his life were to be dominated by this coelacanth and an almost obsessive search for the second specimen. JLB Smith, born in 1897 at Graff-Reinet, was a self-taught ichthyologist who had published several papers on the marine fishes of South Africa. He knew at once when he opened Marjorie’s letter that. Though the last coelacanths were supposed to have died out with the dinosaurs, he was looking at a drawing of a fossil fish: “One of my most constant and peculiar obsessions had always been a conviction that I was destined to discover some quite outrageous creature” He sent to Cape Town for a copy of Arthur Smith Wood-ward’s Catalogue of Fossil Fishes of the British Museum and, after he had received it, positively identified Marjorie’s unusual fish as a coelacanth. But he did not commit himself or risk his reputation in the scientific community until, some time later; he traveled to East London and saw the specimen for himself: “ Yes, there was not a shallow of doubt, scale by scale, bone by bone, fin by fin, it was a true coelacanth. It could have been one of those creatures of 200 million years ago and come alive again.” He gave the fish its formal scientific name, Latimer chalumnae in honour of Miss Courtenay-Latimer who had preserved it, and the river near which it was trawled. From January to June 1939 JLB Smith and his young wife, Margaret, worked furiously on the first scientific paper describing the coelacanth, completing it just four days before the birth of their son William. All this time the coelacanth, pervasive smell and all, stayed in their house. It was then returned to be displayed at the East London Museum. Thousands of people visited the museum to see the famous fish.

Where was it found?

J.L.B. Smith, Rhodes Univ., Grahamstown
On the 22 December, 1938, a fish was netted by fishermen of the Irving and Johnson vessle, Nerine, trawling off the mouth of the Chalumna river on the southeast coast of South Africa. The fish was about 1.5 m (5 ft) long, weighed 57 kg (126 lb), and was covered with deep-blue scales. A young curator of the East London Museum, Marjorie Courtenay-Latimer, as was her usual practise, inspected the catch at the wharf with the permission of Captain Hedrick Goosen, and came across this unusual fish which she kept as a specimen for the museum. She could not identify this fish and wrote a letter, including a rough sketch of the fish, and sent it to Prof. J.L.B. Smith at Rhodes University, Grahamstown, South Africa.The announcement that a Coelacanth had been caught off the Chalumna River mouth was made on 20 February, And so began the amazing and wonderful story of the Coelacanth, considered to be the zoological find of the 20th century and an event that was heralded with banner reports world wide. To date, approximately 200 fish have been caught in and around the Comoros Archipelago. The second Coelacanth known to science was caught off the Comoran island of Anjouan on the 20 December This concluded what Prof. J.L.B. Smith had suspected, these waters were the natural habitat of the Coelacanth. The fish was transported across the island and given to Capt.Eric Hunt who salted the fish to preserve it and set sail on his vessel, “Nduwaro” for Mayotte Island. Hunt arrived at Dzaoudzi, Pamanzi, a small Mayotte islet, early morning of the 22 December. The fish was injected with formalin and Hunt telegraghed J.L.B. Smith on the 22 December Further telegraphs were sent urging Smith to act without delay in order to secure his fish as the French authorities were trying to claim it. Smith and his wife were returning home from an East African expidition on the Dunnotar Castle and when the ship reached Durban on the 24th December, Smith received the cable from Hunt. Because it being Christmas Eve, there were no commercial flights. Smith finally managed to contact the Prime Minister, Dr.D.F.Malan, who also was on vacation at the time, on the 26th December. Permission was granted to use a military aircraft and the Dakota 6832 departed Pretoria on the 28th December, reached Pamanzi on the 29th, returned to Durban that same evening, Grahamstown on the 30th and returned to Pretoria on the 31 December (This is the only aircraft ever to have flown 3000 miles to collect a dead fish) J.L.B. Smith, Rhodes Univ., Grahamstown

Coelacanth Anatomy Fins: 2 dorsals 2 pectorals 2 pelvics 1 anal 1 caudal

Coelacanth Anatomy Unsegmented notochord Rostral organ Intercranial joint Fat filled swim bladder Ovoviviparous

Anatomical comparison between Sarcopterygian, amphibian, and reptile.

Anatomical Similarities to Sharks:
Spiral valve intestine Give birth to live young Long cartilaginous tube instead of backbone Osmoregulatory strategy Anatomical Similarities to Fish: bony head teeth scales

The coelacanth’s phylogenetic classification remains inconclusive
Anatomical Similarities to Tetrapods: fat filled lung fleshy lobed-fins circulatory system inner ear tooth enamel intracranial joint- a feature once found in ancient frogs The coelacanth’s phylogenetic classification remains inconclusive

Subclass Dipnoi Lungfish
While there are seven families of fossil lungfish known, only two survived into the Triassic (and still exist today). There are only three genera of lungfish alive today and each is found on a single continent. The Australian lungfish is Neoceratodus; in South America lives Leipdosiren; and Protopterus lives in Africa. The largest of these is the Australian species, which may grow to as long as 1.8 meters. Though Neoceratodus today is found only in Australia, fossils of that genus and the related Ceratodus have been found almost worldwide in Mesozoic strata, indicating that this group once had a much wider distribution. Lungfish are believed to be the closest living relatives of the tetrapods, and share a number of important characteristics with them. Among these characters are tooth enamel, separation of pulmonary blood flow from body blood flow, arrangement of the skull bones, and the presence of four similarly sized limbs with the same position and structure as the four tetrapod legs. However, there is still debate about the relationships among the Sarcopterygii. Lungfish

Acanthostega Foot of Acanthostega had 8 digits 360 mya
Among the most primitive early tetrapods is Acanthostega, from freshwater sediments deposited during the Late Devonian of Greenland (a cold and dry region today, but a warm, moist equatorial setting during the Devonian). As compared to Eusthenopteron and Panderichthys, a major development in Acanthostega is in the modification of bony fins to form a limb with digits (8 fingers were found on a preserved forelimb). Significantly, the pectoral girdle has become detached from the skull (so that crawling would not be such a "mind jarring" experience), and the pelvic girdle is attached to the vertebral column by means a specialized sacral (hip) vertebra for greater support and more efficient locomotion. However, Acanthostega still posseses many primitive, fish-like characteristics. The vertebrae are delicate, with only weakly developed ribs and largely without well developed zygapophyses (processes that interlock adjacent vertebrae in terrestrial tetrapods). The sacral vertebra is not strongly differentiated from adjacent vertebrae, and the hip girdle is relatively small. It does not seem that Acanthostega could have supported itself on land for any great length of time, and that the limbs were primarily, perhaps exclusively, useful for locomotion in shallow water (where it is more efficient to crawl rather than swim). In this respect, it might have lived in a manner similar to the living giant salamander seen in the video (and which Acanthostega resembled in bodily proportions). The tail supported a caudal fin for propulsion in deeper water. In view of the skull, the external naris of Acanthostega is small, suggesting that, like Eusthenopteron, it was primarily a mouth breather. A preoperculum (one of the opercular series of bones found in osteichthyans) is still present. Bones on the interior of the skull and hip girdle are channeled, suggesting that in life they harbored blood vessels which would have connected to a set of internal gills that were reduced as compared to osteolepiforms, but still functional. Foot of Acanthostega had 8 digits 360 mya

Acanthostega First complete tetrapod with free digits
- eight digits on each hand Retained “fishy” characters: gills tail fin Partial connection between skull and pectoral girdle Labyrinthodont teeth Lateral line Ulna shorter than radius

Ichthyostega Transition fossil from fw Crossopterygian to tetrapod
Ichthyostega (also from the Late Devonian of Greenland), retains a fish-like caudal fin, but exhibits morphology that is better adapted for terrestrial walking as compared to Acanthostega. The ribs of Ichthyostega are long, thick, and supportive, but their overlapping nature would have limited the range of lateral motion considerably. The limbs, hip girdle, and vertebrae are more stoutly constructed than are those of Acanthostega, and the vertebrae possess more strongly developed zygapophyses (so they could work together to produce a supporting framework). These traits indicate Ichthyostega spent considerable time out of the water in between fishing forays. The forelimbs appear to be larger than the hindlimbs, and it has been suggested that terrestrial locomotion in Ichthyostega was similar to that seen in modern sea lions (which wiggle back and forth with their powerful fore-flippers). The hindlimb bears 7 toes; Ichthyostega, Acanthostega, and a few other early tetrapods (all Devonian) are the only representatives that possess more than five digits. It does not appear that any of the first terrestrial vertebrates were specialists for utilizing plants or insects as a potential food source, for they retain the relatively large body size and needle-like teeth of the sarcopterygians, indicating a diet of fish (which are difficult to catch, but can generally be swallowed whole). Nevertheless, coming onto land would have provided Ichthyostega and more advanced tetrapods with three primary advantages over strictly aquatic life. 1) As was the case with plants, land offered a refuge from predators. 2) Basking in the sun provides warm internal temperatures that would produce faster and more efficient digestion of food. 3) Early terrestrial tetrapods could deposit their fish-like eggs into isolated pools of freshwater (lakes and ponds). The developing young would then grow in an environment free from large predators and filled with potential food (larval insects).

Ichthyosetga Much like Acanthostega, but…
- stronger limbs; radius & ulna of equal length - no gills in adults - reduced number of skull bones Still retains panderichthyid-like skull, tail fin, labrinthodont teeth, lateral line First tetrapod known that was capable of life on land

Returns to water to breed Metamorphosis Some toxic
Class Amphibia Characteristics Cold blooded Returns to water to breed Metamorphosis Some toxic Estivation-dry and hot Hibernation- cold 3,500 species

Class Amphibia Mudpuppy (salamander) salamander newt Poison arrow frog
Rana cancrivora Coqui

Class Amphibia Metamorphosis

Increased UV radiation
Class Amphibia “Canaries in the coal mine” Habitat destruction Introduced species Pollution Pesticide use Diseases Over-harvesting Climate change Increased UV radiation Chilling new evidence suggests amphibians may be in worse shape than previously thought due to climate change. Further, the findings indicate that the 70 percent decline in amphibians over the past 35 years may have been exceeded by a sharp fall in reptile populations, even in otherwise pristine Costa Rican habitats. Ominously, the new research warns that protected areas strategies for biodiversity conservation will not be enough to stave off extinction. Frogs and their relatives are in big trouble. Writing in the Early Edition of the Proceedings of the National Academy of Sciences (PNAS), a team of researchers led by Steven M. Whitfield of Florida International University, found that amphibian and reptile populations declined by 75% since 1970 in the protected old-growth lowland rainforest of La Selva Biological Station in Costa Rica. The declines only occurred in primary forests -- neighboring abandoned cacao plantations did not suffer diminished populations. According to the Global Amphibian Assessment, a comprehensive status assessment of the world's amphibian species, one-third of the world's 5,918 known amphibian species are classified as threatened with extinction. Further, more than 120 species have likely gone extinct since 1980.

Amniotic Egg Chorion Allantois Amnion Yolk sac Embryo Amniotic cavity
with amniotic fluid Yolk (nutrients) Shell Albumen

3 chambered heart (except crocks)
Class Reptilia Characteristics Cold blooded Have scales Amniotic egg Dry skin 3 chambered heart (except crocks) 6,500 species

Class Reptilia Saltwater crocodile Marine iguana Marine turtle
Sea snake

Sea Snakes Class Reptilia
Snakes are cold-blooded (poikilotherms). Consequently, their distributions are restricted to warm waters and sea snakes are only found in the Indo-Pacific region. There is concern that if a sea-level canal were constructed across Panama, they could become introduced to the Caribbean. Sea snakes inhabit estuaries, coral reef areas and the open sea and they are often found in large schooling groups. Normally, sea snakes are quite docile and donÕt pose a threat to humans. They have powerful venom which they use to incapacitate fishes or squid. Human fatalities have occurred and these are most common when the snakes wash up on beaches and humans handle the reptiles. They have few natural predators other than sharks, saltwater crocodiles and eagles. Yellow bellied sea snake (sometimes in Hawaii)

Sea Snakes Reproduction: Krates are oviparous and lay eggs on land
Diversity: Mainly marine, 1 fw species Habitat: Primarily tropical; coastal estuaries, coral reefs, open sea; 33-36oC Behavior Aggregates non aggressive Prey: Feed on small fish or squid, which are killed with powerful venom Predators (few) sharks, snapper, grouper, crabs, saltwater crocodiles, raptors; they descend to escape Venom 2-10 times as toxic as that of a cobras Reproduction Some oviparous some viviparous Reproduction: Krates are oviparous and lay eggs on land Hydrophiids are viviparous and produce young in the water Not much known about breeding However, olive sea snake breed in spring; seasonal courtship displays

Sea Snakes Adaptations to life in the sea Osmoregulation: skin is impermeable to salts; salts eliminated by sublingual gland Developing a flattened paddle-shaped tail and a laterally compressed body. Reduced metabolic rate and increased tolerance for low oxygen levels Lungs- greatly enlarged; hydrostatic organ Gaseous exchange - lungs and the skin. Developing salt excreting glands under the tongue. 2.Developing a flattened paddle-shaped tail and a laterally compressed body making it an efficient swimmer. 3.Reducing its metabolic rate. Sea snakes are capable of remaining submerged for up to 2 hours by decreasing its metabolic rate and developing an increased tolerance for low oxygen levels. After one breath at the surface, it can dive again. A sea snake also has valve-like flaps over its nostrils to stop water flowing into the lungs. 4.The lungs of sea snakes are greatly enlarged, extending to the base of the tail enabling a large volume of oxygen to be stored in the lungs. 5.Parts of the lung are believed to function as a hydrostatic organ regulating the snake's buoyancy. 6.Gaseous exchange occurs through both the lungs and the skin. Up to 22% of the oxygen is supplied from the sea water through the skin and all excess carbon dioxide is lost into the sea.

Sea Snakes Reproduction: Krates are oviparous and lay eggs on land
Hydrophiids are viviparous and produce young in the water Not much known about breeding However, olive sea snake breed in spring; seasonal courtship displays Olive Sea Snake

Saltwater crocodiles Largest living crocodilians: 6-7 m long
Class Reptilia Saltwater crocodiles Largest living crocodilians: 6-7 m long Eggs laid and incubated on land Tropical and subtropical Saltwater Crocodiles Saltwater crocodiles are the largest of living crocodilians and adults can reach 6-7 m in length. These seagoing animals may travel thousands of miles in the ocean. They are wide-ranging and may move into freshwater areas as well. They havenÕt entirely left land and must return to lay their eggs which are incubated in a terrestrial nest. Their poikilothermic nature means that their distributions are limited to warm areas. Diets include fishes, invertebrates and vertebrates.

Marine Iguanas Class Reptilia
These are the only marine lizards and they are endemic to the Galapagos Islands off Ecuador. Marine iguanas have flattened tails that assist them in swimming and they have adapted to an aquatic life. Their primary diet are algae that encrust the rocks around the islands. Iguanas dive to feed on the algae and in the process, their bodies undergo substantial cooling. After diving and feeding bouts, they must warm themselves on land to raise their body temperature. During feeding they accumulate a lot of salt that is excreted via specialized salt-glands on their noses. Recently, iguanas have been observed feeding on terrestrial vegetation. The stresses of El Ni–os may have driven them to forage ashore. Marine lizard endemic to Galapagos islands Herbivorous: graze on seaweeds Salt-glands on nose to eliminate excess salt Recently observed feeding on land for first time They return to land to escape predators.

Class Reptilia Marine Turtles (Honu)

Phylogeny of the Amniotes
Therapsids Anapsids Diapsids Synapsids Sauropsids Ancestral amniote

Archaeopteryx

Warm blooded Feathers and wings Hollow bones Horny bill
Class Aves Characteristics Warm blooded Feathers and wings Hollow bones Horny bill Lungs have air sacks Hard egg shell

Class Aves Ratites Carinate

Class Aves

Marine Birds

The skeletons of birds have several adaptations that make them light, flexible, but strong.
The bones are honeycombed to reduce weight without sacrificing much strength.

Warm blooded Have fur or hair Suckle young 3 middle ear bones
Class Mammalia Characteristics Warm blooded Have fur or hair Suckle young 3 middle ear bones A Guide to characteristics of Class Mammalia The Class Mammalia is well represented in Southern Africa. There are 293 species of land mammals and 37 species of marine mammals in the Southern African subregion. That is 330 of the around 5000 mammal species found on Earth! Class Mammalia -- all mammals share three characteristics not found in other animals: 3 middle ear bones; hair; and the production of milk by modified sweat glands called mammary glands. Mammals hear sounds after they are transmitted from the outside world to their inner ears by a chain of three bones, the malleus, incus, and stapes. Two of these, the malleus and incus, are derived from bones involved in jaw articulation in most other vertebrates. Mammals have hair. Adults of some species lose most of their hair, but hair is present at least during some phase of the ontogeny of all species. Mammalian hair, made of a protein called keratin, serves at least four functions. First, it slows the exchange of heat with the environment (insulation). Second, specialized hairs (whiskers or "vibrissae") have a sensory function, letting the owner know when it is in contact with an object in its external environment. These hairs are often richly innervated and well-supplied with muscles that control their position. Third, through their color and pattern, hairs affect the appearance of a mammal. They may serve to camouflage, to announce the presence of especially good defense systems (for example, the conspicuous color pattern of a skunk is a warning to predators), or to communicate social information (for example, threats, such as the erect hair on the back of a wolf; sex, such as the different colors of male and female capuchin monkeys; presence of danger, such as the white underside of the tail of a whitetailed deer). Fourth, hair provides some protection, either simply by providing an additional protective layer (against abrasion or sunburn, for example) or by taking on the form of dangerous spines that deter predators (porcupines, spiny rats, others). Mammals feed their newborn young with milk, a substance rich in fats and protein that is produced by modified sweat glands called mammary glands. These glands, which take a variety of shapes, are usually located on the ventral surface of females along paths that run from the chest region to the groin. They vary in number from two (one right, one left, as in humans) to a dozen or more. Other characteristics found in most mammals include highly differentiated teeth; teeth are replaced just once during an individual's life (this condition is called diphyodonty, and the first set is called "milk teeth); a lower jaw made up of a single bone, the dentary; four-chambered hearts, a secondary palate separating air and food passages in the mouth; a muscular diaphragm separating thoracic and abdominal cavities; highly developed brain; endothermy and homeothermy; separate sexes with the sex of an embryo being determined by the presence of a Y or 2 X chromosomes; and internal fertilization. The Class Mammalia includes around 5000 species placed in 26 orders (systematists do not yet agree on the exact number or on how some orders are related to others). Mammals can be found in all continents and seas. In part because of their high metabolic rates (associated with homeothermy and endothermy), they often play an ecological role that seems disproportionately large compared to their numerical abundance. Subclass Prototheria - Not represented in southern Africa Order Monotremata -- Monotremes: platypus and echidnas Subclass Metatheria (marsupials) - Not represented in southern Africa Order Didelphimorphia Order Paucituberculata Order Microbiotheria Order Dasyuromorphia Order Peramelemorphia Order Notoryctemorphia Order Diprotodontia Subclass Eutheria (placentals) Order Insectivora -- Insectivores: shrews, moles, hedgehogs, tenrecs, etc. Order Macroscelidea -- elephant shrews Order Scandentia -- tree shrews Order Dermoptera -- colugos Order Chiroptera --bats Order Primates --primates Order Xenarthra -- edentates; sloths, armadillos and anteaters Order Pholidota -- pangolins Order Lagomorpha -- rabbits and pikas Order Rodentia -- rodents Order Cetacea -- whales, dolphins, and porpoises Order Carnivora -- carnivores Order Tubulidentata -- aardvark Order Proboscidea -- elephants Order Hyracoidea -- hyraxes Order Sirenia -- dugongs and manatees Order Perissodactyla -- horses, rhinos, tapirs Order Artiodactyla -- antelope, giraffe, camels, pigs, hippos, etc.

Protheria- echidna & platypus Metatheria- marsupial
Class Mammalia Subclasses Protheria- echidna & platypus Metatheria- marsupial Eutheria- true mammals A Guide to characteristics of Class Mammalia The Class Mammalia is well represented in Southern Africa. There are 293 species of land mammals and 37 species of marine mammals in the Southern African subregion. That is 330 of the around 5000 mammal species found on Earth! Class Mammalia -- all mammals share three characteristics not found in other animals: 3 middle ear bones; hair; and the production of milk by modified sweat glands called mammary glands. Mammals hear sounds after they are transmitted from the outside world to their inner ears by a chain of three bones, the malleus, incus, and stapes. Two of these, the malleus and incus, are derived from bones involved in jaw articulation in most other vertebrates. Mammals have hair. Adults of some species lose most of their hair, but hair is present at least during some phase of the ontogeny of all species. Mammalian hair, made of a protein called keratin, serves at least four functions. First, it slows the exchange of heat with the environment (insulation). Second, specialized hairs (whiskers or "vibrissae") have a sensory function, letting the owner know when it is in contact with an object in its external environment. These hairs are often richly innervated and well-supplied with muscles that control their position. Third, through their color and pattern, hairs affect the appearance of a mammal. They may serve to camouflage, to announce the presence of especially good defense systems (for example, the conspicuous color pattern of a skunk is a warning to predators), or to communicate social information (for example, threats, such as the erect hair on the back of a wolf; sex, such as the different colors of male and female capuchin monkeys; presence of danger, such as the white underside of the tail of a whitetailed deer). Fourth, hair provides some protection, either simply by providing an additional protective layer (against abrasion or sunburn, for example) or by taking on the form of dangerous spines that deter predators (porcupines, spiny rats, others). Mammals feed their newborn young with milk, a substance rich in fats and protein that is produced by modified sweat glands called mammary glands. These glands, which take a variety of shapes, are usually located on the ventral surface of females along paths that run from the chest region to the groin. They vary in number from two (one right, one left, as in humans) to a dozen or more. Other characteristics found in most mammals include highly differentiated teeth; teeth are replaced just once during an individual's life (this condition is called diphyodonty, and the first set is called "milk teeth); a lower jaw made up of a single bone, the dentary; four-chambered hearts, a secondary palate separating air and food passages in the mouth; a muscular diaphragm separating thoracic and abdominal cavities; highly developed brain; endothermy and homeothermy; separate sexes with the sex of an embryo being determined by the presence of a Y or 2 X chromosomes; and internal fertilization. The Class Mammalia includes around 5000 species placed in 26 orders (systematists do not yet agree on the exact number or on how some orders are related to others). Mammals can be found in all continents and seas. In part because of their high metabolic rates (associated with homeothermy and endothermy), they often play an ecological role that seems disproportionately large compared to their numerical abundance. Subclass Prototheria - Not represented in southern Africa Order Monotremata -- Monotremes: platypus and echidnas Subclass Metatheria (marsupials) - Not represented in southern Africa Order Didelphimorphia Order Paucituberculata Order Microbiotheria Order Dasyuromorphia Order Peramelemorphia Order Notoryctemorphia Order Diprotodontia Subclass Eutheria (placentals) Order Insectivora -- Insectivores: shrews, moles, hedgehogs, tenrecs, etc. Order Macroscelidea -- elephant shrews Order Scandentia -- tree shrews Order Dermoptera -- colugos Order Chiroptera --bats Order Primates --primates Order Xenarthra -- edentates; sloths, armadillos and anteaters Order Pholidota -- pangolins Order Lagomorpha -- rabbits and pikas Order Rodentia -- rodents Order Cetacea -- whales, dolphins, and porpoises Order Carnivora -- carnivores Order Tubulidentata -- aardvark Order Proboscidea -- elephants Order Hyracoidea -- hyraxes Order Sirenia -- dugongs and manatees Order Perissodactyla -- horses, rhinos, tapirs Order Artiodactyla -- antelope, giraffe, camels, pigs, hippos, etc.

Class Mammalia Whales & Dolphins Polar bear Sea otter Seals & sealions manatee Dugong

Evolution of the mammalian jaw and ear bones

Therapsid (mammal-like reptile)
Therapsids (order Therapsida, class synapsid), are "mammal-like reptiles" that flourished from the Early Permian to the Late Triassic periods (c million years ago) and are thought to have been the precursors of mammals. Aside from the mammals, all the other lines of descent from the therapsid ancestors have become extinct. Therapids share with other orders of the class Synapsida the identity of being tetrapods (four-legged vertebrates) characterized by a pair of holes (one on each side) in their skulls behind the eye sockets. The therapsids were the dominant large terrestrial animals during the later half of the Permian period. Although most of the therapsids went extinct at the end of the Triassic period, the cynodont ("dog-teeth") line of therapsids survived that mass extinction event and produced descendants thought to have become the multitude of mammalian life on Earth today. The order Therapsida is highly diverse and subdivided into the one extant suborder, Cynodontia, and five or six extinct suborders.

Prototherians (Monotremes): Cretaceous-Recent
Egg-laying, aquatic predators on arthropods and worms Milk oozes from the skin (no breasts). Hair Ear bones shift from lower jaw to skull during embryonic development. Electroreception

Metatheria (Marsupials): Cretaceous-Recent
Pouched mammals. Born as gross little embryos. Crawl into pouch, attach to nipple, and develop. Cretaceous ones were fairly opossum-like in their ecology. Later ones are more diverse. Today, they are most diverse on Australia and South America. They share complex type of molar tooth shape with Placental mammals.

(a) A young brushtail possum
Fig (a) A young brushtail possum (b) Long-nosed bandicoot

Eutheria (Placentals): Cretaceous-Recent
Nourish their young internally with a placenta Placentals give birth to offspring that are more "adult" like and independent. Cretaceous ones were shrew-like in their ecology. Later placentals are spectacularly diverse.

Convergent Evolution Marsupial mammals Eutherian mammals Marsupial
Fig Convergent Evolution Marsupial mammals Eutherian mammals Marsupial mammals Eutherian mammals Plantigale Deer mouse Wombat Woodchuck Marsupial mole Mole Wolverine Tasmanian devil Sugar glider Flying squirrel Patagonian cavy Kangaroo

The current hypothesis, based on molecular systematics, for the evolutionary relationships among eutherian orders clusters them into four main clades. Fig Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Marine mammals: Order Sirenia
Sirenian characteristics: Large body size Sparse hair all over body Vegetarians Toenails (on manatees only) Includes: Manatees Dugongs

Marine mammals: Order Carnivora
All members of order Carnivora have prominent canine teeth Includes: Sea otters Polar bears Pinnipeds (flipper-footed) Walrus Seals Sea lions/fur seals Hawaiian Monk Seal

Sea Otter Enhydra lutris Native to north Pacific 394,000 hairs/cm2
No blubber Female 45 lbs; Male 65lbs Diet: Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species. Uses tools Dives to 330 ft Rests in coastal kelp forests STATUS: California, or southern, sea otters are listed as "threatened" under the federal Endangered Species Act (ESA) and "fully protected" under California state law. No other U.S. otter population is currently listed under the ESA. In 2003, there is a push to list a stock of the Alaskan sea otters, or northern sea otters, as "endangered" under the ESA. In Canada , the otter population in British Columbia is classified as "threatened" by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). All of the otters in the U.S. are protected under the U.S. Marine Mammal Protection Act (MMPA). DESCRIPTION: The sea otter has the thickest fur in the animal kingdom. Unlike other marine mammals, the sea otter does not have a layer of blubber (fat) to help keep it warm. If an otter's fur gets coated with oil or any other substance, it can easily die from cold and exposure. SIZE: The sea otter is the largest member of the weasel family. Southern sea otters typically reach about four feet in length. Females average 45 pounds, while males average 65 pounds. Northern sea otters can reach up to 100 pounds. POPULATION: Today there are about 2,500 southern sea otters off the coast of California. There are between 27,500 and 52,500 northern sea otters residing in Alaska, Canada and Washington. There are approximately 15,000 in Russia. Two hundred years ago, demand for the otter's pelt nearly led to its extinction. LIFESPAN: Male sea otters live an average of ten to 15 years, while female sea otters live an average of 15 to 20 years. RANGE: The sea otter?s historic range stretched from Japan, along the coast of Siberia and the Aleutian Chain and down the Alaska, British Columbia, Washington, Oregon and California coast to Baja California. HABITAT:Shallow coastal waters of the northern Pacific. FOOD:Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species. BEHAVIOR: Sea otters are the only mammals other than primates known to use tools. Otters use small rocks or other objects to pry prey from rocks and to hammer or pry open their food. They can dive up to 330 feet when foraging for food. Otters rest in coastal kelp forests, often draping the kelp over their bodies to keep from drifting away. OFFSPRING: Sea otters breed throughout the year. Females give birth to one pup after a gestation period of six to eight months. THREATS: Oil spills, habitat loss, disease, gill net entanglement and conflict with shellfish fisheries. PROTECTION: *CITES, Appendix I, Marine Mammal Protection Act, Endangered Species Act *Convention on International The Sea Otter (Enhydra lutris) is a large otter native to the North Pacific, from northern Japan and Kamchatka east across the Aleutian Islands south to California. The heaviest of the otters, Sea Otters are the only species within the genus Enhydra. Hunted extensively for their luxurious fur—the densest of all mammals with up to 394,000 hairs per square centimeter— from 1741 onwards, sea otter populations were greatly reduced to the point of extermination in many parts of their historic range. By 1911 the world population was estimated to be just 1,000-2,000 individuals in 13 colonies. Its estimated that a half million to a million otters were killed over time and over hunted and the population is thought to have been 150,000 to 300,000 historically before the years of the great hunt. Although several subspecies are still endangered, the otters have since been legally protected, and reintroduction efforts have shown positive results in some areas.

Polar Bear Ursa maritimus
United States, Canada, Russia, Greenland and on the Arctic islands of Norway Male: 10 feet tall and weigh over 1400 lbs Female: seven feet and weigh 650 lbs wild polar bears live up to age 25. Not federally listed as endangered or threatened. The International Union for Conservation of Nature (IUCN), Polar Bear Specialist Group lists most populations as "stable." DESCRIPTION: The polar bear rivals the Kodiak bear as the largest four-footed carnivore on Earth and can live up to 25 years. Although the polar bear?s coat appears white, each individual hair is actually a clear hollow tube that channels the sun?s energy directly to the bear?s skin and helps it stay warm. The polar bear?s entire body is furred, even the bottom of its paws. That helps prevent bears from slipping on the ice. The polar bear is classified as a marine mammal. Its feet are partially webbed for swimming, and its fur is water-repellent. A formidable predator, it has extremely sharp claws. SIZE: Males are 8 to 11 feet long and weigh 500 to 1,100 pounds but can reach as much as 1,500 pounds. Females are smaller, measuring 6 to 8 feet long, and weigh from 350 to 600 pounds, occasionally reaching 700 pounds. POPULATION: Worldwide there are thought to be 22,000-27,000 polar bears in 19 separate populations. They can be found in the United States, Canada, Russia, Greenland and on the Arctic islands of Norway. There are estimated to be about 3,000 to 5,000 polar bears in Alaska. RANGE:Polar bears are found throughout the Arctic and are the most nomadic of all bear species. They travel an average of 5,500 miles a year or 15 miles a day. In the United States, polar bears are located in two Alaskan populations: the Chukchi/Bering Seas of western Alaska and the Beaufort Sea off northern Alaska. HABITAT: The entire circumpolar Arctic region is polar bear habitat. They are equally comfortable in the water and on land. Polar bears can be found on pack ice, coastal islands, coastlines and even out in Arctic waters. They are exceptional swimmers and have been observed in the sea more than 100 miles from the nearest land or pack ice. FOOD: Polar bears are strictly carnivores and feed or scavenge only meat. Their primary prey is the ringed seal though they also take bearded, harp and hooded seals and the occasional walrus youngster. They will also scavenge walrus and whale carcasses. That sometimes results in temporary aggregations of polar bears at such sites. Other species, such as the Arctic fox, rely entirely upon "polar bear left-overs" after the bears have eaten their fill of seal skin and blubber, leaving the remaining meat for such scavengers. BEHAVIOR: The two main focuses of this solitary creature's life are to conserve energy and to hunt. Only pregnant females dig dens and hibernate in the traditional sense for extended periods. The other bears may enter into what is referred to as "walking hibernation" where they remain active and continue to hunt and feed, even though some of their metabolic processes may slow (decreased heart rates, respiration, lowered temperatures, etc.). Polar bears depend mostly on their sense of smell to determine the location of prey. Their white coats make great camouflage for hunting seals, and they will wait patiently for hours next to a seal?s air hole waiting for the seal to take a breath. Once the seal arrives, the polar bear will use its immense strength and sharp claws to clutch the seal and drag it through the small blowhole. OFFSPRING: Females are able to breed at the age of five years. They dig dens either on the coastal mainland or out on the drifting pack ice in late October or early November, and then remain denned until the next spring. An average of two cubs are born, each weighing about 1 pound at birth and growing to about 15 pounds by the time they emerge in the spring. The cubs have much to learn and usually remain with their mothers for more than two years. THREATS: The primary threat facing polar bears today may be global warming. Scientists have already documented measurable effects in the body sizes and reproductive success of bears at Hudson?s Bay. This southern-most population of polar bears has adapted to an ice-free summer by moving onshore at Churchill, Manitoba, and fasting through the short summer season until freeze-up occurs, and the bears can return to the ice. Global warming has resulted in prolonged ice-free periods, and the polar bears are left stranded onshore for longer and longer periods. Break-up in the spring occurs an average of days earlier than 20 years ago and was four weeks earlier in Scientists estimate that for every week of delay in freeze-up, polar bears lose at least 22 pounds of critical fat reserves. Pregnant females are losing so much weight that they fail to produce enough milk for their cubs, which then suffer increased mortality. Once females fail to attain a minimum weight they won?t give birth at all, and scientists can already document a 15 percent drop in birth rates. Another globally produced impact to polar bears are chemical pollutants that find their way into the cold Arctic ecosystems and then never disappear. Such chemicals as PCB?s (polychlorinated biphenyls), banned from the U.S. plastics industry since the 1970s, concentrate in the blubber of prey species that are then eaten by the bears. Such concentrations of these and other toxins are linked to immune deficiencies and generally reduced fitness in some polar bears. The third threat of note is the proposed oil and gas development on the Arctic National Wildlife Refuge in northeastern Alaska. This is the most important onshore denning habitat for polar bears in the United States. About half of the bears from the Beaufort Sea population den onshore, and half of these select the refuge?s coastal plain. This is the very place proposed for oil exploration. Both the seismic exploration phase and an eventual oil extraction phase could introduce serious disturbances that may result in den abandonment and death of the offspring. PROTECTION: CITES* Appendix II, U.S. Marine Mammal Protection Act, Agreement on the Conservation of Polar Bears. Good swimmers Thick blubber Thick fur

Pinnipeds Hawaiian Monk Seal Family Phocidae Walrus Sea Lion
Family Otariidae Family Odobenidae

Biology and Natural History
Order Pinniped (seals, sea lions, & walruses) Family Phocidae- true, earless seals Family Otariidae- eared seals and sea lions Family Odobenidae- walruses 34 known species Evolved 20 mya from Order Carnivora (ancestors of dogs and bears) Differ in possession of external ears and mode of locomotion

Differences between seals and sea lions/fur seals

Hind flippers propel them while swimming Front flippers act as rudders
Hawaiian Monk Seal Family Phocidae Lack external ears Hind flippers propel them while swimming Front flippers act as rudders Travel on land is difficult (wiggle)

Front flippers propel animal when swimming
Sea Lion Family Otariidae Eared seals Front flippers propel animal when swimming Rear flippers act as rudders Fairly mobile on land

Paddle with front flippers Rear flippers act as a rudder
Walrus Family Odobenidae Found in Arctic region Lack external ears Paddle with front flippers Rear flippers act as a rudder Fairly mobile on land

Marine mammals: Order Cetacea
Cetacean characteristics: Blowholes on top of skull Skull telescoped (streamlined shape) Very few hairs Includes: Whales, dolphins, and porpoises Scientists have found fossil skeletons of two new species of primitive whales with well-developed limbs, fingers, and toes—supporting genetic evidence that hippos are the closest modern land-dwelling relatives to the giants of the sea. It has long been known that whales are mammals that moved to the sea about 50 million years ago. But how they are related to other mammals is a controversial issue. Printer Friendly to a Friend What's This? SHARE Digg StumbleUpon Reddit RELATED Killer Whale "Willy" Shows Reluctance to Be Free Rescuers Fail to Free Entangled Whale off U.S. Coast Scientists Mount Assault to Save Endangered Right Whales "Whales are warm-blooded animals like we are—that has been known for a long time," said University of Michigan paleontologist Philip D. Gingerich. "Yet they're so different from other warm-blooded, furry things that it's been a mystery both how they came to live in the sea and what ancestors they might have come from on land." Gingerich, University of Michigan graduate student Iyad Zalmout, and researchers from the Geological Survey of Pakistan and the University of New Hampshire are co-authors of a paper in the September 21 issue of the journal Science that resolves some of the mystery. Their discovery of fossils of walking whales reveals important clues about how these animals got around and what they had in common with living and extinct land-living animals. Some researchers use morphology (the study of an animal's structure and form) to suggest that whales are descended from mesonychians, an extinct group of meat-eating animals that resembled hyenas with hooves. Others use DNA, molecular, and genetic techniques to suggest that whales and hippos are more closely related to one another than either of them is to any other species. The fossils found in Pakistan last year add weight to the second theory: that whales descended from the group of animals known as artiodactyls, whose members include sheep, cows, pigs, camels, deer, and hippos. Artiodactyla (Greek artios, entire or even numbered, and dactylos, finger or toe) are named for the even number of fingers and toes (two or four) found on each hand and foot. The fossils found by Gingerich and the others are the first and only known specimens that have sheep-like ankle bones and archaic whale skull bones in the same skeletons. Some of the ankle bones have signature features that place the whales in the artiodactyls group. Certain ankle bones show specialized features typically associated with adaptation to running. Such features are unique to artiodactyls, living and extinct. The presence of artiodactyl-like ankles in the primitive whales strongly suggests common heritage rather than convergent evolution, said Kenneth D. Rose of the Program for Functional Anatomy and Evolution at Johns Hopkins University School of Medicine in Baltimore, Maryland. Convergent evolution is the process by which different groups of organisms may evolve similar characteristics in response to particular environmental requirements. "While ankles from primitive ancient whales have been discovered before, these are the first that are well-preserved enough to provide clues about whale ancestry," Rose said in a related article published in the same issue of Science. Gingerich's discovery goes a long way toward resolving the conflict about the ancestry of whales, Rose said. "The fossils provide compelling morphological evidence," he said, "that whales are not just related to, but descended from, artiodactyls rather than mesonychians, thus bringing the morphological evidence into accord with molecular data." Gingerich has been searching since the late 1970s for evidence that would clear up the confusion about the ancestry of whales. Other whale fossils he found in Pakistan in the late 1990s were nearly complete but lacked the critical hand and foot bones. "Over and over again, we'd get the same backbones, but the parts we needed were gone," says Gingerich, who speculates that ancient sharks scavenged those parts before the bones became fossilized. Finally last October, on their first morning at a new field site in Pakistan, Gingerich's team found a whale ankle bone that could answer the artiodactyl question. The bone was so clearly like that of an artiodactyl that Gingerich—who previously had embraced the view that whales evolved from mesonychid condylarths—struggled for months to make sense of it, finally concluding without question that whales had artiodactyls' ankles. "Now I even admit the possibility that hippos are a side line of artiodactyls that might be closer to the whales than any other living animals," he said. Gingerich said the legs and feet of the primitive whales were not designed for walking long distances. "It's clear that these animals could hitch their way out of water and back in, like sea lions do today, but they were more aquatic than I realized," Gingerich said. The size and shape of their bones suggest that they had webbed hands and feet and probably also used their tails to propel themselves through the water. Gingerich hopes to return to Pakistan soon to continue looking for whale fossils, and he expects that other researchers will take a closer look at fossils of hippo-like animals to better understand the hippopotamus family tree. Boost for DNA Studies In addition to helping resolve the confusion about whale evolution, the recent discoveries should also lend more credibility to molecular, genetic, and immunological approaches to understanding evolutionary relationships, Gingerich said. "In the last few years, 15 or 20 DNA studies have come out supporting this artiodactyl connection," said Gingerich. "Those weren't taken very seriously, but this finding shows that they need to be. "If the studies are done well, the DNA that animals carry in their bodies today gives us a better picture of the past than we might have thought it did. If we can make reliable inferences from animals that are living today, we can learn a lot about the past much faster. "These techniques will never replace paleontology," he said, "but they will complement it and expand on what we can competently infer." Despite this evidence that cetaceans (whales, dolphins, and porpoises) evolved from artiodactyls, substantial discrepancies remain, Rose said. "If cetacaeans belong to artiodactyls," he said, "then similarities in the cranial and dental morphologies of mesonychians and cetaceans must be the result of convergent evolution or must have been lost in artiodactyls. "Well-preserved ankles of the earliest ancient whales are now needed to confirm that the traits seen in the new skeletons are indeed inherited from early artiodactyls and not a result of convergent evolution," Rose said. The skeletons found by Gingerich and his associates are about 47 million years old, and come from the eastern part of Balochistan Province in Pakistan. The researchers have classified one, Rodhocetus balochistanensis, as a new species of an existing genus, and the other, Artiocetus clavis, as a new species and new genus. The skeleton of Artiocetus was located after pieces of ankle bones were found on the ground. The early part of Gingerich's work was supported by a grant from the National Geographic Society's Committee for Research and Exploration. Recent Stories About Research Supported by the National Geographic Society: DNA Tests Show African Elephants Are Two Species Study Calls Into Question Global Quotas on Bluefin Tuna Skeleton of New Dinosaur Species Found in Madagascar Russian Tombs Hold Clues to Obscure Life of Asian Huns Egyptian Archaeologist Named National Geographic Explorer-in-Residence Total Eclipse May Help Solve Mystery of Sun's "Halo" Expedition Reveals Black Coral's Bleak State Ancient Reptile Was First To Chew Plants

Marine mammals: Order Cetacea

Two suborders of order Cetacea
(55 mya- entered sea) Suborder Odontoceti (toothed whales) Echolocate (send sound through water) Includes killer whale, sperm whale, dolphins, porpoises, and many others Suborder Mysticeti (baleen whales) Have rows of baleen plates instead of teeth Includes blue whale, finback whale, humpback whale, gray whale, and many others

Differences between dolphins and porpoises
Dolphins have: An elongated snout (rostrum) A sickle-shaped (falcate) dorsal fin Conical-shaped teeth Killer whale jawbone

Differences between dolphins and porpoises
Porpoises have: A blunt snout (rostrum) A triangle-shaped dorsal fin Spade-shaped teeth

Echolcation - the location of objects by their echos - is a highly specialized faculty that enables dolphins to explore their environment and search out their prey in a watery world where sight is often of little use. As sound travels four and a half times faster in water than in air, the dolphin's brain must be extremely well adapted in order to make a rapid analysis of the complicated information provided by the echoes. Although the ability to echolcate has only been proven experimentally for a few odontocete species, the anatomical evidence - the presence of the melon, nasal sacs and specialized skull structures - suggests that all dolphins have this ability. The dolphin is able to generate sound in the form of clicks, within its nasal sacs, situated behind the melon. The frequency of this click is higher than that of the sounds used for communication and differs between species. The melon acts as a lens whi ch focuses the sound into a narrow beam that is projected in front of the animal. When the sound strikes an object, some of the energy of the soundwave is reflected back towards the dolphin. It would appear that the panbone in the dolphin's lower jaw receives the echo, and the fatty tissue behind it transmits the sound to the middle e ar and thence to the brain. It has recently been suggested that the teeth of the dolphin, and the mandibular nerve that runs through the jawbone may transmit additional information to the dolphin's brain. As soon as an echo is received, the dolphin generates another click. The time lapse between click and echo enables the dolphin to evaluate the distance between it and the object; the varying strength of the signal as it is received on the two sides of th e dolphin's head enable it to evaluate direction. By continuously emitting clicks and receiving echoes in theis way, the dolphin can track objects and home in on them. The echolocation system of the dolphin is extremely sensitive and complex. Using only its acoustic senses, a bottlenose dolphin can discriminate between practically identical objects which differ by ten per cent or less in volume or surface area. It can do this in a noisy environment, can whistle and echolocate at the same time, and echolocate on near and distant targets simultaneously - feats which leave human sonar experts gasping

Deepest Diver (3km~1.5 miles)

Mysticeti: The baleen whales
Mysticeti whales have baleen instead of teeth Baleen plates: Hang as parallel rows from the upper jaw Are made of keratin Are used as a strainer to capture zooplankton Allows baleen whales to eat krill and small fish by the ton

Baleen

Types of baleen whales Baleen whales include three families:
Gray whale (a bottom-feeder with short baleen) Rorqual whales (medium-sized baleen) Balaenopterids (blue whales, finback whales, and other large whales ) Megapterids (humpback whales) Right whales (surface skimmers with long baleen)

Whale Migration

Whale Carcass Removal I am absolutely not making this incident up; in fact I have it all on videotape. The tape is from a local TV news show in Oregon, which sent a reporter out to cover the removal of 45-foot, eight-ton dead whale that washed up on the beach. The responsibility for getting rid of the carcass was placed with the Oregon State Highway Division, apparently on the theory that highways and whales are very similar in the sense that both are large objects. So anyway, the highway engineers hit upon a plan (remember, I am not making this up) to blow up the whale with dynamite. The thinking was that the whale would be blown into small pieces, which would then be eaten by seagulls and fish. That would be that--a textbook whale removal. So they moved the spectators back up the beach, put a half-ton of dynamite next to the whale and set it off. What follows, on the videotape, is one of the most priceless events in the history of the universe. First you see the whale carcass disappear in a huge blast of smoke and flame. Then you hear the happy spectators shouting "Yayy!" and "Whee!" Then, suddenly, the crowd's tone changes. You hear a new sound like "splud, splap," and you hear a woman's voice shouting "Here come pieces of...OH MY GOD!" Something smears the camera lens. Later, the reporter explains: "The humor of the entire situation suddenly gave way to a run for survival as huge chunks of whale blubber rained down everywhere.“ One piece caved in the roof of a car parked more than a quarter of a mile away!! Remaining on the beach were several large rotting whale sections the size of condominiums... Posted on: Saturday, June 15, 2002 Removal of carcass a whale of a task By Mike Gordon Advertiser Staff Writer State and city officials are used to removing things that wash up on island beaches, but two tons of smelly, decomposing whale carcass was a challenge yesterday. The dead sperm whale — what's left of it, anyway — floated in on Thursday night's high tide, coming to rest at Kualoa on a sliver of beach within sniffing distance of Kamehameha Highway, just north of the ruins of the sugar mill smoke stack at Kualoa Ranch. Normally, the city takes care of removing things that wash ashore but this was too much. "This thing is big," Jeff Walters of the Department of Land and Natural Resources' division of aquatic resources, said yesterday morning as the state weighed its options. "We need something big. We either have to have a crane to lift it up whole or something to cut it up into smaller pieces.“ At one point, he thought a backhoe could be used to chop it up, but anyone getting close to the carcass would have to wear protective clothing. "It is putrid," he said. So yesterday afternoon they hired a crane from Bob's Equipment. By 4 p.m. the biggest chunk had been removed and taken across the highway to Kualoa Ranch. DLNR spokesman Mike Markrich said four large chunks still remaining on on the beach will be taken away today by backhoe. The dead whale was first spotted Wednesday on a reef about 100 yards offshore, and signs were posted warning beachgoers to stay out of the water because of the possibility of sharks. The signs remained up today, but Walters said the carcass is so decomposed that even sharks probably don't want it.

Human Evolution

We are primates. Primates evolved from a small tree dwelling mammal.
Dental evidence from fossils suggests that Primates descended from insectivores in the late Cretaceous (65 mya) Oldest known primate- Purgatorius unio

Characteristics of Primates
Limber shoulder joints Dexterous hands Sensitive fingers Many cases, claws replaced by flat nails Binocular vision Hand-eye coordination Parental care Mostly single births Nurture offspring

Order Primates Suborder Prosimii (prosimians) lemurs and tarsiers
Suborder Anthropoidea (anthropoids) new world monkeys old world monkeys hominoids

Suborder Prosimii Tree Shrew

Suborder Prosimii Lemurs

New & Old World Monkeys

New World vs Old World monkeys
New World monkeys South America Arboreal Prehensile tail Nostrils open to the side Diurnal Live in bands- very social Old World monkeys Africa & Asia Arboreal and ground dwelling No prehensile tail Nostrils open downward Diurnal Live in bands- very social

Apes (Hominoids)

Edward Tyson (1699) depiction of a chimp

Bonobo Chimpanzees

Brain Cavity Size

Bipedalism Introduction Hominid or hominin?
Some scientists use a broader definition of Hominidae which includes the great apes, and instead call the group I am discussing "hominins". For a good discussion of the hominid/hominin terminology issue, read this article by Lee Berger. The word "hominid" in this website refers to members of the family of humans, Hominidae, which consists of all species on our side of the last common ancestor of humans and living apes. Hominids are included in the superfamily of all apes, the Hominoidea, the members of which are called hominoids. Although the hominid fossil record is far from complete, and the evidence is often fragmentary, there is enough to give a good outline of the evolutionary history of humans. The time of the split between humans and living apes used to be thought to have occurred 15 to 20 million years ago, or even up to 30 or 40 million years ago. Some apes occurring within that time period, such as Ramapithecus, used to be considered as hominids, and possible ancestors of humans. Later fossil finds indicated that Ramapithecus was more closely related to the orang-utan, and new biochemical evidence indicated that the last common ancestor of hominids and apes occurred between 5 and 10 million years ago, and probably in the lower end of that range (Lewin 1987). Ramapithecus therefore is no longer considered a hominid. The field of science which studies the human fossil record is known as paleoanthropology. It is the intersection of the disciplines of paleontology (the study of ancient lifeforms) and anthropology (the study of humans). Hominid Species The species here are listed roughly in order of appearance in the fossil record (note that this ordering is not meant to represent an evolutionary sequence), except that the robust australopithecines are kept together. Each name consists of a genus name (e.g. Australopithecus, Homo) which is always capitalized, and a specific name (e.g. africanus, erectus) which is always in lower case. Within the text, genus names are often omitted for brevity. Each species has a type specimen which was used to define it. Sahelanthropus tchadensis This species was named in July 2002 from fossils discovered in Chad in Central Africa (Brunet et al. 2002, Wood 2002). It is the oldest known hominid or near-hominid species, dated at between 6 and 7 million years old. This species is known from a nearly complete cranium nicknamed Toumai, and a number of fragmentary lower jaws and teeth. The skull has a very small brain size of approximately 350 cc. It is not known whether it was bipedal. S. tchadensis has many primitive apelike features, such as the small brainsize, along with others, such as the brow ridges and small canine teeth, which are characteristic of later hominids. This mixture, along with the fact that it comes from around the time when the hominids are thought to have diverged from chimpanzees, suggests it is close to the common ancestor of humans and chimpanzees. Orrorin tugenensis This species was named in July 2001 from fossils discovered in western Kenya (Senut et al. 2001). The fossils include fragmentary arm and thigh bones, lower jaws, and teeth and were discovered in deposits that are about 6 million years old. The limb bones are about 1.5 times larger than those of Lucy, and suggest that it was about the size of a female chimpanzee. Its finders have claimed that Orrorin was a human ancestor adapted to both bipedality and tree climbing, and that the australopithecines are an extinct offshoot. Given the fragmentary nature of the remains, other scientists have been skeptical of these claims so far (Aiello and Collard 2001). A later paper (Galik et al. 2004) has found further evidence of bipedality in the fossil femur. Ardipithecus ramidus This species was named Australopithecus ramidus in September 1994 (White et al. 1994; Wood 1994) from some fragmentary fossils dated at 4.4 million years. A more complete skull and partial skeleton was discovered in late 1994 and based on that fossil, the species was reallocated to the genus Ardipithecus (White et al. 2005). This fossil was extremely fragile, and excavation, restoration and analysis of it took 15 years. It was published in October 2009, and given the nickname 'Ardi'. Ar. ramidus was about 120 cm (3'11") tall and weighed about 50 kg (110 lbs). The skull and brain are small, about the size of a chimpanzee. It was bipedal on the ground, though not as well adapted to bipedalism as the australopithecines were, and quadrupedal in the trees. It lived in a woodland environment with patches of forest, indicating that bipedalism did not originate in a savannah environment. A number of fragmentary fossils discovered between 1997 and 2001, and dating from 5.2 to 5.8 million years old, were originally assigned to a new subspecies, Ardipithecus ramidus kadabba (Haile-Selassie 2001), and later to a new species, Ardipithecus kadabba (Haile-Selassie et al. 2004). One of these fossils is a toe bone belonging to a bipedal creature, but is a few hundred thousand years younger than the rest of the fossils and so its identification with kadabba is not as firm as the other fossils. Australopithecus anamensis This species was named in August 1995 (Leakey et al. 1995). The material consists of 9 fossils, mostly found in 1994, from Kanapoi in Kenya, and 12 fossils, mostly teeth found in 1988, from Allia Bay in Kenya (Leakey et al. 1995). Anamensis existed between 4.2 and 3.9 million years ago, and has a mixture of primitive features in the skull, and advanced features in the body. The teeth and jaws are very similar to those of older fossil apes. A partial tibia (the larger of the two lower leg bones) is strong evidence of bipedality, and a lower humerus (the upper arm bone) is extremely humanlike. Note that although the skull and skeletal bones are thought to be from the same species, this is not confirmed. Australopithecus afarensis A. afarensis existed between 3.9 and 3.0 million years ago. Afarensis had an apelike face with a low forehead, a bony ridge over the eyes, a flat nose, and no chin. They had protruding jaws with large back teeth. Cranial capacity varied from about 375 to 550 cc. The skull is similar to that of a chimpanzee, except for the more humanlike teeth. The canine teeth are much smaller than those of modern apes, but larger and more pointed than those of humans, and shape of the jaw is between the rectangular shape of apes and the parabolic shape of humans. However their pelvis and leg bones far more closely resemble those of modern man, and leave no doubt that they were bipedal (although adapted to walking rather than running (Leakey 1994)). Their bones show that they were physically very strong. Females were substantially smaller than males, a condition known as sexual dimorphism. Height varied between about 107 cm (3'6") and 152 cm (5'0"). The finger and toe bones are curved and proportionally longer than in humans, but the hands are similar to humans in most other details (Johanson and Edey 1981). Most scientists consider this evidence that afarensis was still partially adapted to climbing in trees, others consider it evolutionary baggage. Kenyanthropus platyops This species was named in 2001 from a partial skull found in Kenya with an unusual mixture of features (Leakey et al. 2001). It is aged about 3.5 million years old. The size of the skull is similar to A. afarensis and A. africanus, and has a large, flat face and small teeth. Australopithecus africanus A. africanus existed between 3 and 2 million years ago. It is similar to afarensis, and was also bipedal, but body size was slightly greater. Brain size may also have been slightly larger, ranging between 420 and 500 cc. This is a little larger than chimp brains (despite a similar body size), but still not advanced in the areas necessary for speech. The back teeth were a little bigger than in afarensis. Although the teeth and jaws of africanus are much larger than those of humans, they are far more similar to human teeth than to those of apes (Johanson and Edey 1981). The shape of the jaw is now fully parabolic, like that of humans, and the size of the canine teeth is further reduced compared to afarensis. Australopithecus garhi This species was named in April 1999 (Asfaw et al. 1999). It is known from a partial skull. The skull differs from previous australopithecine species in the combination of its features, notably the extremely large size of its teeth, especially the rear ones, and a primitive skull morphology. Some nearby skeletal remains may belong to the same species. They show a humanlike ratio of the humerus and femur, but an apelike ratio of the lower and upper arm. (Groves 1999; Culotta 1999) Australopithecus sediba A. sediba was discovered at the site of Malapa in South Africa in Two partial skeletons were found, of a young boy and an adult female, dated between 1.78 and 1.95 million years ago (Berger et al. 2010, Balter 2010). It is claimed by its finders to be transitional between A. africanus and Homo and, because it is more similar to Homo than any other australopithecine, a possible candidate for the ancestor of Homo. A. sediba was bipedal with long arms suitable for climbing, but had a number of humanlike traits in the skull, teeth and pelvis. The boy's skull has a volume of 420 cc, and both fossils are short, about 130 cm (4'3"). Australopithecus afarensis and africanus, and the other species above, are known as gracile australopithecines, because their skulls and teeth are not as large and strong as those of the following species, which are known as the robust australopithecines. (Gracile means "slender", and in paleoanthropology is used as an antonym to "robust".) Despite this, they were still more robust than modern humans. Australopithecus aethiopicus A. aethiopicus existed between 2.6 and 2.3 million years ago. This species is known from one major specimen, the Black Skull discovered by Alan Walker, and a few other minor specimens which may belong to the same species. It may be an ancestor of robustus and boisei, but it has a baffling mixture of primitive and advanced traits. The brain size is very small, at 410 cc, and parts of the skull, particularly the hind portions, are very primitive, most resembling afarensis. Other characteristics, like the massiveness of the face, jaws and single tooth found, and the largest sagittal crest in any known hominid, are more reminiscent of A. boisei (Leakey and Lewin 1992). (A sagittal crest is a bony ridge on top of the skull to which chewing muscles attach.) Australopithecus robustus A. robustus had a body similar to that of africanus, but a larger and more robust skull and teeth. It existed between 2 and 1.5 million years ago. The massive face is flat or dished, with no forehead and large brow ridges. It has relatively small front teeth, but massive grinding teeth in a large lower jaw. Most specimens have sagittal crests. Its diet would have been mostly coarse, tough food that needed a lot of chewing. The average brain size is about 530 cc. Bones excavated with robustus skeletons indicate that they may have been used as digging tools. Australopithecus boisei (was Zinjanthropus boisei) A. boisei existed between 2.1 and 1.1 million years ago. It was similar to robustus, but the face and cheek teeth were even more massive, some molars being up to 2 cm across. The brain size is very similar to robustus, about 530 cc. A few experts consider boisei and robustus to be variants of the same species. Australopithecus aethiopicus, robustus and boisei are known as robust australopithecines, because their skulls in particular are more heavily built. They have never been serious candidates for being direct human ancestors. Many authorities now classify them in the genus Paranthropus. Homo habilis H. habilis, "handy man", was so called because of evidence of tools found with its remains. Habilis existed between 2.4 and 1.5 million years ago. It is very similar to australopithecines in many ways. The face is still primitive, but it projects less than in A. africanus. The back teeth are smaller, but still considerably larger than in modern humans. The average brain size, at 650 cc, is considerably larger than in australopithecines. Brain size varies between 500 and 800 cc, overlapping the australopithecines at the low end and H. erectus at the high end. The brain shape is also more humanlike. The bulge of Broca's area, essential for speech, is visible in one habilis brain cast, and indicates it was possibly capable of rudimentary speech. Habilis is thought to have been about 127 cm (5'0") tall, and about 45 kg (100 lb) in weight, although females may have been smaller. Habilis has been a controversial species. Originally, some scientists did not accept its validity, believing that all habilis specimens should be assigned to either the australopithecines or Homo erectus. H. habilis is now fully accepted as a species, but it is widely thought that the 'habilis' specimens have too wide a range of variation for a single species, and that some of the specimens should be placed in one or more other species. One suggested species which is accepted by many scientists is Homo rudolfensis, which would contain fossils such as ER 1470. Homo georgicus This species was named in 2002 to contain fossils found in Dmanisi, Georgia, which seem intermediate between H. habilis and H. erectus. The fossils are about 1.8 million years old, consisting of three partial skulls and three lower jaws. The brain sizes of the skulls vary from 600 to 780 cc. The height, as estimated from a foot bone, would have been about 1.5 m (4'11"). A partial skeleton was also discovered in 2001 but no details are available on it yet. (Vekua et al. 2002, Gabunia et al. 2002) Homo erectus H. erectus existed between 1.8 million and 300,000 years ago. Like habilis, the face has protruding jaws with large molars, no chin, thick brow ridges, and a long low skull, with a brain size varying between 750 and 1225 cc. Early erectus specimens average about 900 cc, while late ones have an average of about 1100 cc (Leakey 1994). The skeleton is more robust than those of modern humans, implying greater strength. Body proportions vary; the Turkana Boy is tall and slender (though still extraordinarily strong), like modern humans from the same area, while the few limb bones found of Peking Man indicate a shorter, sturdier build. Study of the Turkana Boy skeleton indicates that erectus may have been more efficient at walking than modern humans, whose skeletons have had to adapt to allow for the birth of larger-brained infants (Willis 1989). Homo habilis and all the australopithecines are found only in Africa, but erectus was wide-ranging, and has been found in Africa, Asia, and Europe. There is evidence that erectus probably used fire, and their stone tools are more sophisticated than those of habilis. Homo ergaster Some scientists classify some African erectus specimens as belonging to a separate species, Homo ergaster, which differs from the Asian H. erectus fossils in some details of the skull (e.g. the brow ridges differ in shape, and erectus would have a larger brain size). Under this scheme, H. ergaster would include fossils such as the Turkana boy and ER 3733. Homo antecessor Homo antecessor was named in 1977 from fossils found at the Spanish cave site of Atapuerca, dated to at least 780,000 years ago, making them the oldest confirmed European hominids. The mid-facial area of antecessor seems very modern, but other parts of the skull such as the teeth, forehead and browridges are much more primitive. Many scientists are doubtful about the validity of antecessor, partly because its definition is based on a juvenile specimen, and feel it may belong to another species. (Bermudez de Castro et al. 1997; Kunzig 1997, Carbonell et al. 1995) Homo sapiens (archaic) (also Homo heidelbergensis) Archaic forms of Homo sapiens first appear about 500,000 years ago. The term covers a diverse group of skulls which have features of both Homo erectus and modern humans. The brain size is larger than erectus and smaller than most modern humans, averaging about 1200 cc, and the skull is more rounded than in erectus. The skeleton and teeth are usually less robust than erectus, but more robust than modern humans. Many still have large brow ridges and receding foreheads and chins. There is no clear dividing line between late erectus and archaic sapiens, and many fossils between 500,000 and 200,000 years ago are difficult to classify as one or the other. Homo sapiens neanderthalensis (also Homo neanderthalensis) Neandertal (or Neanderthal) man existed between 230,000 and 30,000 years ago. The average brain size is slightly larger than that of modern humans, about 1450 cc, but this is probably correlated with their greater bulk. The brain case however is longer and lower than that of modern humans, with a marked bulge at the back of the skull. Like erectus, they had a protruding jaw and receding forehead. The chin was usually weak. The midfacial area also protrudes, a feature that is not found in erectus or sapiens and may be an adaptation to cold. There are other minor anatomical differences from modern humans, the most unusual being some peculiarities of the shoulder blade, and of the pubic bone in the pelvis. Neandertals mostly lived in cold climates, and their body proportions are similar to those of modern cold-adapted peoples: short and solid, with short limbs. Men averaged about 168 cm (5'6") in height. Their bones are thick and heavy, and show signs of powerful muscle attachments. Neandertals would have been extraordinarily strong by modern standards, and their skeletons show that they endured brutally hard lives. A large number of tools and weapons have been found, more advanced than those of Homo erectus. Neandertals were formidable hunters, and are the first people known to have buried their dead, with the oldest known burial site being about 100,000 years old. They are found throughout Europe and the Middle East. Western European Neandertals usually have a more robust form, and are sometimes called "classic Neandertals". Neandertals found elsewhere tend to be less excessively robust. (Trinkaus and Shipman 1992; Trinkaus and Howells 1979; Gore 1996) Homo floresiensis Homo floresiensis was discovered on the Indonesian island of Flores in Fossils have been discovered from a number of individuals. The most complete fossil is of an adult female about 1 meter tall with a brain size of 417cc. Other fossils indicate that this was a normal size for floresiensis. It is thought that floresiensis is a dwarf form of Homo erectus - it is not uncommon for dwarf forms of large mammals to evolve on islands. H. floresiensis was fully bipedal, used stone tools and fire, and hunted dwarf elephants also found on the island. (Brown et al. 2004, Morwood et al. 2004, Lahr and Foley 2004) Homo sapiens sapiens (modern) Modern forms of Homo sapiens first appear about 195,000 years ago. Modern humans have an average brain size of about 1350 cc. The forehead rises sharply, eyebrow ridges are very small or more usually absent, the chin is prominent, and the skeleton is very gracile. About 40,000 years ago, with the appearance of the Cro-Magnon culture, tool kits started becoming markedly more sophisticated, using a wider variety of raw materials such as bone and antler, and containing new implements for making clothing, engraving and sculpting. Fine artwork, in the form of decorated tools, beads, ivory carvings of humans and animals, clay figurines, musical instruments, and spectacular cave paintings appeared over the next 20,000 years. (Leakey 1994) Even within the last 100,000 years, the long-term trends towards smaller molars and decreased robustness can be discerned. The face, jaw and teeth of Mesolithic humans (about 10,000 years ago) are about 10% more robust than ours. Upper Paleolithic humans (about 30,000 years ago) are about 20 to 30% more robust than the modern condition in Europe and Asia. These are considered modern humans, although they are sometimes termed "primitive". Interestingly, some modern humans (aboriginal Australians) have tooth sizes more typical of archaic sapiens. The smallest tooth sizes are found in those areas where food-processing techniques have been used for the longest time. This is a probable example of natural selection which has occurred within the last 10,000 years (Brace 1983). The A. afarensis foot bone is shown with a human foot indicating where it would be positioned.

African Origins Model According to genetic analysis, Neanderthals diverged from homo sapiens ~500,000 years ago. There has been no major interbreeding, but possibly some transfer of genes e.g. from human males to Neanaderthal females, although candidate human genes conferring natural advantage do have a profile consistent with transfer from Neanderthals

Neandertals and modern humans share a common ancestor, Homo heidelbergensis, which dates back approximately 500,000 years ago. Neandertals first surfaced in the fossil record about 400,000 years ago. They were large-brained hominins – like modern humans – that lived mainly in Eurasia. By comparison, anatomically modern humans appear in the fossil record in Ethiopia dating back to about 190,000 years ago. They also appear in the Middle East by 80, ,000 years ago.

Homo habilis Until 1964, Australopithecus remains had been found in Africa, but remains of the oldest representative of the genus Homo had been recognized only in Asia. In that year, however, Louis Leakey, Phillip Tobias, and John Napier announced the new species Homo habilis, or "handy man". They had to redefine the genus to accommodate this oldest form. The type specimen was a mandible, with associated postcranial bones, and a fragmentary cranial vault; Olduvai Hominid 7 (OH 7). They based their placement of OH 7 in Homo primarily on brain expansion. Until then, an arbitrary lower limit had been set between 700cc and 800cc as the cutoff for the genus Homo. With an estimated cranial capacity of 680cc, Leakey and his colleagues chose to lower this number to 600cc. While calling attention to anatomical differences between OH 7 and Australopithecus, they chose a behavior- the ability to make stone tools-to help place OH 7 in Homo. This point relied on stone tools found in the same geologic horizon as the fossils. The OH 7 mandible is shown at the top right. In the 1960s, many researchers argued that Homo habilis was not a valid species, and that the fossils attributed to H. habilis were really members of other species. But with the discovery of KNM ER 1470, acceptance of Homo habilis became universal. In hindsight, this seems strange since ER 1470 is now considered to belong to a species distinct from H. habilis. There is much debate as to the number of species that existed in Homo 2 million years ago, and KNM ER 1470 is now assigned to the species Homo rudolfensis. The name Homo habilis is reserved primarily for the Olduvai material and several other specimens. The OH 62 partial skeleton of a female H. habilis provides another interesting twist in the debate about early members of the genus Homo. Homo habilis was originally thought to be the ancestor to all later Homo. In a neat, linear progression, later species emerged resulting in what we call modern humans. This is now known not to be the case.

Vertebrate Biology Chapter 34.

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Vertebrate Biology Chapter 34.

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