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Are humans among the descendants of this ancient organism?
Figure 34.1 Are humans among the descendants of this ancient organism?
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Phylogeny of living chordates
Echinodermata (sister group to chordates) Cephalochordata (lancelets) ANCESTRAL DEUTERO- STOME Chordates Urochordata (tunicates) Notochord Myxini (hagfishes) Common ancestor of chordates Craniates Petromyzontida (lampreys) Head Chondrichthyes (sharks, rays, chimaeras) Vertebrates Vertebral column Actinopterygii (ray-finned fishes) Gnathostomes Jaws, mineralized skeleton Actinistia (coelacanths) Osteichthyans Lungs or lung derivatives Figure 34.2 Phylogeny of living chordates Lobe-fins Dipnoi (lungfishes) Lobed fins Amphibia (frogs, salamanders) Legs Reptilia (turtles, snakes, crocodiles, birds) Tetrapods Amniotes Amniotic egg Mammalia (mammals) Milk
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Dorsal, hollow nerve cord Pharyngeal slits or clefts Muscular,
Chordate characteristics Dorsal, hollow nerve cord Muscle segments Notochord Mouth Figure 34.3 Chordate characteristics Anus Pharyngeal slits or clefts Muscular, post-anal tail
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Lancelets are named for their bladelike shape
Lancelets are named for their bladelike shape. They are marine suspension feeders. Adults retain characteristics of chordate body plan. Cirri 2 cm Mouth Pharyngeal slits Atrium Notochord Digestive tract Atriopore Dorsal, hollow nerve cord Segmental muscles Figure 34.4 The lancelet Branchiostoma, a cephalochordate Anus Tail
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Tunicates (Urochordata) are more closely related to other chordates than are lancelets. They are marine suspension feeders commonly called sea squirts. As an adult, a tunicate draws in water through an incurrent siphon, filtering food particles. Juveniles, not adults, have a notochord. Incurrent siphon to mouth Water flow Notochord Dorsal, hollow nerve cord Excurrent siphon Excurrent siphon Excurrent siphon Tail Atrium Muscle segments Incurrent siphon Pharynx with slits Intestine Anus Stomach Tunic Intestine Atrium Figure 34.5 A tunicate, a urochordate Esophagus Pharynx with slits Stomach An adult tunicate A tunicate larva
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Fossil of an early Chordate
5 mm Figure 34.8 Fossil of an early chordate Segmented muscles Pharyngeal slits
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Hagfishes have a cartilaginous skull and axial rod of cartilage derived from the notochord, but lack jaws and vertebrae Slime glands Figure 34.9 A hagfish
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Lampreys represent the oldest living lineage of vertebrates
Lampreys represent the oldest living lineage of vertebrates. They are jawless vertebrates inhabiting various marine and freshwater habitats. Figure A sea lamprey
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Hypothesis for the evolution of vertebrate jaws
Gill slits Cranium Mouth Skeletal rods Figure Hypothesis for the evolution of vertebrate jaws
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Chondrichthyans Figure 34.15 Chondrichthyans Pelvic fins Pectoral fins
(a) Blacktip reef shark (Carcharhinus melanopterus) Figure Chondrichthyans (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei)
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Anatomy of a trout - bony fish - Osteichthyes
Swim bladder Dorsal fin Adipose fin (characteristic of trout) Caudal fin Spinal cord Brain Nostril Cut edge of operculum Anal fin Liver Lateral line Figure Anatomy of a trout, a ray-finned fish Gills Anus Heart Gonad Stomach Urinary bladder Pelvic fin Kidney Intestine
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A Devonian era relative of tetrapods
Bones supporting gills Figure Acanthostega, a Devonian relative of tetrapods Tetrapod limb skeleton
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Origin of Tetrapods Figure 34.20 The origin of tetrapods 430 415 400
Ray-finned fishes Coelacanths Lungfishes Eusthenopteron Panderichthys Tiktaalik Elginerpeton Metaxygnathus Acanthostega Ichthyostega Hynerpeton Figure The origin of tetrapods Greerpeton Amphibians Amniotes PALEOZOIC Silurian Devonian Carboniferous Permian 430 415 400 385 370 355 340 325 310 295 280 265 Time (millions of years ago)
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Amphibians (a) Order Urodela (b) Order Anura (c) Order Apoda
Figure Amphibians (c) Order Apoda
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The “dual life” of a frog
(a) Tadpole Figure The “dual life” of a frog (Rana temporaria) (b) During metamorphosis (c) Mating adults
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The amniotic egg Chorion Allantois Amnion Yolk sac Embryo Amniotic
cavity with amniotic fluid Yolk (nutrients) Figure The amniotic egg Shell Albumen
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Hatching reptiles Figure Hatching reptiles
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Extant reptiles (other than birds).
(a) Tuatara (Sphenodon punctatus) (b) Australian thorny devil lizard (Moloch horridus) Figure Extant reptiles (other than birds) (c) Wagler’s pit viper (Tropidolaemus wagleri) (d) Eastern box turtle (Terrapene carolina carolina) (e) American alligator (Alligator mississippiensis)
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Form fits function: the avian wing and feather
Finger 1 (b) Bone structure Palm (a) Wing Finger 2 Finger 3 Forearm Wrist Figure Form fits function: the avian wing and feather Shaft Shaft Barb Vane Barbule Hook (c) Feather structure
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Archaeopteryx, the earliest known bird
Toothed beak Wing claw Figure Artist’s reconstruction of Archaeopteryx, the earliest known bird Airfoil wing with contour feathers Long tail with many vertebrae
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Diversity among living birds
(a) Emu - flightless (b) Mallards - web feet Figure A small sample of living birds (c) Laysan albatrosses (d) Barn swallows
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evolution of the mammalian ear bones
Key Temporal fenestra Articular Quadrate Jaw joint Dentary Squamosal (a) In Biarmosuchus, an early synapsid, the articular and quadrate bones formed the jaw joint. Middle ear Eardrum Middle ear Eardrum Stapes Inner ear Inner ear Stapes Figure The evolution of the mammalian ear bones Incus (quadrate) Sound Sound Malleus (articular) Present-day reptile Present-day mammal (b) In mammals, the articular and quadrate bones are incorporated into the middle ear.
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an Australian monotreme
Figure Short-beaked echidna (Tachyglossus aculeatus), an Australian monotreme
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Australian marsupials
(a) A young brushtail possum Figure Australian marsupials (b) Long-nosed bandicoot
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Evolutionary convergence of marsupials and placental mammals
Eutherian mammals Marsupial mammals Eutherian mammals Plantigale Deer mouse Wombat Woodchuck Marsupial mole Mole Wolverine Tasmanian devil Sugar glider Flying squirrel Figure Evolutionary convergence of marsupials and eutherians (placental mammals) Patagonian cavy Kangaroo
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Mammalian Diversity (5 species) Monotremes Monotremata ANCESTRAL
Marsupialia Marsupials (324 species) Proboscidea Sirenia Tubulidentata Hyracoidea Afrosoricida (golden moles and tenrecs) Macroscelidea (elephant shrews) Eutherians (5,010 species) Xenarthra Figure Mammalian diversity Rodentia Lagomorpha Primates Dermoptera (flying lemurs) Scandentia (tree shrews) Carnivora Cetartiodactyla Perissodactyla Chiroptera Eulipotyphla Pholidota (pangolins)
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Mammalian diversity Figure Mammalian diversity
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Lemurs Figure Coquerel’s sifakas (Propithecus verreauxi coquereli), a type of lemur
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A phylogenetic tree of primates
Lemurs, lorises, and pottos ANCESTRAL PRIMATE Tarsiers New World monkeys Anthropoids Old World monkeys Gibbons Orangutans Gorillas Figure A phylogenetic tree of primates Chimpanzees and bonobos Humans 60 50 40 30 20 10 Time (millions of years ago)
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New World monkeys and Old World monkeys
Figure New World monkeys and Old World monkeys (a) New World monkey (b) Old World monkey
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Nonhuman apes (a) Gibbon (b) Orangutan (c) Gorilla (d) Chimpanzees
Figure Nonhuman apes (e) Bonobos
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A timeline for some selected hominin species
Paranthropus robustus Homo neanderthalensis Homo sapiens Paranthropus boisei Homo ergaster ? 0.5 1.0 1.5 Australopithecus africanus 2.0 Kenyanthropus platyops 2.5 Australo- pithecus anamensis Australopithecus garhi Homo erectus 3.0 Millions of years ago 3.5 Homo habilis Homo rudolfensis 4.0 4.5 Ardipithecus ramidus Australopithecus afarensis Figure A timeline for some selected hominin species 5.0 5.5 Orrorin tugenensis 6.0 6.5 Sahelanthropus tchadensis 7.0
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Upright posture predates an enlarged brain in human evolution
(a) Australopithecus afarensis skeleton (b) The Laetoli footprints Figure Upright posture predates an enlarged brain in human evolution (c) An artist’s reconstruction of what A. afarensis may have looked like
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160,000-year-old fossil of Homo sapiens
Figure A 160,000-year-old fossil of Homo sapiens
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You should now be able to:
List the derived traits for: chordates, craniates, vertebrates, gnathostomes, tetrapods, amniotes, birds, mammals, primates, humans. Describe the trends in mineralized structures in early vertebrates. Describe and distinguish between Chondrichthyes and Osteichthyes. Describe an amniotic egg and explain its significance in the evolution of reptiles and mammals. Explain why the reptile clade includes birds.
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6. Distinguish among monotreme, marsupial, and eutherian mammals.
7. Define the term hominin. 8. Describe the evolution of Homo sapiens from australopith ancestors, and clarify the order in which distinctive human traits arose. 9. Explain the significance of the FOXP2 gene.
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