4 The Vertebrate Genealogy VertebratesAre represented by mammals, reptiles, amphibians, and fishes.Have unique features, including the cranium and backbone.
5 Nearly All Chordates are Vertebrates with a Skull and Spinal Vertebrae Figure 17.29
6 Characteristics of All Chordates At Some Point During Their Lifetimes Figure 17.30
7 Evolutionary Novelties/Landmarks of Phylum Chordata Development of hinged jawsBony (calcium phosphate) skeleton instead of cartilaginous skeletonTerrestrial AdaptationsInternal lungs instead of external gillsFour legs for walking on landAmniotic egg to avoid dehydration of embryoEndothermy instead of ectothermyFeathers or fur to maintain constant body temp.
9 Jawless Fish (Class Agnatha) The first vertebrates probably evolved about 542 million years ago.Cylindrical and elongated like eelsRetention of all 7 gill slits as adults, breathes using gillsNo paired finsMouth is locked in a circular sucker-shape (no jaws)Skeleton made of cartilageParasitic on other fishIncludes the lampreys and hagfish
10 Evolutionary Tree of the Chordates Figure 17.32
11 Cartilaginous Fish (Class Chondrichthyes) True hinged jawsPredatory or filter feeding carnivoresSkeleton of cartilage5-7 gills slits (slightly fewer than agnathans)Paired pectoral fins used for steeringHeterocercal (asymmetrical) tailMouth behind nose on ventral surfaceLateral line system of pores that detect water currents and vibrationsPlacoid scales (skin feels like sandpaper) migrate anteriorly into mouthIncludes the sharks, skates, and raysSkateManta RayShark Eating a Seal
12 Evolutionary Tree of the Chordates Figure 17.32
13 Bony Fish (Class Osteichthyes) Bony skeleton reinforced by hard calcium saltsFlexible paired pectoral and pelvic finsHomocercal (symmetrical) tailSingle gill slit covered by operculum (gill cover)Swim bladder to maintain buoyancy (forerunner of a lung?)Terminal mouth (at very end)Rounded scales (ctenoid or cycloid)Lateral line sensing system, keen sense of smell and good eyesightClownfish and Anemone
14 Transition To Land and the Development of Legs Figure 17.35
15 Evolutionary Tree of the Chordates Figure 17.32
16 Amphibians (Class Amphibia) A mixture of aquatic and terrestrial adaptationsSemi-functional lungs to extract oxygen out of airWet, slimy skin for diffusion of oxygen from airFour legs (a tetrapod) but relatively weak pectoral and pelvic girdlesMetamorphosis from legless, vegetarian with tail to four-legged, carnivorous adultUsually needs water for reproduction to and to keep growing embryos hydratedIncludes frogs, toads, newts, and salamanders
17 Evolutionary Tree of the Chordates Figure 17.32
18 Reptiles (Class Reptilia) Dry, scaly skin to prevent water lossStronger pelvic and pectoral girdles to facilitate walkingFully-functional lungsInternal fertilization (no need for water to reproduce)Amniotic egg to keep growing embryo wetEctothermic, as with previous vertebratesMost have bony teeth for carnivorous dietIncludes snakes, lizards, turtles, crocodiles, and alligatorsSnake Ritual WrestlingGalápagos Tortoise
19 Age of Reptiles: Mesozoic Dinosaurs included the largest animals ever to live on land.
20 Evolutionary Tree of the Chordates Figure 17.32
21 Birds (Class Aves)Birds evolved from a lineage of small, two-legged dinosaursHollow, air-filled bones to reduce weightHorny beak replaces teeth to reduce weightFeathers for flight and staying warm (evolved from scales)Scaly feet are remnants of reptilian ancestryHighly efficient, specialized lungsEndothermic (maintain constant internal body temp.)Hard-shelled calcium eggsGreatly enlarged sternum to anchor flight muscles
22 Bird wings Are Airfoils Giving Them Lift When They Fly Forward Flapping GeeseSoaring HawkSwans Taking Flight
23 Evolutionary Tree of the Chordates Figure 17.32
24 Vertebrate Animals Chapter 17b Characteristics of Phylum ChordataMajor Evolutionary Novelties in the Chordates/VertebratesFishesJawless Fish (Class Agnatha)Cartilaginous Fish (Class Chondricthyes)Bony Fish (Class Osteichthyes)Amphibians (Class Amphibia)Reptiles (Class Reptilia)Birds (Class Aves)Mammals (Class Mammalia)Primate Evolution (Order Primata)
25 Mammals (Class Mammalia) Arose about 200 million years ago and were probably small, nocturnal insect-eaters.Most mammals are terrestrialFur or hair (endothermic)Nearly all give birth to live young (no egg-laying)Suckle the young with breast milk from mammary glandsMost have special filtration organ in uterus called a placenta
26 Class Mammalia, Order Primata Early primates were arboreal insectivoresOpposable thumbsStereoscopic visionLimber shoulder jointsEyes in front of the faceExcellent eye-hand coordinationExtensive parental care