Chordates 2 Sharks etc Bony fish Osteichthans Lobe fins and lungfish Tetrapods ns Reptiles Birds Feb 27, 2013 Chordates ANCESTRAL DEUTEROSTOME Notochord Common ancestor of chordates Head Vertebral column Jaws, mineralized skeleton Lungs or lung derivatives Lobed fins Limbs with digits Echinodermata Amniotic egg Milk All Chordates have a notochord and a dorsal, hollow nerve cord Chordates Craniates Vertebrates Gnathostomes Osteichthyans Lobe-fins Tetrapods Amniotes Jaws Sharks Sharks and Rays (about 470 species) Figure 34.2b Fish Lungs or lung derivatives Lobed fins Limbs with digits Amniotic egg Milk Bony endoskeleton Ray-finned fish Lobe fin fish Lungfish 1
Ray-finned fish (about 30,000 species) Figure 34.16 Brain Spinal cord Swim bladder Dorsal fin Adipose fin Caudal fin Nostril Cut edge of operculum Gills Kidney Heart Liver Stomach Intestine Gonad Anus Pelvic fin Urinary bladder Anal fin Lateral line Lobe Fins Coelocanth 5 cm Lower jaw Scaly covering Dorsal spine Derived Characters of Tetrapods Tetrapods have some specific adaptations Four limbs, and feet with digits A neck, which allows separate movement of the head Fusion of the pelvic girdle to the backbone The absence of gills (except some aquatic species) Ears for detecting airborne sounds Tiktaalik: a fossil with both fish and tetrapod characteristics Fish Tetrapod Characters Characters Scales Neck Fins Ribs Gills and Fin skeleton lungs Flat skull Eyes on top of skull Head Eyes on top of skull Flat skull Neck Shoulder bones Fin Ribs Elbow Radius Scales Fin skeleton Humerus Ulna Wrist 2
Figure 34.21 Lungfishes Limbs with digits Eusthenopteron Panderichthys Tiktaalik Acanthostega Tulerpeton ns Amniotes Silurian PALEOZOIC Devonian Carboniferous Permian 415 400 385 370 355 340 325 310 295 280 265 0 Time (millions of years ago) Key to limb bones Ulna Radius Humerus 4 limbs Frogs, Salamanders about 6,150 species ns Metamorphosis (a) Tadpole Order Urodela (salamanders) (b) During metamorphosis Order Anura (frogs) (c) Mating adults Many n Populations have been declining Glass frogs show biparental care of eggs Other species have male pregnancy 3
Figure 34.25 Amniotic Egg Lizards, Birds ANCESTRAL AMNIOTE Reptiles Synapsids Diapsids Archosaurs Lepidosaurs Dinosaurs Saurischians Parareptiles Turtles Crocodilians Pterosaurs Ornithischian dinosaurs Saurischian dinosaurs other than birds Birds Plesiosaurs Ichthyosaurs Tuataras Squamates Mammals Figure 34.26 Figure 34.28 Extraembryonic membranes Amnion Allantois Chorion Yolk sac Embryo Amniotic cavity with amniotic fluid Yolk (nutrients) Shell Albumen Lepidosauria Turtles 4
Lepidosaurs Two surviving lineages Tuataras (2 spp) Squamates (the lizards and snakes, many spp) Archosaurs Dinosaurs Birds Crocodilians Birds are the only surviving Dinosaurs The Origin of Birds Toothed beak Early feathers might have evolved for insulation, camouflage, or courtship display Wing claw Airfoil wing with contour feathers Long tail with many vertebrae Derived Characters of Birds Finger 1 (b) Bone structure (a) Wing Palm Finger 2 Forearm Wrist Finger 3 Vane Shaft Shaft Barb Barbule Hook (c) Feather structure 5