Stuart S. Sumida Biology 342. (Simplified)Phylogeny of Archosauria

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1 Stuart S. Sumida Biology 342 (Simplified)Phylogeny of Archosauria

2 Remember, we re studying AMNIOTES. Defined by: EMBRYOLOGICAL FEATURES: amnion, chorion, allantois, yolk sac. ANATOMICAL FEATURES: lack of an intertemporal bone. ALSO, FUNCTIONAL FEATURES: Costal breathing (inhaling using movement of the ribs). Active exhalation using movement of ribs to push air out.

3 ARCHOSAURIA

4 ARCHOSAURS ARE DIAPSID REPTILES ARCHOSAURIA INCLUDES: Crocodylomorpha Pterosauria Dinosasuria Aves (Birds)

5 Crocodylomorpha Pterosauria Eoraptor Herrerasauridae Saurischia Ornithischia Archosauria

6 THE MOST PRIMITIVE DINOSAURS Crocodylomorpha Pterosauria Herrerasauridae? Saurischia Ornithischia Dinosauria Archosauria

7 THE MOST PRIMITIVE DINOSAURS Crocodylomorpha Pterosauria Herrerasauridae Saurischia Ornithischia

8 A perforate acetabulum

9 Crocodylomorpha Pterosauria Herrerasauridae? Saurischia Ornithischia

10 Herrerasauridae: Upper Triassic of Argentina meters long. Long, low skull that is as long as the femur. 24 presacral vertebrae; and the vertebrae are relatively shorter than more primitive forms.

11 Herrerasaurus ischigualastensis Skull reconstruction

12 Herrerasaurus ischigualastensis Reconstruction 24 presacral vertebrae; and the vertebrae are relatively shorter than more primitive forms.

13 Herrerasaurus ischigualastensis

14 Dinosaurian groups more derived than Herrerasaurs may be divided into two groups based on hip construction: SAURISCHIAN ORNITHISCHIAN (Note position of pubis.)

15 ORNITHISCHIA Stegosauria Ankylosauria Pachycephalosauria Ceratopsia Ornithopoda Thyreophora Cerapoda Most ornithischians are herbivores.

16 SAURISCHIA Prosauropoda Sauropoda Theropoda Eoraptor Sauropodomorpha

17 Eoraptor lunensis ( Dawn Raptor ) From the Upper Triassic of Argentina. Once thought to be amongst the most primitive of dinosaurs. Now considered to be a primitive Saurischian.

18 SAUROPODOMORPHA Upper Triassic through end of Cretaceous Features that define Sauropodomorpha primarily associated with adaptations for herbivory, large size and, later, graviportal locomotion: Relatively small head At least ten vertebrae in very long neck. Teeth coarsely serrated. Enlarged sacrum Extremely large thumb with enlarged claw.

19 More primitive Sauropods BIPEDAL, Extremely large thumb with enlarged claw. Seismosaurus, a more derived sauropod.

20 THEROPODA Pronograde bipeds. Pneumatic (hollow) bones. Enlarged hand. Vestigial digits IV and V on hand. Highly extendable digits I-III on hand. Compact, elongate, narrow foot usually missing digit V.

21 Theropod Feet: Note missing V. I II III IV

22 Coelophysis, skull

23 Coelophysis: reconstructed in northern New Mexico

24 THEROPODA Sauropodomorpha Saurischia Theropoda Tetanurae Coelurosauria *Ceratosauria * Maniraptora Coelophysoidea Abelisauridae Spinosauroidea Allosauroidea Compsognathidae Tyrannosauroidea Ornithomimosauria Oviraptorisauria Dromaeosauridae Troodontidae Avialae

25 Daspletosaurus

26 T. rex Predator or scavenger? Probably both

27 How fast could T. rex really run? Could it run 25 miles per hour? 40?

28 Taking animal mass and the strength of both bone and soft tissue into consideration, T. rex tissues and bones would shatter if moving much over ten miles an hour

29 For T. rex to be able to travel at 20 m.p.h. the amount of leg muscle mass required to generate that much force would be about 95% to 110% its total body mass. Clearly impossible. If legs are allowed to account for 40-50% of body mass (very generous), a conservative estimate for cruising speed is 11 miles per hour.

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32 THEROPODA Sauropodomorpha (?)Eoraptor (?)Herresauridae Saurischia Theropoda Tetanurae Coelurosauria Coelophysoidea Abelisauridae Spinosauroidea(?) Allosauroidea Compsognathidae Tyrannosauroidea Ornithomimosauria Oviraptorisauria Maniraptora Dromaeosauridae Troodontidae Avialae

33 AVIALAE: TRUE BIRDS

34 Archaeopteryx lithographica