1. Today – 2/13 Critter in the news Theropoda Gorgon wrap-up

7. Supernovae Responsible for all elements heavier than iron, some of the elements lighter Triggered the collapse of the solar nebula, forming the solar system May drive extinction events, if close enough

8. Last time: Morrison Formation, Western Interior Seaway, Hell Creek Formation Geologic maps Dinosaur evolutionary novelties or derived characters Clades Some big vertebrate clades – Tetrapoda, Amniota

9. Eye socket anapsids – no holes behind the eye socket synapsids – one hole behind the eye socket diapsids – two holes behind the eye socket (profile view)

10. N S Outer space Earth’s core

11. Review session tonight, tomorrow! 5 pm, right here

12. Phylogenetic tree = family tree Older Younger -----------Time---------→

13. Definition: “More closely related” Animal 1 is more closely related to animal 2 than to animal 3 if animal 1 shares a more recent common ancestor with animal 2 than it does with animal 3 Triceratops is more closely related to Hadrosaurus than Stegosaurus because it shares a more recent common ancestor with Hadrosaurus than with Stegosaurus I am more closely related to my sister than my cousin because…

14. Phylogenetic tree = family tree Older Younger -----------Time---------→

15. Scientific definition of Dinosauria Triceratops, living birds, their most recent common ancestor and all of its descendents

17. Dinos! Evolved fast as a result of extinction-driven opportunity to colonize open ecological niches and superior adaptations Likely from South America - best remains of early dinos and their closest relatives found here Meat-eaters + Sauropodomorpha = ?

18. Clade Saurischia Comprised of clade Herrerasauridae, clade Eoraptor, clade Theropoda, clade Sauropodomorpha

19. www.projectexploration.org http://home.no.net/paleo EoraptorEoraptor!

20. Eoraptor, the “Dawn thief” Own clade Late Triassic, at least 228 Ma, Ischigualasto Formation of Argentina 3 feet long, 1 foot tall at hips, maybe 20 lbs So primitive, just barely a dinosaur! Still had five fingers (pinky almost gone). Front teeth typical theropod, back teeth like early herbivorous dinosaurs! Probably omnivorous, eating insects, small animals, plants

21. Ischigualasto Formation

22. Volcanically active floodplain dominated by rivers with strongly seasonal rainfall Ash beds used for dating 40 meter trees, ferns, horsetails 6% of fossil tetrapods are dinos, both saurischians and ornithiscians Rhynchosaurs and cynodonts most common tetrapods – rhynchosaur Scaphonyx makes up over half of all tetrapod fossils

23. rhynchosaur

24. www.ucmp.berkeley.edu Herrerasaurus

25. Named after Victor Herrera, local artist who first found bones in 1958 13 feet long, 450 lbs, 4 ft tall at the hips Very primitive – didn’t have three vertebrae fully incorporated into the pelvic region, still had vestigial pinky

26. Staurikosaurus http://www.ufogenesis.com.br/

27. Staurikosaurus 6-7 feet long, 65 lbs, 2.5 feet tall at hips Probably older than Eoraptor and Herrerasaurus From Brazil’s Santa Maria formation, an anastomosing river system Only two pelvic vertebrae Named for Southern Cross

28. Chindesaurus – last member of clade Herrerasauridae, N AZ and NM, 220 Ma http://members.aol.com/Dinoplanet/chinde.html

29. Theropods: defining characters

32. Clade Theropoda Theropods had long, bowed femurs, strong lower jaws, lightly built skulls with that were attached to the neck with a highly mobile joint, four or less fingers These shared derived characters made theropods well-adapted for running, hunting, and eating meat! Low-density and pneumatized bones Two main clades: Ceratosauridae, Tetanurae

33. Inhale: lungs and posterior air sac fill from outside, anterior air sac fills from lung Exhale: lungs fill from posterior air sac, dead air in anterior air sac goes outside Bird (and theropod) lungs are always getting new air http://scienceblogs.com/pharyngula

38. Pneumatization Theropod vertebrae and skulls have attachment sites for air sacs, like birds Keeps lungs constantly bathed in oxygenated air Lightens body and skull, allowing the evolution of giant skulls like T. rex Allows high levels of activity According to Ward, why did this evolve?

39. Typical theropod tooth

40. Increasing footprint size