Video Notes for 10/17/02

· NW Argentina: foothills of Andes

· Triassic rocks – first remains of Dinos

· 1988 Paul Sereno

· Herrarasaurus – most primitive dino, carnivore, hinge in middle of lower jay = flex around prey

· help understand diversification and radiation of later dinos

· lush wet areas, forests, dominated by reptiles = environment in Triassic

· Desmadsueus – reptile, large herbivore in (now petrified) forest, armor all over

· Postasuchus – early “experimental” dino = failed: longer hind limbs placed underneath body

· Selaphisus – moved legs under body, bipedal: this allowed dinos to take over (faster on feet)

· Extinction at Triassic/Jurassic – dinos at an advantage, survive = radiation

· Herbivores : Carnivores = 20 : 1

· Brontosaurus – 30 tons, largest plant eater: How can such a large animal feed in order to sustain itself?

- hind legs + tail = tripod

- get to foliage up to 34 feet high

- no molars = how chew? guts pulverize plant matter = gastroliths + gizzards

· Use sound to find bones: Seismosaurus

- found gastroliths associated with skeleton

- associated with rib bones

· Plants: increased and fast reproduction = flowers

- example of coevolution with dinos: large animals eating massive amounts, plants needed to reproduce faster

· Low growth plants in early Cretaceous: grazers surpass high bough feeders

· Iguanadon: successful!!!! no gastroliths, it chewed

· Chewing:

- teeth set in, indentation = cheek

- need to grind, move jaw side to side = key to evolution

· Pterosaurs

- skeletal structure: bird like

- long finger bone

- membrane, elastic, thin wing, aerodynamic

· Jack Horner – dinosaur nesting = social behavior; colonies dense

- distance between nests = length of adult dino (e.g. Maiasaurus/ Duckbills)

- dinos cared for young

· Striking similarities between birds and dinos

- nests: same nests year after year

- lived and traveled in organized groups

· Dino peak in late Cretaceous: Very diverse

· Centrasaurs: Herding behavior

· Bones sheared in strong ways = fresh when broken: trying to cross river in flood

- deposited in ox bow lake, decrease in river water level = stranded and carnivores scavenged

· K/T (Cretaceous/Tertiary) boundary = Extinction of Dinosaurs