Lesson 11) Dinosaur Origins

Question 1

Fenestrae

Answer 1

Additional openings in the skull that provide ocean area for large muscle to fill

Question 2

Anapsids

Answer 2

Amniotes that lack fenestrae
- eg) Modern turtles

Question 3

Synapsids

Answer 3

Amniotes w/ one fenestra on each lateral side of skull.
- all mammals
- …. And our close reptilian ancestor (eg- dimetrodon)
- Dimetrodons are not cut ally dinosaurs, it lived during the Permian period
- First group of Amniotes to evolve larger body size (during Permian period)

Question 4

Diapsids

Answer 4

Amniotes w/ one set of fenestrae on lateral sides and top surfaces (2 sets in total )

Split into two groups:
1. Lepidosauromorphs
2. Archosauromorphs

Question 5

Lepidosauromorphs

Answer 5

Diapsids w/ no additional fenestrae
- eg) modern lizards and reptiles, MOSASAURS

Question 6

Which group of Amniotes did dinosaurs belong to? What are dinos?

Answer 6

Archosaurian diapsids
Dinosauromorphan
Avemetatarsalian

Question 7

Archosauromorphs

Answer 7

Have fenestra in front of orbit (antorbital) and a whole in lower jaw (mandibular fenestra)
- *eg) Crodocdiles, birds, TARASAURS
- Note that even tho some species evolve these out, they will keep the label as it is applied to the evolutionary lineage.

Question 8

Avematatarsalians

Answer 8

Dinosaurs, pterosaurs, close relatives

ARcjosaurs characterized by having ankles that Flex like a hinge
- stiffer ankles which help support weight for upright locomotion
- single hinge joint

Question 9

Pseudosuchian

Answer 9

Modern crocodiles

Archosaurs where ankles rotate like a ball-socket
- eg) phytosaur, aetosaurs, prestosuchians, rauisuchids, popsauroids
- reigned in Triassic period

Question 10

Gorgonopsids

Answer 10

Large saver-toothed synapsids of the late Permian period
- top predators

Question 11

Dicynodonts

Answer 11

Tusked synapsids of the late Permian period
- Top herbivores

Question 12

Cynodonts

Answer 12

Small synapsids that evolved intro true mammals

Question 13

Permian mass extinction

Answer 13

252 mil years ago
- Most devastating extinction event
- 70% terrestrials extinct
- 90% marines extinct

Causes are uncertain
- Huge lava deposits (Siberian traps) contribute greenhouse gases to global warming?
- Comet? But no crater to be found.

Question 14

When did dinosaurs evolve?

Answer 14

Only after the Permian extinction, but gained more ground as Triassic grew to a close

• early dinosaurs were small and bipedal, but lacked characteristics that Dinosauria now has: eg) perforated acetaulum: hip socket w/ hole

Question 15

What are some early Saurischian Dinos?

Answer 15

Eoraptor, eodremaeus, Herrerasaurus, Panphagia (all carnivores)

Question 16

What is an early orinthishcian?

Answer 16

Pisanosaurus (herbivore)

Question 17

What was an adaptation not possessed by the first dinosaurs?

Answer 17

Quadrupedal Stance