Lesson 11: Dinosaur Origins

Question 1

Amniotes that completely lack fenestrae are

called __.

Answer 1

anapsids

Question 2

__are amniotes with one fenestra on

each lateral side of their skull.

Answer 2

Synapsids

Question 3

All mammals are
synapsids and so were our close reptilian
ancestors, like the famous sail-backed synapsid __

Answer 3

Dimetrodon

Question 4

Amniotes with one set of fenestrae on the
lateral sides of their skulls and one set on the
top surfaces of their skulls are called

Answer 4

diapsids.

Question 5

__ are diapsids with no additional fenestrae.

Answer 5

Lepidosauromorphs (or lepidosaurs, as we’ll also refer to them here)

Question 6

__ are diapsids with an additional fenestra in front of each orbit (__) and an additional fenestra
on the rear of the lower jaw (__).

Answer 6

Archosauromorphs (or archosaurs, as

we’ll also refer to them here), the antorbital fenestra, the mandibular fenestra

Question 7

Dinosaurs, pterosaurs, and a few of their close
relatives belong to a special group of
archosaurs, and are known as

Answer 7

avemetatarsalians

Question 8

These crocodile-line

archosaurs are called

Answer 8

pseudosuchians.

Question 9

Large saber toothed sinapsids called __ roamed the land in the Permian.

Answer 9

gorgonopsids,

Question 10

and synapsids, like the

tusked __, were the top herbivores

Answer 10

dicynodonts

Question 11

__ would go on to evolve into true mammals, and the early forms looked a little like short-legged dogs. Then, 252 million year ago, disaster struck the world of the synapsids.

Answer 11

Cynodonts