chapter 25 stegasuars

Question 1

What is the key evolutionary novelty shared by all Thyreophorans?

Answer 1

one or more rows of osteoderms above or alongside the vertebral column.

Question 2

The osteoderms of primitive thyreophorans are mainly simple scutes. Describe a scute and the primitive thyreophoran called Scutellosaurus. also say scuts time period and name

Answer 2

-scutes – bony external
shield-like plates overlain with a keratin sheath like crocodile skin.
-Thyreophora are represented by rare Early Jurassic fossils from North America and Europe.
- name means little-shielded lizard
-that lived in what is now Arizona during the Early Jurassic, 196Ma

Question 3

A bit more advanced but still a primitive thyreophoran is Scelidosaurus. Describe
this dinosaur and the incredible David Sole specimen.

Answer 3

-primitive thyreophoran is
Scelidosaurus (“limb lizard”)
that lived in England during the
Early Jurassic, around 191 Ma.
-It was discovered in the 1850’s and
named by Richard Owen. The
initial find was a limb bone, but
then most of the skeleton was
located. Scelidosaurus was the
first find of a dinosaur found
preserved as mostly complete.

Question 4

What are the key evolutionary novelties of the more advanced stegosaurs? and the names meaning?

Answer 4

-Stegosaurs (“plated lizards”)
-key evolutionary novelty:
vertical bony plates and spikes arranged in single or double rows
along the neck, back, and tail.
Other characteristics:
-small head
-short, massive forelimbs
-small, ridged triangular shaped teeth

Question 5

describe Kentrosaurus and what its name means:

Answer 5

Name: Sharp point lizard
- had lots of armour and protection and two large shoulder spikes protruding from behind its front two limbs.

Question 6

Stegosaurus is the ‘roof lizard’. Describe this stegosaurid. What dinos did it live alongside during the “Golden Age of Dinosaurs” in North America?

Answer 6

It lived alongside
these well-known dinosaurs:
-Apatosaurus
-Diplodocus
-Camarasaurus
-Brachiosaurus
-Allosaurus
-Ceratosaurus

Question 7

How did the stegosaurs defend themselves against predators?

Answer 7

it would widen its stance to maintain stability then lower its front half and swing its tail at great force towards predators.

Question 8

When and why did stegosaurs as a group become extinct?

Answer 8

-The stegosaurs decline in diversity and abundance in the Early
Cretaceous, and as a group are extinct soon into the start of the
Late Cretaceous (~100 Ma)
- climate shifts, change in vegetation and new herbivores