Lecture 12

Question 1

What are the shared characters of the Thyreophora?

Answer 1

they have parallel rows of bones that are embedded in the skin called osteoderms

Question 2

How did thyreophorans begin? What did they evolve into?

Answer 2

small and bipedal, evolved into larger quadrapedal dinosaurs

Question 3

What is the advantage of having armor like the thyrophorans?

Answer 3

protection

Question 4

What other dinosaurs besides the thyreophorans had armour? How was it different?

Answer 4

Amaragasaurus, but it was extensions of the vertebrate called neural spines

Question 5

Where are the plates in stegosaurs attached too?

Answer 5

They are embedded in the skin and not attached to the spine

Question 6

What is dermal armor and in which dinosaur lineage do they develop?

Answer 6

In another dinosaur lineage- the saurapods- are osteoderms

Question 7

What kind of chewers were thyreophora? Why?

Answer 7

They were okay chewers, they could crop and strip foliage with their rhampotheca’s (beaks) and had an inset tooth row, but the teeth were small, simple, triangular, and couldnt grind well, their coronoid process is small

Question 8

What sis thyreophora eat?

Answer 8

ferns and cycads less than a metre off the ground

Question 9

What were the two great clades of the thyreophora?

Answer 9

stegosauria
ankylosauria

Question 10

Are there many fossils available for stegosauria?

Answer 10

No, juvenile fossils are rare, have no nests, eggshells or hatchling material, fossils are found globally

Question 11

Why don’t we find fossils of stegosaurus in alberta?

Answer 11

Because the sediment rock we have in laberta is late cretacous, so the rocks to preserve the stegosaurus we don’t have

Question 12

What were the characteristics of stegosauria? (2)

Answer 12

Had plates organized in rows down the neck, back, and tail.
Were 3-9 m long and 300-1500 kg

Question 13

What was the issue with stegosaurs locomotion? What was the solution to this?

Answer 13

They had long hindlimbs which covered more distance per step than short forelimbs, the centre of mass was towards their head.
They either had to walk really slowly or lift the forelimbs up when running.

Question 14

Did stegosaurs run? What was their max speed?

Answer 14

No, because their weight was distributed to their heads so they couldn’t run bipedally, so their max speed was 6.5-7 km/h

Question 15

Was the stegosaurus smart?

Answer 15

no 1/1000 ratio of brain to body size

Question 16

What were the stegosarias brains shaped like?

Answer 16

Had long tiny brains with a slightly enlarged olfactory lobe for smelling

Question 17

Why did the stegosaurs have osteoderms in the form of spikes on their tails?

Answer 17

Defense, the splayed spikes (called thagomizers) were likely slashed from side to side

Question 18

Why did stegosaurs have osteoderms in the form of plates?

Answer 18

Not really for defense, made them look scarier, identified them as diff species and sexes, and may have helped with thermoregulation

Question 19

How did the plates of stegosaurs help with thermoregulation?

Answer 19

a study showed that the natural arrangement of plates in symmetrical pairs would dissipate heat, shaky as other studies showed they don;t have effect and grooves were used to supply nutrients

Question 20

Why did juvenile stegosaurs not have plates or spikes?

Answer 20

because they had to devote more energy into growing

Question 21

What sexual dimorphism existed in stegosaurs?

Answer 21

• Two distinct sizes and shapes of
  plates
• Equal numbers of both sizes
• No intermediate forms

Question 22

What are the characteristics of ankylosaurs? (4 characteristics)

Answer 22

• Encased in an “armor” of osteoderms
• Wide girth so had a large gut
• Longer hindlimbs than forelimbs, but quadrupedal
• Mid sized (usually < 5 m, but up to 9 m), ~3500 kg (2 hippos!)

Question 23

When did anklyosaurs appear?

Answer 23

late cretaceous

Question 24

What are the two main groups of ankylosauria?

Answer 24

Ankylosauridae and nodosauridae

Question 25

What are the characteristics of ankylosauridae and nodosauridae?

Answer 25

1. Ankylosauridae:
   * Shorter, broader head/beak
   * Large, triangular plates attached to
   rear corners of skull
   * Well-armored, but fewer tall spikes
   along body.
   * Tail with a massive, bony club,
   sometimes with paired tail spikes
   or knobs
2. Nodosauridae:
   * Longer, narrow snouts/beak
   * Well-muscled shoulders
   * Tall spikes at the shoulder
   * No tail club

Question 26

What is the differences in beaks of both Ankylosauria and Nodosauridae? What does this suggest?

Answer 26

• Narrow beak of nodosaurids
  suggests selective feeding
  (plucking fruits and foliage)
• Broad beak of ankylosaurids
  suggest that they were less
  selective.

Question 27

Were ankylosaurs smart?

Answer 27

no, had a small ratio of brain to body size

Question 28

Were ankylosaurs good at smelling?

Answer 28

yes, had enlarged olfactory lobes/convoluted nasal passages

Question 29

Were ankylosaurs slow moving? What was their max running speed? walking speed?

Answer 29

yes, max running speed was 10 km/h, walking was 3 km/h

Question 30

What kind of defense did Nodosaurids have?

Answer 30

head-first defense- had no club

Question 31

What kind of defense did ankylosaurids have?

Answer 31

tail-first defense, Base of tail was flexible, but rear became hard with
interlocking vertebrae and ossified tendons. Served as muscle attachment sites for a powerful swing.