Lecture 13

Question 1

What group did the marginocephalians belong to?

Answer 1

Cerapoda

Question 2

What are the two main groups of margincephalians?

Answer 2

Pachycephalosauria
Ceratopsia

Question 3

What were the Pachycephalosauria commonly referred to? were they bipedal or quadrapedal, what kind of skull roofs did they have?

Answer 3

The dome-heads, they were bipedal with thickened skull roofs

Question 4

What were the pachycephalosauria thickened skull roofs good for?

Answer 4

Flank butting

Question 5

Where are the pachycephalosauria found and when?

Answer 5

Only in northern hemisphere (asia and north america), mostly late cretaceous but some early cretaceous forms in asia

Question 6

What are the differences between domes in north american versus asian forms? What recent studies dispute this?

Answer 6

North American forms tend to
have high domes
Asian forms tend to have both high domes and flattened, thickened skulls.
- recent studies show
that at least some of the flattened
skulls may just be juvenile forms
of fully adult, dome-headed
pachycephalosaurs

Question 7

What were the pachycephalosaurs brains characteristics? (3)

Answer 7

Had enlarged olfactory lobes, the brain was tilted down towards the back of the skull, the bones at the back of the skull were rotated downwards

Question 8

What evidence lead people to believe that the pachycephalosaurs head butted?

Answer 8

• The structure of the dome is
  very dense
• Bone fibres are oriented
  perpendicular (at right angles)
  to the external surface of the
  dome
• This may help distribute
  forces around the brain like a
  built-in helmet.

Question 9

How was it tested that the dome of pachycephalosaurs reacted to head butting?

Answer 9

A plastic model of a small pachycephalosaur was built and stress lines mimicked the orientation of the columnar bone, reinforcing idea that the fibrous columns evolved to resist head butting

Question 10

How does the rotated bones at the back of the pachycephalosaurs skull serve as evidence for head butting?

Answer 10

rotation of bones at the back of
the skull minimizes the potential for
violent rotation or dislocation of the head

Question 11

In the spine of pachycephalosaurs, what features made it rigid and limited rotation?

Answer 11

Further down the spine, the vertebrae are uniquely linked with a tongue and groove articulation that made the spine very rigid and limited lateral rotation

Question 12

Where are injuries concentrate din pachycephalosaurs?

Answer 12

concentrated near the apex, due to it being wear direct head on collison occur

Question 13

DO flat headed pachycephalosaurs have injuries?

Answer 13

no

Question 14

How many percent of pachycephalosaurs skulls have injuries representing infections from trauma?

Answer 14

22%

Question 15

Is there a difference in rate of injurt amongst diff genera of pachycephalosaurs?

Answer 15

no

Question 16

How does stygimoloch support evidence that head-butting is only adult behaviour of pachycephalosaurs?

Answer 16

Because it’s skull cap contains blood vessels, so it prob wouldn’t head but- but if it’s juvenile then maybe juveniles didn’t head but but adults did

Question 17

What features did pachycephalosaurs have for visual display? (4)

Answer 17

• Dome
• Canine-like teeth (threat display/biting combat with rivals)
• Knobby/spiny osteoderms on the snout/side of the face and
  marginocephalian shelf
• Likely, the male with the best looking domes, knobs and spikes got to
  perpetuate the family line (but he perpetually had to defend that position)

Question 18

What kind of fossils for pachycephalosaurs can we find in north america? Asia?

Answer 18

North america: Mainly Water-worn skull caps, isolated bones
Asia: Complete skulls and articulated
skeletons.

Question 19

What can we say about the transport distances of pachycephalosaurs after looking at their anatomical fidelity of fossils in north america versus asia? ON TEST

Answer 19

North America:
* Water-worn skull caps,
isolated bones
* Lots of transport before burial
* Lived in/near the mountains
Asia:
* Complete skulls and articulated
skeletons.
* Buried close to where they died
* Lived in a Sahara-desert with
ephemeral streams.

Question 20

All ceratopsians have what features? (5)

Answer 20

• a rostral bone
• Narrow skulls with a hooked beak
• the jugal horns
• a frill
  -thick hooves on all toes

Question 21

Did all ceratopsians have horns? Were they all quadrapedal?

Answer 21

nope and nope

Question 22

Where were ceratopsia found?

Answer 22

In northern hemisphere

Question 23

What did the horns of certaposia consist of? What does that mean for the preservation of ceratopsia?

Answer 23

• The horns consist of a bony core
  with a sheath of keratin, but only the
  core gets preserved.
• Therefore, the horn was much
  larger than what is preserved in
  fossils

Question 24

Did primitive forms of ceratopsia have facial horns?

Answer 24

No

Question 25

The primitive forms of ceratopsia were what? What did their transtion to ceratopsidae (larger qudrapedal more ornamented dinos suggest)?

Answer 25

small, bipedal, and without horns, the transition suggests that display and competition were important

Question 26

Where do we find primitive forms of ceratopsia? Where do we find ceratopsidae?

Answer 26

asia, north america

Question 27

Which ceratopsia migrated to north america first and how?

Answer 27

a ceratopsia similar to proceratops migrated to to the new world through the bering straits

Question 28

Once in northamerica, the clade ceratopsiadae split into what?

Answer 28

chasmosaurines and the centrosaurines

Question 29

What’s the difference between the centrosaurines and the chasmosaurines?

Answer 29

the chasmosaurines:
had long frills, long horns over the orbit and a short horn over the nasal, elongated snouts, and variation in frill
The centrosaurines:
Had typically short frills, typically short horns over the orbitals, and more ornamented frills, big horn near nose

Question 30

Horns were used for what purposes in ceratopsia? (5)

Answer 30

• Display
• ritualized combat
• defense of territories
• maturity
• species identification

Question 31

Centrosaurs competed in what type of combat?

Answer 31

Have few injuries to skull, focused on flank attacks- avoided eyes, ears and snout

Question 32

Chasmosaurines competed in what type of combat?

Answer 32

face to face combat (had mor einjuries around face)

Question 33

What evidence do we have the ceratopsians were herders and competed with each other?

Answer 33

Bone beds with healed wounds