Week 11: Ornithischians

Question 1

shared derived characters of ornithischians

Answer 1

1. pubis is rotated backwards, close and parallel to the ishium
2. predentary bone of their lower jaw, like a beak

Question 2

Characteristics evolved for chewing

Answer 2

1. incisors
2. diastem (move food to back of mouth)
3. dental battery for grinding food
4. cheeks- store food in mouth as it chewed
5. coronoid process- strong muscles attach to jaw
6. leaf shaped teeth for grinding vegitation

Question 3

basal ornithischians

Answer 3

bipedal and looked like theropods, but evolved a chewing skull and longer forearms

Question 4

ornithischian feathers

Answer 4

basal ornithischian had monofilaments, feathers may have been ancestral for all dinosaurs…
(ex) Tianyulong

Question 5

ornithischain phylenology

Answer 5

ornithischians- backwards pubis and predentary bones

Thyreophora- dermal amour on their back
(ex) Ankylosaurs and stegasaurus

Marginocephalia- Pronounced diastem
(ex) ceratopsian and pachycephalosaurs

Ornithipoda- shelf at back of the head
(ex) hadrosaurs and iguanodon

Question 6

thyreophorans

Answer 6

(ex)
Ankylosaurs: amour and spikes
Stegosaurs: plates and spikes

Key characteristic: rows of dermal bones on back

Question 7

scutes and osteoderm

Answer 7

seperate amour plate, made of bone formed in the skin, covered by leathery skin

Question 8

early thyreophorans

Answer 8

mix of bipedal and quadrupedal with simple dermal scutes on neck, back and tail

Question 9

stegasaurs

Answer 9

1. hind limbs longer than fore limbs- better for defense, harder to run
2. small leaf shaped teeth- not in close rows, small cheeks, small coronoid process
3. Low EQ, but good smellers
4. plates covered their neck, back and spikes on their tail

Question 10

stegasaurs plate function

Answer 10

1. Display- bigger and smaller plates could be for attracting mates or difference between male and female
2. thermoregulation- grooves of the plates that contain blood vessels for nutrients transport, not blood
3. defense- make it look bigger and scary (passive defense), spikes (thagomizer) on tail suggest active defense

Question 11

Ankylosaur

Answer 11

1. Continuious sheild of osteoderm, even eyelids
2. fore limbs shorter than hindlimbs. Very heavy
3. leaf shaped teeth and big gut
4. defense- boney club at end of tail

Question 12

diversity in ankylosaur

Answer 12

Late jurassic/early creatous- Ankylosaur with flexible tails (no club)
middle creatous to late creatous- stiff tails not club
late creatous - stiff tail with club

Question 13

two main groups of ankylosaur

Answer 13

Ankylosaur- havily amoured, tail club for defense

Nodosaur- No tail club, bigger spikes on shoulders