Lec 10 Early Archosaur Radiation

Question 1

Synapomorphies of Lepidosauria
(2 cranial, 1 post-cranial)

Answer 1

Reduced or no lacrimal
no postparietal and tabular
fused astragalus and calcaneum

Question 2

Key features of Rhynchocephalia
(all 3 cranial)

Answer 2

1. Enlarged palatine tooth row
2. acrodont dentition
3. posterior extension of dentary

Question 3

Synapomorphies of Squamata
(all 4 cranial)

Answer 3

1. premaxilla fused
2. parietals fused
3. no quadratojugal
4. cranial kinesis

Question 4

Key features of Squamata: Mosasauridae

Answer 4

flipper-like digits, hyperphalangy

Question 5

How does Mosasurs swim

Answer 5

anguilliform motion

Question 6

How did marine reptiles body shape evolve?

Answer 6

Plesiopedal: terrestrially adapted limbs ->
Hydropedal: paddle-shaped limbs ->
hydropedal with stiff trunk and efficient cruising

Question 7

What is hyperphalangy? list 3 marine reptiles with hyperphalangy

Answer 7

increased numbers of phalanges, arranged linearly within a digit

Ichthyosaur, Plesiosaur, Mosasaur

Question 8

Synapomorphies of Archosauromorpha
(2 cranial, 2 post)

Answer 8

1. posterodorsal process on premaxilla
2. midline crest on parietal
3. slender, tapering cervical ribs
4. small anterior and large posterior process on iliac blade

Question 9

Features of Rhynchosauria

(4 all cranial)

Answer 9

wedge-shaped skull with tall beak
many rows of small teeth form tooth plates
short snot
anterodorsally positioned eyes

Question 10

Features of Protorosauria
(2 post-cranial)

Answer 10

long neck
large pectoral girdle

Question 11

Features of Tanystrophenus

Answer 11

very very long neck

Question 12

Synapomorphies of Archosauriformes
(all 4 cranial)

Answer 12

1. No parietal formen
2. antorbital fenestra
3. lateral mandibular fenestra
4. blade-like teeth w/ serrations

Question 13

Synapomorphies of Archosauria
(2 all cranial)

Answer 13

1. antorbital fossa surround antorbital fenestra
2. palatal process of maxillae meet in midline

Question 14

2 clades of Archosauria

Answer 14

Avemetatarsalia, Crurotarsi

Question 15

What the difference b/w Crurotarsi and Avemetatarsalia?

Answer 15

Crurotarsi: Crurotarsal ankle (ankle rotation b/w astragalus and calcaneum)

Avemetatarsalia: mesotarsal ankle (simple hinge joint)

Question 16

Key features of Archosaurs: Phytosauria

Answer 16

long snout
dorsoventrally flat skull
dorsally-positioned nares
heterodonty

Question 17

Key features of Stagonolepididae

Answer 17

upturned pig-like snout
extensive bony armour

Question 18

Key features of Rauisuchidae

Answer 18

massively constructed skull
facultatively bipedal