Diversity of Crocodilians

Distribution

25 sp worldwide

2 in NA

3 families worldwide

Crocs

archosauria

• birds and crocs sister taxa

contains crocodiles and birds

synapomorphies of reptiles (incl birds)

bone similarities

• single occipital condyle

• lower jaw = 5 fused bones

renal similarities

• birds have 3 lobes

• reptiles sometimes have more

scales/ body scales

• betta keratin

• morphological similarities

archosaur synapomorphies

thecodont teeth

• bird ancestors

4th trocanter

• bony knob on thigh for femur muscle attachment

parental care

nests with vegetation

archosauria

pterosaurs

• extinct taxa

• not closely related to birds

• wings evolved independently

• fly on pinky

• bat like wings

synapomorphies of crocodilians

extensive osteoderms

long snouts

thecodont teeth

complete secondary palate

choanae shifted posteriorly

• holes from nostril to skull

external ears covered with skin

diaphragmaticus muscle

crocodilian phylogeny

few lineages

morphological characteristics vs genetics makes two very different trees

fossils

Borealosuchus croc

Tsoabichi greenriverensis

‘Living fossils’

alligatoridae

broad, rounded snout

lower teeth all hidden when mouth closed

no pores on belly scales

mound nests

crocodilidae

narrow rounded snout

4th lower tooth in notch

hole and mound nesters

3 species eat large animals

• incl humans :)

gharidalidae

sister to crocodilidae

very long slender snout

hole nesters

• tomistoma mound

fish eaters