Topic 14 - Turtles and Crocodiles

What are Testudines and their History?

They are turtles and tortoises. They are a monophyletic group. They are a very old lineage that was present in Pangea (200 mya).

Characteristics of Testudines

• bony or cartilaginous shell

• ectothermic

• lay eggs on land

• 3 chambered heart

Testudines in Australia

Australia only has turtles, no tortoises. Many of the turtles here are adapted for dry conditions. In Australia, they can bum breath, which means they can both breath normally through lungs, but also through cloacal respiration.

What are Cocodilia and their History?

They are crocodilians. They are most closely related to birds. Similarities between the two include:

• 4 chambered heart

• parental care

They were present in Pangea (200 mya). They were able easily cross saltwater barriers which lead to them being in many parts of the world.

Characteristics of Crocodilia

• 4 chambered heart

• parental care

• ectothermic

• teeth in sockets

• eyes, ears, and nares on top of their head

• laterally compressed tail

• webbed hind feet

• incredible circulatory system

Crocodilia Reproduction

• all species lay eggs

• 2 strategies

  1. females build nests (saltwater crocodile)

  2. dig holes in hot sand (freshwater crocodile)

• temperature dependent sex determination

• females guard nest and babies for some time

Australian species of Crocodilia

Freshwater crocodile	Saltwater crocodile
Crocodylus johnstoni (“Freshie”) Big males can be up to 3m long Mostly in freshwater They are a slender snouted species Eats a variety of small-ish prey Mostly fish, also frogs, reptiles, birds, small mammals, crustaceans Dig a hole for nest	Crocodylus porosus (“Saltie”) Up to 7m in length Occurs in salt and freshwater habitats They have a varied diet Pretty much anything Includes large vertebrates, and occasionally people Mound nester