turtles and crocodylians

Cryptodires

Neck bends in a vertical plane

Pleurodires

Neck bends in a horizontal plane

Evolution of turtle body plan

Turtles separate the ribs and muscles, ribs are the shell and reduced and lengthens dorsal vertebrate

General turtle features

Dorsal carapace, ventral carapace, anapsid skull

Carapace

Dorsal shell made of scutes

Plastron

Ventral shell

Hinges

Allow shell closure, evolved repeatedly in plastron

Testunidae

Tortoises

Anterior projections of the plastron are used in combat

Trionychidae

Soft shelled turtles

Lack keratinous scutes

Ambush predators

Dermochelyidae

Leatherback sea turtle

Largest extant turtles

Gifantothermy

Chelydridae

Alligator snapping turtle

Cheloniidae

Sea turtles

Use lift based propulsion using forelimbs

Chelidae

Mata mata turtle

Uses powerful suction feeding

Cloacal gill respiration

Aquatic turtles can use cloacal lining to breath

Sympatry

Species that occur in the same location

Allopatry

Species that occur in separate geographical locations

Lateral undulation

Crocodylian, during swimming

Belly crawl

Crocodylian, sprawled limb posture for water to land transition

High walk

Crocodylian, long distance travel

Bound

Crocodylian, smaller ones can gallop using for ventral vertebral flexion

Mechanoreceptors

Small bulges sensitive to pressure in crocodilians

Used for predatory detection and social interactions

Secondary palate

Allows crocodilians to breath with prey in their mouths in land or under water

Unidirectional air flow

In crocodilians and avians

Crocodilian predatory behavior

Ambush

Cooperation

Lures

Subsonic vibrations

Male American alligators use this for nonspecific interactions and parental care

Environmental sex determination

Temperature dependent in crocodilians and turtles

Creching

When young crocodilians stay in large groups guarded by adults