Alligatoridae:

Common Name

Crocodylidae:

Common Name

Gavialidae:

Common Name

Alligatoridae:

Physical characteristics

• mandibular teeth not visible with jaws closed
• broad snout
• unwebbed front feet

Crocodylidae:

Physical characteristics

• mandibular teeth visible with jaws closed

Gavialidae:

Physical characteristics

• long, thin snouts
• extensively webbed hind feet

Alligatoridae:

Distribution

• All genera except Alligator: Central & South America
• Alligator: SE USA, E China

Crocodylidae:

Distribution

All continents except Europe and Asia

Gavialidae:

Distribution

Alligatoridae:

Habitat

• slow-moving freshwater
• swamps
• rivers
• lakes

Crocodylidae:

Habitat

Gavialidae:

Habitat

Crocodylians:

Diet by family

• Alligatoridae & Crocodylidae: carnivorous
• Gavialidae: piscivorous

Crocodylia:

Reproduction type

All families:

• internal fertilization
• oviparous

Crocodylia:

Family with lekking

Crocodylia:

Families with extensive vocal communication and parental care

• Alligatoridae
• Crocodylidae

Crocodylia:

Most aquatic family

Gavialidae:

Characteristic sex difference

Chelydridae:

Common Name

Cheloniidae/Dermochelydae:

Common name

Dermatemydidae/Kinosternidae:

Common name

Emydidae:

Common name

Geoemydidae:

Common name

Testudinidae:

Common name

Caretochelyidae/Trionychidae:

Common name

Chelydridae:

Physical characteristics

• large head with powerful jaws
• small plastron
• long tail
• can't fully retract head/limbs
• poor swimmers

Cheloniidae/Dermochelydae:

Physical characteristics

• limbs modified into paddles
• Dermochelys: carapace with osteoderms embedded in skin

Dermatemydidae/Kinosternidae:

Physical characteristics

Kinosternids:

• small
• elongate shells
• 3 long keels
• release musk from cloaca

Dermatemys:

• large
• aquatic
• flat shell

Emydidae:

Physical characteristics

• fully bony shell with horny plates
• some genera have hinged plastron

Geoemydidae:

Physical characteristics

• pelvic girdle flexes with plastron
• single articulation point between 5th and 6th cervical vertebrae
• no hyomandibular branch of facial nerve
• epipterygoid bone in skull

Testudinidae:

Physical characteristics

• high domed shells
• thick, scaly limbs
• unwebbed feet

Caretochelyidae/Trionychidae:

Physical characteristics

• dorsoventrally flattened
• leathery skin
• long snout and neck
• webbed feet

Chelydridae:

Distribution

• Eastern US
• Central America
• SE Asia

Cheloniidae/Dermochelydae:

Distribution

Worldwide in temperate/tropical oceans

Dermatemydidae/Kinosternidae:

Distribution

• North, Central, and northern South America
• Dermatemys: only southern Mexico

Emydidae:

Distribution

• North and Central America
• Brazil
• Europe
• NW Africa
• W Asia

Geoemydidae:

Distribution

Tropical/subtropical regions of:

• N Africa
• Asia
• Europe

Rhinoclemys:

• Central & South America

Testudinidae:

Distribution

• temperate/tropical regions worldwide
• not Australia

Caretochelyidae/Trionychidae:

Distribution

• North America
• sub-Saharan Africa
• SE Asia

Carettochelys:

• Australia
• New Guinea

Chelydridae:

Habitat

• various freshwater/brackish habitats
• lots of aquatic vegetation
• Chelydra serpentina very pollution tolerant

Cheloniidae/Dermochelydae:

Habitat

• semi-aquatic
• slow-moving streams, lakes
• lots of vegetation
• Dermatemys more aquatic, only leaves water to lay eggs

Emydidae:

Habitat

• semiaquatic (Terrapene is terrestrial)
• ponds, streams, rivers
• Diamondback terrapin: coastal marine/brackish water

• freshwater ecosystems
• marine areas
• tropical forests

• terrestrial
• diverse habitats

• all completely aquatic
• large streams/rivers

Chelydridae:

Diet

• omnivorous
• fish, frogs, snakes, molluscs, crustaceans, aquatic plants, turtles

Cheloniidae/Dermochelydae:

Diet

• marine plants/animals attached to substrate
• leatherback: primarily jellyfish

Dermatemydidae/Kinosternidae:

Diet

Kinosternids:

• carnivorous
• aquatic insects, molluscs, crustaceans

Dermatemys:

• herbivorous
• aquatic plants

• most omnivorous
• some species carnivorous

Geoemydidae:

Diet

• herbivorous
• omnivorous
• carnivorous

Testudinidae:

Diet

• most herbivorous or omnivorous
• dependent on plants

Caretochelyidae/Trionychidae:

Diet

• most carnivorous
• fish, molluscs, crustaceans, carrion
• Carettochelys omnivorous

Testudines:

Families with sex chromosomes

• Geoemydidae
• Caretochelyidae/Trionychidae

Chelydridae:

Reproduction

• lay eggs in nests away from water
• high hatchling/egg mortality

Cheloniidae/Dermochelydae:

Reproduction

• lay eggs every 2-4 years on tropical/warm temperate beaches, at night
• extensive migration to breeding areas
• use Earth's magnetic field to find natal beach

Dermatemydidae/Kinosternidae:

Reprodction

• lay eggs in shallow nests near water
• hatchlings often confused by artificial light

Emydidae:

Reproduction

Geoemydidae:

Reproduction

• several small clutches of eggs/year
• contains species with temperature-dependent sex determination and species with sex chromosomes

Testudinidae:

Reproduction

• small clutches, buried in holes

• females dig nests into sand/gravel near water
• genetic sex determination

Chelydridae:

Miscellaneous

• vicious temper, strong bite
• Alligator snapper has predatory lure inside mouth

Cheloniidae/Dermochelydae:

 Miscellaneous

• leatherback has spines in mouth/esophagous to swallow jellyfish, but dangerous for plastic bags

Emydidae:

Miscellaneous

• often kept as pets
• like to bask
• can live over 100 years

• ~70% of living species are endangered/vulnerable

Testudinidae:

Miscellaneous

• often used as fresh meat by sailors during exploration

Caretochelyidae/Trionychidae:

Miscellaneous

• good swimmers and runners
• bad temper, biters
• can exchange gas through skin in both water and air
• females usually larger than males