Reptiles!!!

Classification

• Kingdom: Animalia• Phylum: Chordata• Subphylum: Vertebrata• Class: Reptilia– Orders:• Crocodilia• Sphenodontia• Squamata• Testudines

Characteristics

• Ectothermic(Cold-blooded)• Regulate body temperature by seeking

or avoiding sun.• Air Breathing • Tetrapods• Scales instead of feathers or hair• Three and a half chambered hearts• Most lay eggs• Amniotes!

Evolutionary Milestone

• The Amniote Egg– Adapted for land.– Allows for full

development inside safety of egg.

Reptile History

• First reptiles appeared around 380 million years ago, during the Pennsylvanian time period, when the climate was warm and humid, and amphibians dominated.

• Many different reptile species appeared during the Triassic, which had a drier, cooler climate.

• Today, 6,500 species of reptile walk and slither on the Earth, and reside on every continent, except Antarctica.

The Four Reptilian Orders

CrocodiliaTestudines

Squamata Sphenodontia

Sphenodontia

• 2 species of Tuatara living in New Zealand; all others went extinct 60 mya.

• Has not changed in 225 million years

• Living fossil!• They have a 3rd

“eye”, have no external ear openings, and males lack a penis.

Crocodilia

• Appeared 85 mya• Large reptiles with

elongated head• Alligators,

Crocodiles, Caimans, and Gharials

• 4 Chambered Heart• Teeth in bony socket• Closest living

relative to birds.

Testudines

• Turtles and Tortoises

• Bodies with two-piece bony shell – Carapace: dorsal;

arose from ribs– Plastron: ventral

• Appeared in fossil record 220 mya

Squamata

• Lizards and snakes• 5640 species!• Tough epidermal

scales made of keratin

• Possess moveable quadrate bone.

• Most variable order in size