Animal Diversity Unit 3 notes

Unit 3
Orders
Squamata
(Class Reptilia, Subclass Dispsida, Superorder Lepidosauria)
- Lizards
- 95% of living reptiles
- Lizard fossils: Permain -> Cretaceous
- Snake fossils: Jurassic
- Diapsid skulls

Sphenodontia
(Class Diapsida, Superorder Lepidosauria)
- Lizard-like
- Well-developed median parietal/pineal eye buried beneath its skin
- Hooked-beak like structure

Crocodilia
(Class diapsida, superorder Archosauria)
- Descendants from Thecodonts
- Archosaurian lineage gave rise to the Mesozoic diversification of dinosaurs and
to birds
- Lineage appeared early triassic
- Large, solid reptiles with flattened snout and laterally-compressed tails
- Eyes, ears and nostrils on top of head
- Semi-aquatic
Family…
- Crocodylidae
- Alligartoridae
- Gavialidae



Classes
Diapsida
Contains (orders):
- Testudines
- Squamata
- Sphenodonta
- Crocodilia
- dinosaurs

, Squamate skulls (lost bone)
- Permitting evolution of a mobile kinetic skull with moveable joints
- Squamates seize and manipulate prey, close jaw with force
- Extreme skull mobility of snakes lead to major diversification

Squamate (lizards)
● Geckos
○ Small, agile, nocturnal forms
○ Adhesive toe pads allow for surface sticking
● Iguanids
● Chameleons
○ Arboreals lizards
○ Extendible tongue
● Skinks
○ No visible neck
○ Smooth shiny scales
○ Small legs
● Monitor lizards
○ The only venomous lizards
○ Typically large and carnivorous

Squamates (snakes)
● Limbless
○ No pectoral or pelvic girdles
○ Short, wide vertebrae
○ Many ribs
○ No eyelids or external ears
● Evolved in the cretaceous from burrowing lizards
● Uses venom, teeth, and constriction to eat without limbs

Skulls and jaws
● Bones not connected (kinetic skull)
Sensory systems
● Poor vision (not tree snakes)
● Binocular vision
● No ears
● Chemical senses
○ Temp-sensing pits