Amniotes / Reptilia ch. 25

Amniotes define

vertebrates with an amniotic egg (mammals, reptiles, birds)

Amniotic egg characteristic

four extraembryonic membranes; highly vascularized; mineralized but flexible egg shell

Four extraembryonic membranes

amnion (encloses the embryo in fluid), allantois (forms a sac to store metabolic wastes), chorion (surrounds the entire contents of the egg), egg shell

Amniotic egg shell define

mechanical support; limits water loss

Advantages of amniotic eggs

laid in dry places; larger, faster-growing embryo; calcium deposited for consumption

lung surface area

amniotes > amphibian

Reptiles characteristics

Ectothermic; one occipital condyle; brain developed

occipital condyle define

bony bump that connects to the first vertebraa

homodont define

teeth are all similar in function and shape

Crocodilians heart

2 atria and 2 ventricles (4 chambered heart)

Beta-kerating protein define

less respiration, less dehydration

osteoderms define

bony plates in dermis beneath the keratinized scales (crocs, turtles, skinks)

Todays turtles characteristics

lack teeth and the jaws have tough, keratinized plates for gripping food

shell on turtles

outer layer (keratin), inner layer (bone)

Reptiles sex assignment

temperature dependent sex determination (lack sex chromosomes); Low = male; high= female

Sphenodonta - Tuataras

New Zealand; slow growing and low reproductive rates, skulls in Mesozoic layers; well developed median parietal eye

Squamata - Lizards and Snakes

95% known species; kinetic skulls (movable); Joints help to open mouth and manipulate prey and increase effective closing force

snake neural spine define

a dorsal projection of a vertebra that functions as a muscle attachment site

Glottis define

a tracheal opening that is thrusted forward between the two mandibles to allow the snake to keep breathing when swallowing large prey

Jacobson’s organs define

a pair of pitlike organs in the roof of the mouth

Snake venoms (most are combination)

Neurotoxic (nervous system), Hemorrhagin (destroys red blood cells)

Thecodont define

teeth that are set in sockets

Temporal fenestrae define

bilaterally symmetrical holes in the temporal bone of skulls

Fenestrae define

openings in the skull or other bones in vertebrates

Vertebrate skull fossils

synapsid, diapsid, anapsid

Dinosaurs groups

Saurischia, Ornithiscia

Saurischia define

Lizard-hipped; three pronged pelvis with hip bones arrangement

Ornithiscia define

Bird-hipped; punis is rotated backward, parallel with ischium

Saurishchia characteristics

Theropods (carnivores and bipedal); Sauropods (Herbivorous and quadrupedal)

Ornithiscia characteristics

all herbivores; armored; bonehead and horned; duck billed and small bipedal dinosaurs