Reptiles Flashcards
three key extant reptile orders
Testudines, Squamata, and Crocodilia
shared characters of reptiles
poikilothermic, keratinized skin (not homologous to fish scales, derived from epidermis), skin sheds (except in Crocodilians)
reproduction in reptiles
internal fertilization, lay external amniotic eggs, limited parental care (except in Crocodilians)
order of Reptilia containing turtles
order Testudines
general characters of Testudines
living fossils, have thick shell that grows with the body, super low metabolic activity
type of skulls seen in Testudines
anapsid skulls
structure of Testudines shell
top is carapace, bottom is plastron, made from vertebra and shell fused together
respiration in Testudines
shell prevents expansion of ribs for breathing, so legs regulate lung expansion instead. can also pump water in and out of the cloaca to directly absorb oxygen into the blood
reproduction in Testudines
have TSD – temperature determines sex of offspring, with cooler weather leading to more males and warmer weather leading to more females
order of Reptilia containing lizards and snakes
order Squamata
suborders contained within order Squamata
Lacertilia and Serpentes
suborder of Squamata known as lizards
suborder Lacertilia
suborder of Squamata known as snakes
suborder Serpentes
key differences between snakes and lizards
snakes evolved once from lizards, snakes lack external ear openings, lizards have eyelids
most important sense in snakes
scent
organ in snakes used for olfaction
Jacobson’s organ
locomotion in snakes
move by pushing on various points in the body with unidirectional scales on ventral surface for traction
internal anatomy of snakes
many paired organs become singular due to the length and small width of the snake body
skull of snakes
kinetic skull, bones can unhinge to accomodate large prey
different toxins used by snakes
hemotoxins (breaks down tissue) and neurotoxins (paralyze nervous system)
movement in lizards
arms set perpendicular to the body make breathing while moving impossible
general characters of Crocodilians
oviparous, four-chambered heart, have heavy armor-like scales, complete secondary palate, have TSD
two major groups of Dinosaurs
Ornithischians and Saurischians
general characters of dinosaurs
limb attachment underneath torso, likely endothermic
group of dinosaurs with pelvises shaped like extant lizards’
Saurischians
group of dinosaurs with pelvises shaped like extant birds’
Ornithischians
characters of Ornithischians
beaked herbivores, quadrupeds
characters of Saurischians
some herbivorous, some predatory, many bipedal
group of dinosaurs that gave way to birds
Saurischians
very important dinosaur fossil that gave evidence of feathered dinosaurs
Archaeopteryx
extinction event that killed 75% of all earth species
K-Pg extinction
date of K-Pg extinction
65 MYA
