vertebrates; reptiles Flashcards
reptilia evolved form
amphibian ancestor 320 MYA
modern reptiles derived from 2 lineages
- parareptilia; turtles and tortoises
- eureptilia: lepidosauromorpha (snakes, lizards, tuatara) and archosauromorpha (dinos, crocs and birds)
parareptilia
turtules and torsoises
eureptilia:
lepidosauromorpha
archosauromorpha
lepidosauromorpha
snakes, lizards, tuatara
archosauromorpha
dinos, crocs, birds
4 orders of reptiles
- testudines; turtles, tortoises
- sphenodonta; tuatara
- squamata; lizards, snakes
- crocodilia; crocs, alligators, caimans, gharials
largest species of testudines
leatherback
two groups of testudines are based on
- on how they withdraw neck into shell
- cryptodira; contract neck; marine turtles, most freshwater turtles, tortoises
- pleurodira; flex neck laterally; some species of freshwater
do testudines have teeth
no, keratinous ridges for grinding and slicing
cryptodira
contract neck; marine turtles, most freshwater turtles, tortoises
pleurodira
flex neck laterally
some species of freshwater turtle
unique features of turtle is
position of limbs within shell: ribs encapsulate the scapulae
sphenodonta
- tuatara,
- native to NZ,
- 2 species,
- lifespan of 100 yrs
- have teeth
- were considered most ancestral of amniotes but not
- diapsid skull
squamates
- lizards first then snakes from lizards
what percent of squamates are venemous
- 60%
- predominantly snakes but also 2 species of lizard: gila monster and mexican beaded lizard
squamates have moveable
- quadrate bones (open mouth real wide)
- allows greater range of motion of mandibles
crocodilia is the closest living relatives of
birds
largest species of crocodilia
australian saltwater croc
posture of crocodilia
- semi-sprawled
- allows them to gallop and go really fast
- ancestors were bipedal
crocodilian sprawled gait was a ____ trait
derived
2 main lineages of dinos
- ornithischia; bird hipped, herbivorous
- saurischia; lizard hipped
includes sauropods which are herbivores and therapods which are carnivores
oviraptor
egg thief
evidence of maternal care in dinos
dinos; therapods (carnivores)
embryos hatches from eggs in similar manner to modern birds
all reptiles must return to _____ to lay eggs or live young
land (exception is sea snakes)
distribution of reptiles is limited by being
ectothermic; body temp determined by environment
endothermic
body produces heat
ecothermic
heat absorbed from environment
homeothermic
body temp constant
poikilothermic
body temp varies
reptilia skin
thick, heavily keratinized stratum corneum
epidermal scales
keratin structures
large plate-like scales of reptiles are called
scutes
what are osteoderms
- plate of bones developed within the dermis
- additional support to epidermis
- crocs, testudines and some lizards
in turtles and toroises; osteoderms (aka plate of shells within dermis)
fused with ribs and vertebra
carapace and plastron
reptilia have ____ vertebra
cervical; with specialzied atlas and axis
describe reptile vertebra
- cervical with atlas and axis
- thoracic and lumbar kind of the same (not distinguished)
- 2 sacral vertebrae
- caudal vertebrae
reptile pectoral girdle
scapula, coracoid, clavicle and inter-clavicle
reptile pelvic girdle
ilium, ischium and pubis, but arranged different to mammals
limb bones of reptiles
similar to mammals
5 digits on each of manus and pes
two reptile skull types
anapsid; no fenestrae; ancestral, turtles and tortoises
diapsid; 2 fenestrae; dinos and cros, snakes, lizards and birds
reptile lungs
- paired
- many lizards have reduced left lung
- snakes have long thin lungs
- crocs and dinos have unidirectional flow like birds
reptile heart
- higher metabolic rate than amphibians
- greater oxygen demands than amphibians
- no typical reptile heart; differ between species
- separate pulmonary and systemic circulations
sexual dimorphisms in reptiles
minimal or non-existent
reptiles and reproductive
viviparous and oviparous or both
viviparous
fertilized eggs retained in oviduct; greater protection
oviparous
- oviduct deposits albumin shell membrane and shell
- in turtles and crocs Ca2+ frp, shell used for calcification of embryonic skeleton
- yolk is source of food
parthenogenesis
- female produces fertilized egg w no man
- embryo is derived from fusion of 2 eggs
- female lizards, fish, insects and birds
pterosaurs
big winged dinos except they are actually reptiles not dinos
