Gnathostome Flashcards
what are gnathostomes?
jawed vertebrates
what are chondrichthyans?
composed of cartilage
sharks, rays, skates
what are ray-finned fish?
have long thin rods in fins
modified for maneuvering, defense
originated in silurian
what are lobe-finned fishes?
rod like bones surrounded by thick muscle in pelvic and pectoral fins
three surviving lineages - tetrapods
what are tetrapods?
limbed vertebrates
features of tetrapods?
four limbs, feet with digits
a neck, which allows separate movement of the head
absence of gills
ears for detecting airborne sounds
how did tetrapods originate?
from lobe finned fish
share traits like ribs, shoulders, but also fins, scales
tiktaalik could walk on fins in water
types of amphibians?
frogs - tail-less
salamanders - tails
caecilians - blind resemble worms
what are amniotes?
have a terrestrially adapted egg
features of amniotic egg?
amnion, chorion, yolk sac, allantois
encloses embryo in fluid filled sack
features of reptiles?
scales - waterproof
lay eggs on land
internal fertilisation
origin of reptiles?
diapsids - holes on each side of skull behind eye
features of birds?
keratin feathers, weight saving adaptions - only one ovary, small gonads, loss of teeth
origin of birds?
descended from dinosaurs, feathers evolved before flight - insulation, courtship
what are ratines?
flightless birds
