Flashcards in chapter 17 (sarcopterygians) Deck (20):
what is a sarcopterygian?
lobe-finned fishes. COSMOID SCALES. 2 dorsals (unlike actinoperygian fishes)
layer of cosmine, thin hard layer of enamel, inner layer of spongy vascular bone, deep layer of lamellar bone. also, dentine
do lungfishes have cosmoid scales?
how does the lobed fins connect to more primitive fishes?
similar to the branching arrangement still embedded in the fins of paddlefishes, sturgeons and sharks.
2 primary groups of sarcopterygian fishes
dipnoi :the lungfishes
when did coelacanths first appear in history?
the Devonian period, "age of fishes"
other than lobed fins, what are the two combinations of characteristics for coelacanths?
large TRI LOBED TAIL (diphycercal tail)
an INTRACRANIAL JOINT (skull bens backwards!)
who found the first coelacanth in '38?
who tried to steal the fame for the first discovered coelacanth?
which dude is a major player in coelacanth research?
what are further characteristics found in LATIMERIA?
lungs (fat-filled sac)
bone much reduced
osmoregulation (retention of urea) THINK SHARKS
uniqure characteristics of the coelacanth
rostral organ (snout): electrosensory system
intracranial joint: head swing upwards
bony skeletons, heterocercal or diphycercal tail, heavy armor of thick cosmoid scales
dramatic reduction in bones, loss of the outer layer of scales, reduction in skull bones, loss of distinct fins, including tail.
modern lungfish are characterized by:
air breathing lungs
plate like teeth
spiral valve intestine
what can be said of fw preference and distribution in lungfishes?
evidence of continental break up since they're fw. (africa and s. america distribution)
why is Sir Richard Owen famous?
declared the lungfish a fish instead of an amphibian
crossopterygians must be the sister group of tetrapods
3 reasons why coelacanths have perhaps labyrinthodont linkage:
paired fins more like tetrapod than lungfish
bones of crossopterygians, particularily cranial, like labyrinthodonts
crossopts have specialized tooth structure like labs.