[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Scales, hair, integumentary structure relationships?
So what of the dermal scales, if some caecilians have dermal scales, does
this imply the trait was lost after the amphibian amniote split?
Or is it more likely the caecilians re-evolved/reverted to dermal scales
(atavism) - which isn't too unlikely.
I completely forgot to mention that the albanerpetontids, known from the
Middle Jurassic to the late Pliocene and probably the sister-group of
Lissamphibia, had well-ossified scales all over their bodies.
Also, the caecilians are the sister-group of the frogs plus salamanders. So
it seems that the loss only happened during the origin of the
A few years back they found a mutant chicken with teeth in its beak -
Really? Can you give us a source for that?
the dermal scales could have been absent in the common ancestor of
amniotes and amphibians, and the genes for dermal scales later
re-activated in the caecilian lineage?
Unlikely, see above.
Some birds (hoatzin, african touraco, the ostrich?) seem to have
re-evolved claws, using the genes already present in their genome
No, most extant birds have small claws on one or two fingers per wing. Check
out the next chicken or turkey on your table!
Its kind of funny to imagine the confusion that would happen if 50 million
years from now, the only chicken fossils known (to whatever palentologists
are still here, of whatever species) had teeth and claws- wouldn't that
make placing them on a tree hard?(would they try to group it with more
primitive toothed birds?)
That would just be two characters out of several hundred (assuming today's
methods of phylogenetics). It would hardly matter.