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NFC: DP -- Turtles
There was some discussion on one of the lists a few weeks back about
turtles and why they are more closely related to mammals than amphibians,
lizards and snakes. Well, here is a brief explanation.
Basically the first point involves the turtles extremely long history.
They diverged from the earliest chordate ancestors before or at the same
time as the dinosaurs. The pelycosaurs split at approximately this time
as well and eventually their line gave rise to the mammals. Thus, the
mammals, reptiles and turtles evolved on separate lineages and are not
evolved one from the other.
Second is the skull characteristics. Turtles have a skull type known as
the "anapsid" skull. Meaning there are holes in the skull for the eyes,
nostrils and one 'extra' hole (known as the anorbital finestra) between
the eye socket and nostril. This is the primitive skull type that was
retained from the early ancestors of all chordates. Mammals developed a
"synapsid" skull, which if memory serves has no extra holes in it while
the reptiles, amphibians and birds have a "diapsid" skull which has two or
more additional holes in it. Scientist contend that since the turtles
have retained the ancestral skull after millions of years that they did
NOT evolve from reptiles, but again are their own separate lineage.
I believe recent DNA test have also shown turtles to have a closer
relationship to mammals than to reptiles. This revelation is
controversial to say the least and while it is accepted around the people
in my university and I believe at the University of Kansas, it is not
universally accepted yet.
Well, that's my review of "General Zoology" for this semester. I got a B
in the class so hopefully I learned something and have passed the
P.S. I presented this from an evolutionists point of view, but in case
any of you were suddenly thinking I had 'converted', I still think
evolution is a crock...at least as explained in it's current form... :-)