[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Reptilian Subclass Parareptilia?
This is indeed a confusing mess, and until the origins of turtles (in
particular) are cleared up, it is going to remain that way. So you were
correct in surmising that there is no simple answer.
The three main competing phylogenies seem to be: (1) parareptiles
include turtles, but exclude Mesosauridae; (2) parareptiles include
Mesosauridae, but exclude turtles; and (3) parareptiles (sensu stricto)
exclude both mesosaurs and turtles. If you had the fourth possibility
(they include both mesosaurs and turtles), I think many workers would just
call them Anapsida .
I personally don't recognize formal intermediate taxa (like
subclasses), and this situation is a very good example why. I just
recognize formal reptilian Orders (which are relatively stable), with a
simple (alphanumeric) code which shows their purported relationships to one
another (within Class Reptilia).
Back in 1994, I placed Orders Testudiniformes (turtles) and
Procolophoniformes next to one another and coded them as sister groups.
Today I would move Order Testudiniformes down among diapsids, probably next
to Sauropterygiformes (but noting that turtles may actually even be close to
the base of archosaurs).
Formal subclasses (and other intermediate taxa) tend to generate
confusion and clog the nomenclature with too many names. But if I *had* to
recognize reptilian subclasses today, I would probably place turtles in
their own subclass, and the rest of the anapsids into two or three other
subclasses. But most of them would only have one Order, so it would be kind
of silly. Therefore I prefer to just have a list of stable Orders and
change the coding when new knowledge becomes available. Unfortunately the
strict cladists and the strict eclecticists prefer to continue standing
their ground and snarl at each other, rather than exploring such middle
ground approaches to classifications. So it goes.
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp