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Re: Unorthodoxies in Reptilian Phylogeny [Romer 1971]
As for the antorbital fenestra in
Varanodon, from what I can tell it seems to be a fenestra above the
maxilla dorsal process and behind the septomaxilla, while the
archosaurian equivalent is of course posteroventral to the maxilla
dorsal process. So non-homologous anyway.
Worse yet, it's probably simply not there. It's just damage to the very
thin lacrimal which stretches (plesiomorphically) from the orbit to the
naris. In Olson 1965, the "fenestra" is shown as so big that it
completely separates the lacrimal in two!
Ironically, the two taxa
listed as linking the captorhinomorphs and archosaurs by Romer
(Mesenosaurus and Elliotsmithia) are now recognized as varanopid
synapsids. So his ideas were no better, merely deriving archosaurs
from generalized "captorhinomorphs" like all other reptiles.
Having read the paper, I'd say Romer was wrong for the right reasons,
and Reig was wrong for the wrong reasons :o)
He apparently had no good evidence for the other clades
being derived separately and Romer noted the high degree of
homoplasy that would entail.
Kuhn-Schnyder was simply the epitome of mid/late-20th-century
phylopessimism: people had come to realize that there was no such thing
as a reliable character, that everything could evolve twice or three
times or six times, and cladistics was unknown to paleontologists -- so
they started to view phylogenetics as a more and more speculative art,
and what hypotheses they did commit to were based on scenarios. The idea
of amniote polyphyly goes back to von Huene in the 1950s and probably
earlier, Säve-Söderbergh in the 1930s, and probably others earlier. In
fact, the only vertebrate "class" whose monophyly wasn't doubted were
the birds, whose direct descent from *Archaeopteryx* was somehow taken
for granted; bird polyphyly had to wait for Kurochkin 1996.
He also thought placodonts and sauropterygians
were distantly related because the former have a broad bone ventral
to their temporal fenestra but the latter have a narrow bone.
Too bad that Romer didn't know about *Paraplacodus* yet, which has a
very narrow upper temporal bar -- looks like a lizard.
Romer derived euryapsids from protorosaurs, in
which he also included the basal diapsid Araeoscelis and the
archosauromorph Trilophosaurus. It seems he was incorrect.
Romer's concept of Euryapsida was a bit of a wastebasket taxon for
everything that had an upper temporal fenestra and hadn't completely
obviously lost the lower one secondarily. Today only the placodonts and
the sauropterygians stay in, and possibly the ichthyosaurs (Romer:
Parapsida) and, if the ichthyosaurs are in, the thalattosaurs (Romer:
Diapsida -- in the wastebasket "Eosuchia").
> How unorthodox was Romer in 1971?
LOL! Whatever Romer said after about 1940 was by definition orthodox
till long after his death! :-D In the 1990s I personally witnessed an
ammonite specialist (but in charge of all paleontology in the museum in
Vienna) take the somewhat tentative opinions in Romer's 1966 textbook as
completely unquestionable fact.