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re: Cearadactylus sausages
David Unwin wrote:
Such a high incidence of homoplasy [80+ perecent] might suggest that
character definitions and scorings need some serious attention.
I'm not happy with the fact either, but data is data. I'm including
palates, rib counts, suture placements, etc. in my cladistic analysis --
"minor" characters that are more likely to follow genetic = cladistic
lines than the more obvious adaptational traits. Also included are digit
and phalanx proportions, sternal complex shapes and head sizes, traits
that are adaptations but do not typically appear on previous analyses.
870 steps. 1 tree. No unresolved nodes.
Peters also noted:
>3. Seven or more pairs of teeth in the premaxilla. (I wish you had
drawn the premax-max suture. Or noted it on a photo. You left it blank.
I draw things in when I can see them in the fossil, or there is clear
evidence for them in illustrations of the fossil material that has been
independently confirmed by others who have studied the actual material.
So in this case, since you did not draw the premax-max suture, by your
reply above I trust that you did not see the premax-max suture, there
was no clear evidence for same elsewhere and you did not trust the
independent confirmation by others (paraphrasing your words). A
premaxillary tooth count depends on where the line is drawn. Without a
line you have no reliable premaxillary tooth count. and without a number
higher than four, your hypothesis falls apart. You need to draw the
Peters also noted: >My scan [attached to personal email] shows that,
like all pterosaurs, except for the real ctenochasmatidae, only four
teeth appear in the premaxilla of basal ornithocheirds ( or
anhanguerids). Here the first premaxillary teeth are gone so three are
present. They are tiny in other forms you are aware of, so it's no big
loss. The suture is visible between 3 and 4. )<
DU wrote [and I'm glad to see the email did not bounce back this time]:
Peters' scan shows two squiggly lines drawn across the premaxillae and
descending between tooth position three and four. I can see no evidence
for a suture in such a position in the illustrations available to me,
and such a suture has not been reported by anyone else for
Cearadactylus. Typically there are four teeth in the premaxillae of
pterosaurs, so if Cearadactylus exhibited the standard condition I would
expect a suture (were it present and visible) to be located one tooth
position further back. Peters states that the first pair of premax.
teeth are gone, but presents no evidence to support this.
Here Dr. Unwin confirms that he is relying on illustrations available to
him, rather than photographs, published or otherwise. Reiterating from
above, in a degraded fossil such as Cearadactylus, a suture can look
like a crack and visa versa. In this case, I am merely pointing out an
overlooked alternative that is more in line with cladistically
established patterns throughout the Pterosauria. I found the suture and
draw the suture in every taxon.
RE: the absent teeth.
Other than what I already said (medial teeth are tiny = vestigial in
related forms), I can't give more evidence for missing teeth. They're
missing! Similarly, in forms in which the 4th wing
phalanx is missing, the related forms have a relatively small 4th wing
phalanx. This is where cladistics really helps. A cladogram shows that
this is the only clade in which the medial premaxillary teeth diminish
and ultimately disappear.
Peters also noted:
>You may have mistakenly assumed that the premaxilla began at the
beginning of the jawline "step." That's not true of Huanhepterus,
either, which also has only four premaxillary teeth and the rostrum is
neither compressed nor rounded, but "sags" ventrally at the tip.
So far as can be determined from figures of Huanhepterus (I have still
to see the original skull) the anterior region of the rostrum was
dorsoventrally compressed and rounded. If someone can provide photos or
drawings to show that this is not the case I would be most interested to
A nice photo may be scanned in Wellnhofer 1991. Note the extent of the
dorsal and ventral keels and the presence of tiny mid maxillary teeth, a
nasoantorbital fenestra and other wonders not apparent in the figures.
Peters also noted:
>4. Teeth project laterally...at least anteriorly. (also in:
Dorygnathus, Angustinaripterus, Haopterus and Diopecephalus).
< In most ctenochasmatids teeth stick our horizontally or sub
horizontally from the anterior part of the jaw. The anterior teeth of
Dorygnathus, Angustinaripterus and in fact most ornithocheirids show
some lateral flare, but are still largely sub vertical.
Peters also noted:
>6. Metatarsal III more than one third the length of the tibia (what
about nearly every long-tailed pterosaur, plus P. antiquus, and
at least one Germanodactylus?)
< Ctenochasmatids are clearly not 'rhamphorhynchoids' as I think anyone
can tell so I see no problem with this.
There are continuous characters that jump over the rhamph/pterodac
hurdle. For instance, some pterodacs, retain unfused basipterygoids,
many retain cervical ribs, and only one retains a peculiar sort of hip
only seen otherwise in Scaphognathus and Pterorhynchus. The anterior
projecting teeth is one such character that _almost_ (jury is still out)
makes it possible for the Pterodactyloidea to be biphyletic. David, you
should have seen how long the tails are on Pterodaustro at the SVP
poster session. Longer than the tibiae.
DU quoted from his text
>>An unusual feature of the mandibles is that they appear, in lateral
view, to achieve their maximum height toward the caudal end of the
symphysis, and are somewhat lower, though of about even height, from
this point to the articular region.
Not unusual at all: Tapejara, Pteranodon, P. antiquus, Anhanguera,
Moreover, as Leonardi & Borgomanero noted (1985), at this point the
mandibles are distinctly deeper than the corresponding region of the
rostrum, a proportion that is different from the typical condition in
pterosaurs where the rostrum is usually the deeper of the two (e.g.
Wellnhofer 1978). '
Also in Dsungaripterus, just before the crest. And in Istiodactylus and
Pteranodon. But otherwise, as you say, a bit unusual. Curiously, not to
be found in ctenochasmatids, including Huanhepterus, the purported
sister taxon, according to your paper.
This letter is getting long. I'll cut it short here.