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Re: the SVP pterosaur talks - rather long reply



I had been going to refrain from responding to the two recent posts in which
David Peters rejected my interpretations of specimens, but seeing that Tom
Holtz had written "George, you have NEVER SEEN the three new taxa: how can
you *POSSIBLY* have an informed opinion on them?" emboldened me.

In his post on the pterosaur talks at SVP, David Peters commented on my talk
and wrote:

"it [the specimen] is not Anurognathus..."

"the lacrimal is a long slender stem (identified as the "pterygoid"...)"

"the lateral pedal digit is too short for Anurognathus"

"all these characters are a good fit for something closer to Batrachognathus
or Dendrorhynchoides"

"Chris's reconstruction included some strange combination of lacrimal, nasal
and jugal ... that resulted in making the antorbital fenestra virtually
disappear"

"a more typical pterosaur skull can be recreated when the lacrimal is
properly placed."


As far as I know David has never examined the specimen I described, and has
not even seen close-up photos of it. David did not talk to me about the
specimen or my reconstruction, and therefore he is totally unaware of the
evidence that supports my interpretation.  As I understand it, David has
based his interpretation of the skull of Anurognathus entirely on published
photographs of the holotype, which he has scanned and manipulated. So let's
look at his statements:

1.  "it [the specimen] is not Anurognathus..." - Notice that this is a
direct statement of fact--it is not presented as an opinion.  This
conclusion was presumably based on David's photointerpretation of the
holotype specimen plus his brief exposure to the new specimen by way of my
talk.  I spent a great deal of time studying the specimen [and the holotype
specimen after interpreting the new specimen!] and what I presented in my
talk barely scratches the surface of what is in my manuscript.  I am well
aware that my interpretation of the skull of the holotype is quite different
from David Peters' interpretation of the skull of Anurognathus, but I can
find no evidence to suggest that the new specimen is not conspecific with
the holotype.  I should note that I am a lumper, and given two specimens
from the same locality I will assume that they are the same taxon unless I
can find evidence that they are not.  Perhaps David is a splitter and starts
from the assumption that all specimens are different unless he can find
evidence that they are the same; if so, there is no point in further
discussion as we are not speaking the same language.

2.  "the lacrimal is a long slender stem (identified as the
"pterygoid"...)" - I do not know what methodology David is using to enable
him to interpret the bone that I identify as the pterygoid as the lacrimal,
but I have relied on the usual combination of topology and homology.  Given
that the skull shows no disturbance other than simple crushing, I do not
understand how the lacrimal could end up well behind the sclerotic ring,
lying ventral to postorbital, and adjacent to the ventral end of the
quadrate.

3.  "the lateral pedal digit is too short for Anurognathus" - Notice that
this is a direct statement of fact--it is not presented as an opinion, nor
is it supported by any evidence.  One of the distal phalanges of the pedal
digit V was incomplete, and its tip broken off.  Perhaps David was basing
his statement on the incomplete digit.  However, even if he is basing his
statement on the complete digit, it reflects typological thinking.  The new
specimen is about 55% the size of the holotype and given only two specimens
we simply do not have any information other than those two data points as to
the allometric growth of pedal digit V or any other structure.  Therefore,
the difference in relative length of the toes of the two specimens, which
incidentally is minor percentagewise, cannot be shown to be significant.

4.  "all these characters are a good fit for something closer to
Batrachognathus or Dendrorhynchoides" - David seems to be of the opinion
that Anurognathus is quite different from Batrachognathus and
Dendrorhynchoides.  I used to think that Peter Wellnhofer's reconstruction
of the skull of Anurognathus was pretty good given the scrappy preservation
of the specimen, and viewed from that mindset Batrachognathus and
Anurognathus seem quite different.  However, after my examinations of the
new specimen and reexamination of the holotype, I realized that there is a
wholly different way to interpret the holotype skull, and it seems to me
that the holotype skull is quite similar to that of Batachognathus given the
different mode of preservation.

5.  "Chris's reconstruction included some strange combination of lacrimal,
nasal and jugal ... that resulted in making the antorbital fenestra
virtually disappear" -  My reconstruction did have an antorbital fenestra,
which lies just where one would expect it in relation to the naris and the
circumorbital bones.  Note that unless one wished to argue that the
sclerotic ring is moved anteriorly, there simply is not much room anterior
to the orbit for the naris and antorbital fenestra.  I do not doubt that the
antorbital fenestra is smaller than David thought it should be, but I
suspect that his ideas about the size of the antorbital fenestra are based
on incorrect interpretations of the skulls of the holotypes of Anurognathus,
Dendrorhynchoides, and Jeholopterus.  If anyone takes the time to look at
the descriptions and illustrations of the skulls of Dendrorhynchoides [see:
Ji Shu'an and Ji Qiang. 1998. A new fossil pterosaur (Rhamphorhynchoidea)
from Liaoning. Jiangsu Geology, 22:199-206. [In Chinese]; Unwin, D. M., Lü
Junchang, and  N. N. Bakhurina.  2000.  On the systematic and stratigraphic
significance of pterosaurs from the Lower Cretaceous Yixian Formation (Jehol
Group) of Liaoning, China. Mitteilungen aus dem Museum für Naturkunde in
Berlin, Geowissenshaftlichen Reihe, 3:181-206.] and Jeholopterus [see: Wang
Xiaolin, Zhou Zhonghe, and Zhang Fucheng.  2002.  A nearly complete
articulated rhamphorhynchoid pterosaur with exceptionally well-preserved
wing membranes and "hairs" from Inner Mongolia, northeast China.  Chinese
Science Bulletin, 47:226-230.] you will see that the skulls are badly
crushed, yet David has produced complete 3D reconstructions of the skulls
without ever seeing them.  These are again based on scanning and
manipulating photographs, but such a methodology is fraught with
difficulties.  For example, I think that an interpretation of the skull of
the new specimen based only on a photograph of the skull would probably be
incorrect (and here I'm just talking about morphology, not homology) because
of variable iron-oxide staining of the bone and the adjacent limestone. I
will readily acknowledge that the skull that I reconstructed seems quite odd
when compared to what we might think of as typical pterosaurs (e.g.,
Rhamphorhynchus), but I based my description and reconstruction of the skull
on microscopic examinations of the specimen and merely attempted to describe
what is there and interpret it within the context of what we know of the
archosauromorph skull.

6.  "a more typical pterosaur skull can be recreated when the lacrimal is
properly placed" -  Note that David can determine this based on his brief
exposure to my line drawing of the skull as preserved and my skull
reconstruction during my talk--Amazing!  While it may be possible to
recreate the skull as a typical pterosaur skull, that was not my goal.  My
goal was to describe and interpret the specimen as it is, not as something
that I would like it to be.


I would suggest that people refrain from commenting on the new specimen
until they have actually examined it, and also that people refrain from
rejecting my interpretation of the skull until they actually understand it.
As Tom Holtz has so often suggested, wait for the paper.

In closing, if any dinolisters out there still think that David Peters knows
what he is talking about when he rejects my interpretations of the new
specimen, please contact me immediately--I happen to know a nice,
well-connected gentleman in Nigeria, who has a fantastic business
proposition, which I am, unfortunately, unable to accept.

Best wishes.

Chris