Re: Smallest flying vertebrate? Immature Anurognathus?

["Chris Bennett" <cbennett@bridgeport.edu>]

I apologize for the delay in replying to Patrick's question, I have been
porting everything over from my old computer to a new one and programs and
messages were in different places.  Perhaps I will finally have an end to
nine months of computers possessed by evil spirits, multiple hard drive
crashes, and a power supply that committed suicide, but not before frying a
beautiful dual CPU motherboard!  However, I am unsure that this is the end
as I have checked the box to insert ">" in front of quoted messages and yet
it has not done it.

----- Original Message -----
From: "Patrick Norton" <ptnorton@msn.com>
To: <cbennett@bridgeport.edu>; "dinosaur_1" <dinosaur@usc.edu>
Sent: Tuesday, December 04, 2001 5:15 PM
Subject: Re: Smallest flying vertebrate?


Chris Bennett wrote:

>As for Anurognathus, the specimen is small and cute and VERY immature.<

What is it about the specimen leads you to believe it's immature? I haven't
read Doderlein's 1923 description of _Anurognathus ammoni_, but Wellnhofer's
description of the specimen on pages 271-273 of "The Illustrated
Encyclopedia of Dinosaurs" (an odd name for a book that includes 170 pages
on pterosaurs) doesn't mention anything that would suggest it was immature
(BTW, there's a nice photo and drawing of the specimen on page 273 of that
book). I have no opinion either way, but I am curious--particularly because
of the emphasis you placed on it being >VERY< immature.

PTN
------ End of Original Message --------------------

 My interpretation of the type of Anurognathus as very immature is based on
size independent indicators of skeletal immaturity that I noted when
examining the specimen.  I have discussed the interpretation of relative age
in pterosaurs in three papers:

1993  Bennett, S. C.  The ontogeny of Pteranodon and other pterosaurs.
Paleobiology, 19:92-106.

1995  Bennett, S. C.  A statistical study of Rhamphorhynchus from the
Solnhofen Limestone of Germany:  Year-classes of a single large species.
Journal of Paleontology, 69:569-580.

1996b  Bennett, S. C.  Year-classes of pterosaurs from the Solnhofen
Limestone of Germany:  taxonomic and systematic implications.  Journal of
Vertebrate Paleontology, 16:432-444.

Note that I vaguely remember a talk at SVP two or more years ago, in which
someone (and I even more vaguely think that they were Peter Dodson or were
somehow associated with Peter Dodson [apologies to all concerned if I'm
wrong in my recollections]) discussed what I termed "immature grain" on
crocodilian bone.  They showed, not surprisingly that the immature
appearance resulting from deposition of new bone on a bone shaft could come
and go depending on whether the crocodilian was actively growing at the
time.  So be cautious is using "immature grain" as an indicator of of
immaturity.  In Pteranodon, which seems to have determinate growth, immature
bone was only present in those individuals that also exhibited other
indicators of skeletal immaturity (i.e., incompletely ossified epiphyses,
non-fusion of bone that fuse in adults).

I hope this answers your question.

Chris


S. Christopher Bennett, Ph.D.
Assitant Professor Of Basic Sciences
College of Chiropractic
University of Bridgeport
Bridgeport, CT  06601