roadkills and cracks

[David Peters <davidrpeters@earthlink.net>]

Andrew Farke wrote: >>I would add to Jaime's comments that photos
sometimes show things that don't
exist. The placement of lighting during photography and the interplay of

shadows can be a major issue with interpreting photographs. A
particularly
personal example occurred while I was writing up my Torosaurus
description
recently--I had taken very careful notes and photographs when I was at
the
museum, and then typed them into the manuscript. Later, back at home, I
read
over the manuscript with the photographs beside me, to cross-check
things.
In a close-up photo of the lateral surface of the skull, I noticed what
appeared to be a suture that I had missed--something very important for
phylogenetic analysis. It looked *incredibly* like a suture to me, based
on
the photograph. . .however, careful checking with my original notes
(taken
with the original specimen in front of me) revealed that this "suture"
was
clearly a crack in the bone (I even went so far as to explicitly note it
as
such, while at the museum). One wonders how often this potential mistake

happens when people try to interpret the squashed Chinese material from
photographs. . .

In favor of photographs, I will add that *sometimes* they can show the
difference between plaster and real bone (the Yale Toro skulls come to
mind.
. .), although this must always be checked against the original.

*********

True. Very true.

And the converse is also true. Go to any reference on pterodactyloids
and look for the anteriormost extent of the jugal. If indicted at all it
usually can be found to terminate somewhere ventral to mid antorbital
fenestra. Nearly everyone misses that portion that sneaks past the
anterior of the antorbital fenestra, first revealed to me by
photographs. It's a synapomorphy that looks like a crack.

And speaking of cracks, there are often two or three cracks in the
rostrum of pterosaurs that look like they could be the
premaxilla-maxilla suture. Very confusing. The one that is correct, it
turns out, is the one that separates the first four teeth from the
others - except in ctenochasmatids in which the teeth appear to be
budding off from each other like Mickey's broomstick in Fantasia.

As I said, it takes observation _and_ recognition.

David Peters