----- Forwarded message from Sive
Finlay <[email protected]> -----
Date: Tue, 12 Mar 2013 08:18:28
-0400
From: Sive Finlay <[email protected]>
Reply-To: Sive
Finlay <[email protected]>
Subject: Choice of 2D image orientations
for comparing skull morphologies
To:
[email protected]
Dear all,
In the literature on 2D morphometric comparisons of
mammalian skull shapes I've noticed some variation among studies in which skull
orientations are used i.e. some include landmarks on the ventral side of the
skull only, or else various combinations of landmarks on the ventral and/or
dorsal/ lateral views of the skulls.
Are there any particular rules or recommendations that
dictate which skull orientations to include in a study or does it just depend on
your research questions and study species?
For my own purposes, I'm comparing skull morphologies across a wide range
(n=110) of insectivore mammal species. I'm interested in quantifying the
similarities among overall skull shape (relative length of the rostrum, height
and shape of the braincase etc.) with particular emphasis on the dentition.
Since I'm looking at a large number of species there is considerable variation
in their skull morphologies which makes reliable identification of homologous
landmarks very tricky. I can locate landmarks on the ventral and lateral views
of my skulls but dorsal views are more difficult for many reasons (suture lines
are not visible in all species and zygomatic arches are only present in some
species etc.)
My current plan is to use a combination of landmark and
sliding semilandmarks to compare images of skulls in ventral and lateral
orientations and use outline (Fourier) analysis of the overall skull shape in
the dorsal orientation. I think this combination of approaches would allow me to
compare both overall skull shape and relative proportions as well as more
detailed analyses comparing species' dentitions.
Are there any technical/ best practice reasons not to take
this combined approach?
Thank you for your
help
Best wishes
Sive
Sive Finlay
IRC EMBARK Initiative Postgraduate Scholar
Macroecology and Macroevolution Research
Group
Zoology
building
----- End forwarded message
-----
