[Taxacom] new ear synapomorphy

[John Grehan]

Scientists probably rarely stick their neck out with a prediction until
all the data is in, but I'm going to stick my neck out anyway. I have
started a web reference page of images for the external ear of primates.
I started this project to test out an impression I had about a possible
unique similarity between humans and orangutans. I am at the point where
I have at least enough comparison to make a prediction and we can then
see how it pans out as I am able to obtain a full range of images. So
the following observations refer to what I have from a very small and
non-replicated sample (except in the case of humans where I have been
able to look at a lot of ears - not that the subjects were aware!).

 

Humans have a very close juxtaposition of the inner and outer helix
about midway. Monkeys do not appear to show this feature (but of course
I have a lot of species to cover yet). According to a single image from
Schultz (144) gibbons do not show this feature. Chimpanzees, bonobos and
gorillas do not show this feature. Instead, like monkeys, they have a
relatively wide spacing between inner and outer helix so that they run
more or less parallel. In gorillas there is a structure not found in any
other primates except, perhaps some chimpanzees. This is a transverse
connecting bar between inner and outer helix about midway. 

 

My impression of orangutan ears for pictures of whole animals was that
they are also like humans in having a close middle juxtaposition of
inner and outer helix. I now have a diagram by Schultz (1968) indicating
that this appears to be the case (see my web page at
http://www.sciencebuff.org/externalear.php)

 

So I am predicting at this time that the orangutan and human ear shares
at least one unique structural feature while chimpanzees and gorillas
not only fail to share this feature, but may also be characterized by
their own unique feature in the form of a connecting cross-bar. These
features make phylogenetic sense if chimpanzees and gorillas are sister
groups, and humans and orangutans are sister groups. 

 

The challenge now lies in obtaining a full range of high quality images.
If any on this list have such images or have contact who could help I
would be most grateful.

 

John Grehan 

 

 

Dr. John R. Grehan

Director of Science and Collections

Buffalo Museum of Science1020 Humboldt Parkway

Buffalo, NY 14211-1193

email: jgrehan at sciencebuff.org

Phone: (716) 896-5200 ext 372

 

Panbiogeography

http://www.sciencebuff.org/biogeography_and_evolutionary_biology.php

Ghost moth research

http://www.sciencebuff.org/systematics_and_evolution_of_hepialdiae.php

Human evolution and the great apes

http://www.sciencebuff.org/human_origin_and_the_great_apes.php