[Taxacom] Chimps and humans

John Grehan jgrehan at sciencebuff.org
Sun Sep 6 09:05:22 CDT 2009

I found I did have the Braga article in my files and had read it at some
time in the past. If found the content to be somewhat confusing and it
was problematic for the lack of detailed comparisons with letters apes
and monkeys.

The abstract refers to "The complete absence of a retroarticular canal
can be considered as a synapomorphy supporting the human-African ape
clade and excluding Pongo.", but in their Table 2 they give observed
frequencies in African apes of 4.2-33.8% (compared with 40-60% in
orangutan). But I could not fine any measurements given for humans.
Braga also states a complete absence of a retroarticular foramen in
humans and African apes on p. 150 so I am confused over whether foramen
and canal are interchangeable or not, and if they are then there is some
contradiction as further on there is reference to the presence of the
retroarticular foramen being 'more general' than its absence.

Strait and Grine 2004 accept Collard and Wood that the condition of the
orangutan is autapomorphic, so some contradiction here. I'll take
another look at this, particularly to clear up my confusion over
reference to a retroarticular canal vs retroarticualr foramen.

Of course none of this matters if it cannot be treated as independently
valid evidence. If the pattern asserted in the article for humans and
African apes had been found between humans and orangutans it would have
just been written off.

John Grehan

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
> Sent: Saturday, September 05, 2009 9:30 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] Chimps and humans
> Dear All,
>        At the risk of opening a new can of worms. I wonder why the
> cause of malaria in orangutans (Plasmodium patecki) is related to
> Plasmodium species that cause malaria in gibbons (not Plasmodium
> infecting the African ape clade).  Also, below are a couple of other
> papers that I ran across.   In particular, emissary canals also show
> orangutans showing the plesiomorphic pattern of gibbons and non-ape
> primates, while the African ape clade shares a synapomorphic pattern
> this regard.
>         -----Ken Kinman
> =================================
> Folia Primatol (Basel). 1995;65(3):144-153,
> Emissary canals in the hominoidea and their phylogenetic significance.
> Braga J.
> "Two emissary canals of the skull base (the retroarticular and
> canals) have been examined in a sample of 1,453 great apes. Our
> imply that emissary vein patterns are distinct for orang-utans and
> African apes. In orang-utans the temporal sinus is frequently present
> and the retroarticular canal is often present. Orang-utans show a
> different external venous system in which the condylar canal is very
> rare. In orang-utans the retroarticular canal resembles the more
> primitive structure in prosimians and is probably homologous with it.
> the African apes, as in humans, the temporal sinus regresses and the
> condylar vein is well developed. The complete absence of a
> retroarticular canal can be considered as a synapomorphy supporting
> human-African ape clade and excluding Pongo. The enlargement of the
> condylar vein is much more frequent in the common chimpanzee. The
> dominance of the condylar vein over the temporal sinus appears to
> progressively during great ape evolution."
> Also:
> =Morphometrics and hominoid phylogeny: Support for a chimpanzee-human
> clade and differentiation among great ape subspecies.
> Proc Natl Acad Sci U S A.  March 2004.
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