Great Apes again (was: Red Ape book...)
kinman2 at YAHOO.COM
Fri Jan 7 12:14:12 CST 2005
After reading the posting on the Red Ape book, I revisited John Grehan's potential synapomorphy listings once again. Quite a few of those listed for a hominid-orangutan clade still appear to be non-independent of one another and could be combined to produce a shortened list. At the same time, evidence for a Pan-hominid clade is downplayed, including the omission of characters such as: (1) axis of ear bones not at an acute angle (Shoshani et al. #103); (2) upper I2 occlusal edge does not slope distally (Shoshani et al. #161); and (3) basal keel of lower canines absent (Shoshani et al. #163).
Grehan also fails to enumerate characters which unite the African (Gorilla-Pan-hominid) clade to the exclusion of orangutans, and here I list just some of the more interesting ones from Shoshani et al.:
(#102) middle ear deepened (more than 8.5 mm)
(#104) area of inner ear greater than 50 square mm
(#106) strong klinorhynchy (orangutans are apparently even less klinorhynchous than gibbons).
(#111) frontal sinus present
(#114) orientation of zygomatic bone very superolateral
(#175) postprotocrista of upper dP4 very well-developed
In conclusion, even if one only looks at morphological characters, it seems to me that he continues (1) to overstate the case for a hominid-orangutan clade: (2) to understate the case for a hominid-chimp clade; and (3) MOST IMPORTANTLY, failing to seriously evaluate the third alternative that neither of these is correct, and that hominids split off between an orangutan clade and a chimp-gorilla clade. This third possibility would certainly explain why hominids have similarities to both orangutans AND to the African apes. Ignoring this very viable third hypothesis is something that both sides of the debate might eventually regret in retrospect. I must admit that because it is a sort of "middle ground" between those two sides of the debate, it just makes it all the more attractive to me. In any case, this is a three-way debate (NOT just two).
---- Ken Kinman
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