[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Gondwana Split Sorts Out Mammalian Evolution
Molecular systematics is indeed revolutionizing our understanding of
the interrelationships among mammalian Orders. And the K-T extinction
probably "shaped" the course of mammalian evolution in the same way it
shaped bird evolution--- namely, massive extinction globally, but most
surviving clades in the southern hemisphere. Therefore the "boreoeutherian"
radiations in the north were probably more "explosive" than the older mammal
groups in the south.
The ungulates are clearly a polyphyletic group (the afrotherian
"Pseudoungulata" clearly arose separately from the "real" ungulates up
north). This splitting of the traditional "Ungulata" is probably one of the
biggest surprises to many morphologists, who believed that hyraxes
(pseudoungulates) were closely related to perissodactyls. Thus McKenna's
clade Altungulata appears to be highly polyphyletic (based on homoplastic
convergences and plesiomorphies).
Yesterday's synapomorphies and clades can become today's polyphyletic
trash. Another reason I think there are way too many names (superordinal in
this case), and coding is preferable (I still have the same mammalian
Orders, but just have to put them into a different sequence). Giving formal
names to all these high clades is not a good idea, and informal names like
"boreoeutherians" would be just as useful.
----- Ken Kinman
Send and receive Hotmail on your mobile device: http://mobile.msn.com