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  •  not squirrels (3+ / 0-)

    Hi ivorybill,

    You are more right than Brian Babylon, who was only sort of wrong.  Most studies (though not all as science does go on!), One of the main hypotheses of primate evolutionary relations is that Primates is part of a larger group called Euarchontaglires that is itself composed of two major groups, Archonta and Glires.

    Archonta includes Primates, Scandentia or tree shrews, and Dermoptera or colugos (also called flying lemurs, although they do not fly and are not lemurs).  An extinct group of mammals known as Plesiadapiformes is most closely related to the living primates (and in fact are classified as Primates by some), and Scandentia and Dermoptera are more closely related to each other than to Primates.  Previously, Chiroptera or bats have also been allied with archontans, but recent analyses based on gene sequences suggest that bats are more distantly related to archontans and glires.  

    Glires is comprised of rodents and lagomorphs or hares and rabbits.  This group is more closely related to Archonta than to any other group of living mammals.

    The extinct Plesiadapiformes have some morphological characteristics similar to rodents and seem to have been ecological similar in many ways.  This could be what led Brian Babylon to suggest that rodents are closely related to primates.

    Indeed, much of the evidence for these relationships and for the earliest representatives of each of the subgroups in the fossil record comes from studying the shapes of teeth, which are very hard and preserve well in the geological record.  Ankle bones and the bones of the skull around the ear region are also very dense and preserve well, and those bones also have much anatomical detail that is informative about evolutionary patterns.  However, over the last 20 years or so, numerous very complete skeletons have been discovered in rocks of the Bighorn Basin in north central Wyoming and these fossils have provided much new and important information on the evolutionary history of early primates (including plesiadapiformes) and relatively early rodents.

    I hope this answers your question!

    •  Appreciate the info (0+ / 0-)

      Read it and am now reading up on Plesiadapiformes.  Good fun!

      “If the misery of the poor be caused not by the laws of nature, but by our institutions, great is our sin.” Charles Darwin

      by ivorybill on Sat Dec 29, 2012 at 06:57:22 AM PST

      [ Parent ]

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