Thursday, 31 January 2013

Did horses learn to climb trees?

 Harland W. Mossman 1898-1991 (National Library of Medicine)

No one with a serious interest in fetal membranes should be without a copy of Mossman’s book Vertebrate Fetal Membranes.  Harland W. Mossman did more than anybody to assimilate information on the placenta in a wide range of mammals and other vertebrates. Together with Kenneth L. Duke he authored an equally important book on Comparative Morphology of the Mammalian Ovary. Mossman’s extensive collection of placentas and ovaries is conserved at The University of Wisconsin Zoological Museum (UWZM). Part of the collection is on a searchable data base. Contact the curator if you cannot find what you are looking for.

Ringtailed lemur (Lemur catta) Wikimedia Commons

Mossman was a man of strong opinions and these included some ideas on mammalian evolution that might be considered idiosyncratic. As reported by David Hill, “He'd launch into impassioned monologues about placentas: ‘If taxonomists would just examine the evidence from the placenta, they'd see that lemurs are actually tree-climbing horses!’" Mossman’s unpublished autobiography at UWZM confirms he held something approaching this view. There are indeed some remarkable resemblances in placenta and fetal membranes between horses and lemurs. But this is yet another example of convergent evolution.

Disclosure: I am Adjunct Curator of The Harland W. Mossman Collection.

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