Elephant Shrews in North America

	There is a mild disagreement between vertebrate paleontologists and molecular biologists over the relationships of various orders of mammals. One of the less publized debates centers around the placement of an obscure order Macroscelidea (Elephant Shrews).
Most molecular phylogenies place Macroscelidea in a Africa clade, called Afrotheria, which includes other mammal orders believed to have originated from Africa (Hyracoidea, Proboscidea). In 1986 the paleontologists J.J. Hartenberger proposed a different origin for Elephant Shrews from an family of Paleocene/Eocene fossil mammals from North America/Europe called Hyopsodontids. His idea was further vindicated by the later discovery in 1991 of early elephant shrew dentitions from Egypt that also showed similar relationships. However, most of these comparisons were made using just teeth. In 1999, I started my own study on the relationship of elephant shrews and hyopsodontids using postcranial information from a rather complete skeleton of Hyopsodus, and came to a more skeptical conclusion. A recently published article in Nature last week, featured postcranial elements of Aphelicus and Haplomylus (two other hyopsodontids) and concluded a North American origin for Elephant Shrews. As a side note the postcranial elements of both taxa show strong similarities, refuting claims that Aphelicus is not a hyopsodontid. Futhermore Haplomylus shows more cursorial adaptations than I would have thought. Hinting at a possible Artiodactyla relationship, first proposed by Ken Rose.
Zack, S.P., Penkrot, T.A., Bloch, J.I. and Rose, K.. 2005. Affinities of 'hyopsodontids' to elephant shrews and a Holarctic origin of Afrotheria. Nature 434, 497-501 (24 March 2005); doi:10.1038/nature03351.