EVIDENCE OF CONGENITAL ERYTHROPOIETIC PORPHYRIA IN ANCIENT SPECIMENS OF THE EASTERN FOX SQUIRREL (SCIURUS NIGER)

Remains of tree squirrels of the genus Sciurus are relatively common components of Pleistocene microvertebrate assemblages and Holocene archaeological deposits. In eastern North America two species (the eastern gray squirrel, S. carolinensis, and the eastern fox squirrel, S. niger) are frequently reported. However, their morphological similarity and generally sympatric distributions make it difficult to distinguish between these taxa in mixed assemblages, complicating paleobiogeographic and paleoenvironmental studies. Congenital erythropoietic porphyria (CEP) occurs in most, if not all, living eastern fox squirrels but is absent in eastern gray squirrels and other members of the genus Sciurus. Due to an excess of uroporphyrin I, the bones of animals with CEP fluoresce pink under ultraviolet (UV) light, especially at approximately 400 nm. Examination of sciurid remains from several paleontological and archaeological sites has confirmed that UV fluorescence can be detected in ancient S. niger remains. This technique provides an inexpensive, non-destructive test that can distinguish between S. niger and S. carolinensis in mixed fossil assemblages, and may aid in understanding how Sciurus populations repopulated North America following the Wisconsinin glaciation.