First fossil manatees in Texas, USA: Trichechus manatus bakerorum from Pleistocene beach deposits along the Gulf of Mexico

Extant manatees were documented on the Texas coastline as early as 1853, but their reported occurrence in Texas waters has been sporadic and poorly documented until relatively recently. We report eight specimens that document the first occurrence of fossil manatees in Texas, and the westernmost fossil occurrence of manatees in the United States. Seven of the specimens were collected along McFaddin and Caplen beaches on the northwest coast of the Gulf of Mexico; one was recovered from Corpus Christi Bay. The fossil specimens reported here include a mandibular symphysis fragment diagnosable as the extinct morphotype denoted by the trinomial Trichechus manatus bakerorum Domning, 2005. Other specimens are diagnosed as Trichechus manatus or as Sirenia. They were found on beaches that are known to produce mammalian taxa characteristic of Pleistocene faunas, and our age assessment is based on that association, and the comparable preservation, color, and density of the manatee bones and bones of extinct taxa of Pleistocene age from the beaches. It is not clear whether the fossils represent remains of a resident population, or the fortuitous preservation of vagrant individuals. However, assuming that the ecological tolerances of manatees in the Pleistocene were comparable to the tolerances of extant populations, the presence of manatees in the northwest Gulf of Mexico in the Pleistocene adds an interesting, if enigmatic, data point for paleoenvironmental reconstructions of the region.