The Pleistocene Rails of North America

Abstract

Wetmore (1931) assigned two fragments of tarsi and a femur from Pleistocene deposits excavated at Seminole Field, Pinellas County, Florida, to the Gray-necked Wood Rail, Aramides cajanea. This species is presently distributed from southern M6xico to Argentina. In view of the Neotropical flavor of much of the Pleistocene fauna of Florida, it was not a wholly unexpected discovery but, unfortunately, the record is based on incorrectly identified material. On restudying the specimens involved (USNM 12192), I found that none pertains to Aramides. The femur is from a small individual (probably a male) of Redshouldered Hawk, Buteo lineatus. The distal right tarsus and proximal right tarsus are from different individuals and are rallid; however, both are from the King Rail, Rallus elegans. Both Buteo lineatus and Rallus elegans were recorded by Wetmore from the Seminole Field site. The tarsi of Aramides and Rallus are quite distinct in their entirety but in the fragmentary condition of the fossils are less easily separated. In the distal fragment, the distal foramen in posterior view is oval and placed higher than in Aramides cajanea, in which the distal foramen is round. The middle trochlea is not as heavy and expanded distally as in A. cajanea, but the scar for the hallux is deeper. In external view, the shaft extending to trochlea 4 is wide and heavy, unlike A. cajanea in which this shaft is narrow and flattened; also, the groove in trochlea 4 does not extend through most of the anterior face of the trochlea as it does in Aramides. In anterior view, the outer extensor groove is longer and deeper than in Aramides. In all these respects, the fossil agrees with Rallus elegans. In the proximal tarsal fragment, in anterior view the intercotylar prominence is lower and flatter than in Aramides; the hypotarsus is not as deeply excavated on the internal face and in internal view the ridge from the internal cotyla is broader and not as sharply marked off from the hypotarsal area as it is in A. cajanea. In these respects this specimen, too, agrees with Rallus elegans. Aramides cajanea must therefore be removed from the fossil record of North America.