A new homolid crab, Zygastrocarcinus carolinasensis n. sp., from the Cretaceous (Campanian) of NE Mexico: Implications for paleobiogeography

Abstract

A new species of the homolid crab, Zygastrocarcinus carolinasensis n. sp., is reported from the Upper Cretaceous (upper Campanian) strata of Coahuila, NE Mexico. Only the anterior part of the ~8 mm wide carapace was preserved in addition to a part of the sternum (sternites 1-6). The sternum is the oldest figured example of a fossil homolid sternum, and also of the entire section of fossil Homoloida. The sternum seems to be similar to extant homolids in general outline, and to an earlier described Eocene homolid. Hitherto, Zygastrocarcinus spp. were only known from the northern part of the USA (Wyoming, Montana, and South Dakota). Thus, the new species extends the geographic range of the genus during the Cretaceous to much of North America. Additionally, this is the second fossil homolid known from Mexico.