Note on a Plastron (Testudines, Pleurodira) from the Lower Cretaceous Crato Member, Santana Formation, Brazil

Abstract

Up to date, turtle remains from the Early Cretaceous Santana Formation were only described from the Romualdo Member (Aptian-Albian) and four species are known: Araripemys barretoi Price, 1973 (Pleurodira: Araripemydidae); Santanachelys gaffneyi Hirayama, 1998 (Cryptodira: Protostegidae); Brasilemys josai Lapparent de Broin, 2000 (Pleurodira: Brasilemydidae), and Cearachelys placidoi Gaffney, Campos & Hirayama, 2001 (Pleurodira: Bothremydidae). Here we report an incomplete plastron (MN 6745-V) from the lower section of this formation, constituted by the laminated limestone layers of the Crato Member (Aptian). Compared to other turtles from the Santana Formation, this material is referable to cf. Araripemys based on the presence of fontanels and the lack of a mesoplastron. It constitutes the oldest Testudines from Brazil, extending the record of Araripemys or a similar taxon deeper into the Aptian.