A new genus and species of Euphractini armadillo (Mammalia, Cingulata) from the late Oligocene Fray Bentos Formation of Uruguay

BOSTELMANN, ENRIQUE; CIANCIO, MARTÍN R.; RINDERKNECHT, ANDRÉS; PEREA, DANIEL

Montevideo, Uruguay

Congreso; I Congreso Uruguayo de Zoología y X Jornadas de Zoología del Uruguay; 2010

Sociedad Zoológica del Uruguay

Paleogene Dasypodidae are uncommon outside Patagonian fossil levels making middle latitude localities of great interest for the study of their early diversity. In Uruguay, the first mention of the occurrence of Oligocene dasypodids was provided by A. Castellanos without a detailed description or formal designation of a repository for the collected materials. A reclassification of the fossil cingulates housed in the Museo Municipal “Prof. Lucas Roselli” (MLR) allows us to recognize a new genus and species of Euphractinae Euphractini. MRL 497, 575, 601 and 773, composes different sets of isolated osteoderms collected in four localities of Nueva Palmira´s neighborhood at the Colonia Department. MNHN 2190 -two fixed osteoderms incorrectly labeled as [Eutatus seguini]- are assigned to this new genus too, and FCDPV-687, from the Santa Lucía River, is referred with doubts to it. Typical fixed osteoderms are large (20 – 30 mm), rectangular to prismatic, and thick. The external surface is smooth, punctuated, and presents convex figures delimited by narrow furrows. The central figure is well defined and does not reach the posterior margin. Its distal portion penetrates between the rami of a U-shaped figure, composing a principal figure that occupies all the posterior half of the osteoderm. Three to four (exceptionally five) well delimited antero-lateral trapezoidal peripheral figures surrounds this principal one. The contact zone between osteoderms is slightly concave and smooth, or covered by poorly developed denticular projections. The piliferous system exhibits a unique condition among euphractins consisting on two large and circular foramina located in the middle of the posterior border, coupled with numerous small size foramina (probably piliferous) placed all around the lateral and posterior margins of the osteoderms. Preliminary evaluation on the Paleogene fossil Euphractini suggests closer affinities of this Uruguayan form with specimens exhumed from the late Oligocene Salla beds in northern Bolivia.