Micro-computed tomography indicates Eurotamandua, putative anteater from the Eocene of Messel, Germany, is related to pangolins, not xenarthrans

Abstract

Eurotamandua joresi, based on an articulated skeleton unearthed half a century ago at the middle Eocene Messel Pit near Darmstadt, Germany, was initially described as the oldest known anteater and the only member of mammalian clade Xenarthra from outside the New World. The implied biogeographical link to South America raised suspicions about the relationships of Eurotamandua and its similarity to true anteaters (Vermilingua). Because the skeleton was held in a private collection for many years, only a cast was available for study after the initial report. Even when the original specimen became accessible, it was clear that important anatomical features were not visible because many bones were in articulation, and the skeleton was compressed in matrix. Moreover, it had been encased in fiberglass-reinforced resin, further obscuring skeletal details. Here we report new evidence revealed through micro-computed tomography of the entire skeleton and digital segmentation of individual elements. For the first time, phylogenetically critical anatomy can be seen in three dimensions. Many unique features, especially of the forelimb, indicate that Eurotamandua was a highly specialized digger most closely related to extinct Holarctic palaeanodonts (Pholidotamorpha: pangolins and their extinct relatives) and not to Xenarthra. Consequently, no Old World xenarthrans are known.