First clear evidence of Anoplotherium (Mammalia, Artiodactyla) in the Iberian Peninsula: an update on the Iberian anoplotheriines.

Anoplotheriines (Mammalia, Artiodactyla) were enigmatic, medium- to large-sized ungulates that lived in Western Europe from the late middle Eocene to the earliest Oligocene. The unusual dental and postcranial specializations of these Paleogene mammals have no equivalent in other Cenozoic or contemporaneous artiodactyls on Holarctic landmasses. They appeared abruptly on the Central European Island around the middle to late Eocene transition, but their origin and dispersal through the different areas of the Eocene European archipelago are uncertain. The Iberian fossil record of anoplotheriines is not as well-known as that of other Western European areas. This study examined anoplotheriine artiodactyl fossils from late Eocene (Priabonian) beds at the Zambrana site (Miranda-Treviño Basin, Araba/Álava, Spain). We assign them to at least two different species of anoplotheriines, one in the genus Anoplotherium and the other tentatively assigned to the genus Diplobune. In addition, we described the first cranial and dental elements of Anoplotherium from the Iberian Peninsula. These fossils are crucial for establishing the chronological framework of the Iberian site of Zambrana and understanding the biodiversity and paleobiogeography of the European Eocene artiodactyl fauna.

First adequately-known quadrupedal sirenian from Eurasia (Eocene, Bay of Biscay, Huesca, northeastern Spain).

Sirenians are the only extant herbivorous mammals fully adapted to an aquatic lifestyle. They originated in Africa during the Paleocene from an undetermined clade of afrotherian mammals, and by the end of the Eocene they were widely distributed across the tropical latitudes. Here we introduce Sobrarbesiren cardieli gen. et sp. nov. It is the first adequately-known quadrupedal sirenian from Eurasia and the oldest record of this clade from western Europe. Fossils have been recovered from the middle Lutetian (SBZ15) site of Castejón de Sobrarbe-41 (Huesca, Spain), and comprise many cranial and postcranial remains, including pelvic girdle and hind limb bones, from at least six sirenian individuals of different ontogenetic stages. Sobrarbesiren shows a suite of characters previously considered synapomorphies of different clades of derived sirenians, such as the presence of the processus retroversus of the squamosal and the pterygoid fossa, combined with ancestral characters such as the presence of an alisphenoid canal, a permanent P5, at least two sacral vertebrae, a primitive pelvis and functional femora and fibulae. Sobrarbesiren is recovered as the sister taxon of Dugongidae and represents a transitional stage of adaptation to aquatic life between the amphibious quadrupedal prorastomids and the aquatic quadrupedal protosirenids.

First record of the genus Microchoerus (Omomyidae, Primates) in the western Iberian Peninsula and its palaeobiogeographic implications.

In this paper we describe new material of Microchoerus (Microchoerinae, Omomyidae, Primates) from Zambrana (Miranda-Trebiño Basin, northern Iberian Peninsula, Spain), a locality assigned to Reference Level MP18 (middle Headonian, Late Eocene). The specimens studied consist of two mandibular fragments, bearing p3-m3 and p4-m3. The teeth resemble in size and morphology those of Microchoerus erinaceus from Hordle Cliff, England, although some differences prevent us from making a definitive ascription to this species. We therefore refer the material from Zambrana to Microchoerus aff. erinaceus. Some traits, such as the development of the mesoconid and hypoconulid in the m1 and m2, and the shape of the hypoconulid lobe in the m3, are intermediate between those of M. erinaceus and Microchoerus edwardsi. Thus, the material from Zambrana is very similar to other species of Microchoerus present in Europe, representing a transitional form between M. erinaceus and M. edwardsi. The described material represents the first discovery of a primate from the Miranda-Trebiño Basin, and also the westernmost record of the genus Microchoerus in the Iberian Peninsula. Moreover, the identification of this microchoerine, with clear similarities to the representatives of this genus described from other European sites, reinforces the idea of the existence of connections between western Iberia and the rest of Europe in the Late Eocene, previously hypothesized after the discovery of typical European artiodactyls in the site of Zambrana.