New data on Propyrotherium (Mammalia, Pyrotheria) from the middle Eocene (Chubut, Argentina): anatomy, age constraints, and phylogeny

VERA BÁRBARA; FOLINO MICAELA; WALTER SOECHTING; NICOLE BÖTTCHER

NATURWISSENSCHAFTEN

SPRINGER

Lugar: Berlin; Año: 2022

0028-1042

Pyrotheria is one of the most peculiar orders of South American native ungulates, whose little known members evolved from the early? Eocene to late Oligocene when they became extinct. Here, we described the most complete material of Propyrotherium saxeum ever found, one the less known representative of pyrotheres that characterized the Eocene of Patagonia (Argentina). It includes a nearly complete mandible and a tusk-like tooth of the same individual, as well as other isolated upper and lower teeth. Propyrotherium saxeum has a dental formula that includes at least P2– M3, and i2?–p3–m3 (p2 is lacking) and characterizes by the some peculiar features of the mandible (e.g., ascending ramus longer than high, hiding laterally the m3 and with a straight incisura mandibular) and dentition (e.g., cristid obliqua connecting lophids on p3–m3; cristid between the posterior lophid and the distal cingulid in m1–m3; P3–M3 and p3–m3 bilophodont; P2 and p3–m3 bi-rooted; P3–M3 three-rooted; paraconid in p3; molarized p4). The phylogenetic analysis recovered Propyrotherium more related to Pyrotherium and Baguatherium, differing from previous hypothesis, and supported the monophyly of Pyrotheriidae as a clade including (Carolozittelia (Griphodon (Pyrotherium, Baguatherium, Propyrotherium))). According to the absolute age by means of U–Pb zircon dating of the Sarmiento Formation at Cañadón Pelado fossil locality, the fossil bearing tuff would have deposited between 39.65 and 40.41 Ma (Bartonian). It provides a chronological framework not only for Propyrotherium but the fauna of Cañadón Pelado.