Monotrematum sudamericanum Pascual, Archer, Ortiz Jaureguizar, Prado, Godthelp, and Hand, 1992

Pascual, Rosendo, Goin, Francisco J., Balarino, Lucía & Udrizar Sauthier, Daniel E., 2002, New data on the Paleocene monotreme Monotrematum sudamericanum, and the convergent evolution of triangulate molars, Acta Palaeontologica Polonica 47 (3), pp. 487-492 : 487-488

Monotrematum sudamericanum Pascual, Archer, Ortiz Jaureguizar, Prado, Godthelp, and Hand, 1992

Emended generic and specific diagnosis.—Cheektooth pattern similar to that of Obdurodon , the most closely similar ornithorhynchid, but double in size. Posterior lobe of m1 single−rooted, but preserving a vertical anterior sulcus that apparently divided two original roots, which remain well separated in Obdurodon species.

Material.— The holotype, MLP 91 −I−1−1 (right M2), and the newly−referred MPEF−PV 1634 (right M2) and MPEF−PV 1635 (right m1) .

Locality and age.— Punta Peligro , southeastern Chubut province ( central Patagonia ), Argentina; Hansen Member (“ Banco Negro inferior”), Salamanca Formation ; early Paleocene (Peligran SALMA, see Bond et al. 1995: fig. 2) .

Measurements.—RM2 (MPEF−PV 1634): W anterior lobe, 10.1 mm; W posterior lobe, 7.5 mm; L 9 mm. Rm1 (MPEF−PV 1635): W posterior lobe, 7.5 mm.