Two unusual specimens of Helaletes in the Yale Peabody Museum collections, and some comments on the ancestry of the Tapiridae (Perissodactyla, Mammalia)

A calvarium, mandible and partial skeleton of Helaletes nanus and a partial upper dentition of Helaletes intermedius, both from the middle Eocene (Bridgerian) of Wyoming, are described and illustrated. Previously unrecognized cursorial specializations in the hindlimb of H. nanus suggest that it was not the direct ancestor of the Tapiridae, as hypothesized by some earlier workers. Alternatively, if H. nanus was the true ancestor of the Tapiridae, an initial tendency toward cursoriality in the hindlimb was later reversed. Only four described specimens are presently referred to H. intermedius. Due to morphological differences observed between these specimens, it is unclear if they all pertain to the same species-level taxon. As presently constituted, the species H. intermedius, might be better referred to a separate genus from Helaletes nanus

Tanyops undans Marsh, 1894: A junior subjective synonym of Protapirus obliquidens Wortman and Earle, 1893 (Mammalia, Perissodactyla)

Tanyops undans Marsh, 1894, a tapirid from upper Oligocene strata of South Dakota, has been almost totally ignored in the literature. Here the unique holotype specimen is redescribed and illustrated for the first time. Tanyops undans is virtually identical in morphology to, and thus a junior subjective synonym of, Protapirus obliquidens Wortman and Earle, 1893

A new species of Isectolophus (Mammalia, Tapiroidea) from the middle Eocene of Wyoming

A partial right dentary bearing M3 from the middle Eocene (Bridger) of Wyoming represents a new species of Isectolophus here designated I. radinskyi. I. radinskyi differs from all other Isectolophus in its smaller size; it is intermediate in size between Homogalax protapirinus and its supposed descendant Isectolophus latidens

A new subfamily, Conacodontinae, and new species, Conacodon kohlbergeri, of the Periptychidae (Condylarthra, Mammalia)

An associated palate and dentaries from the early Paleocene (Puercan), San Juan Basin, New Mexico, are the type of a new species, Conacodon kohlbergeri. This species is cladistically most closely related to C. entoconus. Both species lack the paraconid on P3-4 and have a more complete precingulum on the upper molars. Both Conacodon and Oxyacodon have a lingually expanded hypocone and lack the protocone on P3. These two genera are included in a new subfamily, Conacodontinae. A trichotomy between this subfamily, the Anisonchinae, and Periptychinae cannot be resolved at present

Systematics, functional morphology and macroevolution of the extinct mammalian order Taeniodonta

The Taeniodonta is an archaic order of extinct eutherians known from Puercan (early Paleocene) to Uintan (middle Eocene) strata of the Rocky Mountain intermontane sedimentary basins of western North America and from late Paleocene strata of South Carolina...

Revision of Metacheiromys Wortman, 1903 and a review of the Palaeanodonta

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