Metacone

Abstract: The most derived fruit-eating bats have small canines, wide palates and molars with a distinctive labial rim. Paracone and metacone have moved from a dilambdodont position in the middle of the tooth to the labial side of the tooth where they form the labial cutting edge. Along with the well-developed and close fi tting labial cutting edges of the premolars and canines, this cutting edge skirts nearly the entire perimeter of the palate. The labial rim of the lower teeth fi t inside the labial rim of the upper teeth like two cookie cutters nesting one inside the other. Frugivores have a greater allocation of tooth area at the anterior end of the toothrow, while animalivorous species have more at the posterior end of the toothrow. The area occupied by canines of predators of struggling prey is greater than that for bats that eat non-struggling prey like fruit. In addition, frugivores have wider palates than long while many carnivores have longer palates than wide. Omnivores appear to have a more equal allocation of space to more kinds of teeth, particularly the incisors and non-molariform premolars, on the toothrow than do frugivores or animalivores. The mechanical nature of different food items is discussed and the suggestion made that describing foods in terms of their texture may be more important in tooth design than whether they are fruit or insect or vertebrate.

Abstract: A collection of eutherian mammals consisting of 39 specimens (teeth and jaw fragments) from the ?Aptian or Albian Khoboor Beds in the Gobi Desert, Mongolia, is described. It contains 3 taxa: Prokenna1estes gen.n., assigned to the Otlestidae Nessov, new rank, with 2 shrew size species; P. trofimovi sp.n. and P. minor sp.n.; a heavily worn larger lower molar which will be described elsewhere. It cannot be excluded that P. trofimovi and P. minor are only sexual morphs within the same species. Prokennalestes and Bobolestes Nessov are possibly the oldest known eutherian mammals, but Prokennalestes is morphologically more primitive than Bobolestes. It has a labial mandibular foramen, 5 premolars and 3 molars, 3 cusps in parastylur region, paracone larger than metacone, unwinged conules, no pre- and posteingula, and lower molars with a 3-cusped talonid, which is narrower than the trigonid, Otlestes and Kennalestes may be derived with little modification from Prokennalestes. Prokennalestes gen.n. is congeneric with Prokennalestes Trofimov and Prozalambdalestes Trofimov, which are both nomina nuda.

Abstract: The skull and skeleton of the Mongolian Late Cretaceous (Barungoyotian) marsupial Asiatherium are described, illustrated, and compared to various therian taxa. The study supports the distinctness of Asiatherium from deltatheroidans and eutherians, and the metatherian status (sensu stricto) of asiatheriids, based primarily on the dental formula, but also on cranial, dental, and postcranial characters. Its postcanine dental formula (three premolars and four molars), found only in dentally primitive living marsupials, is shown to be a derived condition within the Theria (tribosphenic mammals, sensu stricto). In addition, the closely twinned hypoconulid and entoconid, correlated with a (relative) hypertrophy of the metacone, an alisphenoid component to the bulla (possibly an independently derived trait), oval (not elliptical) fenestra vestibuli, and an elliptical fenestra cochleae, along with other unmistakenly marsupial-like (and therian as well as pre-therian) postcranial taxonomic properties, all ...

Abstract: Late Cretaceous (Maastrichtian) eutherian mammals are documented from the intertrappean beds of Naskal, Rangareddi District, Andhra Pradesh, India, on the basis of isolated canines, premolars, molars, and mandibular fragments. Besides the previously recorded Deccanolestes hislopi, two additional forms, one with affinities to D. hislopi and a new species, D. robustus, are also described. These mammals are primitive in comparison to North American palaeoryctids in their lack of strong, winged conules and absence of lingual cingula on the upper molars; presence of cristid obliqua at the base of metaconid; and hypoconulid closer to hypoconid than to entoconid. Based on transversely wide upper molars with wide stylar shelf, large parastylar area, paracone and metacone which are high and connate at the base, anteriorly recumbent protocone, tall trigonids and small paraconid on the lower molars, these species are referred to Palaeoryctidae. Most of the similarities between the North American palaeorycti...