Carnivorous dental adaptations in tribosphenic mammals and phylogenetic reconstruction

Abstract

The molar morphology and structure of seven groups of flesh‐eating mammals (Deltatheroida, Borhyaenoidea, Stagodontidae, Dasyuroidea, Creodonta, Carnivora, and Prionogale) are compared. The dental adaptations to carnivorous diet are remarkably similar in the seven groups. Derived taxa within these groups all possess a postvallum‐prevallid shearing with a reduction of the paracone relative to the metacone (except in the Deltatheroida), a large postmetacrista, a reduced stylar shelf, a reduced protocone, a large blade‐like paraconid and a reduced metaconid and talonid. The constancy of these features (regarded as a single functional complex) and of their evolutionary pattern in phylogenetically distant groups, is evidence of their high potential for homoplasy. Therefore these character states should be used with extreme care in reconstructing phylogeny and, when possible, associated to cranial features. Several phylogenetic interpretations using them are discussed, some of which are regarded as poorly supported.

Hyainailourine and teratodontine cranial material from the late Eocene of Egypt and the application of parsimony and Bayesian methods to the phylogeny and biogeography of Hyaenodonta (Placentalia, Mammalia)

“…23. de Muizon & Lange-Badré (1997) noted the difference in paracone height in Hyaenodon and Pterodon but they did not place the distinction into a larger phylogenetic context. In hyainailourines, the metacone is fused to the distal face of the paracone.…”

“…Borhyaenoid metatherians were the dominant carnivores in South America from the Paleocene through the Pliocene (Rose, 2006), and, like hyaenodonts, borhyaenoids formed a shearing carnassial complex between multiple upper and lower molars rather than one carnassial complex between a premolar and molar as in Carnivora. In borhyaenoids (i.e., Miocene Pseudolycopsis and Lycopsis ) the upper carnassial is formed through mesiodistal elongation of the metacone and metastyle rather than the paracone and metastyle as in carnivorans (Van Valen, 1967; de Muizon & Lange-Badré, 1997). The paracone apex in borhyaenoids is distinct from the metacone, and much shorter than the taller shearing metacone.…”

A late Paleocene probable metatherian (?deltatheroidan) survivor of the Cretaceous mass extinction

“…The postvallum/prevallid shearing mechanism is formed only by the salient postmetacrista12252627. This shearing mechanism is convergently emphasized in many phylogenetically distant carnivorous mammals, such as deltatheroidans, borhyaenoids, stagodontids, dasyuroids, creodonts, carnivorans, and Prionogale 28. However, deltatheroidans are strikingly different from these other carnivorous mammals in having a very broad stylar shelf and a paracone saliently larger and taller than the metacone.…”

Craniodental and postcranial morphology ofIndohyaenodon raoifrom the early eocene of india, and its implications for ecology, phylogeny, and biogeography of hyaenodontid mammals

“…Homoplasy and canalization in the dental morphology of carnivorous mammals is well documented (e.g., Muizon and Lange-Badr e, 1997). A potentially underappreciated factor with implications for phylogenetic reconstruction is that many of the dental adaptations associated with increasing carnivorous specialization result in morphologically simpler, less informative molars.…”