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Lower deciduous tooth homologies in Erethizontidae [Rodentia, Hystricognathi]: Evolutionary significance

100%

Candela A. M.

Acta Palaeontologica Polonica

2002

tom 47

nr 4

Cusp and lophid homologies of the lower deciduous teeth (dp4) in erethizontids and other Hystricognathi are specified. On this basis, a new nomenclature for these structures is proposed. The probable primitive condition and evolution of the occlusal patterns of these teeth are also analyzed. In contrast to previous proposals, it is concluded that the mesoconid, mesostylid, and mesolophid of the dp4 of erethizontids can be recognized since the Early Miocene. The anteriormost three lophids of the pentalophodont dp4 of the Erethizontidae would be homologous to the anterolophid, metalophulid II, and mesolophid, respectively. In addition, it may be proposed that the lophids of the dp4 of the Baluchimyinae and Old World Hystricognathi are homologous to those of the erethizontids and the remaining South American Hystricognathi. The pentalophodont pattern is probably the primitive condition of the dp4 of the Hystricognathi.

A primitive cephalomyid hystricognath rodent from the Early Miocene of Northern Patagonia, Argentina

80%

Kramarz A. G.

Acta Palaeontologica Polonica

2005

tom 50

nr 2

A new genus and species, Banderomys leanzai, from the Cerro Bandera Formation (early Miocene?) of Neuquén province, Argentina, is described. It is known through a mandibular fragment with two molars and several isolated cheek teeth. With wear the upper molars develop a bilobate pattern, whereas the lowers molars attain a trilophodont one. Banderomysis referred to the Cephalomyidae because it has an “asymmetric” dental pattern as other members of the family, but it is less hypsodont, and therefore it is more primitive than any other contemporary or older cephalomyids so far known. A phylogenetic analysis suggests that the relationships between the Cephalomyidae and the Cavioidea are closer than what was traditionally assumed. The cephalomyids would have radiated in pre−Deseadan times, from an ancestor with a dentition very close to that of Banderomys, and reached their main diversity during the Deseadan–Colhuehuapian lapse, when they constituted the dominant hypsodont rodent group in South America.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Candela A. M.

1 Kramarz A. G.

1 2005

1 2002

Wyniki wyszukiwania

Lower deciduous tooth homologies in Erethizontidae [Rodentia, Hystricognathi]: Evolutionary significance

A primitive cephalomyid hystricognath rodent from the Early Miocene of Northern Patagonia, Argentina