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Analyzing the impact of conflictive dental characters on the phylogeny of octodontoid rodents

100%
Candela A. M.
Acta Palaeontologica Polonica
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2016
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tom 61
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nr 2
Systematics of fossil octodontoids (Rodentia, Caviomorpha) is in great part based on insights into the knowledge of teeth, making the step of dental characterization certainly relevant for the evolutionary reconstruction of these rodents. Different homology hypotheses were proposed for the same tooth structures, a fact that indicates the importance of knowing on which criteria the dental characters supporting the classifications were based. In this line, I evaluate the step of characterization of certain conflictive molar characters previously used, and their impact on phylogeny of octodontoids. I explore which the criteria followed to propose the hypotheses of correspondences for these characters are in light of the anatomical evidence. Based on the outcome of phylogenetic trees obtained previously, I analyze if the evolutionary transformations are compatible with character states observed in the terminals. New cladistic analyses based on recoded molar characters indicate that, unlike results recently obtained, the unorthodox position of Sallamys, Protadelphomys, and Willidewu as basal ctenomyines is not recovered. The position of Caviocricetus, Acarechimys–Neophanomysas as Octodontinae is not maintained. These results indicate that reanalyses of conflictive dental characters, scrutinizing data matrices, are particularly necessary to evaluate the current controversy on the phylogeny of octodontoids. Lower molar character definition and character states delimitation in octodontoids, being relevant to phylogenetic reconstruction, should be founded on anatomical examination, following explicit criteria of homology. Alternative hypotheses of “primary homology” proposed for the same molar traits in octodontoids indicate that each main group of caviomorphs requires its own anatomical study.
2
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Lower deciduous tooth homologies in Erethizontidae [Rodentia, Hystricognathi]: Evolutionary significance

100%
Candela A. M.
Acta Palaeontologica Polonica
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2002
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tom 47
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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.
3
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Systematic and biostratigraphic significance of a chinchillid rodent from the Pliocene of eastern Argentina

63%
Rasia L. L., Candela A. M.
Acta Palaeontologica Polonica
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2013
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tom 58
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nr 2
Two species of chinchillid rodents, Lagostomus (Lagostomopsis) incisus and “Lagostomus (Lagostomopsis) spicatus”, have been recorded from the Monte Hermoso Formation (Montehermosan–Lower Chapadmalalan, Early Pliocene) of southern Buenos Aires Province, eastern Argentina. L. (L.) incisus is based on skull remains,while “L. (L.) spicatus” is based onmandible remains and fragmentary skulls. Detailed study of specimens recovered from the upper section of the Monte Hermoso Formation, from the Irene “Formation”, and the Chapadmalal Formation (late Early–early Late Pliocene, Buenos Aires Province), some of them represented by associated skull and mandible remains, indicates that L. (L.) incisus and “L. (L.) spicatus” are synonymous, with the valid name being L. (L.) incisus. The differences between both nominal species are here attributed to different ontogenetic states and sexual dimorphism. The stratigraphic provenance of the fossil material of L. (L.) incisus indicates a temporal distribution of this species restricted to theMontehermosan?–Chapadmalalan (Early–early Late Pliocene), instead of the Montehermosan (Early Pliocene).
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