INVESTIGADORES
GELFO javier Nicolas
congresos y reuniones científicas
Título:
Paleogene bunodont ungulates from South America, alternative hypotheses.
Autor/es:
GELFO J. N.; CHORNOGUBSKY, L.
Lugar:
University of Bristol, Bristol, United Kingdom
Reunión:
Otro; 69th Annual Meeting of the Society of Vertebrate Paleontology, Bristol and 57th Symposium of Vertebrate Palaeontology and Comparative Anatomy (SVPCA); 2009
Institución organizadora:
Society of Vertebrate Paleontology
Resumen:
The earliest known therian fossil records from South America show a predominance of
bunodont ungulates. In the traditional view, these comprised archaic ungulates such as
the Mioclaenidae Kollpaniinae and Didolodontidae, plus the litoptern Protolipternidae.
Since the Kollpaniinae were related to a North American family, the last two were the
only strictly bunodont and low-crowned, endemic ungulates from the Paleogene of South
America. Didolodontids and protolipterns were recognized as different groups because the
assignation of postcranial remains, with condylarth-like and litoptern-like morphologies
respectively. However, these assignations were questioned in the case of the didolodontids,
particularly because no complete skeleton or associated postcranium is yet known for any
of them. So, the phylogenetic position of didolodontids is still controversial. A data matrix
of 89 dental and tarsal characters for 26 species (Protoungulatum donnae as an out-group
+ 7 Kollpaniinae + 14 Didolodontidae + 4 Protoliptenidae) was analyzed under parsimony,
firstly considering the didolodontid tarsal assignation as valid, and secondly codifying these
conflictive characters as missing data. Both analyses were carried out, with and without
implied weighting. As a result, the Kollpaniinae were recovered as monophyletic and basal
to the remaining groups in all the analyses. The analysis performed with the complete
tarsal information recovered the Didolodontidae as monophyletic using implied weighting.
In contrast, for this matrix, Protolipternidae were always recovered as a natural group,
even when the two species of Asmithwoodwardia seem not to be related to them. When
the conflictive tarsal characters were not included in the analysis, Didolodontidae resulted
monophyletic in contrast to Protolipternidae. These analyses emphasize two hypotheses. The
postcranium of didolodontids could be condylarth-like, but their monophyly needs to be
verified in a wider context including the rest of the native South American ungulates. Or,
didolodontids may have had a litoptern-like postcranial anatomy, and Protolipternidae are
an artificial group.