INVESTIGADORES
GELFO Javier Nicolas
artículos
Título:
Considerations about the evolutionary stasis of Notiolofos arquinotiensis (Mammalia: Sparnotheriodontidae), Eocene of Seymour Island, Antarctica
Autor/es:
GELFO J. N.
Revista:
AMEGHINIANA
Editorial:
ASOCIACION PALEONTOLOGICA ARGENTINA
Referencias:
Lugar: Buenos Aires; Año: 2016 vol. 53 p. 316 - 332
ISSN:
0002-7014
Resumen:
Notiolofos arquinotiensis is the most abundant terrestrial placental mammal in the Paleogene of the Antarctic continent. Evidencesuggests a South American origin of Sparnotheriodontidae, and an allopatric speciation event for the appearance of N. arquinotiensis. It wasrecorded exclusively on Seymour Island, through most of the La Meseta and Submeseta formations. Isotopic and paleomagnetic calibration ofthe units indicate a relatively continuous fossil record of at least 17.5 m.y. The stasis hypothesis is tested here as opposite to the possibilityof a wider and previously non-identified specific diversity of Antarctic sparnotheriodontids. The material of N. arquinotensis available was comparedin preservation, characters and dental occlusal areas to the more complete phylogenetic relative Sparnotheriodon epsilonoides and theNorth American Meniscotherium chamense. Despite there being no close phylogenetic relationship between Notiolofos and Meniscotherium, themorphological dental similarity between them suggests they could be interpreted as ecologically equivalent taxa. The analysis allows thereassignment of some N. arquinotensis teeth to other dental loci. The results indicate that there are no reasons to justify the presence ofdifferent species through the stratigraphic sequence or to refute the morphological stasis in N. arquinotensis. Stasis among Antarctic Eocenevertebrates is also recorded among Eocene penguins. The ?Plus ça change? model indicate that morphological stasis and punctuated equilibriumwere detected as the usual responses to widely fluctuating physical environments such as those characteristic of temperate regionsand shallow waters. This model fits well with inferences on Antarctic paleoclimate and paleogeography and the land fossil record.
