Las áreas de mitosis forjan nuevos estilos en los estudios sobre paleontología de mamíferos

Abstract

Descriptive and comparative morphology supports mammal phylogeny. Since the 19th century, molars have been compared in order to pinpoint the characteristics which best define lineages. This information is assembled in the classic theories (Cope, 1883; Osborn, 1907). The lack of any explicit assessment on the genetic and embryonic development of the phenotypic criteria makes subjective its taxonomic valuation, creating conflictive hypotheses, and the taxonomy must be constantly revised. The solution comes with establishing the genesis of each molar cusp as a result of the morphogenesis of a specific area in the dental papilla, with high cellular density and intense mitotic activity. This allows us to establish an ontogenetic development which relates each adult characteristic with its corresponding embryonic morphology, where is possible to link the biotechnological data. A reference sequence (SR) is the arrangement of the molar’s assessed characteristics forming an unalterable series and which can be correlated with genotype sequences. Phylogenies are described using reference sequences, with their similarity weighted and located in time and habitat. This specific ontogeny creates a new conceptual base in classic morphology, which is able to correlate the phenotype with DNA sequences, including the use of ancient DNA techniques.