The role of ontogeny on character polarization in early dinosaurs: a new specimen from the Late Triassic of southern Brazil and its implications

Autor(es)

Mueller, Rodrigo Temp ^[1] ; Langer, Max Cardoso ^[2] ; Pacheco, Cristian Pereira ^[1] ; Dias-da-Silva, Sergio ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fed Santa Maria, Programa Posgrad Biodiversidade Anim, Santa Maria, RS - Brazil

^[2] Univ Sao Paulo, Lab Paleontol Ribeirao Preto, Ribeirao Preto - Brazil

^[3] Univ Fed Santa Maria, Ctr Apolo Pesquisa Paleontol Quarta Colonia, Santa Maria, RS - Brazil

• Tipo de documento: Artigo Científico
• Fonte: HISTORICAL BIOLOGY; v. 31, n. 6, p. 794-805, JUL 3 2019.
• Citações Web of Science: 7

Resumo

Only recently, new ontogenetic series of early dinosaurs and related groups have been described. Here, we present an isolated immature dinosauriform femur from the Late Triassic of southern Brazil and investigate its influence on character polarization. Because the specimen shares a number of synapomorphies with Pampadromaeus barberenai, herein we postulate that it corresponds to a juvenile individual of that taxon. Accordingly, we investigate the morphological variation between juvenile and mature individuals of P. barberenai. Scoring these character states into a published phylogenetic data-set of Dinosauromorpha reveals that morphological variation is higher than that observed among closely-related taxa. Ontogenetic variation thus exerts influence on character polarization. In addition, modification of the scores affected by ontogeny produces different topologies, as noted by the reduction in both the number of most parsimonious trees and number of steps, and increased inclusivity of some clades and reduction of polytomies as well. Our study, together with other recent contributions, sheds light on the morphologic pathways seen during dinosauromorph ontogenetic development, which is crucial to more reliably assess phylogenetic reconstructions and macroevolutionary patterns of this widespread and successful group. (AU)

• Processo FAPESP: 14/03825-3 - A origem e irradiação dos dinossauros no Gondwana (Neotriássico - Eojurássico)
• Beneficiário: Max Cardoso Langer
• Modalidade de apoio: Auxílio à Pesquisa - Temático