Evolutionary rates of basal iguanodontians around Jurassic-Cretaceous transition in Europe

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New information on ornithopod dinosaurs from the Late Jurassic of Portugal

Publication . Rotatori, Filippo Maria; Moreno-Azanza, Miguel; Mateus, Octávio; DCT - Departamento de Ciências da Terra; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; Institute of Paleobiology, Polish Academy of Sciences

Ornithopods are one of the most speciose group of herbivorous dinosaurs, rising during the Jurassic and getting extinct at the Cretaceous Paleogene boundary. However, most of the attention has been given to derived forms (hadrosaurids). Herein, cranial and post-cranial ornithopod material from the Upper Jurassic Lourinhã Formation and housed at Museu da Lourinhã is described and discussed. Comparison and phylogenetic analyses has allowed the attribution of the material either to Dryosauridae or to Ankylopollexia. The large-sized taxa conservatively ascribed to Ankylopollexia, resemble more closely Early Cretaceous styracosternans than Late Jurassic taxa. Due to the lack of autapomorphic characters, it was not possible to assign the material to any of the two valid Jurassic ornithopod Portuguese species, Draconyx loureiroi and Eousdryosaurus nanohallucis, although phylogenetic analyses hint a close relationship between the Lourinhã dryosaurid material and E. nanohallucis. Principal Component Analysis plotting limb bones proportions indicates a not fully mature ontogenetic stage for the Portuguese specimens. Comparing the Portuguese ornithopod fauna with the one in Morrison Formation and Kimmeridge Clay Formation, it is remarked the key-role of Portugal to understand biogeographic patterns in the distribution of iguanodontians.

2020Artigo científico

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Evolutionary Rates Of Basal Iguanodontians Around Jurassic-Cretaceous Transition In Europe

Publication . Rotatori, Filippo; Moreno-Azanza, Miguel

Iguanodontian dinosaurs are among the very first members to have been discovered, and since then, several new remains have been discovered all around the globe. These herbivores are especially diverse and abundant in the Early Cretaceous of Europe, North America and Asia. Comparatively, very little is known about Late Jurassic species and several specimens have been overlooked during the years, due also to lower preservation potential. In the present work, we aim to review and describe Late Jurassic Iguanodontian remains recovered mainly from Lourinhã Formation (Portugal) and update with a new set of observations phylogenetic matrices, in order to elucidate systematic relationships and macroevolutionary patterns within the clade. This work reports several undescribed specimens which indicated a hidden taxonomic diversity for the clade. This initial observation was corroborated not just by the reappraisal of type material of taxa already known, but also from the report and description of two species. The species richness of Iguanodontian dinosaurs in the Upper Jurassic beds of Lourinhã Formation is doubled, and the recovery of individuals of different ontogenetic stages indicate the presence of thriving populations. Furthermore, the new data acquired in Portugal, Europe and North America and compiled into the phylogenetic data matrix that was the main novel result of this doctoral project, were analysed with Maximum Parsimony and Bayesian Inference. We recovered a new systematic relationship, and we formally erected a new clade of high-sailed Iguanodontian dinosaurs. Furthermore, tip dated phylogenies indicate that most of the clade of Iguanodontians appeared, diversified and dispersed by the Late Jurassic. The Cretaceous assemblages are the result of extinction events that affected different Iguanodontian lineages. Body size increased by Late Jurassic, and in Early Cretaceous different clades evolved toward different optima, resulting in niche segregation. This thesis remarked on the pivotal role of Western Europe, and in particular Portugal and Iberia, for Iguanodontian dinosaurs' macroevolution.

2024-04Tese de doutoramento

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SFRH/BD/146230/2019