Abstract
We describe a new species of an ornithischian dinosaur, Isaberrysaura mollensis gen. et sp. nov. The specimen, consisting in an almost complete skull and incomplete postcranium was collected from the marine-deltaic deposits of the Los Molles Formation (Toarcian-Bajocian), being the first reported dinosaur for this unit, one of the oldest from Neuquén Basin, and the first neornithischian dinosaur known from the Jurassic of South America. Despite showing a general stegosaurian appearance, the extensive phylogenetic analysis carried out depicts Isaberrysaura mollensis gen. et sp. nov. as a basal ornithopod, suggesting that both Thyreophora and neornithischians could have achieved significant convergent features. The specimen was preserved articulated and with some of its gut content place in the middle-posterior part of the thoracic cavity. Such stomach content was identified as seeds, most of them belonging to the Cycadales group. This finding reveals a possible and unexpected role of this ornithischian species as seed-dispersal agent.
Highlights
Dinosaurs were present in most terrestrial ecosystems for 185 million years, interacting with their physical environment and other living organisms, including plants
The holotype of Isaberrysaura mollensis gen. et sp. nov. is an incomplete articulated skeleton including an almost complete skull and a partial postcranium from a medium-to-large-sized specimen. This specimen was found in marine-deltaic levels of the Los Molles Formation from the Middle Jurassic (Neuquén province, Argentina); these are the first dinosaur remains found in this geological unit
The South American record of Jurassic ornithischian dinosaurs was limited to just a few specimens belonging to Heterodontosauriformes, a clade of small-sized forms that survived in Europe up to the Early Cretaceous[5,6,7]
Summary
Dinosaurs were present in most terrestrial ecosystems for 185 million years, interacting with their physical environment and other living organisms, including plants. Is an incomplete articulated skeleton including an almost complete skull and a partial postcranium from a medium-to-large-sized specimen (estimated length 5–6 m). This specimen was found in marine-deltaic levels of the Los Molles Formation from the Middle Jurassic (Neuquén province, Argentina); these are the first dinosaur remains found in this geological unit. The South American record of Jurassic ornithischian dinosaurs was limited to just a few specimens belonging to Heterodontosauriformes, a clade of small-sized forms that survived in Europe up to the Early Cretaceous[5,6,7]. In 2009 more field work was undertaken, and further fragmentary material was collected
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