Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Rua Maximiliano Vizzotto, 598, São João do Polêsine, Rio Grande do Sul, 97230-000, Brazil.
Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul, 97105-120, Brazil.
Sci Rep. 2024 Jun 20;14(1):12706. doi: 10.1038/s41598-024-63313-3.
Before the rise of dinosaurs and pterosaurs, pseudosuchians-reptiles from the crocodilian lineage-dominated the Triassic land ecosystems. This lineage diversified into several less inclusive clades, resulting in a wide ecomorphological diversity during the Middle and Late Triassic. Some giant pseudosuchians occupied the top of the trophic webs, while others developed extensive bony armor as a defense mechanism, which later evolved as a convergence in the avemetatarsalian lineage. On the other hand, there were groups like the Gracilisuchidae, which was composed of carnivorous forms with lightweight build and less than 1 m in length. The fossil record of gracilisuchids is geographically restricted to China and Argentina, with one ambiguous record from Brazil. In the present study, the first unambiguous gracilisuchid from Brazil is described. Parvosuchus aurelioi gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation, which is associated with the Ladinian-Carnian boundary. Composed of a complete cranium, vertebrae, pelvic girdle and hindlimbs, the new species nests with Gracilisuchus stipanicicorum and Maehary bonapartei in a phylogenetic analysis. Its discovery fills a taxonomic gap in Brazilian pseudosuchian fauna and reveals the smallest known member of this clade from the Dinodontosaurus Assemblage Zone, highlighting the diversity of pseudosuchians during the moment that preceded the dawn of dinosaurs.
在恐龙和翼龙兴起之前,伪鳄类——鳄形超目的爬行动物——主导了三叠纪的陆地生态系统。这个谱系多样化为几个不太包容的进化枝,导致中晚三叠世出现了广泛的生态形态多样性。一些巨型伪鳄类占据了食物链的顶端,而另一些则发展出广泛的骨质装甲作为防御机制,这后来在AVEmetatarsalian 谱系中进化为趋同现象。另一方面,有些群体,如 gracilisuchidae,由肉食性形式组成,体型较轻,长度不到 1 米。 gracilisuchid 的化石记录在地理上仅限于中国和阿根廷,巴西有一个模糊的记录。在本研究中,描述了来自巴西的第一个明确的 gracilisuchid。Parvosuchus aurelioi gen. et sp. nov. 来自圣玛丽亚组的 Dinodontosaurus 组合带,与 Ladinian-Carnian 边界有关。由一个完整的头骨、脊椎、骨盆带和后肢组成,新物种与 gracilisuchus stipanicicorum 和 maehary bonapartei 在系统发育分析中嵌套在一起。它的发现填补了巴西伪鳄类动物群的分类空白,并揭示了来自 Dinodontosaurus 组合带的这个分支中最小的已知成员,突出了恐龙黎明前时期伪鳄类的多样性。