Paes Neto Voltaire D, Pretto Flávio A, Martinelli Agustín G, Battista Francesco, Garcia Maurício, Müller Rodrigo T, Schmitt Mauricio R, Melo Tomaz P, Francischini Heitor, Schultz Cesar L, Pinheiro Felipe, Soares Marina B, Kellner Alexander W
Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis (LAPUG), Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Laboratório de Paleobiologia, Universidade Federal do Pampa - Campus São Gabriel, São Gabriel, Rio Grande do Sul, Brazil.
Sci Rep. 2025 May 30;15(1):18498. doi: 10.1038/s41598-025-99362-5.
The dawn of dinosaurs is marked by the appearance of the saurischian lineages in the Late Triassic fossil record, around 230 million years ago. This early burst of diversification of the group is majoritarily represented by sauropodomorphs and herrerasaurids in late Carnian to early Norian of Brazil, Argentina, India, and Zimbabwe. However, "silesaurids", an older and enigmatic group of quadrupedal dinosauromorphs, were recently found, in some works, as stem ornithischians. In this scenario, dinosaurs would have originated far earlier than the end of the Ladinian, a time in which "silesaurids" are already spread through Gondwana. Despite being also recorded in more recent dinosaur-bearing beds in Brazil, "silesaurids" are absent in strata from the early Carnian, an important time frame for dinosaur evolution. Here we present a new "silesaurid", Itaguyra occulta gen. et sp. nov., that fills up the remaining gap of occurrence of these dinosauromorphs and provides new clues to the success of these putative early ornithischians.
恐龙的起源以蜥臀目谱系在大约2.3亿年前的晚三叠世化石记录中的出现为标志。该类群早期的多样化主要表现为巴西、阿根廷、印度和津巴布韦卡尼晚期至诺利早期的蜥脚形亚目恐龙和赫氏龙。然而，“西里龙类”是一类更为古老且神秘的四足恐龙形类群，在一些研究中，它们最近被发现属于鸟臀目恐龙的祖先。在这种情况下，恐龙的起源可能比拉丁期末期要早得多，而在拉丁期末期“西里龙类”已经遍布冈瓦纳大陆。尽管在巴西较新的含恐龙地层中也有“西里龙类”的记录，但在卡尼早期地层中却没有，而卡尼早期是恐龙进化的一个重要时间框架。在此，我们描述了一种新的“西里龙类”，隐秘伊塔古拉龙（Itaguyra occulta），属名及种名均为新创，它填补了这些恐龙形类群出现记录中的剩余空白，并为这些假定的早期鸟臀目恐龙的成功进化提供了新线索。
