Universidade Federal de Santa Maria, Centro de Apoio à Pesquisa Paleontológica, Rua Maximiliano Vizzotto, 598, 97230-000 São João do Polêsine, RS, Brazil.
Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, Av. Perimetral, 1901, 66077-830 Belém, PA, Brazil.
An Acad Bras Cienc. 2021 Mar 5;93(suppl 2):e20200084. doi: 10.1590/0001-3765202120200084. eCollection 2021.
Recently, the morphology and encephalization of the brain endocast of the Triassic non-mammaliaform probainognathian cynodont Riograndia guaibensis were studied. Here, we analyzed the brain endocast of an additional specimen of this species. The new endocast shows well-defined olfactory bulbs and a median sulcus dividing the hemispheres, traits that were not clearly observed in the first studied specimen. Encephalization quotients were also calculated, revealing similar values to other non-mammaliaform cynodonts and lower than those of the first analyzed specimen. The analyzed cranium is slightly larger than the first studied one and may represent an advanced ontogenetic stage. Hence, these differences may be related to the intraspecific variation of this cynodont or alternatively, to the preservation of each specimen.
最近，对三叠纪非哺乳形似哺乳爬行动物 Riograndia guaibensis 的脑腔骨骼形态和脑量进行了研究。在这里，我们分析了该物种的另一个标本的脑腔骨骼。新的脑腔骨骼显示出明显的嗅球和分隔半球的中央沟，这些特征在第一个研究的标本中没有明显观察到。脑化指数也进行了计算，结果表明与其他非哺乳形似哺乳爬行动物相似，低于第一个分析标本的值。分析的颅骨略大于第一个研究的颅骨，可能代表了一个较高级的个体发育阶段。因此，这些差异可能与这种似哺乳爬行动物的种内变异有关，或者与每个标本的保存有关。
