Quiroga J C
J Hirnforsch. 1980;21(3):299-336.
A natural endocranial cast of the South American cynodont Probainognathus jenseni is studied, and an evaluation of the probable nature of the neocortex at the level of certain cynodonts of the Middle Triassic is made, based in the available paleo-neoneurological information. The endocast of Probainognathus shows well developed olfactory bulbs, long cerebral hemispheres, small anterior colliculi and well represented cerebellum and flooculi. The pineal gland may have been located between the caudal hemispheric poles. No parietal foramen exists. The dorsal surface of the cerebral hemispheres shows a slope at the level of the anterior edge of the caudal fourth part, which is interpreted as the posterior limit of the neocortical plate. At the level of the olfactory peduncles, it is visible a stem vessel; one of its branches distributes on the anterior part of the lateral border of the hemisphere. It is advanced the interpretation that this latter vessel could indicate the paleo-neocortical boundary. The analysis of the neoneurological information led the author to suppose that the neocortex of Probainognathus, and surely of other cynodonts of the Middle Triassic, has shown supplementary somatic sensory and motor, visual and auditory representations, and perhaps incipient primary somati sensory and motor ones, advancing a "polymodal cortex", as it is supposed had stem mammals. Moreover, the histostructure of the neocortex at this state of the evolution may have been in a proisocortical-isocortical stage, that is, in the beginnings of the true neocortex. The confrontation of the paleoneurologic with the neoneurologic information led the author to suppose that Triconodon and Ptilodus have had a neocortex, surely more developed than Probainognathus, but that it is not seen in the endocasts at present studied. The quantitative analysis of Probainognathus' endocast, as well as those of other cynodonts, suggest that certain cynodonts of the Middle Triassic were in an advanced state toward endothermy.
对南美犬齿兽类詹氏原颌兽（Probainognathus jenseni）的一个天然颅内模型进行了研究，并基于现有的古神经学信息，对中三叠世某些犬齿兽类的新皮质可能具有的性质进行了评估。原颌兽的颅内模型显示出发育良好的嗅球、长长的大脑半球、较小的前丘以及发育良好的小脑和绒球。松果体可能位于大脑半球尾极之间。不存在顶骨孔。大脑半球的背表面在尾侧第四部分前缘的水平处呈现出一个斜坡，这被解释为新皮质板的后界。在嗅柄水平，可以看到一条主干血管；它的一个分支分布在半球外侧边缘的前部。有人提出，后一条血管可能指示古新皮质边界。对神经学信息的分析使作者推测，原颌兽以及中三叠世其他犬齿兽类的新皮质已经显示出补充性的躯体感觉和运动、视觉和听觉表征，或许还有初期的初级躯体感觉和运动表征，从而提出了一种“多模式皮质”，就像推测的那样，早期哺乳动物也是如此。此外，在这个进化阶段，新皮质的组织学结构可能处于原同型皮质 - 同型皮质阶段，也就是说，处于真正新皮质的起始阶段。将古神经学信息与神经学信息进行对比后，作者推测三棱齿兽（Triconodon）和褶齿兽（Ptilodus）具有新皮质，肯定比原颌兽的更发达，但在目前研究的颅内模型中并未见到。对原颌兽以及其他犬齿兽类颅内模型的定量分析表明，中三叠世的某些犬齿兽类在向恒温状态发展方面处于高级阶段。
