Platel R
Equipe de Neuroanatomie comparée, Laboratoire d'Anatomie comparée Université Paris 7.
J Hirnforsch. 1989;30(3):325-37.
This study has been carried out on two adults of the species Sphenodon punctatus (Sphenodontidae). The results allowed us to establish the numerical features of the brain organization in this species. Comparisons were done with regard to a sample of forty various species of lizards, in which six species of Lacertids were taken as a mean reference level (Platel, 1975). Opposite to those of the Lacertids (100), the index of encephalization in Tuatara has a low value (70.2), but locates Sphenodon in the neighbourhood of lizards of the family Cordylidae (Cordylus, Zonosaurus). This feature remains the same for the main subdivisions of the brain, according to the value of their structure index (as well as their isoponderal percentage). In most subdivisions, the indices show also low values, except for Epithalamus (359), dorsal thalamus (118) and cerebellum (121); some hypothesis were given according to olfaction, vision and locomotion in Tuatara. On the whole, our results lead us to consider the Tuatara as a few evoluted Lepidosaur (according to its brain organization); comparisons with lizards bring it close to the Lacertomorpha (Type I Lizards), considered by Northcutt (1972) as less advanced saurens than the Dracomorpha (Type II Lizards).
本研究对斑点楔齿蜥（楔齿蜥科）的两只成年个体进行。研究结果使我们能够确定该物种大脑组织的数值特征。我们将其与四十种不同蜥蜴的样本进行了比较，其中六种蜥蜴科蜥蜴被作为平均参考水平（普拉泰尔，1975年）。与蜥蜴科蜥蜴（100）相反，楔齿蜥的脑化指数值较低（70.2），但楔齿蜥与环尾蜥科蜥蜴（环尾蜥属、斑纹蜥属）相近。根据大脑主要亚区的结构指数值（以及它们的等重百分比），这一特征在大脑的主要亚区中保持不变。在大多数亚区中，指数值也较低，除了上丘脑（359）、背丘脑（118）和小脑（121）；根据楔齿蜥的嗅觉、视觉和运动能力给出了一些假设。总体而言，我们的研究结果使我们认为楔齿蜥是一种进化程度较低的鳞龙类（根据其大脑组织）；与蜥蜴的比较使其接近蜥蜴亚目（I型蜥蜴），诺思卡特（1972年）认为蜥蜴亚目比飞龙亚目（II型蜥蜴）的蜥蜴进化程度低。
