Data from: The skull and endocranium of a Lower Jurassic ichthyosaur based on digital reconstructions

Even after 200 years of study, some details of the cranial anatomy of ichthyosaurs, one of the most successful groups of marine vertebrates in the Mesozoic, are still unclear. New information on the braincase, palate and occiput are provided from three-dimensional scans of an exceptionally preserved ichthyosaur (‘Hauffiopteryx’ typicus) skull from the Toarcian (183–174 Ma, Lower Jurassic) of Strawberry Bank, England. This ichthyosaur has unusual, hollow, tubular hyoid bars. The occipital and braincase region is fully reconstructed, creating the first digital cranial endocast of an ichthyosaur. Enlarged optic lobes and an enlarged cerebellum suggest neuroanatomical adaptations that allowed it to be a highly mobile, visual predator. The olfactory region also appears to be enlarged, suggesting that olfaction was more important for ichthyosaurs than has been assumed. Phylogenetic analysis suggests this ichthyosaur is closely related to, but distinct from, Hauffiopteryx, and positioned within Thunnosauria, a more derived position than previously recovered. These results further our knowledge of ichthyosaur cranial anatomy in three dimensions and provide a platform in which to study the anatomical adaptations that allowed ichthyosaurs to dominate the marine realm during the Mesozoic

即便历经200余年的研究，鱼龙（ichthyosaur）——中生代最为成功的海洋脊椎动物类群之一——的颅部解剖学细节仍有诸多未明之处。本研究通过对英国草莓滩（Strawberry Bank）早侏罗世托阿尔阶（1.83亿~1.74亿年前）一件保存异常完好的‘Hauffiopteryx typicus’鱼龙头骨进行三维扫描，获取了其脑颅、腭区及枕区的全新解剖学信息。该鱼龙拥有形态特殊的中空管状舌骨棒。其枕区与脑颅区域已被完整重建，构建出首个鱼龙的数字化颅内膜模。其增大的视叶与小脑暗示其具备神经解剖学层面的适应性特征，使其能够成为高度活跃的视觉捕食者。其嗅觉区域同样呈现增大特征，表明嗅觉对于鱼龙的重要性远超此前的认知。系统发育分析显示，该鱼龙与Hauffiopteryx亲缘关系紧密但自成一类，且被归入鲭鱼龙类（Thunnosauria），其系统发育位置较此前的研究结果更为衍化。本研究结果进一步完善了我们对鱼龙三维颅部解剖学的认知，并为探究鱼龙在中生代称霸海洋所依赖的解剖学适应性特征提供了研究平台。