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

即便经过200余年的研究，中生代（Mesozoic）最成功的海洋脊椎动物类群之一——鱼龙（ichthyosaur）的颅部解剖学细节，仍有诸多尚未阐明之处。本次研究基于英国草莓滩（Strawberry Bank）下侏罗统托阿尔阶（Toarcian，183–174 Ma）中一件保存异常完好的‘Hauffiopteryx’典型种（‘Hauffiopteryx’ typicus）鱼龙头骨的三维扫描数据，提供了关于其脑颅（braincase）、腭骨（palate）及枕区（occiput）的全新信息。该鱼龙拥有非同寻常的中空管状舌骨杆（hyoid bars）。其枕区与脑颅区域已被完整重建，获得了鱼龙类首个数字化颅腔模（cranial endocast）。膨大的视叶（optic lobes）与小脑（cerebellum）暗示其具备适应高度灵活的视觉掠食者生活的神经解剖适应性（neuroanatomical adaptations）。其嗅觉区域（olfactory region）同样呈现膨大状态，表明嗅觉（olfaction）在鱼龙的生存中所扮演的角色比此前所认为的更为重要。系统发育分析（phylogenetic analysis）显示，该鱼龙与豪夫翼龙属（Hauffiopteryx）亲缘关系密切但存在明显区别，且被置于鲭龙类（Thunnosauria）内部，其演化位置比此前恢复的结果更为衍生。本研究进一步拓展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适应性提供了研究平台。