梦幻鬼鱼（Guiyu oneiros）的正型标本是迄今为止全球最古老的保存完整的硬骨鱼乃至有颌脊椎动物化石，发现于云南曲靖至今四亿多年前的志留纪地层中。它的发现将有关包括人类在内的现生脊椎动物起源的探索从泥盆纪推向了更加久远的志留纪。鬼鱼的梦幻之处在于它身上汇集了有颌类动物的众多原始特征。这些特征过去分别出现在有颌类的不同类群中，并被认为是某个类群的衍生特征。梦幻鬼鱼所呈现的特征组合证明，某些类群的衍生特征其实只是有颌类的原始特征。这些认识的改变，最终将对有颌类谱系关系的解释产生深远影响。
中国科学院古脊椎动物与古人类研究所脊椎动物进化系统学重点实验室的乔妥和朱敏在近期的《中国科学》上发表了鬼鱼脑颅形态研究的最新成果。他们根据新的标本和一些之前报导过的鬼鱼标本的脑颅形态研究，首次在鬼鱼支系（包括鬼鱼、斑鳞鱼和无孔鱼）中恢复了颅顶的膜质骨型式。
通过和爪齿鱼、无孔鱼、空棘鱼以及辐鳍鱼类的比较，他们认为后外鼻孔后被眶前骨或前上颌骨眶前突包围是硬骨鱼类的原始特征，肉鳍鱼类和辐鳍鱼类中的泪骨并非同源结构。鬼鱼的筛蝶区结构和斑鳞鱼、无孔鱼以及爪齿鱼极为相似。发达的颅下肌附着区可能提示了鬼鱼发育的颅间关节。
“与杨氏鱼和奇异鱼相似，鬼鱼犁骨附着区具不规则沟脊。而鬼鱼的鼻眶管靠近鼻囊内侧，这一点又与杨氏鱼和孔鳞鱼一致。”乔妥和朱敏说，“垂体孔位于脑颅筛关节稍前处或位于同一水平是鬼鱼支系的共近裔性状”。（生物谷Bioon.com）
鬼鱼脑颅前部腹视
鬼鱼脑颅前部前视
生物谷推荐原文出处：
Science China doi: 10.1007/s11430-010-4089-6
Cranial morphology of the Silurian sarcopterygian Guiyu oneiros
(Gnathostomata: Osteichthyes)
QIAO Tuo1,2 & ZHU Min1*
1 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology,
Chinese Academy of Sciences, Beijing 100044, China;
2 Graduate School of Chinese Academy of Sciences, Beijing 100049, China
Cranial morphological features of the stem-group sarcopterygian Guiyu oneiros Zhu et al., 2009 provided here include the dermal bone pattern and anatomical details of the ethmosphenoid. Based on those features, we restored, for the first time, the skull roof bone pattern in the Guiyu clade that comprises Psarolepis and Achoania. Comparisons with Onychodus, Achoania, coelacanths, and actinopterygians show that the posterior nostril enclosed by the preorbital or the preorbital process is shared by actinopterygians and sarcopterygians, and the lachrymals in sarcopterygians and actinopterygians are not homologous. The endocranium closely resembles that of Psarolepis, Achoania and Onychodus; however, the attachment area of the vomer possesses irregular ridges and grooves as in Youngolepis and Diabolepis. The orbito-nasal canal is positioned mesial to the nasal capsule as in Youngolepis and porolepiforms. The position of the hypophysial canal at the same level or slightly anterior to the ethmoid articulation represents a synapmorphy of the Guiyu clade. The large attachment area of the basicranial muscle indicates the presence of a well-developed intracranial joint in Guiyu.
