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首页> 外文期刊>Journal of Systematic Palaeontology >DESCRIPTION AND SYSTEMATIC RELATIONSHIPS OF TOMOGNATHUS, AN ENIGMATIC FISH FROM THE ENGLISH CHALK
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DESCRIPTION AND SYSTEMATIC RELATIONSHIPS OF TOMOGNATHUS, AN ENIGMATIC FISH FROM THE ENGLISH CHALK

机译：豚鼠的英文描述和系统关系

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摘要

The Upper Cretaceous fish Tomognathus mordax Dixon, 1850, is redescribed, based on newly acid-prepared material that reveals many new structures and reinterpretations of some parts of anatomy previously described. The cranium shows the absence of a supraoccipital, a double jaw joint involving a symplectic and quadrate, a lower jaw incorporating a coronoid, prearticular and a surangular, concave shape of the posterior margin of the maxilla, a single supramaxiila, a 'V'-shaped median rostral with lateral horns and an interopercle that lies in series with the subopercle. These features suggest affinities with the Halecomorphi. Within Halecomorphi, character conflict means that Tomognathus may only be placed as Superfamily Amioidea incertae sedis. It is highly apomorphic in showing parietals, frontals, premaxillae and vomers all fused into median elements, a parasphenoid with scythe-like processes developed along the ascending wings and an infraorbital series reduced to tube-like elements. Tomognathus is one of only three halecomorphs recorded from the English Chalk.
机译：根据新近用酸制备的材料重新描述了上白垩纪鱼类Tomognathus mordax Dixon（1850年），该材料揭示了许多新的结构并重新解释了先前描述的某些解剖结构。颅骨没有上枕骨，双上颌关节包括一个辛和四边形，下颌下颌骨合并了上颌后缘的冠状，关节前和近角凹形，单个上颌上颌，'V'-形的中位延髓，具侧角和与下oper骨串联的oper间。这些功能表明与Halecomorphi有密切关系。在Halecomorphi中，角色冲突意味着Tomognathus只能作为超家族Amioidea incertae sedis放置。它具有高度复晶的形态，表现为顶叶，额叶，前颌骨和前房融合到中位元素中，旁蝶骨沿上升的翅膀长出镰刀状突起，而眶下序列减少为管状元素。 Tomognathus是英语粉笔中仅有的三种变种之一。

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