Bajaichthys elegans from the Eocene of Bolca (Italy) and the overlooked morphological diversity of Zeiformes (Teleostei, Acanthomorpha)

The Eocene (Ypresian) fauna of Bolca, Italy yields a famous assemblage of marine tropical teleosts. One of the most anatomically distinctive teleosts from Bolca is the enigmatic †Bajaichthys elegans, generally interpreted as a member of Lampridiformes (oarfishes and their allies). Re-examination of the type and only specimen of †Bajaichthys contradicts this attribution, and we propose that its original description as a member of Zeiformes (dories) was in fact correct. †Bajaichthys bears numerous derived features of zeiforms not found in lampridiforms, including: a pelvic spine, a first vertebra closely associated with the neurocranium, and a reduced metapterygoid not contacting the quadrate. Lampridiform-like attributes, including a greatly elongated ascending process of the premaxilla, are known to be convergent between this group and Zeiformes. Using a combination of morphological and molecular data, we confirm this revised interpretation and resolve the position of †Bajaichthys withi...

意大利博尔卡的始新世（伊普雷斯期）动物群产出了著名的海洋热带硬骨鱼（teleosts）化石组合。其中解剖学特征最为独特的类群之一是神秘的优雅巴哈鱼（†Bajaichthys elegans），此前学界普遍将其归为月鱼目（Lampridiformes，皇带鱼及其近缘类群）的成员。本次对其唯一模式标本的重新检视推翻了这一分类判定，我们提出其最初被归入海鲂目（Zeiformes，海鲂类）的观点才是正确的。优雅巴哈鱼具备诸多海鲂目特有的衍生性状，而这些特征并未见于月鱼目，具体包括：腹鳍棘、与脑颅（neurocranium）紧密关联的第一椎骨，以及不与方骨（quadrate）相接的缩小后翼骨（metapterygoid）。已知月鱼目与海鲂目之间存在趋同演化的类月鱼目特征，比如前颌骨（premaxilla）极度延长的上升突起。结合形态学与分子数据，我们验证了这一修订后的分类观点，并确定了†Bajaichthys的系统发育位置（原文内容未完整给出）