‘Heteromorph ammonoids’ encompass all ammonoid species whose shapes do not conform to a closely coiled planispiral shell. The term is useful as a broad description for such ammonoids. However, as a concept, ‘heteromorph ammonoids’ no longer has any scientific value or explanatory power. Although such ammonoids have traditionally been considered aberrant forms, they represent instead an integral part of the evolutionary history of the Ammonoidea. ‘Heteromorph ammonoids’, as a whole, are a polyphyletic group, consisting of a heterogeneous mixture of taxa without any phylogenetic, morphological or ecological coherence. Their treatment as a single entity risks conflating convergences and phylogenetic affinities. It also vastly oversimplifies the stunning array of morphologies and ecological niches occupied by these animals. Investigation into the uncoiling (and recoiling) of ammonoids is a legitimate and worthwhile enterprise, especially in view of the realization that this phenomenon occurred several times in the history of the Ammonoidea. However, few insights can be gained by treating ‘heteromorph ammonoids’ as a single entity. Studies of such ammonoids should focus on monophyletic groups within a well-constrained phylogenetic and stratigraphical framework to yield meaningful results.

中文翻译：

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'异型氨类化合物'的概念

“异形菊石”包括所有形状不符合紧密盘绕的平面螺旋壳的菊石物种。该术语可用作此类氨类化合物的广泛描述。然而，作为一个概念，“异形菊酯”不再具有任何科学价值或解释力。尽管此类菊石传统上被认为是异常形式，但它们反而代表了菊石进化史的一个组成部分。整体而言，“异形菊苣”是一个多系群，由分类群的异质混合物组成，没有任何系统发育、形态或生态连贯性。将它们作为一个单一实体进行处理可能会混淆趋同和系统发育亲缘关系。它还大大简化了这些动物所占据的令人惊叹的形态和生态位。对菊石的开卷（和回卷）进行调查是一项合法且有价值的事业，尤其是考虑到这种现象在菊石的历史上曾多次发生。然而，通过将“异形菊酯”视为一个单一的实体，几乎无法获得任何见解。对此类菊石的研究应集中在受良好约束的系统发育和地层框架内的单系群，以产生有意义的结果。