In the present work, we examine a sample of 54 specimens of the heteromorph ammonite genus Ancyloceras d’Orbigny, 1842 from the Argiles à Plicatules Formation (lower Aptian, Lower Cretaceous) of the eastern Paris Basin (NE France). The results are as follows: (1) the sample is regarded as monospecific and assigned to the well-named species Ancyloceras varians d’Orbigny, 1842; (2) its variability is continuous and concerns as well as adult size, coiling and shell ornamentation. Adult size varies by a factor of two from one individual to another. The angle between the proversum and the retroversum is variable. The ornamentation on the spiral and the proversum varies between robust morphotype with trituberculate strong ribs separated by few smooth intercalaries ribs and slender morphotype with feebly tuberculate ribs. There are no arguments in favor of sexual dimorphism in Ancyloceras varians.

在目前的工作中，我们检查了来自东部巴黎盆地（法国东北部）的ArgilesàPlicatules组（下白垩统下阿普提安）的1854年异形morph石属Ancyloceras d'Orbigny的54个标本的样本。结果如下：（1）样品被认为是单特异性的，并被归入命名为Ancyloceras varians的物种奥尔比尼（d'Orbigny），1842年；（2）它的变异性是连续的，并且与成体大小，卷曲和壳饰有关。从一个人到另一个人，成年人的身高相差两倍。副词和反演词之间的角度是可变的。螺旋和pro节上的装饰在三结实的强肋被少量平滑的cal间肋隔开的细长形态和结节微弱的肋的细长形态之间变化。没有任何论点支持苍蝇的性二态性。