Amadori Manuel, Amalfitano Jacopo, Giusberti Luca, Fornaciari Eliana, Carnevale Giorgio, Kriwet Juergen
University of Vienna, Department of Paleontology, Vienna, Austria.
Dipartimento di Geoscienze, Università degli Studi di Padova, Padova, Italy.
PeerJ. 2020 Nov 24;8:e10167. doi: 10.7717/peerj.10167. eCollection 2020.
Associated and isolated teeth of the extinct elasmobranch Agassiz, 1835 from the Upper Cretaceous Scaglia Rossa pelagic limestone of northern Italy are described and discussed here in detail for the first time. The dentition of this widely distributed species consists of low-crowned molariform teeth that exhibit marked and strong occlusal ornamentations suitable for crushing hard-shelled prey. The associated tooth sets and isolated teeth analyzed here are heterogeneous in size and crown outline, but unambiguously belong to a single species. Re-examination of this Italian material consisting of ca. 30 specimens mostly coming from historical collections allows for a rigorous assessment of the intraspecific variability of , including the identification of three different tooth "morphotypes" based on their positions within the jaws. The relatively flat crowns and occlusal sharp and thick ridges indicate a high adaptation for crushing hard-shelled prey in indicating that the durophagous adaptations of this species were certainly more pronounced than in all other species of . We hypothesize that was a third-level predator occupying habitats with abundant thick-shelled prey, such as inoceramid bivalves and ammonites.
本文首次详细描述并讨论了来自意大利北部上白垩统斯卡利亚罗萨远洋石灰岩的已灭绝板鳃亚纲动物（阿加西，1835年）的关联齿和孤立齿。这种广泛分布的物种的齿系由低冠磨牙形牙齿组成，这些牙齿具有明显且强烈的咬合纹饰，适合碾碎硬壳猎物。这里分析的关联齿组和孤立齿在大小和冠轮廓上是异质的，但明确属于单一物种。对这批约30个标本（大多来自历史收藏）的意大利材料进行重新检查，有助于对该物种的种内变异性进行严格评估，包括根据牙齿在颌骨中的位置识别出三种不同的牙齿“形态类型”。相对扁平的冠部以及尖锐且厚实的咬合脊表明，该物种对碾碎硬壳猎物具有高度适应性，这表明该物种的食硬壳动物适应性肯定比所有其他物种更为显著。我们推测，该物种是三级捕食者，占据着有大量厚壳猎物的栖息地，如菊石双壳类和菊石。
