Paleobiological interpretation of the Turonian ammonite species Pseudaspidoceras flexuosum and its epibionts

柔形假aspidoceras flexuosum是一种分布广泛的菊石，是早Turonian（晚白垩世）生物带的标志。来自墨西哥东北部Vallecillo的新材料显示了该物种可能的二态性，包括长刺，迄今为止尚未发现该物种。然而，对于这些刺的存在，最广为接受的解释，即它们是在海底保持平衡的辅助物，在这里是不能适用的。先前对瓦列西略古环境的研究表明，海底的条件对大多数保存下来的生物都是不利的。本项目的目的是在种内研究弯曲棘的解剖和功能，可能的二态性，以及识别前棘断裂的可能性。从其他三种晚白垩世菊石物种中描述了刺，并且可能比迄今为止认识到的晚白垩世菊石更广泛的特征。此外，对附生cirridians（甲壳类）的研究可能会对其寄主P. flexuosum的古生态学有更多的结论。该项目旨在进一步了解迄今为止最受欢迎的化石群之一的难以捉摸的古生物学。

Pseudaspidoceras flexuosum is a widely distributed ammonite species and index for an early Turonian (Late Cretaceous) biozone. New material from Vallecillo, northeastern Mexico, shows a possible dimorphism for this species, including long spines, hitherto not recognized for this species. However, the most widely accepted explanation for the presence of such spines, a balancing aid to rest on the sea-floor, cannot be applied here. Previous studies of the palaeoenvironemt at Vallecillo have shown that conditions at the sea-floor were hostile to most organisms preserved. This project is aimed at an intraspecific study of P. flexuosum regarding anatomy and function of the spines, a possible dimorphism, and the possibility to recognize former spines where they are broken away. Spines were described from three other Late Cretaceous ammonite species and may have been a more widespread feature of Late Cretaceous ammonites than hitherto recognized. In addition, study of epibiontic cirripedians (Crustacea) may allow for additional conclusions on the palaeoecology of their host P. flexuosum. This project intends to contribute to further understanding of the hitherto elusive palaeobiology of one of the most popular fossil groups.