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

屈曲拟甲藻是一种分布广泛的菊石种，也是都罗纪早期(晚白垩世)生物带的标志。来自墨西哥东北部Vallecillo的新材料，显示了本种的可能的二型性，包括长刺，到目前为止还没有为本种识别。然而，对于这种脊椎的存在，最被广泛接受的解释，即在海底休息的平衡辅助工具，不能在这里适用。以前对瓦莱西洛古环境的研究表明，海底的条件对大多数保存下来的生物都是不利的。这个项目的目的是对屈曲螺旋藻的种内研究，关于刺的解剖和功能，可能的二型性，以及识别以前的刺在哪里被折断的可能性。脊骨是由另外三个晚白垩世菊石物种描述的，可能是晚白垩世菊石比迄今所认识到的更普遍的特征。此外，对表生环足动物(甲壳纲)的研究可能会对其宿主屈曲螺旋藻的古生态学做出更多的结论。该项目旨在进一步了解这一最受欢迎的化石群中迄今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.