Top of the food chains: an ecological network of the marine Paja Formation biota from the Early Cretaceous of Colombia reveals the highest trophic levels ever estimated.

This article focuses on the reconstruction and analysis of the first site-specific quantitative ecological network for a Mesozoic marine fauna, based on the Early Cretaceous Paja Formation biota of Colombia. The study quantitatively models trophic interactions among marine producers, consumers, and apex predators, revealing a complex ecosystem dominated by large marine reptiles occupying exceptionally high trophic levels, surpassing those of any extant marine apex predators. Compared to modern Caribbean reef ecosystems, the Paja network lacks a diverse benthic invertebrate and fish fauna, with ammonites forming a distinct mid-trophic level that may represent a unique or underrepresented trophic unit. The findings provide new insights into marine ecosystem complexity during the Mesozoic Marine Revolution and highlight the need to consider taphonomic, environmental, and evolutionary biases when interpreting fossil-based food webs.