Marine fossils in Colombia reveal possible evolutionary transition without mass extinction

A remarkable fossil site in central Colombia provides fresh insights into the evolutionary timeline, revealing a period of significant biological transition without the catastrophic loss of species associated with mass extinctions. Researchers from McGill University and the Centro de Investigaciones Paleontológicas (CIP) have identified a newly recognized pattern known as a "biotic inflection" within the Paja Formation.

This concept describes a time when numerous evolutionary lineages, teetering on the brink of extinction, coexisted alongside newly emerging groups that would later experience a period of rapid diversification.

The Paja Formation, dating back to the Early Cretaceous period, exhibits an unprecedented level of biodiversity thanks to a convergence of favorable environmental conditions. These included warm temperatures, high sea levels, nutrient-rich coastal waters, and new marine connections that linked the eastern Pacific and early Atlantic oceans through what is now Colombia. These conditions, similar to those observed today, likely played a crucial role in driving the observed ecological complexity and evolutionary shift.

The findings, published in the journal Frontiers in Ecology and Evolution, highlight the presence of a wide array of marine life, including giant marine reptiles such as plesiosaurs and marine crocodile relatives, as well as turtles, sharks, crustaceans, and other species. Together, these organisms formed a highly complex marine community, referred to as the Paja Biota, characterized by a rich variety of apex predators.

Further research, including additional fossil sampling, precise dating, and comparative studies with other geological deposits worldwide, is necessary to determine the extent and global implications of this biotic inflection pattern in Earth's history.