Uncovering the Secrets of Colombia’s Rich Fossil Deposits #fossils #paleontology #southamerica #columbia

A Kronosaurus, one of the top predators in Cretaceous-era tropical oceans, prepares to feast on an ammonite. Illustration by Konstantin G / Shutterstock

Smithsonian Magazine has a piece about Columbia's rich fossil deposits.  The formation of the Andes Mountain, about 72 million years ago, revealed many marine fossils from the Cretaceous Period.  

Ammonites—extinct marine cephalopods with distinctive coiled shells—are embedded in walls, floors and roads all across town. Locals and visitors often find fossils when walking unpaved roads and hiking the trails around Villa de Leyva. Before former President Juan Manuel Santos signed a 2018 decree protecting the country’s paleontological heritage, street vendors sold fossils to passing tourists.

During the Lower Cretaceous, between 100 million and 145 million years ago, this region of central Colombia was underwater, and these fossils were part of a complex and diverse marine ecosystem. Back then, this area was part of an ocean overlying a continental shelf next to the recently formed South America in the proto-Caribbean Sea. Its waters were relatively shallow, around 590 to 650 feet deep, and the bottom was toxic for most living things due to high levels of sulfuric acid and low levels of dissolved oxygen. When dead animals and plants fell to the ocean floor, the toxicity protected their remains from scavengers, helping to preserve them. When this portion of the Andes Mountains began to form—around 72 million years ago, according to a recent study—these fossils reached new heights, literally.