When two ecosystems collided, ichthyosaurs re-developed their ability to eat large prey

Overland contact between North and South America has long been a fount of research. The Isthmus of Panama – the narrow strip of land between the two continents – appeared completely about 3.5 million years ago. It allowed contact between terrestrial mammals of North and South America, and resulted in large-scale invasions of placental mammals in South America and the eventual extinction of most southern marsupials.

In the late Jurassic, 150 million years ago, the Earth was emerging from a relatively cold period, the supercontinent Pangea was disintegrating, and the intensity of the extinction spread across ecosystems. During the following period, known as the Early Cretaceous, the planet was warming, global sea levels and atmospheric oxygen rose and the continents continued to break apart.

As a result, two completely isolated oceans, the eastern Pacific Ocean and the western Tethys, which later became the Atlantic Ocean, came together across the Spanish Corridor. This union of oceans during a period of relatively high temperatures created a perfect storm for ecosystem evolution and drivers of new biodiversity in the neotropics—an event that will alter the course of marine ecosystems over the next 60 million years.

biodiversity hotspot

Spanish lane.
(climate archive), Author introduced

Our research team, made up of scientists from Colombia, Canada and Germany, explored the tropics using the fossil record from the Baja Formation, a poorly studied shallow marine sediment in central Colombia that was laid out after the formation of the Spanish Corridor. Our main goal is to understand the origin and evolution of this marine ecosystem, and whether it serves as a potential hotspot for ancient biodiversity – a center for new species emerging and thriving.

We’ve discovered a new species of ichthyosaur, a giant fish-like marine reptile. While examining a beautifully preserved skull specimen of the species we named Sachicarumwe realized that this is the first ichthyosaur of the hyper Cretaceous period.

An image of an ichthyosaur skull
Skull Sachicarum.
(polite, maxwell, larson)And Author introduced

New species of Jurassic ichthyosaurs evolved in Tethys, but they differed in that they had teeth unique to ichthyosaurs: there were many different tooth shapes that served different purposes, from boring to sawing teeth to crushing.

This large ichthyosaur represents a revival of hypertrophic (eating large prey). Although some early ichthyosaurs did, they transitioned to small fish and invertebrates over the next 70 million years. bog down Somehow redeveloped the ability to overeat during this time and place of severe environmental disruption.

big sea animals

bog down It was also one of the last surviving ichthyosaurs. Most ichthyosaurs became extinct by the end of the Jurassic period – a few reached the Cretaceous period but none survived to 100 million years ago. The fossil record of the Baja Formation preserves hints of a changing marine ecosystem.

3D animation of Sachicarum.

These rocks preserve some of the largest marine animals ever discovered, including several ichthyosaurs, huge whale-sized pliosaurs, the first long-necked elasmosaurus and a 10-meter-long crocodile that was the last survivor of a long line of Jurassic marine crocodiles.

The fossil record also contains the oldest known sea turtles in the current sea turtle lineage as well as the origins of many crustaceans living today.

Information in the fossil record helps us reconstruct ancient food web interactions based on what was in the eastern Pacific and western Tethys before their contact and what was there during their contact in the Baga Formation. Changes in these ancient food webs promise to shed light on the ecological and ecological factors that are involved in the long-term sustainability of ecosystems.

ALT
Artist’s reconstruction of the early Cretaceous ecosystem, created for time agothe first illustrated book on the geological history of Colombia.
(time ago / K. Jaramillo and Guillermo Torres Carreno), Author introduced

Closer examination of fossils from this unique time and place provides a new window into what happens when ecosystems collide. So far, we have found that this facilitates the evolution of massive predators and many of the evolutionary origins of new lineages that will persist for millions of years.

These results provide relevant data for a better understanding of the consequences of the Jurassic-Cretaceous extinction on marine fauna and, ultimately, for the emergence of marine ecosystems today.

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