Even in today’s hotspots for crocodylic diversity, it is rare to find more than two or three different crocodylic species in a given location – which is why it’s so surprising that an international group of paleontologists revealed in Nature Communications that, at one point during the late Miocene, at least seven crocodylic species lived sympatrically.
The diversity of species in the Miocene is shown to be largely in sedimentary basins in Colombia, Brazil, Peru, and Venezuela, but the origins of this long-lost diversity are not well understood. Researchers such as Dr. Torsten Scheyer of the University of Zurich and his colleagues are now using taxonomic and stratigraphic work to document and sequence crocodylic remains.
In their paper published this May, the team analyzes over fifty species that lived in the Urumaco region of Venezula, in the deltas of a river that no longer exists. Among them were two newly discovered species – one belonging to the caimans (a subfamily of the family Alligatoridae) and one belonging to the genus Crocodylus (true crocodiles).
Globidentosuchus brachyrostris, the caiman, had spherical teeth that expose facts about their previous lifestyle. Most likely, the creature fed on shellfish, snails, and crabs. Giant crocodiles, like Crocodylus falconensis (which grew to be over 13 feet long!) probably fed on giant turtles, rodents, and smaller crocodiles. According to Dr. Scheyer, during this time period in South America, giant crocodiles were the only predator filling this niche.
So what happened to the crocodylic diversity that once existed in South America? Interestingly, their demise was unrelated to climate change. A tectonic event, known as the “Andean uplift,” changed the courses of rivers. Dr. Sánchez-Villagra explains that the Amazon River began draining in the Atlantic Ocean, rather than the Caribbean, causing the end of the unusual species by the Pliocene, around 5 million years ago.
Read the entire crocodylic diversity study in Nature Communications.
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