UF researchers discover 20-foot-long crocodile species

The fossils were found in a coal mine in northeastern Colombia


University of Florida researcher Alex Hastings displays a pelvic bone of Acherontisuchus guajiraensis, a 60-million-year-old ancestor of crocodiles discovered in northeastern Colombia. (Photo submitted by the University of Florida)

Published: Saturday, October 1, 2011 at 6:40 p.m.
Last Modified: Saturday, October 1, 2011 at 6:40 p.m.

Sixty-million years ago, in the heat and humidity of Paleocene-era Colombia, a snake so large that researchers named it Titanoboa was the reptile king of its domain.

But it wasn't the only giant reptile hunting for fish in the rivers of northern Colombia.

A new species of enormous crocodile, measured at 20 feet long, has been discovered by University of Florida researchers in the same coal mine that Titanoboa was found.



The creature may have been large enough to give Titanoboa competition for the fish they were both ideally adapted to hunt.

The excavations at the site were led by Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History; and Carlos Jaramillo, a paleobotanist with the Smithsonian Tropical Research Institute.

Alex Hastings, a UF Ph.D. student in the department of geological sciences, collected the type-specimen for the species. This fossil set will be used as a comparison tool for future finds.

The crocodile, Acherontisuchus guajiraensis, is the latest prehistoric reptile to be found in the Cerrejon coal mine.

It is named after the river Acheron, which in Greek myth is a branch of the river Styx in the underworld.

Bloch described the coal mine as a hot and humid place, where seams of coal spontaneously combust and give off a sulfuric smoke, giving the entire area a very hellish atmosphere.

The Acherontisuchus species was a cousin to modern-day crocodiles, not their direct ancestors, and it dates back 60 million years.

This places the species at the time immediately following the mass extinction event that claimed the dinosaurs, as well as a wide variety of other life on Earth.

Acherontisuchus belonged to a group that somehow managed to survive the cataclysm.

"One of the questions about this group was how they were able to survive … what advantages did they have?" Hastings said.

"What this new crocodile really contributes to that is that it is the first evidence of a large-bodied member of this group in a freshwater habitat," he said.

Before now, it was thought that only baby crocodiles would spend any appreciable amount of time in freshwater, and that adults would spend most of their time in a saltwater environment.

Their ability to adapt to multiple environments would have helped this family of crocodiles survive the mass extinction and the lean times that followed it.

Hastings said that their survival depended on taking advantage of multiple resources, rather than just what the ocean provided.

Living in freshwater may also have shielded the species from whatever began to kill off the large marine reptiles of the ocean around the same time as the dinosaurs.

Another rival reptile family, the mosasaurs, began to vanish at this point, so whatever environmental pressure took these creatures may have passed over Acherontisuchus.

Bloch said that the species also is important because each new find tells researchers more about the time period they are from.

He said that the tropics are a very mysterious place when it comes to the fossil record because of the predominantly forested land, which makes it difficult to excavate.

Bloch said this is particularly ironic because a lot of the animal diversity today can be found in the tropics, but we know the least about the creatures that lived there during the Paleocene.

Acherontisuchus' size of 20 feet was based on the larger of two individuals found at the site.

Hastings said that there were certainly larger specimens, as well as smaller. Twenty feet places it at the known upper size of modern specimens, such as the reportedly 21-foot saltwater crocodile captured in the Philippines in early September.

To put this size in perspective, and comparing it to modern specimens, Acherontisuchus probably weighed upward of a ton and grew to be more than half the length of an RTS city bus. It had a wide shelf on the back of its head, giving it a very broad, flat appearance.

Like modern gavial crocodiles, its snout was very long and narrow, filled with pointed teeth, making it ideally suited to hunting fish.

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