This is Trilophosuchus rackhami , a miniature crocodile that inhabited north-west Queensland 13.5 million years ago. Its appearance was endearing: it had a short snout and three distinct crests on the top of its skull.
Today’s crocodiles, which are up to 5.2 meters long and weigh up to 520 kg, are some of the most ferocious animals on Earth. But one of its ancient relatives was a little less intimidating: it was only 70 to 90 cm long and weighed 1 to 2 kg.
Beware of stepping on crocodiles in the forest
“This was a truly unique looking crocodile, with a short snout and three distinct ridges on the top of its skull,” said Jorgo Ristevski, PhD candidate at the University of Queensland and lead author of the study.
Fossils of this tiny crocodile, Trilophosuchus rackhami, which roamed the forests of north-west Queensland 13.5 million years ago, were first discovered in 1993 and named Rackham’s three-crested crocodile in honor of Alan Rackham, who runs the Riversleigh Fossil Discovery Center at Mount Isa.
Analyzing the remains
For analysis of the fossil remains, scientists used state-of-the-art technology to scan the skull of the extinct crocodile, revealing previously unknown details about its anatomy. “By micro-CT scanning the beautifully preserved skull, we were able to digitally separate each bone ,” says Ristevski. “We estimate that in adulthood, Trilophosuchus rackhami would have been between 70 and 90 centimeters long and weighed one to two kilograms, which was very small compared to most extant crocodilians.”
“For one of the studies, I digitally reconstructed the brain cavity of Trilophosuchus rackhami and found that it resembles that of some distantly related and potentially terrestrial extinct crocodiles from Africa and South America,” Ristevski said. “We were quite surprised to find this because, evolutionarily speaking, Trilophosuchus rackhami is most closely related to crocodiles today. This may indicate that Trilophosuchus rackhami spent more time on land than most living crocodilians.”
Thanks to this finding, we may be able to understand a little better, in a more reliable and accurate way, the evolution of the crocodile.
“If we could travel back in time to northern Queensland 13 million years ago, you would not only have to watch out for crocodiles at the water’s edge, you would also have to make sure you don’t step on them in the forest ,” the authors conclude.
Referencia: Jorgo Ristevski, Vera Weisbecker, John D. Scanlon, Gilbert J. Price, Steven W. Salisbury. Cranial anatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993. The Anatomical Record, 2022; DOI: 10.1002/ar.25050
Jorgo Ristevski. Neuroanatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993. Journal of Anatomy, 2022; DOI: 10.1111/joa.13732
