It seems that the early crocodilians which roamed the planet during the Late Jurassic weren't as big and terrifying as the formidable beasts we know (and fear) today.
A recent study into an ancient species of crocodilians known as shartegosuchids — the earliest and "least understood" group of the Crocodilia order, according to the University of Witwatersrand in Johannesburg, South Africa — uncovered that these creatures were smaller and more slender than the modern crocodilians we see today.
On top of that, the research, published on June 18 in the journal American Museum Novitates, revealed that these crocodile ancestors had very unusual mouths.
The observations were made on a shartegosuchid fossil discovered in 2010 by an international research team that was exploring Late Jurassic exposures in Mongolia's Gobi Desert. Among the scientists — Prof. Jonah Choiniere of the South African university, which co-authored the new study together with Ph.D. candidate Kathleen Dollman.
The fossil, representing only the snout of a shartegosuchid, was unearthed from a rock sample dated back to 160 million years and analyzed at the American Museum of Natural History in New York.
CT scans of the fossil sample showed that the mouths of shartegosuchids had a lot of different features by comparison with today's crocodilians, including a closed secondary palate.
This discovery was particularly surprising given that scientists previously believed crocodilians evolved their secondary palate much later.This feature also appears in turtles and mammals and has a number of functions, such as allowing crocodilians to breathe under water and reinforcing their skull to create a bigger bite force.
"I was surprised to find that there were many features in the palate and snout that were completely different between shartegosuchids and extant crocodilians," says Dollman.
As she explains, these ancient creatures must have evolved this closed, bony secondary palate for different purposes than today's crocodiles, since they exhibit a different snout shape and palatal structure.
"We would expect to see the same palatal structures and snout shapes in both shartegosuchids and extant crocodiles if they were using it for similar functions and had evolved a closed palate for similar reasons."The fact that the research team came across significant differences in the skeletal make-up of the two species suggests that the ancient crocodilians probably led a very different lifestyle from the mighty reptiles we know today.
"The observed differences tell us that shartegosuchids likely had predation practices to which there is no modern analogue in crocodilians," notes Dollman.
These findings are an indication that the early crocodilians of the Late Jurassic represent the "humble beginnings" of today's apex predators, whose signature mode of attack — their gaping mouths — now boasts "the greatest known bite force in the vertebrate animal kingdom," states a university news release.