Crocodiles are known as terrifying predators, but some of their old relatives who roamed the planet 200 million years ago were vegetarian, research shows.
Fossils have been revealed between three and six members of the crocodile and alligator family with specialized teeth for chewing on plants.
Researchers reconstructed their vegetarian diets by analyzing the fossils of 146 teeth from 16 crocodyliforms.
Many of their & # 39; complex & # 39; teeth were formed unlike any modern herbivore until the herbivores were eradicated together with the dinosaurs 66 million years ago.
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Modern crocodiles had age-old, vegetarian cousins who roamed the planet 200 million years ago, research shows. Pictured: Crocodyliform life reconstructions of two extinct herbivorous varieties
Study author Keegan Melstrom, a PhD student at the University of Utah, USA, said: & The most interesting thing we discovered was how often it seems extinct crocodyliforms ate plants.
& # 39; The carnivores have simple teeth, while herbivores have much more complex teeth.
& # 39; Omnivores, organisms that eat both plant and animal material, fall somewhere in between.
& # 39; Our study indicates that complex-shaped teeth, which we deduce to indicate herbivory, occur at least three times in the extinct family of crocodiles and perhaps even six.
& # 39; Part of my previous research has shown that this pattern applies to living reptiles with teeth, such as crocodiles and lizards.
& # 39; These results told us that the basic pattern between food and teeth is found in both mammals and reptiles, despite very different tooth shapes, and applies to extinct reptiles. & # 39;
Dental fossils revealed between three and six members of the crocodile and alligator family had specialized teeth for chewing on plants. Shown: 3D prints of extinct crocodyliform teeth (blue), a skull of an extinct crocodyliform and skulls of living representatives of this group
This image is a collection of 3D images with fake colors that represent the range in the form of crocodyliform teeth. Carnivores (left), such as the living Caiman, have simple teeth, while herbivores (right) have much more complex teeth
All crocodylians who live today have a similar body shape with relatively simple, conical teeth, ideal for their semi-aquatic generalistic carnivorous lifestyle.
But the dental fossils in the study were clearly non-carnivorous and seemed to have specialized forms that cannot be seen in modern animals.
Mr. Melstrom and Dr. Randall Irmis, chief paleontology curator at the Natural History Museum of Utah, USA, compared the tooth complexity of extinct crocodyliforms with that of living animals to work out what they ate.
They used a method originally developed for use in live mammals – measuring the size and morphological characteristics of the teeth at a resolution of 25 rows of data per tooth.
Researchers reconstructed their vegetarian diets by analyzing the fossils of 146 teeth from 16 crocodyliforms. Pictured: a living descendant of crocodiles, the South American crocodile of the Caiman – a carnivore
Many of their & # 39; complex & # 39; teeth were formed unlike any modern herbivore until the herbivores were eradicated together with the dinosaurs 66 million years ago. Pictured: Reconstructions of extinct carnivorous and mixed meat and herbivorous varieties
Mr Melstrom said the unexpected variety in teeth of crocodyliforms showed they could thrive in a larger range of ecological environments than previously thought.
He also discovered that the herbivores appeared in the evolutionary history of the family shortly after the end of the Triassic extinction some 200 million years ago.
They existed until the Cretaceous mass extinction that butchered all dinosaurs except birds.
The fossil analysis suggested that between three and six species of herbivorous feed developed during the Mesozoic.
Mr. Melstrom said: & # 39; Our work shows that extinct crocodyliforms had an incredibly varied diet.
& # 39; Some were similar to live crocodiles and were predominantly carnivorous, others were omnivores and others probably specialized in plants.
& # 39; The herbivores lived on different continents at different times, some alongside mammals and mammalian relatives, and others not.
& # 39; This suggests that a herbivorous crocodyliform was successful in various environments. & # 39;
He planned to continue to reconstruct the diet of extinct crocodyliforms, including fossil species that lack teeth.
The researcher also wanted to understand why the extinct relatives of crocodiles were so radically diversified after one massive extinction, but not the one who killed the dinosaurs – and whether food ecology had played a role.
The study by the University of Utah and the National History Museum of Utah in the US was published in the journal Current biology.
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