The findings, recently released in the journal Palaeontology, reveal that these early herbivores likely eventually starved to death in aging, the vegetation taking its toll on their teeth.
Three-dimensional design of the skull of Bentonyx from CT scans, revealing the teeth of the upper (blue) and lower (pink) jaws rooted deeply in the bone. Credit: Thitiwoot Sethapanichsakul
” I initially studied the rhynchosaurs years ago,” said team leader Professor Mike Benton from Bristols School of Earth Sciences, “and I was astonished to find that oftentimes they controlled their communities. If you discovered one fossil, you discovered hundreds. They were the sheep or antelopes of their day, and yet they had specialized dental systems that were apparently adapted for handling masses of hard plant food.”
Dr. Rob Coram, who discovered the Devon fossils, said: “The fossils are unusual, but periodically people were entombed throughout river floods. This has actually made it possible to put together a series of jaw bones of rhynchosaurs that varied in age from quite young, possibly even children, through grownups, and including one especially old animal, a Triassic old-timer whose teeth had used right down and most likely had a hard time to get enough nutrition each day.”
” Comparing the sequence of fossils through their life time, we might see that as the animals aged, the location of the jaws under wear at any time moved backward relative to the front of the skull, bringing new teeth and new bone into wear,” said Thitiwoot Sethapanichsakul who studied the jaws as part of his MSc in Palaeobiology. “They were clearly eating actually hard food such as ferns, that used the teeth to the bone of the jaw, meaning that they were generally chopping their meals by a mix of teeth and bone.”
Teeth of upper and lower jaws, X-ray area along the length of the jaws revealing teeth in wear. Tooth wear is so extreme that teeth are worn flat to the bone, and in numerous cases, bone works versus tooth in chomping.
” Eventually, however, after a certain age– were unsure quite how many years– their development slowed down and the location of wear was fixed and simply got much deeper and much deeper,” added Dr Coram. “Its like elephants today– they have a fixed variety of teeth that enter into usage from the back, and after the age of seventy or two theyre on their last tooth, and then thats that.
” We do not believe the rhynchosaurs lived that long, however their plant food was so screening that their jaws simply wore and presumably they eventually starved to death.”
The rhynchosaurs were a fundamental part of the environments on land during the Triassic, when life was recovering from the worlds biggest mass termination, at the end of the preceding Permian Period. These animals belonged to this healing and setting the scene for new types of ecologies when first dinosaurs, and later mammals ended up being dominant, as the contemporary world was being gradually constructed.
By comparing examples of earlier rhynchosaurs, such as those from Devon, with later-occurring examples from Scotland and Argentina, the group was also able to reveal how their dentitions developed through time, and how their distinct teeth allowed them to diversify twice, in the Middle and after that in the Late Triassic. In the end, climate modification, and especially modifications in available plants, appear to have made it possible for the dinosaurs to take over as the rhynchosaurs passed away out.
Recommendation: “Unique dentition of rhynchosaurs and their two-phase success as herbivores in the Triassic” by Thitiwoot Sethapanichsakul, Robert A. Coram and Michael J. Benton, 8 June 2023, Palaeontology.DOI: 10.1111/ pala.12654.
If you found one fossil, you discovered hundreds. Teeth of upper and lower jaws, X-ray area along the length of the jaws showing teeth in wear. Unerupted teeth at left are made from dentine (de) with an enamel (en) cap. Many teeth show the pulp cavity (pc) at the base. Tooth wear is so severe that teeth are used flat to the bone, and in numerous cases, bone works versus tooth in chewing.
Restoration of the rhynchosaur Bentonyx from the Middle Triassic of Devon, about 245 million years earlier. Credit: Mark Witton
Researchers at the University of Bristol have unveiled brand-new insights into the presence of the prehistoric Rhynchosaur, a reptile species that inhabited the Earth roughly 225 to 250 million years earlier, prior to the reign of the dinosaurs.
Rhynchosaurs, a group of reptiles that stay rather enigmatic, were roughly the size of sheep and thrived during the Triassic Period, a date defined by its generally warm climates and tough plants.
In the new research study, the scientists studied specimens found in Devon and utilized CT scanning to see how the teeth used down as they fed, and how new teeth were included at the backs of the tooth rows as the animals grew in size.
