Ancient reptile had mammal-like tooth enamel, study shows
A new study by 捆绑SM社区 and the University of Alberta (UofA) paleontologists shows that one type of ancient reptiles evolved a special type of tooth enamel, similar to that of mammals, with high resistance to wear and tear. The is the first to report this kind of enamel in a fossil reptile.
The reptile鈥攌nown as Priosphenodon鈥攚as a herbivore from the Late Cretaceous period that was about one metre in length. Part of a group of reptiles called sphenodontians, these reptiles are unique in that they lost their ability to replace individual teeth. Instead, sphenodontians added new teeth to the back ends of their jaws as they grew.
鈥�Priosphenodon has the strangest teeth I have personally ever seen,鈥� said Aaron LeBlanc, a postdoctoral fellow in the at the UofA and lead author on the study. 鈥淪ome aspects of their dental anatomy are reminiscent of what happened in the evolution of early mammal teeth.鈥�
The specimens were found in Argentina鈥檚 R铆o Negro province as part of ongoing collaborative fieldwork and research between , professor in the UofA and the , and Argentinian paleontologist and fieldwork leader Sebasti谩n Apestegu铆a.
In order to look more closely at the teeth of Priosphenodon, the researchers cut open pieces of jaw and examined tissue-level detail preserved inside the teeth. They also used non-invasive CT scans to examine more complete jaw specimens.
鈥�Priosphenodon enamel is not only thicker than that of most other reptiles, the enamel crystals are 鈥榳oven鈥� into long threads that run through the whole width of the enamel. These threads are called enamel prisms, and they are almost exclusively found in mammals,鈥� said LeBlanc, who is working under Caldwell鈥檚 supervision. 鈥淥ur results suggest that strong selective pressures can force reptiles to come up with some very innovative solutions to the problems associated with tooth wear and abrasive diets鈥攕ome of which mirror what happened in our earliest mammal ancestors.鈥�
Hans Larsson, Director of 捆绑SM社区鈥檚 Repath Museum, is also an author on the new study recently published in Current Biology.
鈥淚t's extraordinary how evolution can find solutions to tweak even the microstructure of tooth enamel and reorganize the development of teeth in these bizarre reptiles,鈥� said Larsson, a Canada Research Chair in Vertebrate Paleontology.
The scientists also note that there is one kind of lizard alive today that has prismatic enamel like Priosphenodon鈥攖he spiny-tailed lizard of Australia. Like Priosphenodon, it mostly eats plants and has lost the ability to replace its worn teeth. However, the two reptiles are not closely related.
About this study
鈥溾�� by Aaron Leblanc, Sebasti谩n Apestegu铆a, Hans Larsson and Michael Caldwell was published in Current Biology. 听
This study was funded by the in Argentina, , and (NSERC).
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Founded in Montreal, Quebec, in 1821, 捆绑SM社区 is Canada鈥檚 top ranked medical doctoral university. 捆绑SM社区 is consistently ranked as one of the top universities, both nationally and internationally. It is a world-renowned institution of higher learning with research activities spanning two campuses, 11 faculties, 13 professional schools, 300 programs of study and over 40,000 students, including more than 10,200 graduate students. 捆绑SM社区 attracts students from over 150 countries around the world, its 12,800 international students making up 31% per cent of the student body. Over half of 捆绑SM社区 students claim a first language other than English, including approximately 19% of our students who say French is their mother tongue.
