Does the world’s largest prehistoric shark need a dentist, or does it have a bad lunch?
Researchers from North Carolina State University and the North Carolina Museum of Natural Sciences examined the malformed teeth of the Otodus megalodon shark for the root cause: Is it growth or is it nutrition-related? The work could give paleontologists more insight into the developmental processes associated with dental injury in ancient sharks, as well as their feeding behavior.
The subject of debate is an anomaly called double dentition, in which one tooth appears to be “split”. There are several possible causes: During tooth development, two tooth buds may fuse into one or one bud may split in two (a process called germination). Mating and fusion can occur due to disease, genetics, or physical injury to the tooth bud.
“We don’t have a lot of data on double tooth disease in ancient shark species,” said Harrison Miller, a former undergraduate student at North Carolina State and author of the paper describing the work. “So this is an opportunity to fill that gap — and maybe learn more about sharks in the process.”
The researchers examined three abnormal teeth: the 4-inch tooth of O. megalodon, tooth desire the size of the school bus that ruled the oceans in the early Miocene and Pliocene periods (from 11 to 3.7 million years ago); and two Carcharhinus leucas, a much smaller species of bull shark that lived during the same period and still roams the oceans today.
Three oddly shaped teeth indicate some form of multiple dental disease. The researchers compared the teeth to natural teeth of both types and performed a nano-computed tomography (CT) scan of the deformed tooth so they could examine what was going on inside.
While pathological teeth have more internal canals than natural teeth – confirming the incomplete division or union of two teeth during growth – researchers have not been able to determine the exact cause of the growth.
“Part of the difficulty in applying terminology from work to humans and other mammals is sharks,” said Haviv Avrahami, a doctoral student at NC State and co-author of the paper.
“Sharks have a cartilaginous skeleton, not a skeleton, so preserving their jaws is rare in the world. fossil recordUsually we only find isolated teeth. In addition, sharks have different mechanisms for dental development—They have constant replacement teeth, so you can’t see what’s going on in the rest of the jaw to rule out fusion or germination. “
Given what researchers know about this type of disease in modern shark teeth, they tend to point to eating-related injuries as a more likely cause.
“With O. megalodon in particular, the current concept is to eat mostly whales,” Avrahami said. “But we do know that dental abnormalities in modern sharks could be caused by something sharp that cut the evolutionary path. gigi in the mouth. Based on what we’ve seen in modern sharks, the injury was most likely caused by a prickly fish bite or an annoying stingray sting.
“We also know that O. megalodon had nesting sites around Panama, and that relatives of modern stingray species also inhabit the area,” Harrison said. “And these spikes can get really thick. So this type of dental injury could suggest that O. megalodon was more of a common predator – and this O. megalodon in particular was having a bad day.”
Lindsey Zanno, chair of the Department of Paleontology at the North Carolina Museum of Natural Science, associate research professor at NC State and co-author of the paper, agrees.
“When we think of predator-prey encounters, we tend to maintain our sympathy for prey, but the life of a predator, even a giant shark, is no picnic either.”
Jobs appear in bergThis was made possible by Marc Kosteich’s donation to O. megalodon disease age (NCSM 33639) to the North Carolina Museum of Natural Sciences fossil collection.
“We are very grateful to Mark for giving this specimen to the museum so that we can learn more about this ancient animal,” Zanno said. “Many important fossils are hidden in private collections, where they cannot explain our beautiful world.”
Harrison S. Miller et al, Dental disease in lamniform and carcharhiniform sharks with commentary on classification and homology of double tooth disease in vertebrates, berg (2022). DOI: 10.7717 / peerj.12775
North Carolina State University
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