A hunt gone wrong! Creative reconstruction of Otodus megalodon feeding on an ancient swordfish ~ 11– 3.7 million years back. A puncture injury to the tooth gum such as this might have caused gemination of the establishing tooth buds. Credit: Jorge Gonzalez
Did the worlds largest prehistoric shark require an orthodontist, or did it simply have a bad lunch?
Researchers from North Carolina State University (NCSU) and the North Carolina Museum of Natural Sciences examined a deformed tooth from an Otodus megalodon shark to identify the source: was it developmental, or related to feeding? The findings could give paleontologists more insight into the developmental procedures connected with tooth injury in ancient sharks, in addition to feeding behavior.
A leak injury to the tooth gum such as this might have caused gemination of the establishing tooth buds. There are numerous possible causes: during tooth development 2 tooth buds can fuse into one or one tooth bud can split into two (a procedure called gemination). Fusion and gemination and blend can be triggered by disease, genes, or physical injury to the tooth bud.
“But we know that tooth deformities in modern-day sharks can be caused by something sharp piercing the conveyor belt of developing teeth inside the mouth. A tooth injury of this type could show that O. megalodon was more of a generalist predator– and that this O. megalodon in specific simply had a bad day.”
At issue is an irregularity described as double tooth pathology, in which a single tooth appears “split.” There are several possible causes: throughout tooth advancement two tooth buds can fuse into one or one tooth bud can split into 2 (a procedure called gemination). Blend and gemination and combination can be triggered by disease, genetics, or physical injury to the tooth bud.
” We dont have a lot of information on double tooth pathologies in ancient shark species,” says Harrison Miller, former NC State undergraduate student and matching author of a paper explaining the work. “So this was a chance to fill in those gaps– and maybe find out more about the sharks at the same time.”
The researchers analyzed 3 irregular teeth: one 4-inch tooth from O. megalodon, a pinnacle predator the size of a school bus that ruled the seas in the Miocene and early Pliocene durations (from 11 to 3.7 million years ago); and 2 from Carcharhinus leucas, a much smaller sized bull shark types that lived throughout the very same period and still strolls the seas today.
Typical versus deformed O. megalodon and C. leucas teeth. Credit: Matthew Zeher
All 3 oddly-shaped teeth showed a kind of double tooth pathology. The scientists compared the teeth to normal teeth from both types and performed nano-CT imaging of the deformed teeth so that they might analyze what was going on within.
While the pathological teeth did have more internal canals than normal teeth– verifying either the insufficient splitting or signing up with of two teeth during advancement– the scientists were not able to definitively develop a developmental cause.
” Part of the difficulty remained in using terms from work in humans and other mammals to sharks,” says Haviv Avrahami, NC State doctoral trainee and paper co-author.
” Sharks have cartilaginous skeletons, not boney skeletons, so preservation of their jaws is uncommon in the fossil record, and typically, we only find the individual isolated teeth. In addition, sharks have various systems for tooth advancement– they have continuous tooth replacement, so you cant take a look at what is taking place in the remainder of the jaw to rule out fusion or gemination.”
Given what the researchers understand about this type of pathology in contemporary shark teeth, nevertheless, they lean towards feeding-related injury as a more probable cause.
” With O. megalodon in particular, the existing understanding is that they fed mostly on whales,” Avrahami says. “But we understand that tooth deformities in contemporary sharks can be brought on by something sharp piercing the conveyor belt of establishing teeth inside the mouth. Based on what we see in modern-day sharks, the injury was probably caused by chewing down on a spiny fish or taking a nasty stab from a stingray barb.”
” We also understand that O. megalodon had nesting premises around Panama, and that relatives of modern stingray species also occupied that location,” Harrison states. “And these spines can get really thick. So a tooth injury of this type might show that O. megalodon was more of a generalist predator– which this O. megalodon in particular simply had a bad day.”
Lindsay Zanno, head of paleontology at the N.C. Museum of Natural Sciences, associate research study professor at NC State and co-author of the research, concurs.
” When we consider predator-prey encounters, we tend to schedule our sympathy for the prey, however the life of a predator, even a gigantic megatooth shark, was no cakewalk either.”
The work appears in the journal PeerJ, and was made possible by Mark Kostichs donation of the pathological O. megalodon tooth (NCSM 33639) to the Paleontological Collections of the N.C. Museum of Natural Sciences.
” Were exceptionally grateful to Mark for gifting this specimen to the museum so we might find out more about these ancient animals,” Zanno states. “So many important fossils are hidden away in personal collections, where they are not able to shed new light on our wondrous world.”
Referral: “Dental pathologies in lamniform and carcharhiniform sharks with discuss the classification and homology of double tooth pathologies in vertebrates” by Harrison S. Miller?, Haviv M. Avrahami and Lindsay E. Zanno, 11 May 2022, PeerJ.DOI: 10.7717/ peerj.12775.