The Oldest Toothache

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Edward Drinker Cope was not exactly known for having a sunny disposition. One of the key players in the “Bone Wars” of the late 19th century, his long-running feud with fellow bone sharp Othniel Charles Marsh is the stuff of scientific legend. The two former friends tussled over everything from fossil sites to the naming rights for extinct creatures, and their embarrassing spat spilled into public view via The New York Herald in 1890.

Marsh was not the only source of regular discomfort and irritation Cope faced. In the early 1990s, photographer Louis Psihoyos and writer John Knoebber borrowed the naturalist’s bones for an extended — and unauthorized — road trip to meet some of Cope’s intellectual descendants. Along the way, they met with paleontologist Paul Sereno, who recognized that Cope had tooth abscess that undoubtedly made the cantankerous fossil hunter extra grumpy near the time of his death in 1897.

A specimen of one of the many prehistoric creatures Cope named during his career also suffered from a painful dental pathology. Found in the approximately 275 million-year-old rock of the midwestern United States, Labidosaurus belonged to an early radiation of lizard-like reptiles known as captorhinids, and Cope initially described it in 1896. Numerous specimens have been found since that time, but one — CMNH 76876 — shows the earliest evidence of bacterial infection yet discovered in a land-dwelling vertebrate.

The peculiar dental anatomy of Labidosaurus was at least partly to blame for the reptile’s ailment. According to paleontologists Robert Reisz, Diane Scott, Bruce Pynn and Sean Modesto, a difference in tooth replacement may have made the reptile more susceptible to injury and disease. In other reptiles of the time, the teeth were only loosely fixed in the jaw and were constantly in the process of being replaced by newer teeth that erupted in the same sockets. Labidosaurus and other captorhinids, by contrast, not only had teeth that were more strongly fixed to the jaw, but new teeth erupted at a slower rate in different positions. If one of their teeth was broken, the area would be more susceptible to infection owing to the long and unusual pattern of replacement.

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A line drawing of the skull of Labidosaurus (top), and a close-up of the lower jaw designated CMNH 76876 showing two missing teeth (tp1, tp3) and an abscess. From Reisz et al., 2011.

In the Labidosaurus specimen examined by Reisz and colleagues, the first and third teeth in the jaw were broken. The sockets had been filled in with bone. This was strange. In other reptiles, the broken teeth would have been lost and new ones would have taken their place, but in this Labidosaurus a pathology had developed instead. Three empty tooth sockets and a nearby abscess also showed signs of a deep infection, and the degree to which the pathology developed indicated that the animal had been living with the damage for some time.

We will never know exactly what happened, but the scientists behind the new study were able to reconstruct the sequence of events. The unfortunate Labidosaurus had lost the two teeth at the front of the jaw first, and oral bacteria had become trapped inside the jaw when the damaged tooth roots were covered by bone. Things only got worse from there. The bacteria triggered a severe bone infection, leading to the loss of three teeth and irreversible damage in the inflamed, pus-oozing portion of the jaw. If this chronic infection did not contribute to the death of the Labidosaurus, it was still active when the animal died.

Cope was not a particularly close relative of Labidosaurus — the ancestors and collateral relatives of mammals had already split from their common ancestor with reptiles long before 275 million years ago — but the injuries in the influential naturalist and the lizard-like reptile can be traced back to a similar condition. Though the anatomy of our own jaws is different than that of Labidosaurus, we only get two sets of teeth during our lifetime, and this gives injury and disease the opportunity to run rampant if we do not seek treatment. Cope could have partially blamed his chronic tooth trouble on our evolutionary inheritance from earlier mammals , though his enmity towards Marsh alone left him feeling plenty sore.

[This essay was originally posted on April 21, 2011]

Top image: A restoration of Labidosaurus by А. Кац. Image from Wikimedia Commons.

References: Reisz, R., Scott, D., Pynn, B., & Modesto, S. (2011). Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance Naturwissenschaften DOI: 10.1007/s00114-011-0792-1