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Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance


We report on dental and mandibular pathology in Labidosaurus hamatus, a 275 million-year-old terrestrial reptile from North America and associate it with bacterial infection in an organism that is characterized by reduced tooth replacement. Analysis of the surface and internal mandibular structure using mechanical and CT-scanning techniques permits the reconstruction of events that led to the pathology and the possible death of the individual. The infection probably occurred as a result of prolonged exposure of the dental pulp cavity to oral bacteria, and this exposure was caused by injury to the tooth in an animal that is characterized by reduced tooth replacement cycles. In these early reptiles, the reduction in tooth replacement is an evolutionary innovation associated with strong implantation and increased oral processing. The dental abscess observed in L. hamatus, the oldest known infection in a terrestrial vertebrate, provides clear evidence of the ancient association between terrestrial vertebrates and their oral bacteria.

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We thank Craig Willson and Janet Loucks, Thunder Bay Regional Health Sciences Centre, for the CT scans; David Berman, CMNH, for the loan of CMNH 76876; and Matt Vickaryous, University of Guelph, for help with the literature search. This research was supported by Discovery Grants from the Natural Sciences and Engineering Research Council of Canada (to RRR and SPM).

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Correspondence to Robert R. Reisz.

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Communicated by Sven Thatje

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Reisz, R.R., Scott, D.M., Pynn, B.R. et al. Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance. Naturwissenschaften 98, 551 (2011). https://doi.org/10.1007/s00114-011-0792-1

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  • Paleozoic tetrapods
  • Osteomyelitis
  • Captorhinidae
  • Dental abscess
  • Early Permian