Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Aug 19;13(1):4882.
doi: 10.1038/s41467-022-32621-5.

Permian hypercarnivore suggests dental complexity among early amniotes

Tea Maho  1   2 , Sigi Maho  2 , Diane Scott  2 , Robert R Reisz  3   4
Affiliations

Permian hypercarnivore suggests dental complexity among early amniotes

Tea Maho et al. Nat Commun. .

Abstract

The oldest known complex terrestrial vertebrate community included hypercarnivorous varanopids, a successful clade of amniotes with wide geographic and temporal distributions. Little is known about their dentition and feeding behaviour, but with the unprecedented number of specimens of the varanopid Mesenosaurus from cave deposits in Oklahoma, we show that it exhibited serrations on the tooth crowns, and exceptionally rapid rates of development and reduced longevity relative to other terrestrial amniotes. In contrast, the coeval large apex predator Dimetrodon greatly increased dental longevity by increasing thickness and massiveness, whereas herbivores greatly reduced tooth replacement rates and increased dental longevity. Insectivores and omnivores represented the primitive condition and maintained modest replacement rates and longevity. The varied patterns of dental development among these early terrestrial amniotes reveal a hidden aspect of dental complexity in the emerging diverse amniote community, very soon after their initial appearance in the fossil record.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Tooth replacement in maxillary dentition of Mesenosaurus efremovi.
a Reconstruction of M. efremovi skull in lateral view. Note that gaps in dentition represent shed teeth that are being replaced. b Maxillary dentition of ROMVP 85456 in lingual view. c Tooth family with a functional tooth and two successive replacement teeth. d Tooth family with a functional tooth and a single replacement tooth. e Photograph of maxilla (ROMVP 85524) in occlusal view showing the pattern of tooth replacement, with new teeth developing in the sockets of old teeth after the latter were shed.
Fig. 2
Fig. 2. Incremental lines of Mesenosaurus efremovi.
a ROMVP 85502, lingual view of fragmented dentary with dashed red lines through the plane of the LL section of the functional and replacement teeth. b Whole view of tooth family LL section near crown apex. c Closeup view of functional tooth LL cross-section showing incremental lines, white arrows. d Closeup view of replacement tooth TR cross-section showing incremental lines, white arrows.
Fig. 3
Fig. 3. Incremental lines of Dimetrodon cf. D. limbatus.
a Lateral view of Dimetrodon. b ROMVP 85510, maxillary tooth family, photographed in lingual view showing the plane of LL section through the functional tooth and replacement tooth. c Whole view of longitudinal LL section near the crown apex of functional and replacement tooth. d Closeup view of functional tooth LL cross-section showing incremental lines, white arrows. e Closeup view of replacement tooth LL cross-section showing incremental lines, white arrows. Skull drawing was modified from Reisz and Brink and Reisz.
Fig. 4
Fig. 4. Incremental lines of Edaphosaurus sp.
a Lateral view of Edaphosaurus. b USNM PAL 706602, maxillary tooth family, photographed in lingual view showing the plane of LL section through the functional tooth and replacement tooth. c Whole view of longitudinal LL section near crown apex of functional and replacement tooth. d Closeup view of functional tooth LL cross-section showing incremental lines, white arrows. Skull drawing was modified from Romer and Price and Modesto.
Fig. 5
Fig. 5. Rates of tooth replacement and age across a range of taxa.
a Relationship between the total number of incremental lines of von Ebner (age) for the functional tooth and the tooth families replacement rate or period (days). The symbols indicate the type of feeding behaviour, with circles representing carnivory, triangles representing herbivory, square representing insectivory, and diamond representing omnivory. b Phylogenetic tree of all taxa (n = 11) used in the analyses, displaying the age in millions of years ago (length of bars) and tooth longevity (gradient in branch colours). c Phylogenetic tree of all taxa (n = 9) used in the analyses, displaying the age in millions of years ago (mya) (length of bars) and tooth replacement rate (gradient in branch colours). Reconstructed using the ‘contMap’ function in the ‘phytools’ R package. The tree was modified from Maddin, Evans, and Reisz and Reisz and Sues. Source data are provided as a Source Data file.
Fig. 6
Fig. 6. Paleogeographic distribution of the fossil taxa in Late Paleozoic Pangea.
The amniotes Mesenosaurus, Oromycter, Opisthodontosaurus, Captorhinus, Delorhynchus, Colobomycter, and the stem amniote Seymouria were collected at the Dolese quarry, Richards Spur, Oklahoma, USA (red dot); the varanopid Watongia was found in Blaine County, Oklahoma (blue dot); the sphenacodontid Dimetrodon was collected at Briar Creek Bonebed, while Edaphosaurus was found at Hog Creek, Arroyo Formation, Clear Fork Group, Texas (orange and brown dots); the haptodontine and Haptodus were found at the Garnett Quarry, Anderson County, Kansas (white dot); Ennatosaurus is from the Moroznitsa locality, Mezen, Russia (black dot). Map illustrated by The PLATES Project, Institute for Geophysics, University of Texas at Austin.
See this image and copyright information in PMC

References

    1. Edmund, A. G. & Royal Ontario Museum. Tooth Replacement Phenomena in the Lower Vertebrates (Royal Ontario Museum, 1960).
    1. Kline LW, Cullum D. A long term study of the tooth replacement phenomenon in the young green iguana, Iguana iguana. J. Herpetol. 1984;18:176. doi: 10.2307/1563746. - DOI
    1. Bertin TJC, Thivichon-Prince B, LeBlanc ARH, Caldwell MW, Viriot L. Current perspectives on tooth implantation, attachment, and replacement in Amniota. Front. Physiol. 2018;9:1630. doi: 10.3389/fphys.2018.01630. - DOI - PMC - PubMed
    1. Juuri E, et al. Sox2 marks epithelial competence to generate teeth in mammals and reptiles. Development. 2013;140:1424–1432. doi: 10.1242/dev.089599. - DOI - PMC - PubMed
    1. Richman, J. M., Whitlock, J. A. & Abramyan, J. Stem Cells in Craniofacial Development, Regeneration, and Repair (eds Huang, G.T.-J. & Thesleff, I.) 135–151 (Wiley-Blackwell, 2013).

Publication types

LinkOut - more resources