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Johan Lindgren

Johan Lindgren

Senior lecturer

Johan Lindgren

Dental histology of mosasaurs and a marine crocodylian from the Campanian (Upper Cretaceous) of southern Sweden: incremental growth lines and dentine formation rates

Author

  • Johan Gren
  • Johan Lindgren

Summary, in English

Mosasaurs are an extinct group of secondarily adapted aquatic lizards that became the dominant marine tetrapods in the Late Cretaceous oceans. They continuously shed and replaced their teeth in order to maintain a functional dentition at all times; however, the process of tooth development in mosasaurs is still incompletely known. Based on incremental line width measurements and growth line counts, we assess dentine formation rates in three mosasaur taxa (Dollosaurus, cf. Platecarpus and Tylosaurus) and one genus of marine crocodylian (Aigialosuchus), all from the lower Campanian (Upper Cretaceous) of southernmost Sweden. Two sets of periodic dentinal markings characterized by concentric, alternating opaque and transparent laminae are recognized: one set comprising thin bands situated 6-34 m apart (depending on taxon), which is superimposed onto a second set of coarser bands where spaces vary between 102 and 275 m. Assuming that the finer striations represent daily increments (i.e. lines of von Ebner), it is estimated that the deposition of dentine at the sectioned level of the tooth-crowns took 342 (cf. Platecarpus), 426 (Dollosaurus), 487 (Tylosaurus) and 259 (Aigialosuchus) days, respectively. The coarser bands contain between 11 and 13 thin striations each, and are thus considered to be homologous to similar periodic dentinal markings in extant vertebrates, i.e. Andresen lines. Prolonged tooth development times in large-toothed taxa, such as Tylosaurus, presumably increased the risk of long-term incapacity to capture prey after dental trauma, an evolutionary trade-off which may have been compensated for by allometric modifications of the teeth.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2014

Language

English

Pages

134-143

Publication/Series

Geological Magazine

Volume

151

Issue

1

Document type

Journal article

Publisher

Cambridge University Press

Topic

  • Geology

Keywords

  • Andresen
  • dentine
  • histology
  • increments
  • Mosasauridae
  • teeth
  • von Ebner

Status

Published

ISBN/ISSN/Other

  • ISSN: 0016-7568