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

Research output: Contribution to journalArticle

Abstract

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.

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Subject classification (UKÄ) – MANDATORY

  • Geology

Keywords

  • Andresen, dentine, histology, increments, Mosasauridae, teeth, von Ebner
Original languageEnglish
Pages (from-to)134-143
JournalGeological Magazine
Volume151
Issue number1
Publication statusPublished - 2014
Publication categoryResearch
Peer-reviewedYes

Related research output

Johan Gren, 2017 Dec, Lund: Lund University, Faculty of Science, Department of Geology, Lithosphere and Biosphere Science. 105 p.

Research output: ThesisDoctoral Thesis (compilation)

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