Tooth replacement rates in early chondrichthyans: a qualitative approach

Hector Botella*, Jose I. Valenzuela-Rios, Carlos Martinez-Perez

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

25 Citations (Scopus)

Abstract

The continuous replacement of teeth throughout their lifetime is a common characteristic of most chondrichthyans. This process was already present in the earliest representatives of the group. It has been well established that different species of extant sharks show rapid tooth replacement rates; however, some authors have suggested that in early chondrichthyans this rate might have been much slower. Here we present a qualitative approach to analyse tooth replacement rates in the Early Devonian shark Leonodus carlsi, the earliest tooth-bearing shark known to date. For this, we have examined 1,103 isolated teeth from Celtiberia, Spain. Our study provides strong evidences of an extremely slow dental replacement in this primitive chondrichthyan based on three independents analyses: (1) statistical analysis of the wear degree, demonstrating that teeth remain functional for a long period of time; (2) analysis of both the histological and the morphological features of the teeth cusps suggests that this chondrichthyan used a maturation process that optimizes its function, thus worn teeth show an efficient working shape that implies their teeth remained functional for a long time after being modelled by use; and (3) estimations of size increments between teeth (delta s) of the same dental family for some recent sharks whose rates of replacement were known prove that delta s is inversely proportional to the rate of replacement (R(2) = 0.8327). The estimated values of tooth replacement rates obtained from delta s for L. carlsi and for some Late Devonian cladoselachian sharks are significatively slower than those observed in current sharks.

Original languageEnglish
Pages (from-to)365-376
Number of pages12
JournalLethaia
Volume42
Issue number3
DOIs
Publication statusPublished - Sep 2009

Keywords

  • Early chondrichthyans
  • tooth replacement
  • histology
  • tooth wear
  • Leonodus carlsi
  • Early Devonian
  • SHARKS
  • GROWTH

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