Abstract
Tooth replacement rate is an important contributor to feeding ecology for polyphyodont animals. Dinosaurs exhibit a wide range of tooth replacement rates, mirroring their diverse craniofacial specializations, but little is known about broad-scale allometric or evolutionary patterns within the group. In the current broad but sparse dinosaurian sample, only three non-avian theropod tooth replacement rates have been estimated. We estimated tooth formation and replacement rates in three additional non-avian theropod dinosaurs, the derived latest Cretaceous abelisaurid Majungasaurus and the more generalized Late Jurassic Allosaurus and Ceratosaurus. We created the largest dental histological and CT dataset for any theropod dinosaur, sectioning and scanning over a dozen toothed elements of Majungasaurus and several additional elements from the other two genera. Using this large sample, we created models of tooth formation time that allow for theropod replacement rates to be estimated non-destructively. In contrast to previous results for theropods, we found high tooth replacement rates in all three genera, with Allosaurus and Ceratosaurus rates of ~100 days and 56 days for Majungasaurus. The latter rate is on par with those of derived herbivorous dinosaurs including some neosauropods, hadrosaurids, and ceratopsians. This elevated rate may be a response to high rates of tooth wear in Majungasaurus. Within Dinosauria, there is no relationship between body mass and tooth replacement rate and no trends in replacement rate over time. Rather, tooth replacement rate is clade-specific, with elevated rates in abelisaurids and diplodocoids and lower rates in coelurosaurs.
Highlights
Tooth formation time and replacement rate are related to feeding mechanics and diet and can help reconstruct paleoecology and paleodemography [1,2,3]
Controls on tooth formation and replacement rates in relation to body mass, feeding ecology, and phylogeny, especially regarding the loss of teeth on the lineage leading to birds, remain debated [4,5]
Novel CT data for additional dinosaur species can be used with our models to estimate tooth formation and replacement rates, refining when, where, and in precisely which clades elevated tooth replacement rates evolved
Summary
Tooth formation time and replacement rate are related to feeding mechanics and diet and can help reconstruct paleoecology and paleodemography [1,2,3]. Controls on tooth formation and replacement rates in relation to body mass, feeding ecology, and phylogeny, especially regarding the loss of teeth on the lineage leading to birds, remain debated [4,5]. Evolution of tooth replacement rates in dinosaurs https://www.nationalgeographic.org/grants/ grant-opportunities/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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