The teeth of Changchunsaurus: Rare insight into ornithopod dinosaur tooth evolution
The teeth of Changchunsaurus parvus, a small herbivorous dinosaur from the Cretaceous of China, represent an important and poorly-known stage in the evolution of ornithopod dentition, according to a study published in the open-access journal PLOS ONE by Jun Chen of Jilin University in China and colleagues.
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The skull of the holotype specimen of C. parvus (JLUM L0304-j-Zn2) [Credit: Chen et al., 2018] |
Changchunsaurus parvus belongs to an early branch at or near the origins of the ornithopods, and thus may provideinsight into the ancestral state of ornithopod tooth development. In this study, Chen and colleagues took thin sections from five jaw bones of Changchunsaurus to investigate tooth composition as well as how the teeth are maintained throughout the life of the animal using histological techniques.
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The wavy appearance of the enamel of Changchunsaurus in thin section and under cross-polarized light [Credit: Chen et al., 2018] |
Features of the jaws and teeth are often used to assess dinosaur phylogeny. In addition to investigating the evolution of ornithopod dentition, this study also identifies new dental traits that might help sort out ornithischian relationships in future analyses. But the authors note that this is only the first in-depth study at a dinosaur near the base of the ornithopod family tree, and that more studies on more dinosaurs will be needed to fill in the full picture of this group's evolution.
Professor Chen Jun summarizes: "These tissue-level details of the teeth of Changchunsaurus tell us that their teeth were well-adapted to their abrasive, plant-based diets. Most surprisingly, the wavy enamel described here, presumably to make it more resistant to wear, was previously thought to be exclusive to their giant descendants, the duckbilled dinosaurs."
Source: PLOS [November 07, 2018]
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