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Dinosaur Teeth Evolution and Function Using Synchrotron Transmission X-ray Microscopy (free pdf)

Ben Creisler

A new paper in open access:

Chun-Chieh Wang, Yen-Fang Song, Sheng-Rong Song, Qiang Ji, Cheng-Cheng
Chiang, Qingjin Meng, Haibing Li, Kiko Hsiao, Yi-Chia Lu, Bor-Yuan
Shew, Timothy Huang & Robert R. Reisz (2015)
Evolution and Function of Dinosaur Teeth at Ultramicrostructural Level
Revealed Using Synchrotron Transmission X-ray Microscopy.
Scientific Reports 5, Article number: 15202 (2015)

The relationship between tooth form and dietary preference is a
crucial issue in vertebrate evolution. However, the mechanical
properties of a tooth are influenced not only by its shape but also by
its internal structure. Here, we use synchrotron transmission X-ray
microscopy to examine the internal microstructures of multiple
dinosaur teeth within a phylogenetic framework. We found that the
internal microstructures of saurischian teeth are very different from
advanced ornithischian teeth, reflecting differences in dental
developmental strategies. The three-tissue composition (enamel–mantle
dentin–bulk dentin) near the dentinoenamel junction (DEJ) in
saurischian teeth represents the primitive condition of dinosaur
teeth. Mantle dentin, greatly reduced or absent from DEJ in derived
ornithischian teeth, is a key difference between Saurischia and
Ornithischia. This may be related to the derived herbivorous feeding
behavior of ornithischians, but interestingly, it is still retained in
the herbivorous saurischian sauropods. The protective functions of
mantle dentin with porous microstructures between enamel and bulk
dentin inside typical saurischian teeth are also discussed using
finite-element analysis method. Evolution of the dental modifications
in ornithischian dinosaurs, with the absence of mantle dentin, may be
related to changes in enamel characteristics with enamel spindles
extending through the DEJ.