Enamel–dentin differentiation alters modeled stress transfer in a Maastrichtian crocodyliform tooth

Some finite element analyses of fossil teeth have assigned homogeneous, dentin-like material properties, although the consequences of this simplification for tissue-specific stress transfer remain poorly resolved. Here, an isolated crocodyliform tooth, SC000903, from the Maastrichtian Yuliangzi Formation was investigated using external morphology, high-resolution micro-computed tomography, three-dimensional reconstruction, and finite element analysis. Its subconical crown, smooth enamel, lingual curvature, and distinct cervical constriction support referral to Crocodyliformes indet. Micro-CT reveals marked apicobasal variation in enamel thickness and a labiolingually compressed pulp-cavity system with fine apical and mesiodistal branching canals. To test the effects of tissue differentiation, a homogeneous dentin-like model was compared with an anatomically reconstructed enamel–dentin composite model under standardized apical loads of 500 and 1000 N. Relative to the homogeneous model, the composite model increased the proportion of above-threshold enamel by 81.48% and 156.29%, while decreasing the corresponding proportion in dentin by 21.05% and 22.58%, respectively. Total above-threshold volume changed only modestly, indicating that tissue differentiation primarily redistributed modeled high-stress regions from dentin toward enamel rather than uniformly increasing whole-tooth mechanical vulnerability. Homogeneous models may therefore remain useful for broad comparisons of crown-scale behavior but may be inadequate when tissue-specific stress transfer or localized above-threshold regions are central to functional interpretation. SC000903 also provides the first detailed crocodyliform record from the Yuliangzi Formation and represents one of the northernmost formally documented Maastrichtian crocodyliform occurrences in Asia.