129-72 Additional Cranial Anatomy of the Early-Diverging Aetosaurine Stenomyti huangae Reveals Morphological and Biomechanical Variation: Interpretation for Dietary Specialization

Abstract:

The heavily armored aetosaurs (Pseudosuchia) are well known throughout much of the Late Triassic (237–201.4 Ma) and have been widely used as a biostratigraphic control for strata lacking more quantitative constraints. Though cranial elements are limited for various taxa, skull anatomy provides important insight into ecological diversity, feeding adaptations, and evolution in aetosaurs. The cranial remains recovered of Stenomyti huangae, an early-diverging aetosaurine from Upper Triassic outcrops in Eagle Basin, Colorado (Chinle Formation), allows for further morphological interpretations of early aetosaurs. High-resolution synchrotron computed tomography (CT) was used to digitally segment and reconstruct the cranial elements using non-destructive imaging techniques for ease of description and interpretation. To assess variation in cranial morphology and its possible functional implications, the reconstructed anatomy was compared with previous descriptions of Aetosaurus ferratus, Aetosauroides scagliai, Typothorax coccinarum, Neoaetosauroides engaeus, Desmatosuchus haplocerus, and Paratypothorax andressorum. 

New observations from reconstructed cranial elements of Stenomyti huangae reveal unique features differing from many derived aetosaurs, including a narrow, tapered snout, elongated ascending process, and bulbous dentition that comparatively suggest alternate jaw morphology and feeding mechanics influencing dietary specialization. The comparative study between S. huangae and related aetosaurs revealed that these characteristics vary widely from the commonly more robust skull morphology and respective specialized dentitions. The previously suggested heterogeneity in feeding mechanics and food strategy among aetosaur taxa is consistent with these physical distinctions, reinforcing that aetosaurs did not reflect a single generic herbivorous feeding style, but rather occupied a variety of ecological niches through morphological diversification. This study contributes further anatomical information for evolutionary comparisons and advances our knowledge of the functional and ecological variety within Aetosauria by expanding on the known cranial anatomy of Stenomyti huangae.

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