Complex rostral neurovascular anatomy of <i>Riojasuchus tenuisceps</i> (Archosauria: Pseudosuchia) and implications for trophic hypotheses in ornithosuchids

Ornithosuchids are distinctive pseudochian archosaurs from the Late Triassic whose feeding habits remain debated. Previous paleoneurological and histological studies provided limited information about their paleobiology. To address this, we analyzed the craniofacial neurovascular anatomy of Riojasuchus tenuisceps to infer its functional and ecological implications and to reassess hypotheses about ornithosuchid feeding behavior. The holotype and a referred specimen were studied. The snout of PVL 3828 was analyzed using micro-computed tomography, enabling digital reconstruction of the rostral neurovascular system. We applied a quantitative framework, including ordinary least squares regressions and principal component analysis, to compare neurovascular patterns across Triassic pseudosuchians (e.g., Erpetosuchidae, Gracilisuchidae, and Loricata). The premaxilla exhibits a complex internal anatomy, with neurovascular canals connecting to external foramina. Our results reveal a foramen density significantly higher than the group's baseline, a configuration that differs from other pseudosuchians and resembles the mechanosensory systems of extant crocodilians and some birds. These findings indicate that R tenuisceps may have used its snout for tactile prey detection, protection from mechanical forces during feeding, or to maintain a high vascular supply. Combined with biomechanical and osteological data, this supports a wading-foraging behavior rather than scavenging or active terrestrial hunting, highlighting a sophisticated resource partitioning and an underestimated ecological diversity among Triassic pseudosuchians.