Modeling the ancient geography of Xenacanthus requires focusing intently on what hydrological feature?

Extent of large, continental interior drainage systems

When attempting to reconstruct the paleogeographic map illustrating where Xenacanthus thrived, the focus must shift entirely away from typical marine coastal indicators. Because the shark was restricted to inland aquatic environments, modeling its range demands intense concentration on the extent and configuration of large, continental interior drainage systems that were prevalent, especially during the early Permian and late Carboniferous epochs. The distribution of Xenacanthus was inherently limited and defined by the flow and boundaries of these ancient river basins, making the study of its locations intrinsically linked to understanding ancient continental hydrology rather than just marine ecology.