Doliodus problematicus (Whiteaves 1881; Traquair 1893; Miller, Cloutier and Turner 2003; Maisey et al. 2018; Early Devonian) was considered the 'oldest articulated chondrichthyan' and a transitional taxon between acanthodians and sharks. Here Doliodus nests with Xenacanthus. which as similar two-pointed teeth. The skull is wider, the maxilla is flat and the dual-pronged teeth are oriented medially). This was probably a nocturnal bottom feeder. Like spiny sharks and catfish the leading edge of the pectoral fin was a spine. Note the ventral branchials remain between the jaws. The dorsal branchials were not preserved, but must have been located behind the jaws. The ventral carapace was retained. |
