A new porolepiform-like fish,Psarolepis romeri, gen. et sp. nov. (Sarcopterygii, Osteichthyes) from the Lower Devonian of Yunnan, China

Publisher Website
Google Scholar
Abstract
A new sarcopterygian fish, Psarolepis, gen. nov. (Sarcopterygii, Osteichthyes) is described from the Lower Devonian of Eastern Yunnan, China. The new genus manifests many porolepiform-like features that are commonly used to distinguish porolepiforms from osteolepiforms, such as internasal cavity well developed, parasphenoid not protruding forward to ethmoidal region, vomeral area rectangular in shape and not meeting at median line, dorsal part of interorbital wall broad and tectum orbitale well developed, external surface of lower jaw with three large fossae, and well developed parasymphysial plates at anterior tip of lower jaws. This new form also shares some features with Powichthys, Youngolepis and Diabolepis that are not found in typical porolepiforms, such as intracranial joint situated at the level of the trigeminal exit, posterior face of ethmosphenoid facing posteroventrally, X-type skull table, and sutures always visible between premaxilla and the rest of the frontoethmoidal shield. Unique features of the new form include: complete lack of ventral or ventrolateral endoskeletal opening of the nasal cavity; extremely short sphenoidal region; presence of postorbital pillar flanking lateral cranial wall; supraorbital sensory canal not reaching anterior part of snout; median rostral toothed and taking part in upper jaw margin; and lower jaw with five coronoids. This new form probably represents a basal member of the clade that includes Powichthys, Youngolepis, Diabolepis and Dipnoi (=Dipnoiformes of Cloutier, 1990). The unusual character combination raises interesting questions about the interrelationship of the Dipnomorpha (sensu Ahlberg, 1991) and helps to illustrate the possible character transformation sequence of the stem lineage of dipnoans.