Tubular phosphatic microproblematica from the Early Ordovician of China

Fenhsiangia zhangwentangi gen. et sp. nov., is named for an animal represented by a phosphatic tube-like exoskeleton with the internal walls ornamented by stellate-based rounded tubercles. As vertebrates are the only animals known to possess stellate tubercles of phosphatic material in the dermal skeleton, yet our remains do not show any morphological or histological similarity to primitive fish bone, we suggest that Fenhsiangia was an ancestral protovertebrate, possibly an ascidian or related form. A second form, here referred to as Fenhsiangia sp. differs in that the tubercles are flat-topped or concave, and the external walls are deeply pitted with lines of small pustules bordering the depressions. The Upper Cambrian and Ordovician could have been a time of great diversity and radiation for protovertebrates. with the evolution of the first true vertebrates resulting from this radiation. □ Ordovician, China, phosphatic microproblematica, protovertebrate.