First Record ofPetalodusOwen, 1840 (Chondrichthyes, Petalodontidae) in the Lower Permian (Cisuralian) of China

Abstract

AbstractThe Petalodontiformes are a small intriguing group of Permo–Carboniferous chondrichthyans.Petalodusis the longest known petalodont genus generally considered representative of the order. The first definite fossil record of seven well‐preservedPetalodusteeth has been found in the Qianshi limestone in the Lower Permian (Cisuralian) middle–upper Taiyuan Formation in Yangquan City, Shanxi Province, North China. The specimens are characterized by petal‐shaped teeth with a spade‐like crown, and a long, tongue‐shaped root; the crown is circled with a band or cingulum composed of imbricated ridges at the base. All seven teeth are assigned to the speciesP. ohioenesisbecause of their vertically narrow cingulum and much longer root.Petalodusis a worldwide genus, with fossil localities mainly concentrated in the Laurussia supercontinent. The occurrence ofPetalodusteeth in Yangquan not only is the first fossil record in China, but also only the second record in Asia. The Yangquan fossil site was part of the paleoequatorial North China Craton during the Early Permian, and was isolated from Laurusia and East Gondwana by the Paleo‐Tethys Ocean. The successful dispersal ofPetalodusfrom Laurusia to the North China Block along Paleo‐Tethys may support the possibility thatPetalodustaxa were active free‐swimmers rather than bottom dwellers. The new finding increases the petalodont diversity in eastern Asia, and also sheds new light on the distribution and stratigraphic range.