The lower Ordovician conodont Eoplacognathus crassus Chen & Zhang, 1993

Abstract

An important species of Lower Ordovician platform conodonts, Eoplacognathus crassus Chen & Zhang, is described and illustrated. Prior to its recognition by Chen & Zhang in 1993, it was referred to other species of Lower Ordovician platform conodonts. It is now known from exceptionally well‐preserved material, which permits detailed study of the ontogenetic morphology. The species has a wide distribution in China, and has also been found in the Baltoscandian area and Poland. Its vertical range is restricted to the upper part of the Amorphognathus variabilis‐Microzarkodina flabellum Conodont Subzone and the lower part of the Asaphus “raniceps” Trilobite Zone of the Kundan Stage (Lower Ordovician) in Sweden. It was recently obtained from the very uppermost part of Undulograptus austrodentatus Graptolite Zone in south China. It is clearly an important species for international stratigraphic correlation. Zhang Jianhua, 1997: The Lower Ordovician conodont Eoplacognathus crassus Chen & Zhang, 1993. GFF, Vol. 119 (Pt. 1, March), pp. 61–65. Stockholm. ISSN 1103–5897.