Lower Ordovician graptolites of North China

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updated August 8, 2005

LOWER ORDOVICIAN GRAPTOLITE-FAUNAS OF NORTH CHINA
Y.C. SUN
Palaeontologia Sinica, Series B, 1935, XIV, 2, 5-14

I n t r o d u c t i o n

         " Hitherto the only known graptolite-faunas of North China were those of the Pingliang formation of Kansu of Middle Ordovician age, although a single fragment of graptolite was already reported from the Kaolishan formation (late Upper Cambrian), Shantung."
          "In 1930 when the Author conducted the National Peking University Field Class in the Kaiping Basin, Chaokuochuang, were discovered the Dictyonema faunas in the greenish-gray argillutytes of the Yehli formation. These faunas are associated with Lingulella. The following species described in this memoir:"

Dictyonema flabelliforme var. orientale Sun (var. nov.)
Callograptus bulmani Sun (sp. nov.)
Dendrograptus irregularis Sun (sp. nov.)
Dedrograptus grabaui Sun (sp. nov.)
Acantograptus kuoi Sun (sp.nov.)

          "This assemblage is certainly that of the Dictyonema flabelliforme zone in England and of Tremadocian age. This zone is, indeed, the oldest Ordovician graptolite zone so far known in China."
          "More recently the Author was again accompanied by the Class of 1936 of the National Peking University and Drs. Yin and Sze obtained again a large collection of graptolites from the upper horozon of the Yehli formation with the following species."

"Dichograptus separatus var. hopeiensis Sun (var. nov.)
Desmograptus yehliensis Sun (sp. nov.)
Loganograptus logani var. kaipingensis Sun (var. nov.)
Didymograptus fearnsidesi Sun (sp. nov.)
Didymograptus nitidus (Hall)
Dendrograptus cf. grabaui Sun (sp. nov.)"

          "This assemblagae is certainly that of the Dichograptus zone of England, indicating early Arenigian age."
          "It is clear that zone 1 (the zone of Dictyonema flabelliforme) and zone 3 (the Dichograptus zone) are definitely represented in the Kaiping Basin. The intermediate zone of Europe - the Bryograptus zone (zone 2) has not yet been found in China. Another interesting fact is that the lower zone of the Yehli formation is characterized by an abundance of Dendrograptus and Dictyonema flabelliforme of comparatively high types which are quite unlike those of the Upper Mississippi Valley, while the upper zone is distinguished by the small and primitive form of Didymograpotus together with Dichograptus, Loganograptus, Desmograptus and few Dendrograptus."
          "The name "Yehli formation" was first proposed in 1920 by Prof. A.W. Grabau and myself for the Lower Ordovician, argillaceous limestone in which two species of Suecoceras were obtained by me. The Author revisited the Kaiping Basin in 1921 in company with Dr. C.C. Young [...]."
          "The discovery of the graptolite-faunas is of great important as these faunas not only confirm the exact age of the Yehli formation but also indicate a close connection of the seas of Europe and of Asia as well as the close relationship of the Palaeogeography of these two widely separated regions."
          "Briefly, the Yehli formation id bounded by the overlying Liangchiashan formation and the underlying Fengshan formation, and is characterized by the abundance of Tremadocian-Arenigian graptolites. It is certainly equivalent to the Canadian of North America."