Early Devonian monograptids of the telleri biozone in the UraIs-Tien Shan fold area

Abstract

Morphology and· stratigraphic distribution of five previously known and one new Lower Devonian monograptids of Pai-Khoi and Tien Shan areas of the USSR are described. Certain major evolutionary trends are recognized among post-hercynicus monograptids and three lineages are identified. Stratigraphic distribution of monograptids within combined section of the Lower Devonian in both areas provide new data concerning the range of taxa investigated. While the M. telleri biozone comprises the entire stratigraphic interval from hercynicus to the yukonensis Zone, successive. appearances of other species are used to distinguished five discrete zonal subdivisions. Correlation and age of graptolite bearing beds of ·the Lower Devonian in both areas are discussed.