Wenlock, Ludlow, and Pridoli? graptolites from Yulin, Guangxi, China

Abstract

Late Wenlock and Ludlow transition graptolites are better developed and more diverse in the Yulin region of Guangxi Province, South China, than elsewhere in China. The upper Homerian (upper Wenlock) graptolites, while moderately diverse, are not amenable to a zonal subdivision because key species such as Colonograptus praedeubeli, Colonograptus deubeli, and Colonograptus ludensis are found to completely overlap in their occurrences. Ludlow graptolites, all probably assignable to the lowest Ludlow nilssoni–colonus Biozone, include Lobograptus progenitor, Colonograptus colonus, Colonograptus gerhardi, and Bohemograptus bohemicus (sensu lato). The single occurrence of Monograptus cf. rectiformis Príbyl is the only species suggestive of Pridoli-age strata. The overall faunal assemblages are composed predominately of cosmopolitan species, but two species, Colonograptus gerhardi and Monograptus cf. rectiformis, provide minor support for the suggestion that the Yunkai Block in which the Yulin region is situated was originally part of Gondwanaland.