The stratigraphical relationships of the earliest monograptidae, and the dimorphograptidae

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Abstract
SUMMARY: The earliest monograptids are shown to appear at exactly the same time (base of the vesiculosus Zone in Scotland) as Dimorphograptus and Rhaphidograptus, and the earliest species of these two genera are those with long uniserial portions, the forms wiht shorter uniserial portions appearing in the overlying cyphus Zone. Akidograptus is entirely restricted to the premonograptid beds. One of the earliest monograptids is described as Monograptus cyphus var. praematurus var. nov., which has a distinct and earlier range than M. cyphus s.s. Lapworth.

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