Early Ludlow monograptids with Devonian morphological affinities

Abstract
Nilssoni-scanicus Zone deposits (Silurian, early Ludlow) from the Leintwardine and Long Mountain districts of Britain, and the Calarasi Borehole, Moesian Platform of Romania, have yielded a species of monograptid which, while resembling rare Ludlow Monoclimacis spp., has strong morphological affinities with Devonian monograptids such as Monograptus ramstalensis Jaeger. Because of the occurrence of such structures at a surprisingly low horizon caution is suggested in identifying age from monotypic assemblages. The difficulties surrounding the affinities of the low Ludlow species necessitates a provisional open nomenclature as Monograptus sp. The possible evolutionary significance is discussed.

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