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Adaptive radiation of monograptids after the Late Wenlock crisis

100%

Koren T. N., Urbanek A.

Acta Palaeontologica Polonica

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1994

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tom 39

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nr 2

137-167

Succession of late Wenlock graptolites in the Kursala Formation, Tien Shan (Kirghizia), documents of the early recovery phase after the global C. lundgreni Event. Pristiograptus dubius was the only survivor among monograptids. After displaying a mass occurrence and an increased variation, the P. dubius stem lineage splits into two main trends: line A, represented by Pristiograptus idoneus and line B, represented by Colonograptus? praedeubeli. The former leads to Lobograptus? sherrardae, a generalized forerunner of such diverse trends as linograptids, cucullograptids and possibly also neocucullograptids (via Bohemograptus). The latter initiates the Colonograptus-Saetograptus line. The P. idoneus - L.? sherrardae lineage shows distinct gracilization, an apomorphic feature, while the other one preserves ancestral robustness, a plesiomorphic character. Hence, the bulk of the later monograptids of Gorstian and Ludfordian age may be derived from the P. dubius stem lineage. In respect of this conservative lineage a non-cladistic approach is prefered, because its morphological spectrum and evolutionary potential, and as we believe its specific identity, were preserved, in spite of numerous speciation events, until the early Pridoli.

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Late Caradoc and early Ludlow Radiolaria from Baltic erratic boulders

80%

Gorka H.

Acta Palaeontologica Polonica

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1994

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tom 39

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nr 2

169-179

Glacial erratic boulders of the Ostseekalk type, late Caradoc in age, contain spumellarian radiolarians with their skeleton substituted by iron minerals secondarily oxidized to goethite. Species of both the Inaniguttidae, characterized by the presence of a small spherical central shell, and Entactiniidae, with a transverse central bar, have been identified. A similar radiolarian assemblage, but with original siliceous skeletons preserved, has been identified in a graptolitic lirnestone boulder, early Ludlow in age.

3

Silurian aphrosalpingid sphinctozoans from Alaska and Russia

70%

Rigby J. K., Nitecki M. H., Soja C. M., Blodgett R. B.

Acta Palaeontologica Polonica

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1994

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tom 39

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nr 4

341-391

Ograniczanie wyników

3 Acta Palaeontologica Polonica

1 Blodgett R. B.

1 Gorka H.

1 Koren T. N.

1 Nitecki M. H.

1 Rigby J. K.

1 Soja C. M.

1 Urbanek A.

3 1994

Adaptive radiation of monograptids after the Late Wenlock crisis

Late Caradoc and early Ludlow Radiolaria from Baltic erratic boulders

Silurian aphrosalpingid sphinctozoans from Alaska and Russia