Monograptus
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| Monograptus Temporal range:
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| Monograptus spiralis | |
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| Genus: | Monograptus Geinitz, 1852
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Monograptus is a genus of graptolites in the order Graptoloidea. This particular genus is the last stage of the graptoloid evolution before its extinction in the early Devonian. A characteristic of the genus includes one uniserial stipes with very elaborate thecae. This particular genus contains large number of graptolite species and may not be monophyletic.
Biostratigraphic significance
[edit]The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum (FAD) of Monograptus uniformis as the defining biological marker for the start of the Lochkovian, 419.2 ± 3.2 million years ago, the earliest stage of the Devonian.[1] ICS has assigned the FAD of Monograptus parultimus defining biological marker for the start of the Pridoli epoch, 423.0 ± 2.3 million years ago, of Monograptus turriculatus (together with the replacement of the brachiopod Eocoelia intermedia with E. curtisi) for the start of the Telychian, 438.5 ± 1.1 million years ago, and of Monograptus austerus sequens for the start of the Aeronian, 440.8 ± 1.2 million years ago, all stages of the Silurian.
References
[edit]- ^ Gradstein, F. M. et al. ICS on Stage, page 5. Retrieved 2015-06-16.
External links
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