''Monograptus'' is a genus of graptolites in the Order

Graptoloidea Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ...

. 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

theca In biology, a theca (plural thecae) is a sheath or a covering. Botany In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a comm ...

e. This particular genus contains large number of graptolite species and may not be monophyletic.

Biostratigraphic significance

The

International Commission on Stratigraphy The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigr ...

(ICS) has assigned the

First Appearance Datum First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particu ...

(FAD) of ''Monograptus uniformis'' as the defining biological marker for the start of the

Lochkovian The Lochkovian is one of three faunal stages in the Early Devonian Epoch. It lasted from 419.2 ± 3.2 million years ago to 410.8 ± 2.8 million years ago. It marked the beginning of the Devonian Period, and was followed by the Pragian Stage. It is ...

, 419.2 ± 3.2 million years ago, the earliest stage of the Devonian.Gradstein, F. M. et al. ''ICS on Stage''
page 5. Retrieved 2015-06-16. 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 In the geologic timescale, the Telychian is the age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon. The Telychian Age was between 438.5 ± 1.2 million years ago (Ma) and 433.4 ± 0.8 Ma. The Telych ...

, 438.5 ± 1.1 million years ago, and of ''Monograptus austerus sequens'' for the start of the

Aeronian In the geologic timescale, the Aeronian is an age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that began 440.8 ± 1.2 Ma and ended 438.5 ± 1.1 Ma (million years ago). The Aeronian Age succeeds ...

, 440.8 ± 1.2 million years ago, all stages of the Silurian.

References

External links

PhotoArticle
english.fossiel.net—"graptolite ''Monograptus'' from Bornholm, Denmark" Graptolite genera Silurian animals Graptoloidea Index fossils Fossils of Algeria Fossils of Sweden Paleozoic life of British Columbia Paleozoic life of the Northwest Territories Paleozoic life of Nunavut Paleozoic life of Quebec Paleozoic life of Yukon {{devonian-animal-stub