Nemagraptus

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Nemagraptus
Temporal range: Darriwilian–Sandbian,
~469.42–452.72  Ma
Nemagraptus gracilis Sandbian lower boundary.webp
N. gracilis from the Sandbian lower boundary
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Hemichordata
Class: Pterobranchia
Subclass: Graptolithina
Order:† Graptoloidea
Family:† Dicranograptidae
Genus:† Nemagraptus
Emmons, 1855
Type species
†Nemagraptus gracilis
(J. Hall, 1847)
Other species
  • †N. subtilisHadding, 1913

Nemagraptus is an extinct genus of graptolites which had an almost worldwide distribution during the Darriwilian and Sandbian (Ordovician). Two species are known: N. gracilis and N. subtilis.

Contents

History

Nemagraptus gracilis was first collected from the Hudson River Shale and Normanskill Formation of New York State in 1843, and Hall (1847) assigned the species to Graptolithus as G. gracilis using specimen YPM IP 020351 as the holotype and specimen AMNH 30458 as the lectotype. [1] Emmons (1855) created the genus Nemagraptus for another species, N. elegans. [2] Törnquist identified the first record of N. gracilis in Europe in 1865, [3] and Elles and Wood (1904) moved G. gracilis into Nemagraptus, synonymising N. elegans with N, gracilis in the process. [4] Three-dimensional remains belonging to N. gracilis were identified in 2007 from boreholes across Latvia and Estonia. [5]

Hadding (1913) named and described Nemagraptus subtilis as the second species assigned to the Nemagraptus genus. He identified the species based on specimens found in the Dicellograptus shale sequence in Skåne County, Sweden between 1910 and 1912. [6]

Starting with Bergström et al. (2000), the lower boundary of the Sandbian was defined as the first appearance datum of N. gracilis in that section. [7]

Distribution

Nemagraptus has been identified from: Argentina, Bolivia, Canada, China, Czech Republic, England, Estonia, Kazakhstan, Latvia, New Zealand, Peru, Sweden, the United States, and Wales. [8]

Description

It lived in deep water environments. [9] The thecae possess considerable overlap, and it has isolated metasicula as the main synapomorphy. [10]

Nemagraptus was a colony-forming organism with two s-shaped branches, which in turn split into several short branches. [11]

Classification

Nemagraptus is a graptolite and has been classified into the family Dicranograptidae and the subfamily Nemagraptinae. [5]

References

  1. ↑ Hall, J. (1847). Natural History of New York, Pt. VI, Paleontology of New York, 1. Albany, New York, 338 p.
  2. ↑ Emmons, E. (1855). American Geology, 1, Pt. 1. Albany, New York, 194 p.Google Scholar
  3. ↑ Törnquist, S. L. Descriptions of Ordovician graptolites from Baltoscandia, 1901 & 1904.
  4. ↑ Elles, G. L., and Wood, E. M. R. (1904). A monograph of British graptolites. Palaeontographical Society, London, 4:135–180.Google Scholar
  5. 1 2 NõLvak, Jaak; Goldman, Daniel (2007). "BIOSTRATIGRAPHY AND TAXONOMY OF THREE-DIMENSIONALLY PRESERVED NEMAGRAPTIDS FROM THE MIDDLE AND UPPER ORDOVICIAN OF BALTOSCANDIA" . Journal of Paleontology. 81 (2): 254–260. doi:10.1666/0022-3360(2007)81[254:BATOTP]2.0.CO;2. ISSN   0022-3360.
  6. ↑ Hadding, A. (1913). Undre Dicellograptusskiffern i Skåne. Lunds Universitets Årsskrift, 9(15):1–91.
  7. ↑ Bergström, Stig M.; S. C. Finney; Chen Xu; Christian Pålsson; Wang Zhi-hao; Yngve Grahn (2000). "A proposed global boundary stratotype for the base of the Upper Series of the Ordovician System: The Fågelsång section, Scania, southern Sweden" (PDF). Episodes. 23 (2): 102–109. doi: 10.18814/epiiugs/2000/v23i2/003 . Retrieved 20 September 2012.
  8. ↑ J. J. Sepkoski, Jr. (2002). A compendium of fossil marine animal genera. Bulletins of American Paleontology 363:1-560
  9. ↑ "Llanfawr Quarry". geoguide.scottishgeologytrust.org. Retrieved 12 February 2026.
  10. ↑ "Nemagraptus". graptolite.treatise.geolex.org. Retrieved 12 February 2026.
  11. ↑ Frank H.T. Rodes, Herbert S. Zim and Paul R. Shaffer (1993) - Nature Guide Fossils (the origin, preparation and arrangement of fossils), Zuidnederlandse Uitgeverij N.V., Aartselaar. ISBN D-1993-0001-361
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