Article

Read

Meganeuropsis

from Wikipedia, the free encyclopedia
Meganeuropsis
Temporal occurrence
Artinscium or kungurium
approx. 280 million years
Locations

Kansas and Oklahoma, USA

System
Arthropoda
Insects (Insecta)
Flying insects (Pterygota)
Meganisoptera
Meganeuropsis
Scientific name
Meganeuropsis
Carpenter, 1939

Meganeuropsis is an extinct genus of insect. It belongs to the group Meganisoptera (alternative name Protodonata, “giant dragonflies”), an extinct group that forms the stem group or a sister group of the recent dragonflies, but had numerous original characteristics (plesiomorphs) compared to them. The species Meganeuropsis permiana is generally considered to be the largest winged insect species that has ever lived.

Species

Within the genus, two species have been described, both after finds from the Wellington Formation, which was deposited in the Lower Permian.

  • Meganeuropsis permiana[1] from a limestone quarry of the famous Elmo fossil deposit, Dickinson County, Kansas, USA.[2]
  • Meganeuropsis americana[3] after finds from Midco, Noble County (Oklahoma).

According to David A. Grimaldi and Michael S. Engel[4] both names are synonymous, a possibility already considered by the first describer Frank M. Carpenter. If one follows this view, the genus comprises only the former species.

Description and finds

Meganeuropsis permiana was described[1] after two wing fragments found separately, but closely adjacent, by Carpenter himself in the Elmo limestone quarry. The first fragment includes the wing base and part of the proximal wing, the second a section from the middle of the wing. Since portions of the veining contain overlapping areas, they could not have been sections of the same wing. It seems likely that the fragments are each from a forewing and hindwing. The shape of the entire wing was estimated by redrawing it based on the wing outline of the previously found giant dragonfly Meganeura monyi from the preserved fragments. Carpenter reconstructs on this basis a wing length of 330 millimeters, from which he deduces a wingspan of 710 millimeters. Of the second species, Meganeuropsis americana, there is a fossil of an almost completely preserved wing that was still 280 millimeters long; its total length is estimated at 305 millimeters. Today it is on display at the Harvard Museum of Natural History.[5] Although the total length is estimated to be somewhat smaller, it is still the largest fossil insect wing actually preserved. In addition, there is a second well-preserved wing and a good dozen other fragments that have been assigned to this species, all of which were found by G.O.Raasch in Midco, Oklahoma. Here, in 2000, Roy Beckemeyer discovered another hindwing fragment, now in the Johnston Geology
Museum of Emporia State University, Emporia, Kansas.[6]

The genus Meganeuropsis is considered closely related to the European Meganeura according to wing veining, and both are often united in one family Meganeuridae.[7] However, the family is difficult and uncertain to delimit from other families of giant dragonflies, so that some authors refrain from assigning it to a family altogether as a precaution. The genus can be distinguished from other American giant dragonflies, in addition to its size, by the enlarged precostal field in the wing, which extends to the middle of the wing.[8] The genus is differentiated from related genera by some details of wing veining. Fossils of parts of the body other than the wings have never been found.

Location

The Wellington Formation is a rock series of the Lower Permian exposed for about 270 kilometers in Kansas and Oklahoma, from Elmo in the north to Midco near Perry, in the south. In the middle sections the formation is shrouded by a thick layer of loess and is almost never exposed above ground. Nearly 200 fossil insect species have been described from the formation..[9] have been described from the formation, making it one of the most diverse Permian insect sites in the world. The formation reaches 214 metres in thickness and comprises marine, brackish and limnetic (deposited in freshwater) sediments, including anhydrite and rock salt deposits. The fossils are from the so-called Carlton Limestone near the base of the formation, which is only a few metres thick.[10] Contrary to the often expressed impression that the fauna of that time was mainly characterized by giant insects, most of the species found are relatively small (average wingspan about 22 millimeters), only a few reached the dimensions of giant dragonflies. 10 of a total of only 13 species with wingspans over 50 millimetres belonged to this group. Little is known about their way of life; in particular, it is unclear whether their larvae, like those of recent dragonflies, lived in water. For the adult giant dragonflies, a predatory mode of feeding is considered certain. Since no flying vertebrates existed at that time, they were probably apex predators of the fauna of the time.

At the time of deposition, the region was close to the equator. The limestone was deposited in a coastal plain at the edge of a large inland salt lake. Fossil gilled crabs resembling the recent genus Triops were found from the lake sediments; the waters are generally thought to have been quite hostile to life. The flying insects were probably blown in and perished here.

Individual references

  1. a b Frank Morton Carpenter: The Lower Permian Insects of Kansas. Part 8: Additional Megasecoptera, Protodonata,Odonata, Homoptera, Psocoptera, Protelytroptera, Plectoptera, and Protoperlaria. In Proceedings of the American Academy of Arts and Sciences. 73 (3), 1939, PP. 29-70. JSTOR 25130151
  2. Roy J. Beckemeyer: The Permian Insect Fossils of Elmo, Kansas. In Kansas School Naturalist. 46 (1), 2000. (online)
  3. Frank Morton Carpenter: Lower Permian Insects from Oklahoma. Part 1: Introduction and the Orders Megasecoptera, Protodonata, and Odonata. In: Proceedings of the American Academy of Arts and Sciences. 76 (2), 1947, PP. 25-54. JSTOR 20023497
  4. D. Grimaldi, M. S. Engel: Evolution of the Insects. Cambridge University Press, 2005, ISBN 0-521-82149-5, p. 175.
  5. DRAGONfly. The largest complete insect wing ever found. In: Harvard Magazine. November/December 2007.
  6. Roy J. Beckemeyer: Hind Wing Fragments Of Meganeuropsis (Protodonata: Meganeuridae) from the Lower Permian of Noble County, Oklahoma. In: Bulletin of American Odonatology. 9(3/4), 2006, S. 85–89.
  7. André Nel, Günther Fleck, Romain Garrouste, Georges Gand, Jean Lapeyrie, Seth M. Bybee, Jakub Prokop: Revision of Permo-Carboniferous griffenflies (Insecta: Odonatoptera: Meganisoptera) based upon new species and redescription of selected poorly known taxa from Eurasia. In: Palaeontographica Division A. 289, Deliveries 4-6, 2009, pp. 89-121.
  8. Michael S. Engel: Megatypus parvus spec. nov., a new giant dragonfly from the Lower Permian of Kansas (Protodonata: Meganeuridae). In: Odonatologica. 27(3), 1998, S. 361–364.
  9. The entomofauna of the Lower Permian fossil insect beds of Kansas and Oklahoma, USA. In: African Invertebrates. 48 (1), April 2007, pp. 23-39.
  10. R. R. West, K. B. Miller, W. L. Watney: The Permian System in Kansas. (= Kansas Geological Survey Bulletin. 257). 2010, ISBN 978-1-58806-333-X.