Pteraspis

from Wikipedia, the free encyclopedia
Pteraspis
Pteraspis rostrata

Pteraspis rostrata

Temporal occurrence
Sandbium to Eifelium
466 to 388 million years
Locations
Systematics
Sub-stem : Vertebrates (vertebrata)
Class : Pteraspidomorphi
Subclass : Heterostraci
Order : Pteraspidiformes
Family : Pteraspididae
Genre : Pteraspis
Scientific name
Pteraspis
Kner , 1847

Pteraspis is an extinct genus of the order Pteraspidiformes . This primitive, jawless fish ( Agnatha )belongingto the Heterostraci lived mainly during the Pragian in the Lower Devonian .

etymology

The name Pteraspis is a combination of the Greek words πτερόν pterón (wing) and ἀσπίς aspis (shield) and can be represented as a winged shield .

Initial description

Pteraspis was scientifically described for the first time by Rudolf Kner in 1847 , but Louis Agassiz had already established the taxon Pteraspis rostrata in 1835 . Other important adaptations come from Huxley (1861), Woodward (1891) and Sepkoski (2002).

Taxonomy

artistic reconstruction of Pteraspis stensioei , now Larnovaspis stensioei

The genus Pteraspis together with numerous be sister named after her family of Pteraspididae (sometimes just Pteraspidae), including Althaspis , Anchipteraspis , Archaeoteuthis , Brachipteraspis , Canadapteraspis , Chiastolepis , Cosmaspis , Cyathaspis , Doryaspis , Errivaspis , Escharaspis , Eucyclaspis , Europrotapsis , Gigantaspis , Grumantaspis , Holaspis , Kallostracon , Lampraspis , Larnovaspis , Loricopteraspis , Miltaspis , Mylopteraspidella , Mylopteraspis , Oreaspis , Palaeoteuthis , Pholidosteus , Podolaspis , protaspis , Protopteraspis , Psephaspis , Rhachiaspis , Rhinopterspis , Scaphaspis , Sphagodus , Stegobranchiaspis , Tolypaspis , Tolypelepis , Ulutitaspis , Unarkaspis and Zascinaspis . Subtaxa are Pterapis crouchi , Pteraspis dixoni , Pteraspis dunensis , Pteraspis mitchelli , Pteraspis rostrata and Pteraspis stensioei . The type fossil is Pteraspis rostrata Agassiz 1835, also known as Pteraspis rostratus or Cephalaspis rostratus .

features

Upper shield of Pteraspis crouchi

Pteraspis reached 20 to 25 centimeters in length and was somewhat flattened dorsoventrally. Like other Heterostraci, it also had armor that covered the front part of its body and protected it from predators such as Eurypterids . At the same time, the armor served as a phosphate reserve in times of need. The armor , undoubtedly the result of the amalgamation of individual scales , was not uniform, but divided into a dorsal and ventral shield. It was also traversed by small canals that were probably connected to the sense organs . The eye region was protected by two smaller orbital plates, the side region by two cornual plates. The rear trunk and the caudal fin were covered by strong, roof-tile-like overlapping scales. The caudal fin was built extremely asymmetrically with a very large and strong ventral lobe, but it should have been very effective with rapid changes of direction. Besides the tail fin, Pteraspis had no other fins , but despite his armor he was a good swimmer. Stiffened wing-like appendages protruded from its gills (hence the name pteraspis ), which extended from the protective branchial plates and probably stabilized it while swimming. There was also a horn-shaped rostrum in front of the eyes , which gave it a very hydrodynamic shape. Around the ventrally seated mouth opening there were some smaller plates (oral plates) that helped him to eat. The eyes were small and sat on the side. On his back, behind the slightly curved, large dorsal spur , Pteraspis carried further spines, which may have served as additional protection against possible attackers.

Way of life

Drepanaspis (left) and Pteraspis (right), Senckenberg Museum

It is believed that pteraspis lived on plankton floating below the surface of the sea . That he lived in the open sea can be seen from the association with other marine fossils. Nevertheless, finds have also been made in the fluvial facies area.

Occurrence

The following sites of Pteraspis are known:

Individual evidence

  1. ↑ Lankester, ER: I. — On a New Cephalaspis Discovered in America, etc. Volume 7 , 1870, p. 397 , doi : 10.1017 / S0016756800209485 .
  2. ↑ JHG Melo: The Malvinokaffric realm in the Devonian of Brazil . Ed .: NJ McMillan, AF Embry and DJ Glass, Devonian of the World, Volume I. Canadian Society of Petroleum Geologists, Calgary, Alberta, Canada 1988, p. 669-703 .
  3. ^ W. Stuermer and F. Schaarschmidt: plants in the Hunsrueckschiefer . In: Petrified life in X-ray light . tape 11 , 1985, pp. 19-25 .
  4. ^ V. Havlicek and J. Vanek: The biostratigraphy of the Ordovician of Bohemia . In: Sbornik Geologickych Ved, Paleontology . tape 8 , 1966, pp. 7-69 .
  5. ^ M. Dumbrava and A. Blieck: Review of the Pteraspidiform heterostracans (Vertebrata, Agnatha) from the Devonian of Podolia, Ukraine, in the Theodor Vascautanu Collection, Bucharest, Romania . In: Acta Palaeontologica Romanniae . tape 5 , 2005, p. 163-171 .
  6. ↑ VP Gritsenko, AA Istchenko, LI Konstantinenko and PD Tsegelnjuk: Animal and plant communities of Podolia . In: AJ Boucot and JD Lawson (Eds.): Paleocommunities - a case study from the Silurian and Lower Devonian . 1999, p. 462-487 .
  7. ^ White, EI: New Pteraspids from South Wales . tape 94 , 1938, pp. 85 , doi : 10.1144 / GSL.JGS.1938.094.01-04.05 .
  8. ^ Gibson, S .: Field Meeting Report: Fossil fish remains in the Devil's Hole section, near Morville, led by Maggie Rowlands and Peter Tarrant 10th April 1988 . In: Proceedings of the Shropshire Geological Society . tape 8 , 1988, pp. 7-11 .
  9. ^ RE Plotnick: Habitat of Llandoverian-Lochkovian eurypterids . In: AJ Boucot and JD Lawson (Eds.): Paleocommunities - a case study from the Silurian and Lower Devonian . 1999, p. 106-136 .
  10. ^ WH Lang: On the plant-remains from the Downtonian of England and Wales . In: Philosophical Transactions of the Royal Society . 227B, 1937, pp. 245-291 .