Tartuosteus

Tartuosteus is an extinct genus of jawless fish from the Devonian of Eastern Europe. It is notable for its large size in comparison to other Ostracoderms, reaching a width of 1.5 m (4.9 ft).[1]

Tartuosteus
Temporal range:
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Agnatha
Order:
Heterostraci
Suborder:
Psammosteidei
Family:
incertae sedis
Genus:
Tartuosteus

Obruchev, 1961
Type species
Psammolepis gigantea
Gross, 1933

Description

Like other Psammosteid Heterostracans, Tartuosteus had a broad and flattened body which was almost as wide as it was long, being 1 meter wide and an estimated 1.5 meters long. This impressive width is owed to its extended branchials, which are large wing-like bony fins extending from the body. The branchials of Tartuosteus form a boomerang-like shape, while the center of the body dips deeply into a keel-like protrusion.[1]

These branchials are so large that when measured for the amount of lift they can produce, its lift-to-drag ratio is comparable to that of a jet airplane. This lift force would provide Tartuosteus with an efficient cruising ability while reducing maneuverability. This suggests that Tartuosteus was effective at exploiting widely distributed food sources, possibly plankton in the water column, or at escaping predation.[2]

Species

Tartuosteus has a somewhat convoluted taxonomic past, with species being lumped into and out of the genus and others being declared based on poor remains. There are two species which are unproblematically members of the genus.[3]

  • T. giganteus (Gross, 1933)[4][5]
  • T. maximus Mark-Kurik, 1965[6]

There are also two species which are problematically members of the genus, but are based on poor remains. Elgaia luhai was formerly a member of the genus, but is now considered to be separate.[3]

  • T.? (Rohonosteus) ornatus Rohon, 1899
  • T.? zheleznogorskensis Moloshnikov, 2009[7]

See also

Sources
  1. Mark-Kurik, E; Obruchev, D (1968). "ON THE EVOLUTION OF THE PSAMMOSTEIDS (HETEROSTRACI)". Eesti NSV Teaduste Akadeemia Toimetised. Keemia. Geoloogia. 17 (3): 279. doi:10.3176/chem.geol.1968.3.10. ISSN 0424-6373.
  2. Dec, Marek (2019). "Hydrodynamic performance of psammosteids: new insights from computational fluid dynamics simulations". Acta Palaeontologica Polonica. 64. doi:10.4202/app.00623.2019. ISSN 0567-7920.
  3. Glinskiy, Vadim (2017). "Phylogenetic relationships of psammosteid heterostracans (Pteraspidiformes), Devonian jawless vertebrates". Biological Communications. 62 (4): 219–243. doi:10.21638/11701/spbu03.2017.402. ISSN 2542-2154.
  4. Gross, W. (1933). "Die Fische des baltischen Devons". Palaeontographica (79): 1–74.
  5. Obruchev, D.V. (1961). "Genus Tartuosteus (Psammosteidae) from the Middle Devonian of the Baltic Region". Paleontol. Zh. (22): 107–111.
  6. Obruchev, D.V. and Mark-Kurik, E.Yu., Psammosteidy (Agnatha, Psammosteidae) devona SSSR (Psammosteids (Agnatha, Psammosteidae) from the Devonian of the USSR), Tallinn: Inst. Geol. Akad. Nauk Est. SSR, 1965.
  7. Moloshnikov, S. V. (2007). "Psammosteiforms (Agnatha, Heterostraci) from the Lower Frasnian of the Mikhailovskii Mine, Kursk Region, Russia". Paleontological Journal. 41 (5): 558–563. doi:10.1134/s0031030107050115. ISSN 0031-0301.


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