Leptolepis: Difference between revisions

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Revision as of 15:35, 23 February 2016

Leptolepis
Temporal range: 242.0–112.6 Ma Middle Triassic to Early Cretaceous[1]
Leptolepis dubia
Scientific classification
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Leptolepis

Agassiz, 1843
Type species
Cyprinus coryphaenoides

Leptolepis ("delicate scale") is an extinct genus of teleost fish that lived from the Middle Jurassic period until the Early Cretaceous. The genus is one of the earliest recognized teleost genera.

Appearance

Reconstruction of Leptolepis koonwarriensis
Restoration of a Leptolepis school

Leptolepis was about 30 centimetres (12 in) long, and resembled a modern herring, although it was not a close relative of those fish. It was the first true bony fish to really live up to the name, possessing a skeleton completely made of bone[citation needed]; some previous genera such as Pholidophorus had skeletons composed of bone and cartilage. Another modern development in Leptolepis were its scales, which lacked the covering still present in previous genera. These two developments made swimming easier, as the bony spine was now more resistant to the pressure caused by the S movements made while swimming.[3]

Mass graves of Leptolepis have indicated that it probably lived in schools which would provide some protection from predators while the creatures fed on surface plankton. Pelagosaurus was a known predator of Leptolepis after a Pelagosaurus fossil was found with Leptolepis remains in its stomach.

The Morrison cf. Leptolepis

Known only from a single nearly complete skeleton found at Rabbit Valley, Colorado.[4] A 13 centimetres (5 in) fish that was deeper bodied than its co-occurring contemporaries Morrolepis and Hulettia.[4] The Morrison cf. Leptolepis probably had a live mass of about 37 grams (1.3 oz).[4] It is the only teleost fish known from the formation and was morphologically more highly derived than other Morrison fish.[4] A specific example of apomorphy in cf. Leptolepis is its "more modern tail structure" compared to Morrolepis.[4] It is believed to have fed on fish and small invertebrates.[4]

References

  1. ^ "†Leptolepis Agassiz 1843". Paleobiology Database. Fossilworks. Retrieved 30 January 2016.
  2. ^ New Mexico Museum of Natural History and Science
  3. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 39. ISBN 1-84028-152-9.
  4. ^ a b c d e f Foster, J. (2007). "cf. Leptolepis." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. p. 135.