Astraspis

Astraspis
Temporal range: 467–443 Ma
middle-late Ordovician
Astraspis desiderata
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Pteraspidomorphi
Subclass: Astraspida
Order: Astraspidiformes
Genus: †Astraspis
Walcott, 1892
Species
  • †Astraspis desiderata
  • †Astraspis splendens

Astraspis ('star shield') is an extinct genus of primitive jawless fish from the Ordovician of Central North America including the Harding Sandstone of Colorado and Bighorn Mountains of Wyoming. It is also known from Bolivia.[1] It is related to other Ordovician fishes, such as the South American Sacabambaspis, and the Australian Arandaspis.

Description

Nearly complete fossils suggest the living animals were about 200 mm (7.9 in) in length. The body had a mobile tail covered with small protective plate-like scales of less than 1 mm (0.039 in) and a forebody covered with plate-like scales larger than 2 mm (0.079 in). The specimen from North America (described by Sansom et al., 1997) is to have had relatively large, laterally-positioned eyes and a series of eight gill openings on each side. The specimen was generally oval in cross-section. The protective bony plates covering the animal were composed of aspidin (chemically similar to modern shark's teeth), covered by tubercles composed of dentine.[2] It is from these tubercles (which are generally star-shaped) that the name 'Astraspis' (literally "star-shield") is derived.

References

  1. ↑ Sacabambaspis janvieri. PY Gagnier - Vertébré ordovicien de Bolivie, 1993
  2. ↑ Sansom IJ, Smith MP, Smith MM and Turner P (1997) "Astraspis: The anatomy and histology of an Ordovician fish" Palaeontology, 40 (3): 625–642.

Other sources

Michael J. Benton, Vertebrate Palaeontology, 3rd edition, 2005


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