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. 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 in length. The body had a mobile tail covered with small protective plate-like scales of less than and a forebody covered with plate-like scales larger than . 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.<ref>Sansom IJ, Smith MP, Smith MM and Turner P (1997) "Astraspis: The anatomy and histology of an Ordovician fish" Palaeontology, 40 (3): 625–642.</ref> It is from these tubercles (which are generally star-shaped) that the name 'Astraspis' (literally "star-shield") is derived. References Other sources Michael J. Benton, Vertebrate Palaeontology'', 3rd edition, 2005 External links Palaeos' Pteraspidomorphi Pteraspidomorphi genera Ordovician jawless fish Late Ordovician animals Ordovician fish of North America Prehistoric fish of South America Fossils of Bolivia Fossil taxa described in 1892