Jawless Vertebrates - Digital Atlas of Ancient Life
2020年5月29日 · Astraspids lived during the Ordovician period and are represented by only two species in the genus Astraspis. Detailed information about the group is available on the Tree of Life website.
Astraspis – the anatomy and histology of an Ordovician fish | The ...
Astraspis is a pteraspidomorph agnathan with a dorsal headshield formed from polygonal tesserae, and a ventral shield composed of more irregular tesserae. The tesserae are surmounted by star-shaped or smooth, round or ovate tubercles.
Astraspida - Tree of Life Web Project
The Astraspida, or astraspids, are a small group of fossil, armored, fossil jawless vertebrates, which lived in the Middle Ordovician (about 450 million years ago) in North America. They are placed among the Pteraspidomorphi because of the …
Astraspis desiderata
Astraspis desiderata is an early, armored fish from the Ordovician period, dating from about 450 mya.The name Astraspis means "star shield," deriving from astr- "star," and -aspis "shield" [Gk]. It belongs to the phylum Chordata, the class Pteraspida, and the subclass Astraspida.
A Reassessment of Astraspis desiderata , the Oldest North ... - AAAS
The most recently found specimen of Astraspis was reexamined and found to show the orbit, a series of eight branchial openings and a complete tail, structures hitherto undescribed in any Ordovician vertebrate.
Astraspis - The anatomy and histology of an Ordovician fish
1997年8月1日 · Astraspis is a pteraspidomorph agnathan with a dorsal headshield formed from polygonal tesserae, and a ventral shield composed of more irregular tesserae. The tesserae are surmounted by...
Astraspis - Prehistoric Wildlife
2013年4月26日 · Named for the star shaped denticles that covered the body, Astraspis was an Ordovician era jawless fish similar to Arandaspis and Sacabambaspis. Astraspis also seems to have had a lateral line, a series of sensory organs that run down length of the sides of the body, as in modern fish.
A reassessment of Astraspis desiderata, the oldest North …
Though two genera have been known from the Harding Sandstone of North America since 1892, there are still only three articulated specimens known, two of Astraspis desiderata and one of Eriptychius americanus.
A Reassessment of Astraspis desiderata, the Oldest North …
The most recently found specimen of Astraspis was reexamined and found to show the orbit, a series of eight branchial openings and a complete tail, structures hitherto undescribed in any Ordovician vertebrate.
ASTRASPIS AND ERIPTYCHIUS WILLIAM L. BRYANT (Read April 25, 1936) ABSTRACT The discovery of a vertebrate fauna in the Harding Sandstone, of middle Ordovi-cian age, was announced by Walcott more than forty years ago. Two genera described at that time remain the oldest known vertebrate fossils. Yet they never have been
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