Cyathaspidida are extinct spindle-shaped fish that lived near or in the bottom of the ocean floor roughly 420 million years ago.
These interesting creatures were completely protected by armored plates, including a scaled tail. They moved more like tadpoles using a scaled tail because they did not have fins. Fossils of this species are rarely found, and the tails are virtually never fossilized, generally leaving just the head shields.
Americaspis was originally described in 1884 by Edward Waller Claypole as Palaeaspis americana. It was the first Silurian ostracoderm (extinct jawless fish) discovered in the Western Hemisphere. It was later reassigned to the genus Americaspis.
This fossil shows two dorsal shields in matrix.
Type: Jawless Armored Fish (cyathaspids) Species: Americaspis americana Age: Late Silurian (420 million years ago) Formation: Wills Creek Formation Locality: Perry County, Pennsylvania
