Pteraspidiformes is an extinct order of heterostracan agnathan vertebrates known from extensive fossil remains primarily from Early Devonian strata of Europe and North America, and from Upper Silurian Canada.
Pteraspidiformes is an extinct order of heterostracan agnathan vertebrates known from extensive fossil remains primarily from Early Devonian strata of Europe and North America, and from Upper Silurian Canada.
==Anatomy== thumb|left|Rhinopteraspis fossil A pteraspidiform heterostracan has the cephalothorax enclosed in armor, formed from several plates, including dorsal, ventral, rostral, pineal plates, a dorsal spine derived from a scale, and a large, scale-covered tail. Many genera were benthic, others were apparently active swimming nekton. Delicate, finger-like components of the anterior end of the ventral plate forming the edges of the mouth suggest that pteraspidiform heterostracans were filter-feeders that selectively filtered specific sized plankton from the water column.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).