Psammosteidae is an extinct family of flattened, benthic heterostracan

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s that lived in

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine current power * Marine debris * Marine energy * Marine habitats * Mari ...

and

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime enviro ...

environments in Europe, Russia & North America. They arose during the

Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...

, with the first (and best) known genus, '' Drepanaspis'' from the

Hunsrück The Hunsrück () is a long, triangular, pronounced mountain range, upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle (river), Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued ...

lagerstätte A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserv ...

. The Psammosteids were the only heterostracans that survived the Upper

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during ...

extinction event during the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

, dying out in the extinction event at the very end of the Devonian.

References

''Palaeos Vertebrates''
Devonian jawless fish Prehistoric jawless fish families Heterostraci Famennian extinctions Early Devonian first appearances {{Devonian-jawless-fish-stub