The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by a few million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.
Anaspida is an extinct group of jawless fish that existed from the early Silurian period to the late Devonian period. They were classically regarded as the ancestors of lampreys, but it is denied in recent phylogenetic analysis, although some analysis show these group would be at least related. Anaspids were small marine fish that lacked a heavy bony shield and paired fins, but were distinctively hypocercal.
Birkenia is a genus of extinct anaspid fish from Middle Silurian strata of Northern Europe, and Middle Silurian to possibly Earliest Devonian strata of Arctic Canada. Birkeniid anaspids are covered by a series of small plates on the head and rod-shaped scales in a cheveron-like pattern on the trunk.
Nanahughmilleria is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Nanahughmilleria have been discovered in deposits of Devonian and Silurian age in the United States, Norway, Russia, England and Scotland, and have been referred to several different species.
Stylonurella is a genus of prehistoric eurypterid. It is classified within the Parastylonuridae family and contains three species, S. arnoldi and S. beecheri from the Devonian of Pennsylvania, United States and S. spinipes from the Silurian of Kip Burn, Scotland.
Erettopterus is a genus of large predatory eurypterid, an extinct group of aquatic arthropods. Fossils of Erettopterus have been discovered in deposits ranging from Early Silurian to the Early Devonian, and have been referred to several different species. Fossils have been recovered from two continents; Europe and North America. The genus name is composed by the Ancient Greek words ἐρέττω (eréttō), which means "rower", and πτερόν (pterón), which means "wing", and therefore, "rower wing".
Stylonuroides is a genus of prehistoric eurypterid. The genus is classified as a stylonurine but more precise classification has proven difficult, with the genus remaining classified as incertae sedis within the suborder. The genus contains two species, S. dolichopteroides from the Silurian of Ringerike, Norway and S. orientalis from the Devonian of Lake Shunet, Southern Siberia.
Rhinocarcinosoma is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Rhinocarcinosoma have been discovered in deposits ranging of Late Silurian age in the United States, Canada and Vietnam. The genus contains three species, the American R. cicerops and R. vaningeni and the Vietnamese R. dosonensis. The generic name is derived from the related genus Carcinosoma, and the Greek ῥινός, referring to the unusual shovel-shaped protrusion on the front of the carapace of Rhinocarcinosoma, its most distinctive feature.
Andreolepis is an extinct genus of prehistoric fish, which lived around 420 million years ago. It was described by Walter Gross in 1968 based on scales found in the Hemse Formation in Gotland, Sweden. It is placed in the monogeneric family Andreolepididae and is generally regarded as a primitive member of the class Actinopterygii based on its ganoid scale structure; however some new research regards it as a stem group of osteichthyans.
The Sundvollen Formation is a geologic formation cropping out along the northern and eastern shores of Steinsfjorden, Oslo Region, Norway. It preserves fossils dating back to the Gorstian to Ludfordian stages of the Late Silurian period.
Anglaspis is an extinct genus of cyathaspidiform heterostracan agnathan. Fossils are found in marine strata of Europe, from the late Silurian period until the genus' extinction during the Early Devonian. As with other cyathaspidiforms, individuals of Anglaspis had dorsal and ventral plates covering the forebody, gill pouches, and nasal openings that lay on the roof of the oral cavity.
Furcacaudidae, the "'fork-tailed' agnathans," is an extinct family of thelodontid agnathans from the Lochkovian stage of the Early Devonian epoch and Wenlockian epoch of the Silurian, known from fossils found in Northern Canada. It is the type family of the order Furcacaudiformes, and itself currently includes 6 known species. It was officially described in 1998 by Mark V. H. Wilson and Michael W. Caldwell.
Birkeniiformes is an extinct order of jawless fish belonging to the class Anaspida.
Septentrionia is an extinct genus of jawless fish belonging to the family Septentrioniidae. It is the type genus of its family.
Liivilepis is an extinct genus of jawless fish belonging to the family Septentrioniidae.
Eysyslopterus is a genus of eurypterid, an extinct group of aquatic arthropods. Eysyslopterus is classified as part of the family Adelophthalmidae, the only clade within the derived ("advanced") Adelophthalmoidea superfamily of eurypterids. One fossil of the single and type species, E. patteni, has been discovered in deposits of the Late Silurian period in Saaremaa, Estonia. The genus is named after Eysysla, the Viking name for Saaremaa, and opterus, a traditional suffix for the eurypterid genera, meaning "wing". The species name honors William Patten, an American biologist and zoologist who discovered the only known fossil of Eysyslopterus.
This timeline of eurypterid research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of eurypterids, a group of extinct aquatic arthropods closely related to modern arachnids and horseshoe crabs that lived during the Paleozoic Era.
Tiiu Märss is an Estonian geologist and palaeoichthyologist.
Ramsaasalepis is an extinct genus of jawless fish. Its the type and only genus of the family Ramsaasalepididae, and contains the single species Ramsaasalepis porosa.
Tahulalepididae is an extinct family of jawless fish belonging to the order Birkeniiformes.
