Conodonts are an extinct group of eel-looking agnathan (jawless) vertebrates, classified in the class Conodonta. For many years, they were known only from fossils of their spiky oral elements, which are usually found in isolation and are now called conodont elements, while knowledge about soft tissues remains limited. A resilient group of prehistoric fish, conodonts existed in the world's oceans for over 300 million years, from the Cambrian to the beginning of the Jurassic. Due to their cosmopolitan distribution, conodont elements are widely used as index fossils, fossils used to define and identify geological periods.
Cladophorales are an order of green algae, in the class Ulvophyceae.
Echinognathus is a genus of eurypterid, an extinct group of aquatic arthropods. The type and only species of Echinognathus, E. clevelandi, is known from deposits of Late Ordovician age in the United States. The generic name is derived from the Neo-Latin echino- ("spiny") and the Greek gnáthos ("jaw"), in reference to a spiny endognathary appendage part of the fossil type material.
Bunodes is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Bunodes was regarded as part of the clade Planaterga. Fossils of the single and type species, B. lunula, have been discovered in deposits of the Silurian period in Ludlow, England. Bunodes is the type genus of the family Bunodidae, the other genera of the same family being Limuloides. There are 64 direct children of Bunodes.
Synziphosurina is a paraphyletic group of chelicerate arthropods previously thought to be basal horseshoe crabs (Xiphosura). It was later identified as a grade composed of various basal euchelicerates, eventually excluded from the monophyletic Xiphosura sensu stricto and only regarded as horseshoe crabs under a broader sense. Synziphosurines survived at least since early Ordovician to early Carboniferous in ages, with most species are known from the in-between Silurian strata.
Eurypteridae is an extinct family of eurypterids that lived in the Silurian and Devonian periods. The family is one of three families contained in the superfamily Eurypteroidea, which in turn is one of the superfamilies classified as part of the suborder Eurypterina. The family contains two genera, Erieopterus and Eurypterus.
Ceratiocaris is a genus of paleozoic phyllocarid crustaceans whose fossils are found in marine strata from the Upper Ordovician until the genus' extinction during the Silurian. They are typified by eight short thoracic segments, seven longer abdominal somites and an elongated pretelson somite. Their carapace is slightly oval shaped; they have many ridges parallel to the ventral margin and possess a horn at the anterior end. They are well known from the Silurian Eramosa formation of Ontario, Canada.
Paleontology in Iowa refers to paleontological research occurring within or conducted by people from the U.S. state of Iowa. The paleozoic fossil record of Iowa spans from the Cambrian to Mississippian. During the early Paleozoic Iowa was covered by a shallow sea that would later be home to creatures like brachiopods, bryozoans, cephalopods, corals, fishes, and trilobites. Later in the Paleozoic, this sea left the state, but a new one covered Iowa during the early Mesozoic. As this sea began to withdraw a new subtropical coastal plain environment which was home to duck-billed dinosaurs spread across the state. Later this plain was submerged by the rise of the Western Interior Seaway, where plesiosaurs lived. The early Cenozoic is missing from the local rock record, but during the Ice Age evidence indicates that glaciers entered the state, which was home to mammoths and mastodons.
The Decorah crater, also called the Decorah impact structure, is a possible impact crater located on the east side of the city of Decorah in Iowa, United States. It is thought to have been caused by a meteor about 200 metres (660 ft) wide which struck during the Middle Ordovician Period, circa 470 million years ago.
Pentecopterus is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils have been registered from the Darriwilian age of the Middle Ordovician period, as early as 467.3 million years ago. The genus contains only one species, P. decorahensis, that is the oldest known eurypterid, surpassing other Ordovician eurypterids, such as Brachypterus, in age by almost 9 million years. The generic name derives from the penteconter, a warship from ancient Greece, and the suffix -pterus, which means "wing" and is often used in other genus of eurypterids. The specific name refers to Decorah, Iowa, where Pentecopterus was discovered.
Stig M. Bergström is a Swedish-American paleontologist.
Appalachignathus is a genus of multielement conodonts from the Middle Ordovician of North America.
Protoconodonts are an extinct group of Cambrian animals known from fossilized phosphatic tooth-like structures. They were originally described as an informal group of early conodonts, though more recent studies consider them to be more closely related to chaetognaths.
Carcinosomatoidea is an extinct superfamily of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". It is one of the superfamilies classified as part of the suborder Eurypterina.
The conodont feeding apparatus is a series of phosphatic-mineralized elements, resembling a set of “teeth”, which are found lining the oral surface of the conodont animal.
Winneshiekia is an extinct genus of dekatriatan, a clade of chelicerate arthropods. Fossils of the single and type species, W. youngae, have been discovered in deposits of the Middle Ordovician period in Iowa, in the United States. The name of the genus is derived from the Winneshiek Shale, the formation in which it was discovered. The species name youngae honors Jean N. Young, an American geologist who contributed greatly to the discovery of the Winneshiek Shale.
Venustulus is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Venustulus was regarded as part of the clade Prosomapoda. Fossils of the single and type species, V. waukeshaensis, have been discovered in deposits of the Silurian period in Wisconsin, in the United States. Venustulus is one of the few synziphosurine genera with fossil showing evidence of appendages, the other ones being Weinbergina, Anderella and Camanchia. Despite often being aligned close to horseshoe crabs, it has been found that Venustulus and its relatives form a group made up of various basal euchelicerate arthropods more distant to the xiphosurans.
Camanchia is a genus of synziphosurine, a paraphyletic group of fossil chelicerate arthropods. Camanchia was regarded as part of the clade Prosomapoda. Fossils of the single and type species, C. grovensis, have been discovered in deposits of the Silurian period in Iowa, in the United States. Alongside Venustulus, Camanchia is one of the only Silurian synziphosurine with fossil showing evidence of appendages.
Douglasocaris is a genus of bivalved arthropod from the Middle Ordovician Douglas Lake Member of the Lenoir Limestone from Douglas Dam Tennessee.
The Winneshiek Shale is a Middle Ordovician (Darriwilian-age) geological formation in Iowa. The formation is restricted to the Decorah crater, an impact crater near Decorah, Iowa. Despite only being discovered in 2005, the Winneshiek Shale is already renowned for the exceptional preservation of its fossils. The shale preserves a unique ecosystem, the Winneshiek biota, which is among the most remarkable Ordovician lagerstätten in the United States. Fossils include the oldest known eurypterid, Pentecopterus, as well as giant conodonts such as Iowagnathus and Archeognathus.
