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Conodonts are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which are usually found in isolation and are now called conodont elements. Knowledge about soft tissues remains limited. They existed in the world's oceans for over 300 million years, from the Cambrian to the beginning of the Jurassic. Conodont elements are widely used as index fossils, fossils used to define and identify geological periods. The animals are also called Conodontophora to avoid ambiguity.
The Tremadocian is the lowest stage of Ordovician. Together with the later Floian Stage it forms the Lower Ordovician Epoch. The Tremadocian lasted from 485.4 to 477.7 million years ago. The base of the Tremadocian is defined as the first appearance of the conodont species Iapetognathus fluctivagus at the Global Boundary Stratotype Section and Point (GSSP) section on Newfoundland.
Promissum is an extinct genus of conodonts, primitive chordates, that lived during the Upper Ordovician period.
The Dapingian is the third stage of the Ordovician period and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The top of the Floian is defined as the first appearance of the conodont species Baltoniodus triangularis which happened about 470 million years ago. The Dapingian lasted for about 2.7 million years until about 467.3 million years ago.
Archeognathus is a fossilized jaw apparatus of a large predatory conodont from the Ordovician period. Its large size has made classification difficult, and it has historically been compared to conodonts and gnathostomes since its remains were first discovered in Missouri. Complete articulated jaw apparatus of Archeognathus primus are common in the Winneshiek Shale lagerstätte of Iowa, allowing its identity as a conodont to be secured.
Prioniodontida, also known as the "complex conodonts", is a large clade of conodonts that includes two major evolutionary grades; the Prioniodinina and the Ozarkodinina. It includes many of the more famous conodonts, such as the giant ordovician Promissum (Prioniodinina) from the Soom Shale and the Carboniferous specimens from the Granton Shrimp bed (Ozarkodinina). They are euconodonts, in that their elements are composed of two layers; the crown and the basal body, and are assumed to be a clade.
Periodon is a genus of conodonts which existed in what is now Canada, Iran, Argentina, China, Russia, and the United States during the Ordovician Period. It was described by Hadding in 1913, and the type species is P. aculeatus.
Iapetognathus is a genus of cordylodan conodonts. It is one of the oldest denticulate euconodont genera known.
Notiodella is an extinct conodont genus in the family Balognathidae. It has been described from a 17-element apparatus from the Soom Shale Lagerstätte in South Africa.
Paracordylodus is an extinct genus of conodonts in the clade Prioniodontida, also known as the "complex conodonts". The species P. gracilis has been recovered from the chert of the Narooma Terrane, a geological structural region on the south coast of New South Wales, Australia.
Walter C. Sweet was an American paleontologist.
Appalachignathus is a genus of multielement conodonts from the Middle Ordovician of North America.
Rhipidognathidae is a family of multielement conodonts from the Ordovician.
William Madison Furnish was an American paleontologist. He taught at the University of Iowa.
Prioniodus is an extinct genus of conodonts in the family Balognathidae from the Ordovician.
Acanthodus is an extinct genus of conodonts.
Histiodella is an extinct genus of conodonts.
Distacodontidae is an extinct family of conodonts in the order Conodontophorida.
Panderodus Is an extinct genus of jawless fish belonging to the order Conodonta. This genus had a long temporal range, surviving from the middle Ordovician to late Devonian. In 2021, extremely rare body fossils of Panderodus from the Waukesha Biota were described, and it revealed that Panderodus had a more thick body compared to the more slender bodies of more advanced conodonts. It also revealed that this conodont was a macrophagous predator, meaning it went after large prey.
