Iniopterygiformes is an extinct order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes...

-like cartilaginous fish
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...

 that lived from the Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 to Carboniferous
The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 periods (345-280 million years ago). Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s of them have been found in Montana, Indiana, Illinois, and Nebraska. The Iniopterygians are characterized by large pectoral fins, wing-like projections on their backs, mounted high on the body and denticulated bony plates on the head and jaws. Iniopterygian sharks were small, and their average length was about 1.5 feet (45 cm.). The elongated pectoral fins had denticles along the leading edge which may have had a role in mating. They are thought to have been able to move their pectorals in a vertical plane,”flying” through the water much like modern-day flying fish.

The majority of iniopterygians are placed within the family Sibyrhinchidae. Members of this family include Sibyrhinchus denisoni, Inioptera richardsoni, and Inioxyele. Ironically, Iniopteryx
Iniopteryx is an extinct genus of cartilaginous fish. It is from the Pennsylvanian epoch of the Carboniferous period, approximately 300 million years ago. Their fossils have been found in North America, primarily in two states: Ohio and Montana...

, the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

, has not yet been assigned to a specific family, though some experts place it in its own monotypic family, "Iniopterygidae." The closest modern-day relatives of the Iniopterygii are the Chimaeras (Chimaeriformes) also known as ghost sharks, rabbit fish or rat fish.

These fish had several unusual features: massive skulls with huge eye sockets, shark-like teeth in rows, tails with clubs, enormous pectoral fins that were dorsalized or placed almost on their backs, and bone-like spikes or hooks on the tips of their fins. Most iniopterygians were fairly small, averaging about 6 inches to 1.5 feet (45 cm.) in length, with the largest approaching sizes of 50 centimeters (20 inches) at most.

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