Tselfatiiformes is an extinct order of

bony fish Osteichthyes ( ; ), also known as osteichthyans or commonly referred to as the bony fish, is a Biodiversity, diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondricht ...

es from the

infraclass In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of or ...

Teleostei Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

. The order represents the most important radiation of marine teleosts during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period. Fossils of tselfatiiforms are known from Europe, North America, central and northern South America, the Middle East and North Africa.Joseph S. Nelson: ''Fishes of the World''. John Wiley & Sons, 2006, . The order appeared in the upper

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

on the coasts of Europe and North Africa and spread during the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

and

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

on the Proto Atlantic to the coasts of northern South America, the Gulf of Mexico and into the

Western Interior Seaway The Western Interior Seaway (also called the Cretaceous Seaway, the Niobraran Sea, the North American Inland Sea, or the Western Interior Sea) was a large inland sea (geology), inland sea that existed roughly over the present-day Great Plains of ...

. In the

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by ...

and

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

they were very common in North American coastal waters, but disappeared from Europe and North Africa. A few species still lived in the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

in the Gulf of Mexico and only plethodids survived until the end of

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

Features

The genera and species of the Tselfatiiformes had a high-backed body. The dorsal fin took up most of the length of the back. The pectoral fins were high. Ventral fins could be present or absent; if present, they were supported by six or seven fin rays. The caudal fin was forked and had 18 main fin rays. The majority of the fin rays were unsegmented. The upper jaw was formed by the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

and

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

. The palate was also toothed.

Systematics

The tselfatiiforms could not initially be assigned to a larger kinship group within the Teleostei.Louis Taverne & Mireille Gayet: Phylogenetical relationships and palaeozoogeography of the marine Cretaceous Tselfatiiformes (Teleostei, Clupeocephala). Cybium 2005, 29 (1) More recent cladistic studies on the basis of their osteological characteristics have made it clear that they are primitive

Clupeocephala Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

ns and represent the plesiomorphic sister group of a clade from

Otocephala Otocephala is a clade of ray-finned fishes within the infraclass Teleostei that evolved some 230 million years ago. It is named for the presence of a hearing (otophysic) link from the swimbladder to the inner ear. Other names proposed for the gro ...

(

Clupeomorpha Clupeomorpha is a superorder of ray-finned fish which belongs to the clade Otocephala. Represented today only by the diverse, economically-important order Clupeiformes (containing herrings, anchovies and allies), it was formerly even more diverse ...

and

Ostariophysi Ostariophysi is the second-largest superorder of fish. Members of this superorder are called ostariophysians. This diverse group contains 10,758 species, about 28% of known fish species in the world and 68% of freshwater species, and are present ...

)Arratia, G., 2010: The Clupeocephala revisited: Analysis of characters and homologies. Revista de Biologia Marina & Oceanografia 45: 635–657. Reference page. and

Euteleostei Euteleostei, whose members are known as euteleosts, is a clade of bony fishes within Teleostei that evolved some 240 million years ago, although the oldest known fossil remains are only from the Early Cretaceous. It is divided into Protacanthopt ...

References

Prehistoric ray-finned fish orders {{Paleo-rayfinned-fish-stub