''Sphenacanthus'' (from el, σφήν , 'wedge' and el, ἄκανθα , 'spine') is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of a chondrichtyan xenacanthiform that belongs to the Sphenacanthidae family and lived from the

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...

, through

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

until the

Late Permian Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

period in

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

and

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

.V. E. Pauliv, E. V. Dias, and F. A. Sedor. 2012
A new species of sphenacanthid (Chondrichthyes, Elasmobranchii) from the Rio do Rasto Formation (Paraná basin), southern Brazil
''Revista Brasileira de Paleontologia'' 15:243-250 It lived 359 million years ago, and probably it was one of the first member of the elasmobranchians, the lineage that leads to the modern

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...

s. ''Sphenacanthus'' probably hunts small fishes and, unlike their modern-day relatives, its inhabited fresh water lagoons. ''Sphenacanthus'' had seven fins, two in the upper part and five in the underside, and it had a heterodont dentition and mandibles relatively long and deeper. ''Sphenacanthus serrulatus'' is still only known from incomplete neurocranial remains and associated dermal material. These suggest that it was a relatively large shark, probably well over one meter in length when fully grown. Its body form was probably similar to that of other phalacanthous sharks.

JOHN John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second ...

R. F. DICK, ''Sphenacanthus'', a Palaeozoic freshwater shark, ''Zoological Journal of the Linnean Society'', Volume 122, Issue 1-2, January 1998, Pages 9–25, https://doi.org/10.1111/j.1096-3642.1998.tb02523.x

Paleobiology

''Sphenacanthus'' was discovered in Carboniferous terrains of Scotland (Visén Oil Shale Groups), in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, in ancient fresh water systems, a habitat that also is known in the

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande d ...

in Brazil (

Rio do Rasto Formation The Rio do Rasto Formation is a Late Permian sedimentary geological formation in the South Region of Brazil. The official name is Rio do Rasto, although in some publications it appears as ''Rio do Rastro''. Geography It is found mainly in the B ...

). Another findings, like those of the Puertollano Bason in Spain suggests that also it lived in zones of marine influence, in brackish waters. It shared its environment with other primitive sharks, including to ''

Xenacanthus ''Xenacanthus'' (from Ancient Greek ξένος, xénos, 'foreign, alien' + ἄκανθος, akanthos, 'spine') is a genus of prehistoric sharks. The first species of the genus lived in the later Devonian period, and they survived until the end of ...

'' of one meter in length and the similar species, '' Tristychius arcuatus''. It is possible that ''Sphenacanthus'' may have preyed on its smaller relatives.

Paleobiology

References

Further reading