''Kentisuchus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

gavialoid Gavialoidea is one of three superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial ''Gavialis gangeticus'' and the false gharial ''Tomistoma schlegelii'' are ...

crocodylia Crocodilia () is an Order (biology), order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorp ...

n, traditionally regarded as a member of the subfamily

Tomistominae Tomistominae is a subfamily of crocodylians that includes one living species, the false gharial. Many more extinct species are known, extending the range of the subfamily back to the Eocene epoch. In contrast to the false gharial, which is a fres ...

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s have been found from

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

and

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

that date back to the early

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. The genus has also been recorded from

Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...

, but it unclear whether specimens from Ukraine are referable to ''Kentisuchus''.

Species

The genus ''Kentisuchus'' was erected by

Charles Mook Charles is a masculine given name predominantly found in English and French speaking countries. It is from the French form ''Charles'' of the Proto-Germanic name (in runic alphabet) or ''*karilaz'' (in Latin alphabet), whose meaning was ...

in 1955 for the species ''"Crocodylus" toliapicus'', described by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomy, comparative anatomist and paleontology, palaeontologist. Owen is generally considered to have been an outstanding naturalist with a remarkabl ...

, in 1849.

William Buckland William Buckland Doctor of Divinity, DD, Royal Society, FRS (12 March 1784 – 14 August 1856) was an English theologian, geologist and paleontology, palaeontologist. His work in the early 1820s proved that Kirkdale Cave in North Yorkshire h ...

named ''"Crocodylus" spenceri'' on the basis of a partial skull found from the

Isle of Sheppey The Isle of Sheppey is an island off the northern coast of Kent, England, neighbouring the Thames Estuary, centred from central London. It has an area of . The island forms part of the districts of England, local government district of Borough ...

Kent Kent is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Essex across the Thames Estuary to the north, the Strait of Dover to the south-east, East Sussex to the south-west, Surrey to the west, and Gr ...

, England. In 1888

Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was a British naturalist, geologist and writer of numerous books on natural history. He was known for his contributions to zoology, paleontology, and biogeography. He worked extensively in cata ...

considered ''"C." toliapicus'' synonymous with ''"C." champsoides'' and ''"C." arduini'', named by De Zigno, and reapplied the name ''"C." spenceri'' to all of these species. The genus name ''Kentisuchus'' was constructed only after it was realized that these specimens were clearly distinct from the genus ''

Crocodylus ''Crocodylus'' is a genus of true crocodiles in the family Crocodylidae. Taxonomy The Genus, generic name, ''Crocodylus'', was proposed by Josephus Nicolaus Laurenti in 1768. ''Crocodylus'' contains 13–14 extant taxon, extant (living) species ...

'' and that some specimens originally assigned to ''"C." spenceri'' belonged to entirely different genera and species. ''"C." arduini'' was reassigned to the new genus '' Megadontosuchus'' in the same paper that ''Kentisuchus'' was first described in. A 2007 review of European Eocene tomistomines synonymized ''K. toliapicus'' and ''K. champsoides'' with ''K. spenceri''.

Phylogenetics

''K. spenceri'' is closely related to '' Megadontosuchus'' and ''

Dollosuchoides ''Dollosuchoides'', colloquially known as the Crocodile of Maransart, is an extinct monospecific genus of gavialoid crocodilian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found in the Brussels Formatio ...

''. An apparent close relationship between ''K. spenceri'' and '' Eosuchus lerichei'' has been used to imply that the latter species was a tomistomine, while it is now thought that ''Eosuchus'' is a basal

eusuchia Eusuchia is a clade of neosuchian Crocodylomorpha, crocodylomorphs that first appeared in the Early Cretaceous, which includes modern Crocodilia, crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survi ...

n that lies outside the crocodilian

crown group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor ...

. Below is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

based morphological studies comparing skeletal features that shows ''Kentisuchus'' as a member of

, related to the

false gharial The false gharial (''Tomistoma schlegelii''), also known by the names Malayan gharial, Sunda gharial and tomistoma is a freshwater crocodilian of the Family (biology), family Gavialidae native to Peninsular Malaysia, Borneo, Sumatra and Java. It ...

: Based on morphological studies of

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

, the tomistomines (including the living

) were long thought to be classified as

crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include ...

s and not closely related to gavialoids. However, recent molecular studies using

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The ...

have consistently indicated that the

(''Tomistoma'') (and by inference other related extinct forms in

) actually belong to

Gavialoidea Gavialoidea is one of three superfamily (zoology), superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial ''Gavialis gangeticus'' and the false gharial ''Tomi ...

(and

Gavialidae Gavialidae is a family of large semiaquatic crocodilians with elongated, narrow snouts. Gavialidae consists of two living species, the gharial (''Gavialis gangeticus'') and the false gharial (''Tomistoma schlegelii''), both occurring in Asia. Man ...

). Below is a

from a 2018

tip dating Tip dating is a technique used in molecular dating that allows the inference of time-calibrated phylogenetic trees. Its defining feature is that it uses the ages of the samples to provide time information for the analysis, in contrast with traditio ...

study by Lee & Yates simultaneously using morphological, molecular (

), and

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithost ...

(

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

age) data that shows ''Kentisuchus'' as a

, more basal than the

last common ancestor A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assu ...

to both the

gharial The gharial (''Gavialis gangeticus''), also known as gavial or fish-eating crocodile, is a crocodilian in the family (biology), family Gavialidae and among the longest of all living crocodilians. Mature females are long, and males . Adult males ...

and the

Paleobiology

The close relation of ''Kentisuchus'' and ''

'', which are known from European localities that were on the mainland during the early Eocene, to '' Megadontosuchus'', which is known from

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

localities that were once part of a Tethysian

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...

, suggests that it came to these islands after a dispersal event south from mainland

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

rather than north from

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

.Kotsakis, T., Delfino, M., and Piras, P. (2004). Italian Cenozoic crocodilians: taxa, timing and palaeobiogeographic implications. ''Palaeogeography, Palaeoclimatology, Palaeoecology'' 210(1):67-87.

References

External links

''Kentisuchus''
in the

Paleobiology Database The Paleobiology Database (PBDB) is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database originated in the NCEAS-funded Phanerozoic Marine Pale ...

{{Taxonbar, from=Q6392046 Gavialoidea Eocene crocodylomorphs Eocene reptiles of Europe Prehistoric pseudosuchian genera