''Dakosaurus'' 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 ...

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. Extinct crocodylomorphs were considerably mor ...

within the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Metriorhynchidae Metriorhynchidae is an extinct family of specialized, aquatic metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period ( Bajocian to early Aptian) of Europe, North America and South America. The name Metriorhynchid ...

that lived during the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

and

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

. It was large, with teeth that were

serrated Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pr ...

and compressed lateromedially (flattened from side to side). The genus was established by

Friedrich August von Quenstedt Friedrich August von Quenstedt (10 July 1809 – 21 December 1889) was a German geologist and palaeontologist. Life Von Quenstedt was born at Eisleben in Saxony, and educated at the Humboldt University of Berlin. After a period as assistant i ...

in 1856 for an isolated tooth named ''Geosaurus maximus'' by Theodor Plieninger in 1846. ''Dakosaurus'' was a

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

that spent much, if not all, of its life out at sea. The extent of its adaptation to a marine lifestyle means that it is most likely that it mated at sea, but since no eggs or nests have been discovered that have been referred to ''Dakosaurus'', whether it gave birth to live young at sea like

dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...

s and

ichthyosaur Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of the Mesozoic era; based on fo ...

s or came ashore like

turtle Turtles are reptiles of the order (biology), order Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Crypt ...

s is not known yet. The name ''Dakosaurus'' means "biter lizard", and is derived from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

' ("biter") and -' ("lizard").

Discovery and species

The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

''Dakosaurus maximus'', meaning "greatest biter lizard", is known from

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 ...

discoveries in Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

-Early

Tithonian In the geological timescale, the Tithonian is the latest age (geology), age of the Late Jurassic Epoch and the uppermost stage (stratigraphy), stage of the Upper Jurassic Series. It spans the time between 149.2 ±0.7 annum, Ma and 143.1 ±0.6 (mi ...

).Fraas E. 1902. Die Meer-Krocodilier (Thalattosuchia) des oberen Jura unter specieller Berücksichtigung von ''Dacosaurus'' und ''Geosaurus''. ''Paleontographica'' 49: 1-72. When isolated ''Dakosaurus'' teeth were first discovered in

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, they were mistaken for belonging to the

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

Megalosaurus ''Megalosaurus'' (meaning "great lizard", from Ancient Greek, Greek , ', meaning 'big', 'tall' or 'great' and , ', meaning 'lizard') is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic Epoch (Bathonian stage, 166 ...

''.Quenstedt FA. 1843. ''Das Flötzgebirge Württembergs: mit besonderer rücksicht auf den Jura''. Tübingen: Laupp, 493. The type species ''D. maximus'' was originally named as a species of ''Geosaurus'' in 1846 by Theodor Plieninger, creating the species ''G. maximus''. In 1856 von Quenstedt made Plieninger's ''Geosaurus maximus'' teeth a new genus with the name ''Dakosaurus''. He explained the etymology as Greek ''dakos'' "Biss"

ite ITE or Ite may refer to: Places * Ite (village), Walloon name of the Belgian village of Ittre * Ite District in Tacna Region, Peru Brands and enterprises * Interactive Television Entertainment, a defunct Danish media company * ITE Group, an organi ...

in 1858 in German, adding "denn wenige kommen seinem furchtbaren Gebiss gleich" or few can match its terrible set of teethQuenstedt FA. 1858. ''Der Jura''. Tübingen: Laupp, 842 pp.(pgs. 785-786) He gave the meaning of Greek ''dakos'' more correctly as "Beisser"

iter ITER (initially the International Thermonuclear Experimental Reactor, ''iter'' meaning "the way" or "the path" in Latin) is an international nuclear fusion research and engineering megaproject aimed at creating energy through a fusion process s ...

in another description in 1859 in which he classified ''Dakosaurus'' as a dinosaur.Quenstedt FA. 1859. ''Handbuch der Petrefaktenkunde''. Tübingen: Laupp, 1239 pp. Named in 1871 by

Emanuel Bunzel Emanuel Bunzel (1828–1895), was an Austrian paleontologist. Biography Emanuel Bunzel was born in Prague, Kingdom of Bohemia (today the Czech Republic), in 1828. In 1871, he described a skull fragment found in an Austrian coal mine in 1859 by ...

, the remains attributed to ''

schnaitheimi'' (found in Schnaitheim,

) are now believed to have belonged to ''Dakosaurus maximus'' as per Carrano ''et al.'' (2012). Fossil specimens referrable to ''Dakosaurus'' are known from Late Jurassic deposits 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 ...

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 ...

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

,Steel R. 1973. Crocodylia. ''Handbuch der Paläoherpetologie, Teil 16''. Stuttgart: Gustav Fischer Verlag,116 pp.

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

,Radwańska U, Radwański A. 2003. The Jurassic crinoid genus ''Cyclocrinus'' D’Orbigny, 1850: still an enigma. ''Acta Geologica Polonica'' 53 (2003),(4): 301-320.

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

,Ochev VG. 1981. arine crocodiles in the Mesozoic of Povolzh'e''Priroda'' 1981: 103

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

,Vignaud P, Gasparini ZB. 1996. New ''Dakosaurus'' (Crocodylomorpha, Thalattosuchia) from the Upper Jurassic of Argentina. ''Comptes Rendus de l'Académie des Sciences de Paris, Series II'' 322: 245-250. and

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

.Buchy M-C, Stinnesbeck W, Frey E, Gonzalez AHG. 2007. First occurrence of the genus ''Dakosaurus'' (Crocodyliformes, Thalattosuchia) in the Late Jurassic of Mexico. ''Bulletin de la Société Géologique de France'' 178 (5): 391-397. Teeth referrable to ''Dakosaurus'' are known from Europe from the Oxfordian.BM(NH), Trustees of the. 1983. ''British Mesozoic Fossils, sixth edition''. London: Butler & Tanner Ltd., 209 pp.Benton MJ, Spencer PS. 1995. ''Fossil Reptiles of Great Britain''. London: Chapman and Hall, 386 pp. ''Dacosaurus'' (Sauvage, 1873) is a misspelling of ''Dakosaurus'', and thus a synonym.Sauvage HE. (1873). Notes sur les reptiles, fossiles. ''Bulletin de la Société Géologiques de France, série 3'': 365-384. ''Dakosaurus andiniensis'', meaning "biter lizard from the Andes", was first reported in 1985 from the

Neuquén Neuquén (; ) is the capital city of the Argentine province of Neuquén and of the Confluencia Department, located in the east of the province. It occupies a strip of land west of the confluence of the Limay and Neuquén rivers which form t ...

Basin, a very rich fossil bed in the

Vaca Muerta The Vaca Muerta Formation, commonly known as Vaca Muerta ( Spanish for ''dead cow''), is a geologic formation of Late Jurassic to Early Cretaceous age, located in the Neuquén Basin in northern Patagonia, Argentina. It is well known as the host ...

, Argentina. However, it was not until 1996 that the binomen ''Dakosaurus andiniensis'' was erected. Two later discovered skulls, the specimina MOZ 6146P and MOZ 6140P, have indicated that ''D. andiniensis'' is unique among the metriorhynchids (the family of stem-crocodilians most specialised for marine life) with its short, tall snout, which lent it the popular nickname "

Godzilla is a fictional monster, or ''kaiju'', that debuted in the eponymous 1954 film, directed and co-written by Ishirō Honda. The character has since become an international pop culture icon, appearing in various media: 33 Japanese films p ...

" in press reports about its description. This species has a fossil range from the late Jurassic to early Cretaceous (Late

-Early

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 143.1 ±0.6 Ma and 137.05 ± 0.2 (million years ago) ...

).Gasparini Z, Pol D, Spalletti LA. 2006. An unusual marine crocodyliform from the Jurassic-Cretaceous boundary of Patagonia. ''Science'' 311: 70-73. '' Dakosaurus nicaeensis'', named in 1913 by Ambayrac, was mistakenly classified as a

megalosaurid Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. They were a relatively ...

dinosaur; now it is assigned as the sole species in the genus ''

Aggiosaurus ''Aggiosaurus'' is an extinct genus of geosaurine metriorhynchid crocodyliform known from the Late Jurassic (late Oxfordian stage) of Nice, southeastern France. It contains a single species, ''Aggiosaurus nicaeensis'', which was named by H. Amb ...

''. BuffetautBuffetaut E. 1982. ''Aggiosaurus nicaeensis'' Ambayrac, 1913, from the Upper Jurassic of south-eastern France: A marine crocodilian, not a dinosaur. ''Neues Jahrbuch für Geologie und Paläontologie, Monatshefte'' (8): 469-475. in 1982 demonstrated that it was in fact a metriorhynchid, closely related to, if not a member of ''Dakosaurus''. As the type specimen is poorly preserved it is considered ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

''. Incomplete skull specimens of ''Dakosaurus'' have been discovered in Kimmeridgian age rocks from Mexico; they have not yet been referred to a specific species of ''Dakosaurus''.Buchy M-C. 2008. New occurrence of the genus ''Dakosaurus'' (Reptilia, Thalattosuchia) in the Upper Jurassic of north-eastern Mexico with comments upon skull architecture of ''Dakosaurus'' and ''Geosaurus''. ''Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen'' 249 (1): 1-8.

Description

All currently known species would have been large, measuring approximately long. Its body was streamlined for greater hydrodynamic efficiency, which along with its finned tail made it a more efficient swimmer than modern crocodilian species.Massare JA. 1988. Swimming capabilities of Mesozoic marine reptiles: implications for method of predation. ''Paleobiology'' 14 (2):187-205.

Classification

''Dakosaurus''–when it contained the species ''D. andiniensis'', ''D. maximus'', and ''D. manselii''–had long been considered

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

, that is, not consisting of a common ancestor and its descendants,Young MT. 2007. The evolution and interrelationships of Metriorhynchidae (Crocodyliformes, Thalattosuchia). ''Journal of Vertebrate Paleontology'' 27 (3): 170A.Wilkinson LE, Young MT, Benton MJ. 2008. A new metriorhynchid crocodilian (Mesoeucrocodylia: Thalattosuchia) from the Kimmeridgian (Upper Jurassic) of Wiltshire, UK. ''Palaeontology'' 51 (6): 1307-1333. until a 2012 study moved ''D. manselii'' to the formerly invalid genus '' Plesiosuchus''.

Palaeobiology

Salt glands

The incomplete skull specimens from the Mexican species of ''Dakosaurus'' preserves the chamber in which the well-developed

salt gland The salt gland is an organ (anatomy), organ for excreting excess salt (chemistry), salts. It is found in the cartilaginous fishes subclass elasmobranchii (sharks, rays, and skates), seabirds, and some reptiles. Salt glands can be found in the r ...

s (known from ''

Geosaurus ''Geosaurus'' is an extinct genus of marine crocodyliform within the family Metriorhynchidae, that lived during the Late Jurassic and the Early Cretaceous. ''Geosaurus'' was a carnivore that spent much, if not all, its life out at sea. No ''Geosa ...

''Fernández M, Gasparini Z. 2000. Salt glands in a Tithonian metriorhynchid crocodyliform and their physiological significance. ''Lethaia'' 33: 269-276. and ''

Metriorhynchus ''Metriorhynchus'' is an extinct genus of marine crocodyliform that lived in the oceans during the Late Jurassic. The type species, ''M. brevirostris'' was named in 1829 as a species of ''Steneosaurus'' before being named as a separate genus by ...

''Gandola R, Buffetaut E, Monaghan N, Dyke G. 2006. Salt glands in the fossil crocodile ''Metriorhynchus''. ''Journal of Vertebrate Paleontology'' 26 (4): 1009-1010.) would have been housed. Unfortunately, there was no preservational evidence of the glands themselves.

Diet

''Dakosaurus'' was the only marine crocodyliform to have evolved teeth that are both lateromedially compressed and serrated; not only that, but they were much larger than those of metriorhynchid genera. These characteristics, along with their morphology, which fall within the 'Cut' guild of Massare (1987) - and are analogous to modern

killer whale The orca (''Orcinus orca''), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. The only extant species in the genus '' Orcinus'', it is recognizable by its black-and-white-patterned body. A cosmopolit ...

teeth - indicate that ''Dakosaurus'' was an

apex predator An apex predator, also known as a top predator or superpredator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the hig ...

.Massare JA. 1987. Tooth morphology and prey preference of Mesozoic marine reptiles. ''Journal of Vertebrate Paleontology'' 7: 121-137. The enlarged

supratemporal fenestrae Temporal fenestrae are openings in the Temple (anatomy), temporal region of the skull of some Amniote, amniotes, behind the Orbit (anatomy), orbit (eye socket). These openings have historically been used to track the evolution and affinities of re ...

of ''Dakosaurus'' skulls would have anchored large adductor muscles (jaw closing),Holliday CM, Witmer LM. Archosaur adductor chamber evolution: integration of musculoskeletal and topological criteria in jaw muscle homology. ''Journal of Morphology'' 268 (6): 457-484. ensuring a powerful bite. As their skulls are triangular in shape, with deeply rooted, large, serrated teeth and a bulbous, deep, mandibular symphysis (like

pliosaur Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive toot ...

s), dakosaurs would also have been able to twist feed (tear chunks of flesh off potential prey).Martill DM, Taylor MA, Duff KL, Riding JB, Brown PR. 1994. The trophic structure of the biota of the Peterborough Member, Oxford Clay Formation (Jurassic), UK. ''Journal of the Geological Society, London'' 151: 173-194.

Palaeoecology

''Dakosaurus maximus'' is one of several species of metriorhynchids known from the Altmühltal Formation (

Solnhofen limestone The Solnhofen Limestone or Solnhofen Plattenkalk, formally known as the Altmühltal Formation, is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organi ...

, early Tithonian) of

Bavaria Bavaria, officially the Free State of Bavaria, is a States of Germany, state in the southeast of Germany. With an area of , it is the list of German states by area, largest German state by land area, comprising approximately 1/5 of the total l ...

, Germany. Alongside three other metriorhynchid species, it has been hypothesised that

niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...

enabled several species of crocodyliforms to co-exist. ''Dakosaurus'' and ''Geosaurus giganteus'' would have been top predators of this Formation, both of which were large, short-snouted species with serrated teeth. The remaining two species ('' Cricosaurus elegans'' and '' Rhacheosaurus gracilis'') and the teleosaurid Aeolodon would have fed mostly on fish.Andrade MB, Young MT. 2008
High diversity of thalattosuchian crocodylians and the niche partition in the Solnhofen Sea
. The 56th Symposium of Vertebrate Palaeontology and Comparative Anatomy From the slightly older Nusplingen Limestone (late Kimmeridgian) of southern Germany, both ''D. maximus'' and ''C. suevicus'' are contemporaneous. As with Solnhofen, ''Dakosaurus'' was the top predator, while ''C. suevicus'' was a fish-eater.Dietl G, Dietl O, Schweigert G, Hugger R. 2000. ''Der Nusplinger Plattenkalk (Weißer Jura zeta)'' - Grabungskampagne 1999.

References

External links

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{{Taxonbar, from=Q18819 Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Late Jurassic crocodylomorphs Late Jurassic crocodylomorphs of North America Jurassic Mexico Fossils of Mexico Early Cretaceous crocodylomorphs of South America Jurassic Argentina Cretaceous Argentina Fossils of Argentina Late Jurassic crocodylomorphs of Europe Jurassic France Fossils of France Jurassic Spain Fossils of Spain Jurassic Switzerland Fossils of Switzerland Cretaceous United Kingdom Fossils of Great Britain Solnhofen fauna Fossil taxa described in 1856