''Dakosaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

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 ...

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. During Mesozoic and early Cenozoic times, cro ...

within the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

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 Metriorhync ...

that lived during the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

and

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

. 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 (July 10, 1809 – December 21, 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 ...

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 whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

that spent much, if not all, 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 within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...

s and

ichthyosaur Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...

s or came ashore like

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

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

Greek Greek may refer to: Greece 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 ...

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

Discovery and species

The

type species In 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 species that contains the biological type specimen ...

''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 preserved ...

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 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

-Early

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the K ...

).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 is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, they were mistaken for belonging to the

theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...

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

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

''.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" itein 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 by replicating, on Earth ...

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 Heidenheim an der Brenz, or just Heidenheim (; Swabian: ''Hoidna'' or ''Hoirna''), is a town in Baden-Württemberg in southern Germany. It is located near the border with Bavaria, approximately 17 km south of Aalen and 33 km north of ...

) 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 country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

,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 is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

,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 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 ...

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

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

,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 (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

.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 (; arn, Nehuenken) 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 w ...

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 roc ...

, 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'', originating from a series of Japanese films. The character first appeared in the 1954 film ''Godzilla'' and became a worldwide pop culture icon, appearing in various media, including 32 films produc ...

" 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 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (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 relative ...

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. Amba ...

''. Buffetaut Buffetaut 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 s ...

''. 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 and weighing . 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 In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

, 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 ''Plesiosuchus'' is an extinct genus of geosaurine metriorhynchid crocodyliform known from the Late Jurassic (late Kimmeridgian to early Tithonian stage) of Dorset, England and possibly also Spain. It contains a single species, ''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 for excreting excess 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 rectum of sharks. Birds and reptile ...

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 or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus ''Orcinus'' and is recognizable by its black-and-white pa ...

teeth - indicate that ''Dakosaurus'' was an

apex predator An apex predator, also known as a top predator, 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 highest trophic lev ...

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

supratemporal fenestrae The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

of ''Dakosaurus'' skulls would have anchored large

adductor muscles The adductor muscles of the hip are a group of muscles mostly used for bringing the thighs together (called adduction). Structure The adductor group is made up of: *Adductor brevis *Adductor longus *Adductor magnus * Adductor minimus This is o ...

(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 tooth ...

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 Mörnsheim Formation ( Solnhofen limestone, early Tithonian) of

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

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

niche partitioning In ecology, niche differentiation (also known as niche segregation, niche separation and niche partitioning) refers to the process by which competing species use the environment differently in a way that helps them to coexist. The competitive excl ...

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 suevicus ''Cricosaurus'' is an extinct genus of marine crocodyliforms of the Late Jurassic. belonging to the family Metriorhynchidae. The genus was established by Johann Andreas Wagner in 1858 for three skulls from the Tithonian (Late Jurassic) of Germany ...

'' and ''

Rhacheosaurus gracilis ''Rhacheosaurus'' is an extinct genus of marine crocodyliform belonging to the family Metriorhynchidae. The genus was established by Christian Erich Hermann von Meyer in 1831 for skeletal remains from the Tithonian (Late Jurassic) of Germany.Mey ...

'') and the

teleosaurid Teleosauridae is a family of extinct typically marine crocodylomorphs similar to the modern gharial that lived during the Jurassic period. Teleosaurids were thalattosuchians closely related to the fully aquatic metriorhynchoids, but were less ad ...

Steneosaurus ''Steneosaurus'' (from el, στενός , 'narrow' and el, σαῦρος , 'lizard') is a dubious genus of teleosaurid crocodyliform from the Middle or Late Jurassic (Callovian or early Oxfordian) of France. The genus has been used as a was ...

'' 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 Nusplingen is a municipality of the Zollernalbkreis, Zollernalb district of Baden-Württemberg, Germany. History In 1803, Nusplingen became a possession of the Principality of Hohenzollern-Sigmaringen, who traded the town in 1813 to the Kingdom ...

Plattenkalk (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

Scientists reveal prehistoric terror
-

CNN CNN (Cable News Network) is a multinational cable news channel headquartered in Atlanta, Georgia, U.S. Founded in 1980 by American media proprietor Ted Turner and Reese Schonfeld as a 24-hour cable news channel, and presently owned by the M ...

Illustration
-

National Geographic ''National Geographic'' (formerly the ''National Geographic Magazine'', sometimes branded as NAT GEO) is a popular American monthly magazine published by National Geographic Partners. Known for its photojournalism, it is one of the most widely ...

{{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