Dakosaurus

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Dakosaurus
Temporal range:
Late Jurassic - Early Cretaceous,
157–137  Ma
Dakosaurus maximus.JPG
D. maximus neotype SMNS 8203, Staatliches Museum für Naturkunde Stuttgart
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Crocodyliformes
Suborder: Thalattosuchia
Family: Metriorhynchidae
Tribe: Geosaurini
Clade: Dakosaurina
Genus: Dakosaurus
von Quenstedt, 1856 [1]
Type species
Geosaurus maximus
Plieninger, 1846
Species
  • Dakosaurus maximus
    (Plieninger, 1846 [2] )
  • Dakosaurus andiniensisVignaud & Gasparini, 1996 [3]
Synonyms

Dakosaurus is an extinct genus of crocodylomorph within the family Metriorhynchidae that lived during the Late Jurassic and Early Cretaceous. It was large, with teeth that were serrated and compressed lateromedially (flattened from side to side). The genus was established by Friedrich August von Quenstedt in 1856 for an isolated tooth named Geosaurus maximus by Theodor Plieninger in 1846. [2] Dakosaurus was a carnivore 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 dolphins and ichthyosaurs or came ashore like turtles is not known yet. The name Dakosaurus means "biter lizard", and is derived from the Greek dakos ("biter") and σαῦρος -sauros ("lizard").

Discovery and species

D. andiniensis specimen MOZ 6146P. Dakosaurus andiniensis.png
D. andiniensis specimen MOZ 6146P.
D. maximus specimen SMNS 82043. Dakosaurus maximus 1.JPG
D. maximus specimen SMNS 82043.

The type species Dakosaurus maximus, meaning "greatest biter lizard", is known from fossil discoveries in Western Europe (England, France, Switzerland and Germany) of the Late Jurassic (Late Kimmeridgian-Early Tithonian). [7] [8]

When isolated Dakosaurus teeth were first discovered in Germany, they were mistaken for belonging to the theropod dinosaur Megalosaurus . [9] The type species D. maximus was originally named as a species of Geosaurus in 1846 by Theodor Plieninger, creating the species G. maximus. [2]

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" [bite] in 1858 in German, adding "denn wenige kommen seinem furchtbaren Gebiss gleich" [for few can match its terrible set of teeth]. [10] He gave the meaning of Greek dakos more correctly as "Beisser" [biter] in another description in 1859 in which he classified Dakosaurus as a dinosaur. [11]

Named in 1871 by Emanuel Bunzel, [6] the remains attributed to Megalosaurus schnaitheimi (found in Schnaitheim, Germany) are now believed to have belonged to Dakosaurus maximus as per Carrano et al. (2012). [12]

Fossil specimens referrable to Dakosaurus are known from Late Jurassic deposits from England, France, Switzerland, Germany, [7] Poland, [13] Russia, [14] Argentina, [3] and Mexico. [15] Teeth referrable to Dakosaurus are known from Europe from the Oxfordian. [16] [17]

Dacosaurus (Sauvage, 1873) is a misspelling of Dakosaurus, and thus a synonym. [4]

Dakosaurus andiniensis, meaning "biter lizard from the Andes", was first reported in 1985 from the Neuquén Basin, a very rich fossil bed in the Vaca Muerta, Argentina. However, it was not until 1996 that the binomen Dakosaurus andiniensis was erected. [3] 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" in press reports about its description. This species has a fossil range from the late Jurassic to early Cretaceous (Late Tithonian-Early Berriasian). [18]

Dakosaurus nicaeensis , named in 1913 by Ambayrac, was mistakenly classified as a megalosaurid dinosaur; now it is assigned as the sole species in the genus Aggiosaurus . Buffetaut [19] 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 .

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. [15] [20]

Description

Size of D. maximus Dakosaurus maximus.png
Size of D. maximus

All currently known species would have been large, measuring approximately 4–5 m (13–16 ft) long. [21] [22] Its body was streamlined for greater hydrodynamic efficiency, which along with its finned tail made it a more efficient swimmer than modern crocodilian species. [23]

Classification

Dakosaurus–when it contained the species D. andiniensis, D. maximus, and D. manselii–had long been considered paraphyletic, that is, not consisting of a common ancestor and its descendants, [24] [25] [26] [27] until a 2012 study moved D. manselii to the formerly invalid genus Plesiosuchus . [28]

Palaeobiology

D. maximus leaping after two Gnathosaurus Dakosaurus2.jpg
D. maximus leaping after two Gnathosaurus

Salt glands

The incomplete skull specimens from the Mexican species of Dakosaurus preserves the chamber in which the well-developed salt glands (known from Geosaurus [29] and Metriorhynchus [30] ) would have been housed. Unfortunately, there was no preservational evidence of the glands themselves. [15]

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. [18] These characteristics, along with their morphology, which fall within the 'Cut' guild of Massare (1987) - and are analogous to modern killer whale teeth - indicate that Dakosaurus was an apex predator. [31]

The enlarged supratemporal fenestrae of Dakosaurus skulls [8] would have anchored large adductor muscles (jaw closing), [32] ensuring a powerful bite. As their skulls are triangular in shape, with deeply rooted, large, serrated teeth and a bulbous, deep, mandibular symphysis (like pliosaurs), dakosaurs would also have been able to twist feed (tear chunks of flesh off potential prey). [33]

Palaeoecology

D. andiniensis harassing a Caypullisaurus Caypullisaurus Dak1.jpg
D. andiniensis harassing a Caypullisaurus

Dakosaurus maximus is one of several species of metriorhynchids known from the Mörnsheim Formation (Solnhofen limestone, early Tithonian) of Bavaria, Germany. Alongside three other metriorhynchid species, it has been hypothesised that niche partitioning 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 and Rhacheosaurus gracilis ) and the teleosaurid Steneosaurus would have fed mostly on fish. [34]

From the slightly older Nusplingen 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. [35]

See also

Related Research Articles

Aggiosaurus is an extinct genus of geosaurine metriorhynchid crocodyliform known from the Late Jurassic of Nice, southeastern France. It contains a single species, Aggiosaurus nicaeensis, which was named by H. Ambayrac in 1913.

<i>Machimosaurus</i> Genus of reptiles

Machimosaurus is an extinct genus of machimosaurid crocodyliform from the Late Jurassic and Early Cretaceous. The type species, Machimosaurus hugii, was found in Switzerland. Other fossils have been found in England, France, Germany, Portugal, Switzerland and Tunisia. Machimosaurus rex is the largest named teleosauroid and thalattosuchian, with an estimated length of up to 7.15 m (23.5 ft). Machimosaurus is the largest known crocodyliform of the Jurassic.

<i>Metriorhynchus</i> Extinct genus of reptiles

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 the German palaeontologist Christian von Meyer in 1832. The name Metriorhynchus means "Moderate snout", and is derived from the Greek Metrio- ("moderate") and -rhynchos ("snout").

<span class="mw-page-title-main">Metriorhynchidae</span> Extinct family of reptiles

Metriorhynchidae is an extinct family of specialized, aquatic metriorhynchoid crocodyliforms from the Middle Jurassic to the Early Cretaceous period of Europe, North America and South America. The name Metriorhynchidae was coined by the Austrian zoologist Leopold Fitzinger in 1843. The group contains two subfamilies, the Metriorhynchinae and the Geosaurinae. They represent the most marine adapted of all archosaurs.

<i>Enaliosuchus</i> Dubious extinct genus of sauropsids

Enaliosuchus is a dubious genus of extinct marine crocodyliform within the family Metriorhynchidae that lived during the Valanginian stage of the Early Cretaceous. It is known from fossil remains found in France and Germany and it was first described in 1883,. The name Enaliosuchus means "Marine crocodile", and is derived from the Greek Enalios- ("marine") and -suchos ("crocodile"). Two species are known: the type species E. macrospondylus, described in 1883, and the second species E. schroederi, described in 1936, which was likely the same animal as E. macrospondylus.

<i>Geosaurus</i> Extinct genus of reptiles

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 Geosaurus eggs or nests have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to give birth to live young out at sea. Where Geosaurus mated, whether on land or at sea, is currently unknown. The name Geosaurus means "Mother of Giants lizard", and is derived from the Greek Ge- and σαῦρος -sauros ("lizard"). The name Geosaurus was established by the French naturalist Georges Cuvier in 1824.

<i>Teleidosaurus</i> Genus of large reptiles

Teleidosaurus is an extinct genus of carnivorous metriorhynchoid crocodyliform from Middle Jurassic deposits of Normandy, France. The name Teleidosaurus means "Complete lizard", and is derived from the Greek Teleidos- ("complete") and σαῦρος -sauros ("lizard").

<i>Neustosaurus</i> Extinct genus of reptiles

Neustosaurus is a genus of marine crocodyliform from the Early Cretaceous. Neustosaurus was a carnivore that spent much, if not all, its life out at sea. No Neustosaurus eggs or nest have been discovered, so little is known of the reptile's lifecycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to give birth to live young out at sea. Where Neustosaurus mated, whether on land or at sea, is currently unknown. The name Neustosaurus means "Swimming lizard", and is derived from the Greek Neustos- ("swimming") and σαῦρος -sauros ("lizard").

Teleosaurus is an extinct genus of teleosaurid crocodyliform found in the Middle Jurassic Calcaire de Caen Formation of France. It was approximately 3 metres (10 ft) in length. The holotype is MNHN AC 8746, a quarter of a skull and other associated postcranial remains, while other fragmentary specimens are known. The type species is T. cadomensis, but a second species, T. geoffroyi may also exist. It was previously considered a wastebasket taxon, with many other remains assigned to the genus.

Purranisaurus is an extinct genus of marine crocodyliform from the Middle to Late Jurassic period of Chile and Vaca Muerta of Argentina. Rusconi originally regarded Purranisaurus potens to be a plesiosaur; however, Gasparini demonstrated that it was in fact a metriorhynchid crocodyliform, and that may be a junior synonym of Metriorhynchus. It was about 3.3 m (11 ft) long.

<i>Plesiosuchus</i> Extinct genus of reptiles

Plesiosuchus is an extinct genus of geosaurine metriorhynchid crocodyliform known from the Late Jurassic of Dorset, England and possibly also Spain. It contains a single species, Plesiosuchus manselii.

<i>Rhacheosaurus</i> Extinct genus of reptiles

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 of Germany. It was a relatively small reptile, measuring between 1.39 and 1.57 m long.

<i>Suchodus</i> Extinct genus of reptiles

Suchodus is an extinct genus of marine crocodyliform from the Middle to Late Jurassic period of England and France. It measured between 3.3 and 4.7 m in total body length.

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 of Germany. The name Cricosaurus means "Ring lizard", and is derived from the Greek Krikos- ("ring") and σαῦρος -sauros ("lizard"). It was a relatively small reptile, with C. suevicus and C. araucanensis measuring 2 m (6.6 ft) and 3.2 m (10 ft) in total body length, respectively.

<i>Steneosaurus</i> Extinct genus of reptiles

Steneosaurus is a dubious genus of teleosaurid crocodyliform from the Middle or Late Jurassic of France. The genus has been used as a wastebasket taxon for thalattosuchian fossils for over two centuries, and almost all known historical species of teleosauroid have been included within it at one point. The genus has remained a wastebasket, with numerous species still included under the label ‘Steneosaurus’, many of which are unrelated to each other.

<i>Gracilineustes</i> Extinct genus of reptiles

Gracilineustes is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic. Gracilineustes was a carnivore that spent much, if not all, its life out at sea. It was a small reptile, with G. leedsi measuring 2.25–3.11 m (7.4–10.2 ft) long and G. acutus measuring 3.77 m (12.4 ft) long.

<i>Torvoneustes</i> Extinct genus of reptiles

Torvoneustes is an extinct genus of metriorhynchid thalattosuchian. It is known from skull and postcranial remains found in the Kimmeridge Clay Formation of Dorset and Wiltshire, England, the Virgula Marls of Switzerland and also from Oaxaca, Mexico . The holotype skull of the type species was initially assigned to the species Metriorhynchus superciliosus. Postcranial remains were later discovered from the same quarry as the skull, and then these specimens were recognised as belonging to a new species of Dakosaurus, as D. carpenteri. The species was named to honour Simon Carpenter, an amateur geologist from Frome in Somerset, who discovered the fossils.

<i>Macrospondylus</i> Extinct genus of reptiles

Macrospondylus is an extinct genus of machimosaurid teleosauroid crocodyliform from the Early Jurassic (Toarcian) of Europe. Fossils are known from the Posidonia Shale of Germany, the Whitby Mudstone of the United Kingdom, and the "schistes bitumineux" of Luxembourg.

<span class="mw-page-title-main">Geosaurinae</span> Extinct subfamily of reptiles

Geosaurinae is a subfamily of metriorhynchid crocodyliforms from the Middle Jurassic to the Early Cretaceous of Europe, North America and South America. Named by Richard Lydekker, in 1889, it contains the metriorhynchids Suchodus, Purranisaurus, Neptunidraco, Tyrannoneustes, Torvoneustes, Dakosaurus, Geosaurus and Plesiosuchus. The last four taxa form a tribe within Geosaurinae, the Geosaurini. Geosaurinae is one of two subfamilies of Metriorhynchidae, the other being Metriorhynchinae.

<i>Thalattosuchus</i> Extinct genus of reptiles

Thalattosuchus is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic. Thalattosuchus was named in 2020. Thalattosuchus was a carnivore that spent much, if not all, its life out at sea. No Thalattosuchus eggs or nests have been discovered, so little is known of the reptile's life cycle, unlike other large marine reptiles of the Mesozoic, such as plesiosaurs or ichthyosaurs which are known to have given birth to live young out at sea. Where Thalattosuchus mated, whether on land or at sea, is currently unknown. The name Thalattosuchus means "sea crocodile".

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