Dakosaurus

D. andiniensis specimen MOZ 6146P.

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]

Size of D. maximus

All currently known species would have been large, measuring approximately 4–5 m (13–16 ft) long and weighing 200–275 kg (441–606 lb).[21][22][23] Its body was streamlined for greater hydrodynamic efficiency, which along with its finned tail made it a more efficient swimmer than modern crocodilian species.[24]

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,[25][26][27][28] until a 2012 study moved D. manselii to the formerly invalid genus Plesiosuchus.[29]

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.[35]

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.[36]

• List of marine reptiles

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