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= Euronecturus grogu =

Euronecturus grogu is an extinct type species of the genus Euronecturus (Proteidae) from in Hambach, Germany. It appeared in the early middle Miocene (late Orleanian, MN 5) in Europe.

E. grogu is additionally an important finding, because of its high phylogenetic similarity to the oldest known prodeid fossil Paranecturus garbanii (Maastrichian, late Cretaceous), whereas it has low phylogenetic similarity to other European proteids (Mioproteus and Proteus). This allows the assumption, two different lineages of Proteidae would have inhabited Europe during the Cenozoic.

Discovery and Naming
Euronecturus grogu was discovered in the Hambach 6C main seam, of a lignite mine in Hambach, Germany (50° 540 44″ N, 6° 290 51″ E; Fig. 1), that exposes the miocenic Ville Formation. The genus is part of the Hambach 6C fauna (middle Miocene (late Orleanian, MN 5).

Its genus name (Euronecturus) is assembled of Euro (reference to its appearance in Europe) and necturus (reference to its similarity and suggested phylogenetic affinity to Paranecturus and Necturus).

The specific epithet of its Type species “Euronecturus grogu” referes to a character of the popular Star Wars series “The Mandalorian” called Grogu.

One of its distinctive morphological features (secondary dorsal crest, further described below), is usually rarely preserved.

Description
E. grogu was described, based on five atlases from several individuals. These are the only fossil remainings in Hambach 6C, that can undoubtedly attributed to Euronecturus. Some distinctive morphological features justify to define a new genus and species:


 * Its secondary dorsal crest differs from all known proteids, however this feature is very rarely preserved.
 * small posteriorly-directed postzygapophyses
 * wide and deep ventral fossa between the anterior cotyles

It allows furthermore exceptional resemblance with an North American relative, Paranecturus garbanii, based on the similar morphology of the atlas.

Phylogeny
The phylogenetic relationship of E. grogu is based on the work of Macaluso et al., 2022.

Paleoecology
Hambach 6C of the Ville Formation contains sediments typical for an estuarine environment: a large river system, surrounded by extended coal swamps. This is also covered by paleontological evidence:


 * Marine and freshwater fish (e.g.: sharks and rays)
 * amphibians (e.g.: salamanders, anurans)
 * reptiles (e.g.: turtles, alligators)
 * marine and semi-aquatic mammals (e.g.: dolphins, beavers)

The climatological setting of Hambach 6C was subtropical:


 * humid, warm, distinct seasonality
 * mean annual precipitation 900 to 1000 mm
 * mean annual temperature 15.7 to 18 °C

Significance of E. grogu for paleontology
E. grogu shows high phylogenetic similarity to the oldest known proteid fossil Paranecturus garbanii from Northern America (Maastrichian, late Cretaceous). This is outstanding, regarding the time difference between the occurrence of both species, and the low phylogenetic similarity of E. grogu to other European proteids (Mioproteus and Proteus). This allows the assumption, two different lineages of Proteidae would have inhabited Europe during the Cenozoic.

The authors who described E. grogu hypotise, its ancestors could have colonised Europe via the De Geer or Thulean route (via Greenland to west Eurasia, Fennoscandia or Great Britain) in stead of Beringia. The other hypothesis is, E. grogu could be a relic from times, when Northern America and Europe shared similar faunal elements.