''Praearcturus'' is an extinct genus of

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

, most likely a

scorpion Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

, known from the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

period of what is now Britain. It is the only genus in the family Praearcturidae and contains the single species ''P. gigas''.

Taxonomic history

The type fossil was discovered in Rowlestone,

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 ...

, and was described as a giant

isopod Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

in 1871 by Henry Woodward. It was later interpreted as a

by Rolfe (1980), who claimed that it was based on the personal communications by L. Størmer (1974) and E. N. Kjellesvig-Waering (1978) and the published figures by Rolfe (1969). While type specimen is from the Lower Devonian of

Old Red Sandstone Old Red Sandstone, abbreviated ORS, is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the eastern seaboard of North America. It ...

, single tergite remain is known from Lower Devonian of

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

and fragmentary cuticles referrable to this genus is known from

Famennian The Famennian is the later of two faunal stages in the Late Devonian epoch. The most recent estimate for its duration is that it lasted from around 371.1 to 359.3 million years ago. An earlier 2012 estimate, still used by the International Commis ...

of Portishead. Based on comparisons to modern scorpions, the species could have reached a total length of nearly , possibly making it one of the largest scorpions known. However, a 2024 study was uncertain whether ''Praearcturus'' could be identified as a scorpion, due to the fragmentary material showing no definitive features of scorpions and arachnids. Braddy (2024) also questioned its identity as a scorpion and considered that the original interpretation as a

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

is more likely, with the supposed

pedipalp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...

(claw) of a scorpion more likely being a

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds ...

of a crustacean. He further supported his argument based on the "grooves and pustular ornament on its carapace and cheliped, and recurved first tergum", and suggested that ''Bennettarthra'' could be synonymous with ''Praearcturus'' as both taxa show similar morphological features. In a 2024

conference A conference is a meeting, often lasting a few days, which is organized on a particular subject, or to bring together people who have a common interest. Conferences can be used as a form of group decision-making, although discussion, not always d ...

abstract, however, it was noted that a redescription of ''Praearcturus'' is in preparation, which the authors claim confirms the genus' scorpion identity.

References

{{Taxonbar, from1=Q101245777, from2=Q107576534 Prehistoric arthropods Devonian arthropods Fossil taxa described in 1871