Praearcturus

Praearcturus Temporal range: Lochkovian PreꞒ Ꞓ O S D C P T J K Pg N
Praearcturus sp.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Family:	† Praearcturidae
Genus:	† Praearcturus Woodward, 1871
Species:	†P. gigas
Binomial name
†Praearcturus gigas Woodward, 1871
Synonyms
Bennettarthra annwnensis? Fayers, Trewin & Morrissey, 2010

Praearcturus is an extinct genus of arthropod, either a crustacean or a scorpion, known from the Devonian 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, and was described as a giant isopod in 1871 by Henry Woodward. ^{[1] [2]} It was later interpreted as a scorpion 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). ^[3] While type specimen is from the Lower Devonian of Old Red Sandstone, ^{[4] [5]} single tergite remain is known from Lower Devonian of Wyoming and fragmentary cuticles referrable to this genus is known from Famennian of Portishead. ^{[4] [6]} Based on the scorpion interpretation, the species could have reached a total length of nearly 1 metre (3.3 ft), possibly making it one of the largest scorpions known. ^[7]

However, the 2024 study noted the uncertainty in identifying Praearcturus as a scorpion due to the fragmentary material showing no definitive features of scorpions and arachnids. ^[5] Braddy (2024) also questioned its identity as a scorpion and considered that the original interpretation as a crustacean is more likely, with the supposed pedipalp (claw) of a scorpion more likely being a cheliped 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. ^[8] In the 2024 conference abstracts, it was noted that a redescription to support its identity as a scorpion is in preparation. ^[9]

References

1. "Mindat.org". www.mindat.org. Retrieved 2021-12-28.
2. Woodward, H. (1871). "On the remains of a giant isopod Praearcturus gigas (H. Woodward) from the Old Red Sandstone of Rowlestone quarry, Herefordshire". Transactions of the Woolhope Field Naturalist's Club. 1870: 266–270.
3. Rolfe, W.D.I. (1980). "Early Invertebrate Terrestrial Faunas" (PDF). In Panchen, A.L. (ed.). The Terrestrial Environment and the Origin of Land Vertebrates. Vol. Systematics Association Special 15. Academic Press. pp. 117–157.
4. Kjellesvig-Waering, E. N. (1986). "A restudy of the fossil Scorpionida of the world". Palaeontographica Americana. 55: 1–287.
5. Dunlop, Jason A.; Garwood, Russell J. (2024-12-06). "A review of fossil scorpion higher systematics". PeerJ. 12: e18557. doi: 10.7717/peerj.18557 . ISSN   2167-8359. PMC   11627080 .
6. Lamsdell, James C.; Braddy, Simon J.; Tetlie, O. E. (2009). "Redescription of Drepanopterus abonensis (Chelicerata: Eurypterida: Stylonurina) from the late Devonian of Portishead, UK". Palaeontology. 52 (5): 1113–1139. Bibcode:2009Palgy..52.1113L. doi:10.1111/j.1475-4983.2009.00902.x. S2CID   129243775.
7. Dunlop, J. A.; Selden, P. A. (2013). "Scorpion fragments from the Silurian of Powys, Wales" (PDF). Arachnology. 16 (1): 27–32. doi:10.13156/arac.2013.16.1.27. S2CID   128679832.
8. Braddy, S. J. (2024). "Carcinosomatoid eurypterid palaeoecology and phylogeny: ichnology and palaeocommunities". Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 312 (2): 167–181. doi:10.1127/njgpa/2024/1206.
9. Howard, Richard J.; Edgecombe, Gregory D.; Legg, David A. (2024). A revision of Praearcturus gigas and a critical review of Palaeozoic scorpion gigantism (PDF). The Palaeontological Association 68th Annual Meeting. p. 60.