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Dicranocaris[1] is an extinct genus of arthropod that lived in the Wheeler Shale formation[5] of what is now modern day Utah[2] during Drumian of the Cambrian period. The type and only species is Dicranocaris guntherorum.[3][2]

Morphology

Dicranocaris measured up to 10 cm in body length. The dorsal exoskeleton (tergite) comprise of a semicircular cephalic (head) shield followed by a 12-segmented trunk. At least the second to fifth trunk segments possess tergopleurae (lateral extension of trunk tergite) and the last 3 segments are tube-like. A narrow telson (tail) expand and bifurcate distally.[1][6]

Cephalic and trunk appendages are evident in some fossil materials, especially the laterally-preserved specimens. However, details are obscured by their poor preservation,[1] and the identification of those lateral specimens as D. guntherorum is considered questionable as well.[6]

Classification

The taxonomic affinity of Dicranocaris is uncertain. Initially it was identified as an arachnomorph,[1][2] later a possible megacheiran.[5][7][8] A material once though to be Dicranocaris was later described as Dytikosicula in 2015,[8] but this might be synonymous with Dicranocaris after all.[9] In 2020, another putative Dicranocaris specimen was later identified as Messorocaris.[6] Recent studies suggest Dicranocaris is more closely related to Messorocaris and both are tentatively grouped under Habeliida (stem-group chelicerates).[6][10]

References

  1. ^ a b c d e f Briggs, Derek E. G.; Lieberman, Bruce S.; Hendricks, Jonathan R.; Halgedahl, Susan L.; Jarrard, Richard D. (2008). “Middle Cambrian arthropods from Utah”. Journal of Paleontology. 82 (2): 238–254. doi:10.1666/06-086.1. ISSN 0022-3360.
  2. ^ a b c d e Dicranocaris in the Paleobiology Database
  3. ^ a b “Dicranocaris”. www.mindat.org. Retrieved 1 September 2025.
  4. ^ Dicranocaris guntherorum in the Paleobiology Database
  5. ^ a b Hendricks, Jonathan R.; Lieberman, Bruce S. (May 2008). “New phylogenetic insights into the Cambrian radiation of arachnomorph arthropods”. Journal of Paleontology. 82 (3): 585–594. doi:10.1666/07-017.1.
  6. ^ a b c d Lerosey‐Aubril, Rudy; Kimmig, Julien; Pates, Stephen; Skabelund, Jacob; Weug, Andries; Ortega‐Hernández, Javier (2020). Zhang, Xi‐Guang (ed.). “New exceptionally preserved panarthropods from the Drumian Wheeler Konservat‐Lagerstätte of the House Range of Utah”. Papers in Palaeontology. 6 (4): 501–531. doi:10.1002/spp2.1307. ISSN 2056-2799.
  7. ^ Ortega‐Hernández, Javier; Legg, David A.; Braddy, Simon J. (2013). “The phylogeny of aglaspidid arthropods and the internal relationships within Artiopoda”. Cladistics. 29 (1): 15–45. doi:10.1111/j.1096-0031.2012.00413.x. ISSN 0748-3007.
  8. ^ a b Conway Morris, Simon; Selden, Paul A.; Gunther, Glade; Jamison, Paul G.; Robison, Richard A. (2015). “New records of Burgess Shale-type taxa from the middle Cambrian of Utah”. Journal of Paleontology. 89 (3): 411–423. doi:10.1017/jpa.2015.26.
  9. ^ Lerosey-Aubril, Rudy; Skabelund, Jacob (January 2018). “Messorocaris , a new sanctacaridid-like arthropod from the middle Cambrian Wheeler Formation (Utah, USA)”. Geological Magazine. 155 (1): 181–186. Bibcode:2018GeoM..155..181L. doi:10.1017/S0016756817000504.
  10. ^ Lerosey-Aubril, Rudy; Ortega-Hernández, Javier (2026-04-01). “A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates”. Nature: 1–7. doi:10.1038/s41586-026-10284-2. ISSN 1476-4687.