Camenellan

Camenellan
Temporal range: Early Cambrian
Reconstruction and life restoration of the camenellan Wufengella
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Stem group: †"Tommotiida"
Informal group: †Camenellans
Genera
  • Camenella Missarzhevsky in Rozanov & Missarzhevsky, 1966
  • Dailyatia Bischoff, 1976
  • Kelanella Missarzhevsky in Rozanov & Missarzhevsky, 1966; = Bengtsonia, Tesella, Sonella[1]
  • Kennardia Laurie, 1986
  • Lapworthella
  • Shetlandia Wrona, 2004
  • Wufengella Guo et al. 2022
Reconstruction of the scleritome of Dailyatia bacata

The camenellans, consisting of the genera Camenalla, Dailyatia, Kennardia, Kelanella, Wufengella and Lapworthella, are a (probably monophyletic) group of Tommotiid invertebrates from the Cambrian period, reconstructed as sister to all others[clarification needed] (plus brachiopods and phoronids). They are primarily known from isolated sclerites, but are believed to have a scleritomous, Halkieria-like construction.[2][3] This was confirmed by the discovery of Wufengella, known from articulated remains, which showed camenellans to be mobile, worm-like animals.[4]

Dailyatia and Camenella have distinct dorsal (symmetrical) and lateral (asymmetric) sclerite morphologies. The same has been asserted for Lapworthella[5] even though that has not always been the common perception.[3]

It has been argued that Camenella, Kelanella and Lapworthella, assuming a slug-like anatomy, had an anterior 'head valve' followed by pairs of asymmetric valves running in pairs along their dorsal surface.[5]

The 'head valve' in Lapworthella - that is the bilaterally symmetric Morph A valve - is thought to have fused from two ontogenetically separate sclerites.[5] Dailyatia has a similar double-mounded structure at the tip of its A type sclerites.[2]

Growth rings in all are marked out by prominent external ridges.[2][5]

  1. ^ Devaere, L. et al. The tommotiid Kelanella and associated fauna from the early Cambrian of southern Montagne Noire (France): implications for camenellan phylogeny. Palaeontology 57, 979–1002 (2014).
  2. ^ a b c Skovsted, C. B., Betts, M. J., Topper, T. P. & Brock, G. A. The early Cambrian tommotiid genus Dailyatia from South Australia. Mem. Assoc. Australas. Palaeontol. 48, 1–117 (2015).
  3. ^ a b Murdock, D. J. E., Donoghue, P. C. J., Bengtson, S. & Marone, F. Ontogeny and micro-structure of the enigmatic Cambrian tommotiid Sunnaginia Missarzhevsky, 1969. Palaeontology 55, 661–676 (2012).
  4. ^ Guo, Jin; Parry, Luke A.; Vinther, Jakob; Edgecombe, Gregory D.; Wei, Fan; Zhao, Jun; Zhao, Yang; Béthoux, Olivier; Lei, Xiangtong; Chen, Ailin; Hou, Xianguang; Chen, Taimin; Cong, Peiyun (2022). "A Cambrian tommotiid preserving soft tissues reveals the metameric ancestry of lophophorates". Current Biology. Online: S0960–9822(22)01455–5. doi:10.1016/j.cub.2022.09.011. ISSN 1879-0445. PMID 36170853.
  5. ^ a b c d Devaere, L. & Skovsted, C. B. New early Cambrian sclerites of Lapworthella schodakensis from NE Greenland: advancements in knowledge of lapworthellid taxonomy, sclerite growth and scleritome organization. Geol. Mag. (2016). doi:10.1017/S0016756816000698