Camenellan

{{Short description|Extinct informal group of invertebrates}} {{Automatic taxobox | fossil_range = Early Cambrian | image = Wufengella_reconstruction.jpg | image_caption = Reconstruction and life restoration of the camenellan ''Wufengella'' | image_upright = | taxon = Camenellans | authority = | subdivision_ranks = Genera | subdivision = {{Genus list | Camenella |Missarzhevsky in Rozanov & Missarzhevsky, 1966 | Dailyatia | Bischoff, 1976 | Kelanella | Missarzhevsky in Rozanov & Missarzhevsky, 1966; {{=}} ''Bengtsonia'', ''Tesella'', ''Sonella''<ref name=Devaere2014>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).</ref> | Kennardia | Laurie, 1986 | Lapworthella | | Shetlandia | Wrona, 2004 | Wufengella | Guo et al. 2022 }} }} left|thumb|300x300px|Reconstruction of the scleritome of ''Dailyatia bacata'' The '''camenellans''', consisting of the genera ''Camenella'', ''Dailyatia'', ''Kennardia'', ''Kelanella'', ''Wufengella'' and ''Lapworthella'', are a (probably monophyletic) group of Tommotiid invertebrates from the Cambrian period, reconstructed as sister to all other lophophorates (plus brachiopods and phoronids). They are primarily known from isolated sclerites, but are believed to have a scleritomous, ''Halkieria''-like construction.<ref name="Skovsted2015">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).</ref><ref name="Murdock, D. J. E. 1969">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).</ref> This was confirmed by the discovery of ''Wufengella,'' known from articulated remains, which showed camenellans to be mobile, worm-like animals.<ref name=":0">{{Cite journal |last1=Guo |first1=Jin |last2=Parry |first2=Luke A. |last3=Vinther |first3=Jakob |last4=Edgecombe |first4=Gregory D. |last5=Wei |first5=Fan |last6=Zhao |first6=Jun |last7=Zhao |first7=Yang |last8=Béthoux |first8=Olivier |last9=Lei |first9=Xiangtong |last10=Chen |first10=Ailin |last11=Hou |first11=Xianguang |last12=Chen |first12=Taimin |last13=Cong |first13=Peiyun |date=2022 |title=A Cambrian tommotiid preserving soft tissues reveals the metameric ancestry of lophophorates |journal=Current Biology |issue=21 |volume=32 |pages=S0960–9822(22)01455–5 |doi=10.1016/j.cub.2022.09.011 |issn=1879-0445 |pmid=36170853 |doi-access=free|bibcode=2022CBio...32E4769G |hdl=1983/bede5ebd-85b8-4b09-b54e-a892489f33fb |hdl-access=free }}</ref>

''Dailyatia'' and ''Camenella'' have distinct dorsal (symmetrical) and lateral (asymmetric) sclerite morphologies. The same has been asserted for ''Lapworthella''<ref name="Devaere2016"/> even though that has not always been the common perception.<ref name="Murdock, D. J. E. 1969"/>

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.<ref name=Devaere2016>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</ref>

The 'head valve' in ''Lapworthella'' - that is the bilaterally symmetric Morph A valve - is thought to have fused from two ontogenetically separate sclerites.<ref name=Devaere2016/> ''Dailyatia'' has a similar double-mounded structure at the tip of its A type sclerites.<ref name=Skovsted2015/>

Growth rings in all are marked out by prominent external ridges.<ref name=Skovsted2015 /><ref name=Devaere2016/>

== Taxonomy== Two families:<ref name=Skovsted2015/>

Kennardiidae <small>Laurie, 1986</small>: three sclerite morphs, one of which (conventionally termed the A morph) is bilaterally symmetrical, the other two occurring in sinistral and dextral variants. Includes ''Kennardia'' and ''Dailyatia'', and questionably ''Shetlandia''

Lapworthellidae: sclerites occur in something of a morphological continuum, but essentially form a single type with a sinistral and dextral version, possibly with the anterior-most pair of sclerites fusing into a single bilaterally-symmetrical, dual-tipped sclerite.

''Dailyatia'' species:<ref name ="Skovsted2015"/> {{species list | D. ajax |Bischoff, 1976 (type) | D. bacata |Skovsted ''et al.'', 2015 | D. braddocki | Evans & Rowell, 1990 | D. decobruta | Betts, 2019<ref>{{cite journal|doi = 10.4202/app.00586.2018|url = http://app.pan.pl/archive/published/app64/app005862018.pdf|volume = 64|issue = 3|title = Early Cambrian shelly fossils from the White Point Conglomerate, Kangaroo Island, South Australia|journal = Acta Palaeontologica Polonica|year = 2019|last1 = Betts|first1 = Marissa|last2 = Claybourn|first2 = Thomas|last3 = Brock|first3 = Glenn|last4 = Jago|first4 = James|last5 = Skovsted|first5 = Christian|last6 = Paterson|first6 = John|doi-access = free|access-date = 2019-08-30|archive-date = 2019-08-30|archive-url = https://web.archive.org/web/20190830073000/http://app.pan.pl/archive/published/app64/app005862018.pdf|url-status = live}}</ref> | D. helica |Skovsted ''et al.'', 2015 | D. macroptera |(Tate, 1892) | D. odyssei |Evans & Rowell, 1990 }}

==References== {{Reflist}}

Category:Prehistoric protostomes Category:Cambrian invertebrates Category:Paleozoic life of New Brunswick Category:Paleozoic life of Newfoundland and Labrador Category:Paleozoic life of Nova Scotia Category:Cambrian genus extinctions