Camenellan
Extinct informal group of invertebrates
From Wikipedia, the free encyclopedia
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 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]
| Camenellan Temporal range: | |
|---|---|
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| Reconstruction and life restoration of the camenellan Wufengella | |
Scientific classification  | |
| Kingdom: | Animalia |
| Order: | Tommotiida |
| Informal group: | †Camenellans |
| Genera | |
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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]
Taxonomy
Two families:[2]
Kennardiidae Laurie, 1986: 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:[2]
- D. ajax Bischoff, 1976 (type)
- D. bacata Skovsted et al., 2015
- D. braddocki Evans & Rowell, 1990
- D. decobruta Betts, 2019[6]
- D. helica Skovsted et al., 2015
- D. macroptera (Tate, 1892)
- D. odyssei Evans & Rowell, 1990
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