Mobergella

Mobergella is a millimetric Lower Cambrian shelly fossil of unknown affinity, usually preserved in phosphate and particularly well known from Swedish strata, where it is diagnostic of lowermost Cambrian rocks.[1] Originally interpreted as a monoplacophoran,[1] the circular, cap-shaped shell resembles a hyolith operculum, with concentric rings on its upper surface, and seven pairs of internal muscle scars. It is never found in association with a conch, and its affinity therefore remains undetermined.[2] Nevertheless, its heavy musculature does seem to indicate that it functioned as an operculum.[3]

Mobergella
Temporal range: Lower Cambrian
Scientific classification
Kingdom: Animalia
Phylum: incertae sedis
Family: †Mobergellidae
Genus: †Mobergella
Moberg, 1892
Species
  • M. (= Discinella) holsti Moberg, 1892
  • M. radiolata Bengtson, 1968
  • M. turgida Bengtson, 1968

Some specimens bear evidence of healed injuries.[1]

It's also been compared to the Kirengellids, which are probably brachiopods.[4]

Occurrence

The genus is unique to Lower Cambrian strata and has been found throughout the northern hemisphere.[5]

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References
  1. Bengtson, S. (1968). "The problematic genus Mobergella from the Lower Cambrian of the Baltic area". Lethaia. 1 (4): 325–351. doi:10.1111/j.1502-3931.1968.tb01625.x.
  2. Conway Morris, S. (1995). "Enigmatic shells, possibly halkieriid, from the Middle Cambrian Burgess Shale, British Columbia". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 195 (1): 319–331. doi:10.1127/njgpa/195/1995/319.
  3. Topper, Timothy P; Skovsted, Christian B (2017). "Keeping a lid on it: Muscle scars and the mystery of the Mobergellidae" (PDF). Zoological Journal of the Linnean Society. 180 (4): 717. doi:10.1093/zoolinnean/zlw011.
  4. Dzik, J. 2010: Brachiopod identity of the alleged monoplacophoran ancestors of cephalopods. Malacologia 52:97–113.
  5. Skovsted, C. B. (2003). "Mobergellans (Problematica) from the Cambrian of Greenland, Siberia and Kazakhstan". Paläontologische Zeitschrift. 77 (2): 429–443. doi:10.1007/BF03006952.


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