''Tannuolina'' is a genus of

tommotiid Tommotiids are an extinct group of Cambrian invertebrates thought to be early lophophorates (the group containing Bryozoa, Brachiopoda, and Phoronida). The majority of tommotiids are mineralised with calcium phosphate rather than calcium car ...

, belonging to the

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

stem lineage. Its phosphatic shells exhibit a complex series of open pores/chambers/channels in outer shell layer.Kouchinsky, A., Bengtson, S. & Murdock, D. J. E. A new tannuolinid problematic from the lower Cambrian of the Sukharikha River in northern Siberia. Acta Pal. Pol. 55, 321–331 (2010). It is conventionally interpreted as an essentially

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

d organism, similar to '' Micrina'', though some use the unequal ratio of stellate to

mitrate Mitrates are an extinct group of stem group echinoderms, which may be closely related to the hemichordates. Along with the cornuta, cornutes, they form one half of the Stylophora. Morphology The organisms were a few millimetres long. Like the e ...

sclerites A sclerite ( Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonl ...

to argue for a

halkieriid The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the smal ...

-like anatomy.Li, G.-X. & Xiao, S.-H. ''Tannuolina'' and ''Micrina'' (Tannuolinidae) from the Lower Cambrian of Eastern Yunnan, South China, and Their Scleritome Reconstruction. J. Paleontol. 78(5), 900–913 (2004). More recently a tube-like construction inspired by '' Eccentrotheca'' has been proposed.Skovsted, C. B., S. Clausen, J. J. Álvaro, and D. Ponlevé. 2014: Tommotiids from the early Cambrian (Series 2, Stage 3) of Morocco and the evolution of the tannuolinid scleritome and setigerous shell structures in stem group brachiopods. Palaeontology 57:171–192.

Species

* ''T. fonini'' Esakova ''in'' Esakova & Zhegallo, 1996 * ''T. maroccana'' Skovsted & Clausen ''in'' Skovsted, Clausen, Álvaro & Ponlevé, 2014 * ''T. multifora'' Fonin & Smirnova, 1967 * ''T. pavlovi'' Kouchinsky ''et al.'', 2010 * ''T. zhangwentangi'' Qian & Bengtson, 1989

References

Cambrian brachiopods Prehistoric brachiopod genera {{cambrian-animal-stub Cambrian genus extinctions