About Natural History

What Latouchella is.

Latouchella represents the name of the blog, so it seems only natural that a post should be dedicated to this fascinating mollusc!

Why fascinating? After all it only is a rather small shell with very few systematic characters and not particularly spectacular. But in its simplicity it is a quite amazing creature: it is the oldest known genus of molluscs (its type species is the oldest mollusc known to date), and its systematic position is still fuzzy. Is it a Monoplacophoran or a Gastropod?

In palaeontology classes, we learned that it is most probably a Monoplacophoran of the family Helcionellidae, but the classification of Bouchet and Rocroi (2005) does not attribute them a certain phylogenetic position.

The genus appeared during the very beginning of the Cambrian, the Tommotian epoch (lower Cambrian of Russia and Kazakhstan). It presents similarities with the current Monoplacophoran Neopillina (c.f. Picture 1), without them being conclusive as to the precise phylogenetic position.

Picture 1: Neopilina sp.

The type species was first described by E.S. Cobbold (1921), in “The Cambrian horizons of Comley (Shropshire) and their Brachiopoda, Pteropoda, Gasteropoda and etc.” in the Quarterly Journal of the Geological Society of London (vol. 76, pp. : 325-386).

The type species, Latouchella costata (picture 2), was found western England, in lower Cambrian sediments, by E.S. Cobbold. The age, the structure, the mystery around this fossil make it a unique creature in the history of Evolution, especially since it represents such an important clade as the one of Mollusca.

Picture 2: Latouchella costata


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