Abstract

The recovery of well-preserved silicified larvae from the early Tournaisian of Montagne Noire, southern France, allows the first description of the early ontogeny of proetoid trilobites, survivors of the end-Devonian Hangenberg extinction event. The fauna comprises various taxa that can only partly and tentatively be assigned to the genera Liobolina, Diacoryphe, and Pedinocoryphe without specific attribution. The close resemblance of these larvae to previously described proetoid larvae from the Ordovician and Devonian emphasizes the ontogenetic homogeneity of this superfamily. Moreover, it supports the view that the Proetida is composed of two clades: the Aulacopleuroidea/Bathyuroidea group and the Proetoidea. The Carboniferous anaprotaspides exhibit an unusually wide size-range that may provide evidence of the acquisition of an extended planktonic period in the early ontogeny of at least some Carboniferous proetoids. This change in the ontogenetic strategy may have enabled proetoid trilobites to survive during the end-Devonian biocrises.

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