21133 - Museum Grade Exceptional Soft Bodied Marrellomorph (Furca mauretanica) Ordovician

Nice and rare marrellomorph primitive arthopod Furca (VanRoy 2006; Van Roy et al. 2010; Rak et al. 2012). This non-biomineralized taxon was first described by Fritsch (1908a,b) on the basis of isolated head shields from the Sandbian of the Letná Formation in the Czech Republic. Fritsch (1908a,b) interpreted the fossils as crinoid larvae, but later Perner (1919) suggested a marrellomorph affinity for the fossils, a view also followed by Chlupáč (1999a,b).

However, in the absence of the rest of the body, lingering doubts
over the affinities of Furca remained (Chlupác 1999a,b), until exquisitely preserved complete specimens were discovered in the Fezouata biota (Van Roy 2006; Van Roy et al. 2010). Furca shares the head shield morphology of marrellids, with three pairs of curved projections bearing marginal spines. These marginal spines are more pronounced than in the middle Cambrian Marrella splendens from the Burgess Shale, and closer in size to those of the Early Devonian genus Mimetaster hexagonalis. The appendages show similarities to
those of both M. splendens and M. hexagonalis. Mimetaster hexagonalis and Marrella have long been regarded as closely related (Stürmer & Bergström 1976; Bartels et al. 1998; Kühl & Rust 2010). It comes from the Lower Ordovician of the Famous Fezouata Formation. Positive and Negative specimen.

The conservation of soft parts in the fossil record is somewhat exceptional and only occurs under certain and exclusive taphonomic conditions. For example, anoxic substrates without oxygen, where the organic matter has difficulty decomposing.

The Fezouata Formation occurs in the lower part of the Lower to lower Middle Ordovician Outer Feijas Group, in the western, central and eastern Anti-Atlas
Mountains, southern Morocco (Destombes et al.1985; Gutierrez-Marco & Martin 2016).

It comes from The Konservat-Lagerstätten of Lower Fezouata Fm that spans the entire Tremadoc stage of the Ordovician system and is only present in the Moroccan Anti-Atlas. The discovery of the Fezouata biota in the latest Tremadocian of southeastern Morocco has significantly changed our understanding of the early Phanerozoic radiation. The shelly fossil record shows a well-recognized pattern of macroevolutionary stasis between the Cambrian Explosion and the Great Ordovician Biodiversification Event, but the rich soft-bodied Fezouata biota paints a different evolutionary picture. The Fezouata assemblage includes a considerable component of Cambrian holdovers alongside a surprising number of crown group taxa previously unknown to have evolved by the Early Ordovician. Study of the Fezouata biota is in its early stages, and future discoveries will continue to enrich our view of the dynamics of the early Phanerozoic radiation and of the nature of the fossil record.