Fezouata Formation

File:Fezouata Biota.jpg|Reconstruction of the Fezouata Biota, featuring roughly 50 different species. The largest animal, Aegirocassis benmoulai (just over 2 metres in length), is depicted swimming just above the seafloor. Over 1,500 non-mineralized specimens, representing 50 distinct taxa that have a composition similar to earlier Burgess Shale type biotas, have been recovered from the formations in addition to a less abundant shelly fauna. lobopods, barnacles, annelids, radiodonts (e.g. Aegirocassis), possible halkieriids, marrellomorphs, paleoscolecid worms, nektaspids, skaniids as well as the expected problematica. Other Ordovician oddballs are also present, including mitrates, machaeridians, cheloniellids and xiphosurans in abundance. == Depositional setting ==

The fossiliferous strata were deposited just above storm wave base (offshore to lower shoreface transition), at between water depth. Organisms were likely buried in situ. Because of its placement above storm wave base, storms would have mobilized sediment that could be quickly deposited, trapping animals and leading to their preservation. Consequently, the assemblage is dominated by benthic organisms. == Preservation ==

Fossils of the Fezouata Formation, which are usually squashed flat (although some do retain some degree of their original three-dimensionality) are often coated with a dusting of pyrite, and tin; this aspect of the fossil preservation is very similar to that at Chengjiang. Non-mineralized appendages are often preserved. While the formation as a whole is over thick, only two intervals, and thick, provide exceptional preservation.{{cite web |last1=Saleh |first1=Farid |last2=Pittet |first2=Bernard |last3=Perrillat |first3=Jean-Philippe |last4=Lefebvre |first4=Bertrand |title= Orbital Control on Exceptional Fossil Preservation (abstract only) |url=https://pubs.geoscienceworld.org/gsa/geology/article-abstract/47/2/103/567985/orbital-control-on-exceptional-fossil-preservation?redirectedFrom=fulltext |website=geoscienctworld.org (subscription w/ free abstract) == Location and stratigraphy ==

The fossils occur within an area of , in southeast Morocco's Draa Valley, north of Zagora. Stratigraphically productive layers are found through a -thick column of rock that spans the Tremadocian and Floian epochs. == History ==

The Lagerstätten were first identified in the late 1990s when a local fossil collector, Ben Moula, showed some of the finds to a PhD student who was then working in the area. IUGS geological heritage site In respect of the 'exceptional fossil preservation bridging the Cambrian Explosion and the Great Ordovician Biodiversification', the International Union of Geological Sciences (IUGS) included the 'Ordovician Fezouata Shale Fossil Site at Jbeltizagzaouine' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an IUGS Geological Heritage Site as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.' == Paleobiota ==

After and subsequent literature: Radiodonts Apart from the four named species of Fezouata radiodonts, three other unnamed species occur in the formation: a third species of Pseudoangustidontus, an aegirocassisine, and a sediment-sifting hurdiid. Other arthropods Many arthropods of the Fezouata Biota remain unnamed and undescribed. These include synziphosurines, xiphosurans (horseshoe crabs), chasmataspidids, phyllocarids, ostracods, a canadaspidid, a leanchoiliid, a cheloniellid ("Eoduslia"), a possible retifaciid, and a lepadomorph barnacle. Fezouata stylophoran fossils include soft tissue preserved among the skeletal elements, helping to unravel controversial details of their anatomy and ecology.'' Overall diversity is rather low, and species which were common in temperate and tropical seas are apparently absent. The Fezouata Formation appears to be an exemplar of the 'subpolar domain', an assemblage of cold-water coastal conodonts native to the South Polar region of the Early Ordovician. Similar conodont faunas are known from Early Ordovician deposits in Central Europe, which was also located near the South Pole. The 'subpolar domain' survived into the Middle Ordovician and expanded into areas now found in the Middle East.'' Sessile forms, such as Didymograptus, Dictyonema, Webbyites'', and rhabdopleurids, are also present but much more rare. The graptolites of the Fezouata Formation are distributed over 10 biozones. In order, these zones are: the Anisograptus matanensis zone (1), Rhabdinopora flabelliformis anglica zone (2), "Adelograptus" tenellus zone (3), Aorograptus victoriae zone (4), Araneograptus murrayi zone (5), Hunnegraptus copiosus zone (6), ?Cymatograptus protobalticus zone (7), ?Baltograptus jacksoni zone (8), Baltograptus minutus zone (9), and the "Azygograptus interval" (10). Not all of the index taxa which these zones are named for are known from the Fezouata Formation. The Tremadocian-Floian boundary is approximately at the level between the Hunnegraptus copiosus and ?Cymatograptus probalticus zones. Many of the sponges have affinities with Cambrian taxa common in Burgess Shale-type faunas. == References ==