Pseudoangustidontus

Pseudoangustidontus (meaning "false Angustidontus") is a genus of hurdiid (peytoiid) radiodont from the Lower Ordovician of Morocco. This genus includes two described species, '''Pseudoangustidontus duplospineus and Pseudoangustidontus izidigua', which both belong to the smaller Aegirocassisinae subfamily, however, a third unnamed species is also known. This animal is only known from the Fezouata Formation, a lower Ordovician fossil site in Morocco that is of Konservat-Lagerstätten status, meaning that the fossils from this site are exceptionally well preserved. This taxon was first described in 2006, but due to the fragmentary remains known at the time, its classification was debated, but with more complete fossils, this taxon was identified as a hurdiid radiodont in 2023. Similarly to its larger relative, Aegirocassis benmoulae, this radiodont is thought to have lived a primarily filter feeding lifestyle, using its numerous auxiliary spines to grab small organisms from the water.

== Background == Located in the Draa Valley of southeastern Morocco, the Fezouata Formation is a lower Ordovician (Tremadocian – Floian) aged geologic formation well known for its exceptional preservation of soft-bodied marine organisms. The soft body producing layers of the formation, known as the Fezouata Lagerstätte, were first identified in the late 1990s, when Ben Moula, a local fossil collector in the area, showed some uncovered specimens to a PhD student working in the area, and the soon to be discovered ecosystem would come to be known as the Fezouata Biota. The formation is especially important, as it helped bridge the gap between Cambrian-type and Ordovician-type faunas, showing that many groups of organisms once thought to have gone extinct at the end of the Cambrian, survived the transition into the Ordovician. The site is highly productive, with around 50 distinct taxa being represented from over 1,500 specimens, with the majority of said specimens coming from two small intervals of the formation around and thick, compared to the nearly thickness of the whole formation. During the Ordovician, the area that would become Morocco was situated much closer to the South Pole then it is today, and the ecosystem of Fezouata lived in a storm wave base roughly 50 and 150 metres (160 and 490 ft) underwater. The organisms in the environment were preserved in situ, and because of storms in the area helping to facilitate rapid sediment deposition, the majority of known organisms were benthic in nature.