Citation:
Abstract:
The thiolliericrinids, although having a stem in the adult stage, are classified as comatulids (Comatulida) that are usually identified as stemless forms. They first appeared in the Bajocian (Middle Jurassic), and their last occurrence is noted in the Hauterivian (Early Cretaceous). Herein we report a thiolliericrinid crinoid from the Aptian of northern Africa (Algeria). This is the youngest thiolliericrinid crinoid ever recorded. Previously, the youngest thiolliericrinid (Thiolliericrinus) came from the Hauterivian (Lower Cretaceous) of France, Germany, Portugal, and Switzerland. This youngest thiolliericrinid has a smooth and irregular centrodorsal with no cirrus socket. The radials are irregular; some of them are variable in size and display no visible basal plates externally. The latter feature is typical of evolutionarily advanced Early Cretaceous thiolliericrinids (e.g., Heberticrinus or Loriolicrinus). Additionally, the present record is also the only representative of thiolliericrinids with a cup strongly oblique on the stem.