Fossil Record 23(2): 141-149, doi: 10.5194/fr-23-141-2020
A revision of Ophidiaster davidsoni de Loriol and Pellat 1874 from the Tithonian of Boulogne (France) and its transfer from the Valvatacea to the new forcipulatacean genus Psammaster gen. nov.
expand article infoMarine Fau, Loïc Villier§, Timothy A. M. Ewin|, Andrew S. Gale|
‡ Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland§ Centre de Recherche en Paléontologie – Paris, Sorbonne Université, 4 place Jussieu, 75005 Paris, France| Department of Earth Sciences, The Natural History Museum London, Cromwell Road, South Kensington, London, SW7 5BD, United Kingdom
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Forcipulatacea is one of the three major groups of extantsea stars (Asteroidea: Echinodermata), composed of 400 extant species, butonly known from fewer than 25 fossil species. Despite unequivocal membersbeing recognized in the early Jurassic, the evolutionary history of thisgroup is still the subject of debate. Thus, the identification of any newfossil representatives is significant. We here reappraise Ophidiaster davidsoni de Loriol andPellat 1874 from the Tithonian of Boulogne, France, which was assigned toanother major extant group, the Valvatacea, and reassign it within a newforcipulatacean genus, Psammaster gen. nov. Psammaster davidsoni gen. nov. possess key Forcipulataceasynapomorphies including compressed ambulacrals and adambulacrals andtypical organization of the body wall and arm ossicles. A phylogeneticanalysis including Psammaster davidsoni gen. nov. does not place it within any existingforcipulatacean family. Instead, Psammaster davidsoni gen. nov. exhibits a mix of plesiomorphicand derived characters and is resolved as a sister clade to a large groupincluding the Asteriidae, Stichasteridae, and Heliasteridae. Removal of thisspecies from the Ophidiasteridae means their oldest fossil representativenow dates from the Santonian, Upper Cretaceous.