Open AccessThe debated question of asymmetrical rhynchonellids (Brachiopoda, Rhynchonellida): examples from the Late Cretaceous of Western Europe
Author(s) -
Danièle Gaspard,
Sylvain Charbonnier
Publication year - 2020
Publication title -
bulletin de la société géologique de france
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.584
H-Index - 53
eISSN - 1777-5817
pISSN - 0037-9409
DOI - 10.1051/bsgf/2019016
Subject(s) - cenomanian , cretaceous , paleontology , genus , geology , western europe , zoology , biology , european union , economic policy , business
Many Cretaceous asymmetrical rhynchonellid brachiopods (Brachiopoda, Rhynchonellida) have long been considered as Rhynchonella difformis (Valenciennes in Lamarck, 1819). After a revision, Owen (1962) included the Cenomanian specimens from Europe in Cyclothyris M’Coy, 1844. Later, Manceñido et al. (2002) confirmed this decision and critically mentioned the name of another asymmetrical rhynchonellid genus from Spain, Owenirhynchia Calzada in Calzada and Pocovi, 1980. Specimens with an asymmetrical anterior margin (non particularly ecophenotypical), from the Late Coniacian and the Santonian of Les Corbières (Aude, France) and Basse-Provence (SE France) are here compared to specimens of the original Cenomanian species C. difformis . They are also compared to new material from the Northern Castilian Platform (Coniacian-Santonian, N Spain) and to Rhynchonella globata Arnaud, 1877 (Campanian, Les Charentes, Dordogne, SW France) and Rh. vesicularis Coquand, 1860 (Campanian, Charente, SW France). These observations document the great morphological diversity among all these species and lead us to erect a new species: Cyclothyris grimargina nov. sp. from the type material of Arnaud, and two new genera: Contortithyris nov. gen. including Contortithyris thermae nov. sp., Beaussetithyris nov. gen. including Beaussetithyris asymmetrica nov. sp. All of these brachiopods fundamentally present an asymmetrical state which origin is discussed.