Jurassic Bryozoans of the Family Eleidae (Melicerititida, Stenolaemata)

Abstract

Skeletal morphology of bryozoans of the family Eleidae d’Orbigny, 1852 (Melicerititida, Stenolaemata) and of three of its species from the Middle Callovian (Middle Jurassic) of the Moscow region—Elea lyapini Viskova, 2011, E. troshkovensis Viskova, 2011, and E. taylori Viskova, 2011 was analyzed, confirming that these species belong to the family Eleidae. Along with opercula (calcareous and possibly non-calcareous) and eleozooids (heterozooids), they are characterized by funnel-shaped autozooids, facettes and the distal position of apertures with a straight proximal edge, the absence of peristomes and a number of other characters. This morphology is considered to have resulted from the restructuring of the basic plan of the cylindrical autozooid of tubuliporid bryozoans that happened after the Permian–Triassic crisis at the time of the first radiation of bryozoans during the extensive Callovian transgression.