Metacrininae Klikushin, 1977

Roux, Michel & Philippe, Michel, 2021, Early Miocene stalked crinoids (Echinodermata) from the southern Rhodanian basin (southeastern France). Paleoenvironments and taxonomy, Zootaxa 5052 (3), pp. 301-331 : 317

Subfamily Metacrininae Klikushin, 1977

Remarks. Metacrininae differ from all other Isocrinida in having more than 2 IBr with IBr2 bearing the first pinnule, and a muscular synarthry at IIBr1+2. The primibrachitaxis has a synostose at IBr4+5 when the number of IBr is>4. Their stalk symplexies display closed ZP and axial grooves in ZIP (Roux 1977, 1981). Two genera with a synostosis at IBr1+2 are distinguished in extant Metacrininae ( Améziane-Cominardi 1991, Bourseau and Roux 1989, Hess 2011, Roux 1981): Saracrinus with usually 3–6 IBr (mode 4) and <10 IIBr, and Metacrinus having usually>4 IBr (mode 7) and>10 IIBr. The Eocene species Metacrinus fossilis Rasmussen, 1980 and Eometacrinus australis Baumiller and Gazdzicki, 1996 have a proximal crown with 5 IBr and 9–10 IIBr. Such an arm pattern is intermediate between Saracrinus and Metacrinus . Eometacrinus differs in having an axial ligamentary synarthry at IBr1+2. Metacrinus seymouriensis Rasmussen, 1980 is only known from pluricolumnals found in the Maastrichtian.