Isocrania

Isocrania Temporal range: Turonian–Danian PreЄ Є O S D C P T J K Pg N
Isocrania egnabergensis, 7 mm Ø
Scientific classification
Kingdom:	Animalia
Phylum:	Brachiopoda
Class:	Craniata
Order:	Craniida
Family:	Craniidae
Genus:	†Isocrania Jäckel, 1902
Species
I. egnabergensis (Retzius, 1781) type species= Crania engabergensis, regularly misspelled as ignabergensis I. barbata (Von Hagenow, 1842) = Crania barbata I. borealis Ernst, 1984 I. campaniensis Ernst, 1984 I. costata (J. Sowerby, 1823) = Crania costata I. paucicostata (Bosquet, 1859) = Crania paucicostata I. phosphatica Simon, 1998 I. praecostata Ernst, 1984 I. restricta Ernst, 1984 I. sendeni Simon, 2007

Isocrania is an extinct genus of brachiopods found during the Upper Cretaceous. Early representatives were attached to the underground, but later species are presumed to be free living at an increasingly earlier age. This was probably an adaptation to the increasing very thick and fine sedimentation during the latest Cretaceous.

Isocrania egnabergensis, lateral view

internal

Isocrania is round to ovate, up to 1 cm in diameter, and has 15-65 strong ribs, that start at ±½mm from the origin of growth (or umbo). These ribs may extend beyond the edge of the valves. The umbo is not precisely in the centre of the valve. The attachment area is smaller than usual, and virtually absent in adults of later species. The dorsal valve is conical, the ventral valve flat to conical, flatter for adolescents and earlier species. The inner edge of the valves is flattened and grainy.

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