Composition of the Jurassic (Hettangjan-Tithonian) foraminiferal communitie
s in three paleozoo-chores: Tethyan, Boreal-Atlantic, and Arctic, is consid
ered. Foraminiferal taxons of all ranks (from species to orders) are analyz
ed with an emphasis given to the generic lever, which objectively reflects
the macroevolutionary process in the geological record. The Triassic-Jurass
ic boundary is marked by the mass extinction of foraminifers (about 55 gene
ra) that was particularly pronounced among miliolids (22), involutinids (11
), rotaliids (7), and lagenids (4).(1) Five major stages of foraminiferal e
volution in the Jurassic are outlined: (I) Rhaetian-Lias (including the Het
tangian Planorbis Zone) stage marked by the crisis in the foraminiferal dev
elopment; (II) initial Early Jurassic stage characterized by the low divers
ity in the Hettangian-initial Sinemurian and by a sharp diversity increase
at the end of the Sinemurian, in the Pliensbachian (particularly, in the la
te substage), and Toarcian; (III) Middle Jurassic (pre-Callovian) stage dis
playing the crisis trend at the Toarcian-Aalenian boundary and the taxonomi
c diversity increase in the Bajocian-Bathonian assemblages, particularly in
the Tethys; (TV) Callovian-Oxfordian bloom universally accompanied by an i
ntense radiation; and (V) Kimmeridgian-Tithonian stabilization period. The
most important event in the evolution of Jurassic foraminifers was the appe
arance of first planktonic genera in the Bajocian. The foraminiferal divers
ity dynamics was fluctuating against the general background of about two-fo
ld increase in the taxa abundance during the period from the Hettangian to
Tithonian (60 and 127 new genera, respectively, versus 243 known genera of
Jurassic foraminifers).