Jurassic Cladocera (Crustacea, Branchiopoda) with a description of an extinct Mesozoic order

This paper describes extinct Jurassic Cladocera (Crustacea: Branchiopoda) from four well-known palaeontological sites. Leptodorosida zherikhini sp. nov., gen. nov. from Ust'-Baley (Lower Jurassic) belongs to an extinct family, Leptodorosididae fam. nov., and a new order, the Cryptopoda ordo nov. This order differs from the Haplopoda and the Onychopoda in having serially-similar filtering limbs with valves completely covering the post-cephalic body. Cryptopoda differs from the Anomopoda and Ctenopoda in having antennae II with both exopod and endopod possessing four segments. Segments 2-4 of the exopod (and perhaps the endopod) possess numerous setae. A second cryptopod, Leposida ponomarenkoi sp. nov., gen. nov., was found in Chalunikha and Unda (Uppermost Jurassic). So, the extinct Crypopoda existed for at least 25 million years during the Jurassic. Our finding of an extinct order possessing characters intermediate between recent cladoceran orders provides fossil evidence for cladoceran monophyly. I also describe a new ctenopod, Smirnovidaphnia smirnovi sp. nov., gen. nov. from Ust'-Baley as a member of the family Sididae. It belongs to the tribe Sidini of the subfamily Sidinae, but differs from recent genera of this tribe in having numerous setae on the second exopod segment. Archedaphnia testacea Smirnov, 1971, previously described from Novospasskoye (Lower-Middle Jurassic), is apparently a ctenopod, and, most probably, a member of Smirnovidaphnia gen. nov. Finally, I found claws, presumably belonging to unknown claclocerans, from the Ust'-Baley and four other localities from the Lower to Upper Jurassic. I conclude that cladocerans were present and common in Mesozoic waters.