A revision of the extinct Mesozoic family Prochydoridae Smirnov, 1992 (Crustacea: Cladocera) with a discussion of its phylogenetic position Author Kotov, Alexey A. text Zoological Journal of the Linnean Society 2009 2009-02-28 155 2 253 265 https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2008.00412.x journal article 3182 10.1111/j.1096-3642.2008.00412.x e78a1472-d6c2-41b4-84d9-cbacfa420a67 0024-4082 4687730 ARCHEOXUS MIRABILIS SMIRNOV, 1992 ( FIGS 1D–E , 4A–H) Smirnov, 1992a: 112 , figs 1A–C, 2A, B, 4A, F, 9C, 12A, F Type locality: Khotont, Jurassic–Cretaceous boundary (see above). Holotype : PIN 4307 /2028 and 2036 (impression and counter-impression). Paratypes : PIN 4307 /2001, 2007, 2011, 2012, 2015, 2023 and PIN 4307 /2033. The recent state of Smirnov’s (1992a) paratypes PIN 4307 /2006, 2010, 2034 and 2037 is too poor for their accurate determination . Other material studied: PIN 4307 /2007-2 (an impression on the same rock fragment with paratype 2007), 2018, 2041, 2047 . Diagnosis: As for the genus. Description: Body moderately high (height/length = 0.72–0.79), subovoid in lateral view, dorsum regularly convex, postero-dorsal angle ill defined or absent. Head about 0.4¥ body length, head capsule of the ‘chydorid-type’, covered with a ‘flat’ head shield, with thin, pointed rostrum. Valve ventral margin without denticles or setae. Postabdominal claw supplied with denticles. Antenna II relatively long. Exopod length 0.32–0.35 body length, its proximal segment large, with length approximately as length of 2+3 segments. Endopod somewhat shorter than exopod, its proximal segment somewhat longer than second segment. Antennal formula (4–5)–(1)–(3)/(1)–(1)–(3). Mandible small, mandibular joint located exactly at the point where margins of head and the well-chitinized valves come together. In specimens where the head and valve were separated, the mandibular joint remained associated with valve ( Fig. 4B ). Gut thin, not convoluted ( Fig. 4A ). Length 2.0– 2.9 mm .