Acadoparadoxides, SNAJDR, 1957

Laibl, Lukáš, Esteve, Jorge & Fatka, Oldřich, 2016, Enrollment And Thoracic Morphology In Paradoxidid Trilobites From The Cambrian Of The Czech Republic, Fossil Imprint 72 (3 - 4), pp. 161-171 : 166

Acadoparadoxides cf. sacheri ( BARRANDE, 1852)

Text-fig. 5b

Well preserved complete specimens of this species are very rare, and detailed information about the thoracic structure and pleural morphology is thus limited. The exoskeleton is micropygous, with rather sub-rectangular thorax. The posterior-most pleurae of A. cf. sacheri seem to be separated by comparatively wide gaps (cf. Barrande 1852: pl. 9, fig. 30, Šnajdr 1958: pl. 17, fig. 1). Articulating half-rings length (sag.) varies between 50–45% of the axial ring length. Pleurae in the anterior part of the thorax are fulcrate ( Text-fig. 5b ). At their anterior margin, they bear a narrow (sag.) flange that widens abaxially, and ends with a small projection near the fulcrum ( Text-fig. 5b ). Pleural spines are comparatively long and saber-like in shape. The petaloid-like terrace lines are sub-parallel to anterior margin of the pleural spines, and are developed on their dorsal surfaces ( Text-fig. 5b ). The ventral doublure of pleural spines is poorly preserved.

Figures

Text-fig. 5. Thoracic structure, articulating and coaptative devices of H. minor (a, d, f–g), P. paradoxissimus gracilis (c, e, h–j) and A. cf. sacheri (b): a – specimen no. NM-L 46550, internal mold of pleurae; b – specimen no. NM-L 4776, internal mold of pleura; c – specimen no. NM-L 46551, internal mold of pleurae; d – specimen no. NM-L 46550, internal mold of axial rings and articulating half-rings; e – specimen no. NM-L 46552, internal mold of axial rings and articulating half-rings; f – specimen no. NM-L 46550, detail of pleural spine; g – specimen no. NM-L 41157, external mold of pleural spines; h – specimen no. NM-L 46547, external mold of pleural spines; i – specimen no. NM-L 46548, external mold of pleural spines; j – specimen no. NM-L 46549, pleural spines. Abbreviations: ahr – articulating half ring; alp – antero-lateral projection of flange; bp – backward projection at base of pleural spine; dtl – dorsal terrace lines; fl – flange; fu – fulcrum; ptl – petaloid-like terrace lines; vf – ventral furrow of pleural spine; vtl – ventral terrace lines.