Paradoxides

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 : 163

Paradoxides paradoxissimus gracilis ( BOECK, 1827)

Text-fig. 2

Two partially enrolled specimens are discussed. The first specimen ( Text-fig. 2a , NM-L 4373) is 115 mm long and strongly flexed in the middle part of the thorax, so the cephalon and anterior-most part of the thorax are sub-parallel with the posterior-most part of the thorax and the pygidium. The cephalon is not in contact with pygidium and the specimen shows large lateral gaps filled by sediment. The maximal bending of the thorax is achieved from the 7 th to the 16 th tergite. From the dorsal view, the axial part of the anterior half of the body does not accurately overlap the posterior part; the posterior part is slightly inclined to the left. This specimen shows both left librigena and rostral-hypostomal plate preserved in situ. All pleurae are horizontally oriented in relation to the particular axial ring, and their distal parts and pleural spines do not overlap.

The second specimen ( Text-fig. 2b , GBA 1896/004/0057) was described and figured by Pompeckj (1896: pl. 16, fig. 1). This specimen is 160 mm long and has the posterior part of the trunk (behind the 10 th thoracic tergite) flexed anteroventrally. The dorsal part of its internal mold consists of cranidium and the anterior part of thorax; the 10 th posterior tergite is slightly inclined backwards. The antero-ventrally flexed posterior part of the thorax is partly seen under the exfoliated pleurae on the left side, and is also slightly imprinted on the right side of the body. From the position of the ventral part, it can be inferred that the pygidium, when preserved, is located approximately under the occipital ring, and that the posterior part of the thorax does not cover the entire ventral surface of the exoskeleton. The librigenae of this specimen are not preserved, nor is the rostral-hypostomal plate.

Figures

Text-fig. 2. Paradoxides paradoxissimus gracilis (BOECK, 1827); Jince Formation, Paradoxides paradoxissimus gracilis Biozone, Příbram-Jince Basin: a – specimen no. NM-L 4373, from dorsal (a1), oblique lateral (a2) and ventral (a3) view; b – specimen no. GBA 1896/004/0057, dorsal view; c – outstretched specimen no. NM-L 41167, dorsal view. Abbreviations: rp – rostral-hypostomal plate.