Fig. 62. Eocrinoid brachiolar plates A in An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia

Fig. 62. Eocrinoid brachiolar plates A (A–H) and associated thecal-plates (I–L) from lower Cambrian Emyaksin Formation, Bol'shaya Kuonamka River, Anabar Uplift, Siberia; sample 7/42.3. A. Twisted, elongated, brachiolar-plate, SMNH Ec 31488, A1, view of longitudinal articulation (proximal articulation to the base); A2, lateral, oral view (proximal articulation to the base); A3, close-up of proximal articulations with depression surrounding the aboral canal (to the left) and oral groove on the left (composed of half median-furrow and lateral depression to the right); A4, oblique view of distal (upward) and longitudinal articulations. B. Plates articulated longitudinally with irregularly undulose proximal and distal articulation facets, SMNH Ec 314899; B1, oral view with aboral canal visible upward due to the slightly eroded floor of oral, median furrow (proximal articulation to the base); B2, oblique view of proximal articulation with crescentic concavity (aboral canal most probably secondary filled) and distinct tripartite food-groove. C. Oral view of 2 plates articulated longitudinally with undulose, offset proximal (to the base) and distal articulations, SMNH Ec 31490. D. Distal view of isolated brachiolar plates with concave articulation, wide oral-groove (upper-left) and large, oval aboral-groove (upper-right), SMNH Ec 31491. E. Flat and elongated brachiolar plate, SMNH Ec 31492; E1, oblique view of proximal articulation (aboral canal to the right); E2, oblique aboral view of the longitudinal articulation (made of two longitudinal ridges delimiting aboral canal; to the right), the flat distal (to the top) and the angular proximal articulation (to the base). F. Flat brachiolar-plate in lateral (median) view with flat longitudinal articulation-ridge (aboral canal to the right), SMNH Ec 31493. G. Two articulated brachiolar plates (to the middle) delimiting a large, oval aboral-canal partly preserved in diagenetized matrix with thecal plates of unknown affinity (to the top and base), SMNH Ec 31494. H. Articulated (in the middle, aboral canal filled by exogenous grain) and isolated brachiolar plates partly preserved in diagenetized matrix, SMNH Ec 31495. I–L. Rounded to polygonal, concavo-convex thecal plates of unknown affinity. I. Outer view of plates partly preserved in matrix, SMNH Ec 31496. J, K. Outer views of plates ornamented with meshwork, SMNH Ec 31497 and SMNH Ec 31498, respectively. L. SMNH Ec 31499, slightly broken, rounded thecal-plates; L1, outer-surface ornamented with tubercles; L2, inner and L3, lateral view showing the smouth concave inner surface. Scale bar: 600 μm, except I, 1200 μm.