GOGIID EOCRINOIDS (ECHINODERMATA) FROM THE LOWER CAMBRIAN BALANG FORMATION, GUIZHOU PROVINCE, CHINA, SOME WITH PRESERVED SOFTPART SUTURAL PORE STRUCTURES

Numerous complex articulated specimens of a new gogiid eocrinoid have been recently discovered in the Lower Cambrian (Duyunian) Balang Formation outside the city of Kaili in eastern Guizhou Province, China. Gogiids are found in the upper half of the 600 m thick formation in silty shales. The single species is clavate with numerous narrow sutural pores in adult specimens. Stalk is long, gradationally plated with theca, commonly with rosettes of added intercalated plates and with a small distal attachment disc. The exothecal brachioles are counter-clockwise spiraled, and have very tall pointed cover plates. Juvenile specimens have sequentially; (?)1-0-1 (2 brachioles), 2-0-2 (4 brachioles) and a primary 2-1-2 (5 brachioles) pattern, the latter attained in early mature stages. Commonly at thecal height ca. TH = 10 to 12 mm, the exothecal brachioles branch to the final stage (10 brachioles). Sutural pores appear late in ontogeny, TH = ca.6 mm, in a narrow band directly under the ambulacrum and can persist to TH = ca.10 mm. After TH = ca. 9 mm sutural pore development commonly develops distally down the theca and by TH = 16 mm the entire theca is covered by pores. Rarely, soft part impressions of sutural pores are preserved and appear to be pocket-like structures that extend from the margins of the pore into the theca to a depth of about the maximum width of the pore opening. These impressions are found in clusters and their morphology suggests that they everted to the outside by postmortem putrefaction gases. It seems unlikely that these (postmortem) blisters were protruding to the outside in life; their anchoring to the theca extends from the inside of the pore and not from the base of the well developed pore rims. This internal pocket structure may well be the precursor to diplopores, rhomb structures and cothurnopores and is more a parsimonious explanation than fragile external respiratory blisters. The Balang gogiid like the similar Sinoeocrinus lui from the basal Middle Cambrian Kaili Biota appear to attach directly (bioglue?) to the seafloor and not to organic remains. .