New Observations On The Vetulicola Longbaoshanensis From The Lower Cambrian Guanshan Biota (Series 2,Stage 4),South China

Cambrian vetulicolians are enigmatic metazoans which play an important role in understanding the early animal evolution.Vetulicola longbaoshanensis Yang et al.,2010 is a unique species reported from the Guanshan Biota,Cambrian Series 2 and Stage 4 at eastern Yunnan,South China,which expands our understanding of vetulicolians.Here new exceptionally preserved materials of V.longbashanensis from the Lower Cambrian Wulongqing Formation(the so-called Guanshan Biota)both in Wuding and Kunming areas are described,in which the gill structures of V.longbaoshanensis are well preserved.The gill structures of our fossils are much more complicated than those in the type species:the gill sac is gourd-shaped and can be divided into a smaller anterior part and a larger posterior part,prominent gill silt and dense gill filaments present in the joint of the two parts.Comparative analyses indicates that vetulicolians from the Guanshan Biota are comparable with the Vetulicola rectangulata Luo et Hu,1999 of the Chengjiang Biota in gross morphology.However,compared with the Vetulicola rectangulata,the Guanshan forms with a larger body size,a higher length/height ratio of anterior body,and the gill sac width/anterior height ratio is bigger,probably typifying the derive characters anticipated of vetulicolians.These new materials,therefore,shed new light on our understanding of vetulicolians morphology and the early evolution of the gill structures.