Graptolite ( H emichordata, P terobranchia) preservation and identification in the C ambrian S eries 3

Due to inadequate preservation, pterobranchs are often difficult to identify in the fossil record, and a better understanding of preservational modes and diagenetic and metamorphic effects is needed for their recognition. Pterobranch hemichordates are common in C ambrian S tage 5 and younger sedimentary rocks, but are frequently overlooked. Often, pterobranch hemichordate colonies have been considered to be algal remains or hydroids. Re‐examination of C ambrian B urgess Shale algae reveals that the genera Y uknessia and D alyia can be recognized as putative early representatives of pterobranch hemichordates. Distinct fusellar construction of the individual zooidal tubes and branching of the creeping proximal part of the colonies are found in the morphologically similar rhabdopleurid pterobranch genus S phenoecium . The erect tubes of S phenoecium do not branch and can reach a length of several centimetres. The development of the fusellar construction in this taxon shows a highly irregular development of the suture patterns, but a fairly consistent height of the individual fuselli. The taxon is widely distributed in the C ambrian S eries 3, but has regularly been identified as a hydroid or an alga. S phenoecium wheelerensis from the C ambrian W heeler S hale of U tah is described as new.