2026/07/16 by Sreyas Dasaradi · 1 voice
Earth and Planetary Sciences · Environmental Science · #Ichthyology and Marine Biology #Paleontology and Evolutionary Biology #Paleontology and Stratigraphy of Fossils
paper · doi:10.31233/osf.io/h3fj9_v2
openalex publication_date 2026/07/16 · openalex created_date 2026/07/17 · openalex updated_date 2026/07/17
Hemichordates today comprise two major groups: the free-living, vermiform Enteropneusta and the sessile, tube-dwelling Pterobranchia. The Burgess Shale enteropneust Oesia disjuncta has recently been suggested to build tubes of another enigmatic fossil, Margaretia dorus, which would shed considerable light on the evolution of the Hemichordata. By reviewing prior descriptions of Margaretia and related taxa, as well as comparing the details of Margaretia’s construction to those of undeniable hemichordate tubes, this paper finds that Margaretia could not have been secreted by a hemichordate, and that it may more likely represent an early complex alga. Less than 2% of Oesia specimens are found associated with Margaretia, suggesting that Oesia was not a tube-dwelling organism and supporting an ancestrally vagile epibenthic mode of life for Hemichordata.