2006/11/21 by Nicholas J. Butterfield · 6 citations
Earth and Planetary Sciences · #Marine Biology and Ecology Research #Paleontology and Stratigraphy of Fossils #Geology and Paleoclimatology Research
paper · doi:10.1002/bies.20507
openalex publication_date 2006/11/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/22
The fossil record plays a key role in reconstructing deep evolutionary relationships through its documentation of the early diverging stem groups leading to extant phyla. In the middle Cambrian Burgess Shale, two famously problematic worms, Odontogriphus and Wiwaxia, have recently been reinterpreted as stem-group molluscs based on their shared expression of a putative radula and putative ctenidia in Odontogriphus. More detailed analysis of these fossil structures, however, reveals pronounced anatomical and histological discrepancies with molluscan analogues, such that they are more reliably interpreted as primitive features of the superphylum Lophotrochozoa. In the absence of any obviously derived characters, Odontogriphus could be placed in the stem group of the Lophotrochozoa or on the stem of any of its constituent phyla, whereas the dorsal covering of chaetae in Wiwaxia identifies it as a stem-group polychaete. Despite their close relationship, these two jawed, segmented worms could conceivably represent the early stages of two separate phyla.