The holotype amber specimen, number Tad-277, is currently housed in the fossil collection of the Birbal Sahni Institute of Palaeobotany in Lucknow, India and the second known adult, Tad-96 is in the collections of the American Museum of Natural History.
Reconnoitered by the New Zealand Antarctic Research Program (NZARP) Allan Hills Expedition, 1964, and named after Marie Stopes, authority on Carboniferous palaeobotany, and hence associated with the geology of the area.
In botany, in addition to a memoir on the minute structure of Volvox (1852), his work on the structure of fossil plants established British palaeobotany on a scientific basis; Williamson ranks with Adolphe Theodore Brongniart as one of its founders.