Graptolites (Graptolithina) + pterobranchs (Pterobranchia) = hemichordate class Graptolithoidea.
Graptolite NetScience, Earth Sciences, Paleontology, Invertebrates - Graptolite Net. Links to graptolite and pterobranch pages, abstracts, articles, graptolite researchers.
Graptolites (Graptolithina) + pterobranchs (Pterobranchia) = hemichordate class Graptolithoidea.
Graptolite Net