A new thalassematid echiuran worm from the Middle Ordovician Castle Bank Biota of Wales, UK
chiurans (spoonworms) are a very distinctive group of polychaete annelids that had long been considered to constitute a separate phylum. Their fossil record is extremely limited, although trace fossils that have been suggested to be attributable to them date back as far as the Cambrian Period. The...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Institute of Paleobiology PAS
2023-12-01
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| Series: | Acta Palaeontologica Polonica |
| Subjects: | |
| Online Access: | https://www.app.pan.pl/archive/published/app68/app011072023.pdf |
| Summary: | chiurans (spoonworms) are a very distinctive group of polychaete annelids that had long been considered to constitute a separate phylum. Their fossil record is extremely limited, although trace fossils that have been suggested to be
attributable to them date back as far as the Cambrian Period. The oldest body fossils are from the Carboniferous Mazon
Creek Biota, and preserve only limited morphological detail. New material from the Middle Ordovician (Darrivilian,
Didymograptus murchisoni Biozone) Castle Bank Biota of Wales shows fine detail of the morphology of a new
taxon, Llwygarua suzannae gen. et sp. nov., including several details that indicate an assignment to the derived family
Thalassematidae, allied to the speciose genus Ochetostoma. These details include proboscis morphology, anterior setae,
and muscle organisation within the trunk. An additional specimen is described in open nomenclature, as it may be either a
distinct species, or a juvenile of Llwygarua suzannae gen. et sp. nov. with a relatively elongated proboscis. These worms
demonstrate a very early and previously unrecognised diversification of the echiuran grown group, further supporting an
early diversification of Annelida as a whole. |
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| ISSN: | 0567-7920 1732-2421 |