ArticleBMC evolutionary biology2015
The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa.
Article in BMC evolutionary biology, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers.
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10 citing papers in PubMed.
- Two exceptionally preserved biotas from North Dakota reveal cryptic Ordovician shelf ecologies.Proceedings of the National Academy of Sciences of the United States of America · 2025Article
- Early Ordovician sea scorpions from Morocco suggest Cambrian origins and main diversification of Eurypterida.Proceedings. Biological sciences · 2025Article
- Convergent evolution of giant size in eurypterids.Proceedings. Biological sciences · 2024Article
- Late Ordovician eurypterid preserves oldest euchelicerate musculature in pyrite.Biology letters · 2024Article
- Five new malformed trilobites from Cambrian and Ordovician deposits from the Natural History Museum.PeerJ · 2023Article
- Spines and baskets in apex predatory sea scorpions uncover unique feeding strategies using 3D-kinematics.iScience · 2022Article
- A miniature Ordovician hurdiid from Wales demonstrates the adaptability of Radiodonta.Royal Society open science · 2020Article
- Insights into the 400 million-year-old eyes of giant sea scorpions (Eurypterida) suggest the structure of Palaeozoic compound eyes.Scientific reports · 2019Article
- A common arthropod from the Late Ordovician Big Hill Lagerstätte (Michigan) reveals an unexpected ecological diversity within Chasmataspidida.BMC evolutionary biology · 2019Article
- A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids.Die Naturwissenschaften · 2015Article
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5 authors.
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Abstract
backgroundEurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years.
resultsThe new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted.
conclusionsThe relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them.
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