# Pruemopterus

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***Pruemopterus*** is a [genus](/source/Genus) of [eurypterid](/source/Eurypterid), an extinct group of aquatic [arthropods](/source/Arthropod). The [type](/source/Type_species) and only species of *Pruemopterus*, *P. salgadoi*, is known only from a single fossil specimen discovered in [geological deposits](/source/Deposition_(geology)) of [Early Devonian](/source/Early_Devonian) age in [Germany](/source/Germany). The name of the genus is derived from the [Prüm river](/source/Pr%C3%BCm_(river)) and the surrounding Prüm valley, which contains the finding place of the fossil, and the [Ancient Greek](/source/Ancient_Greek) [πτερόν](https://en.wiktionary.org/wiki/%CF%80%CF%84%CE%B5%CF%81%CF%8C%CE%BD) (*pteron*, "wing"), referring to the eurypterid swimming paddles, and the species name honors the Brazilian photographer and photojournalist [Sebastião Salgado](/source/Sebasti%C3%A3o_Salgado).

*Pruemopterus* was a very small eurypterid, with the only known specimen measuring about 2.5 centimeters (0.98 in) in length. Although superficially similar to the related genus *[Parahughmilleria](/source/Parahughmilleria)*, *Pruemopterus* can be distinguished from other [adelophthalmoid](/source/Adelophthalmoidea) eurypterids by several features, most notably its wide and vaguely rectangular carapace (head plate) and its rounded, rather than elongated, eyes. *Pruemopterus* lived alongside other Early Devonian animals, including several other eurypterid genera, in a shallow [brackish](/source/Brackish_water) to [fresh water](/source/Fresh_water) environment.

## Description

*Pruemopterus* was a very small [eurypterid](/source/Eurypterid), only measuring about 2.5 centimeters (0.98 in) in length. The [carapace](/source/Carapace) (head plate) of *Pruemopterus* was vaguely rectangular in shape, and was about 3.8 millimeters (0.15 in) long and 7.5 millimeters (0.3 in) wide. The [compound eyes](/source/Compound_eyes) of *Pruemopterus* were round and placed in an [anterior](/source/Anterior) centrimesial (forward-central) position. Along the seventh to twelfth segments of the [opisthosoma](/source/Opisthosoma) ([posterior](/source/Posterior_(anatomy)) body), *Pruemopterus* had strong lateral epimera ("extensions" along the edges). The posterior body of *Pruemopterus* was relatively wide, with the pretelson (the last body segment, before the tail) being about half as long as it was wide. The [telson](/source/Telson) ("tail") itself was lanceolate (lance-shaped) and robust. As in other adelophthalmoids, the walking legs of *Pruemopterus* were spiniferous (having [spines](/source/Spine_(zoology))). Though they are only preserved fragmentarily, the amount of spinosity (how spiniferous the legs were) appears to have been similar to the related *[Adelophthalmus](/source/Adelophthalmus)*. The genital appendage (a ventral "rod" part of the [reproductive system](/source/Eurypterid#Reproductive_biology)) is present in the only known specimen but it is poorly preserved, with its [distal](/source/Distal) end missing. It spanned from the first to the third [sternite](/source/Sternite) (ventral half of the body segment) and was of type A, that is, the specimen was female.[1]

## History of research

The only known specimen of *Pruemopterus* was discovered by the German paleontologist Markus J. Poschmann in the 1980s. It was discovered in a now disused sandstone quarry within the municipality of [Hermespand](/source/Hermespand), close to the village itself and to that of [Willwerath](/source/Willwerath), in [Weinsheim](/source/Weinsheim,_Bad_Kreuznach), Germany. The fossil [deposits](/source/Deposition_(geology)) the specimen was uncovered in belong to the [Klerf Formation](/source/Klerf_Formation) and are of [Early Devonian](/source/Early_Devonian) age, specifically the uppermost Lower [Emsian](/source/Emsian) epoch.[1]

The fossil was not formally described by Poschmann until 2020, when he determined that the combination of traits displayed suggested that it was an adelophthalmoid eurypterid similar to *[Parahughmilleria](/source/Parahughmilleria)*, known from the same deposits, but differing in features of its carapace, opisthosoma and telson. Poschmann thus named the new [genus](/source/Genus) and species *Pruemopterus salgadoi* to accommodate the specimen. The specimen is today housed at the Generaldirektion Kulturelles Erbe, Direktion Landesarchäologie/Erdgeschichte in [Koblenz](/source/Koblenz), Germany, and is part of the State Collection of Natural History of Rhineland-Palatinate. Originally given the provisional designation 355-D by Poschmann, the specimen now has the repository number PWL 2014/5186-LS a,b (a being the part and b being the counterpart of the [compression fossil](/source/Compression_fossil)).[1]

The generic name *Pruemopterus* is derived from the [Prüm river](/source/Pr%C3%BCm_(river)) and the surrounding Prüm valley, wherein Hermespand and Willwerath are located, and the suffix '-*opterus*', derived from the [Ancient Greek](/source/Ancient_Greek) [πτερόν](https://en.wiktionary.org/wiki/%CF%80%CF%84%CE%B5%CF%81%CF%8C%CE%BD) (*pteron*, "wing"), often used in naming eurypterids due to the broad, wing-like swimming appendages of the [eurypterine](/source/Eurypterina) suborder. The species name *salgadoi* honors the Brazilian photographer and photojournalist [Sebastião Salgado](/source/Sebasti%C3%A3o_Salgado).[1]

## Classification

Poschmann referred *Pruemopterus* to the eurypterid family Adelophthalmidae, then considered the only family within the superfamily [Adelophthalmoidea](/source/Adelophthalmoidea). In particular, Poschmann noted that morphological comparisons with other adelophthalmid genera suggest that *Pruemopterus* was most closely related to *Parahughmilleria*. Still, *Pruemopterus* differs from other adelophthalmoid eurypterids mainly in features of its carapace and its eyes. The short and rectangular carapace of *Pruemopterus*, and its eyes being rounded rather than elongated, easily distinguishes the genus from the adelophthalmid genera *[Pittsfordipterus](/source/Pittsfordipterus)*, *[Bassipterus](/source/Bassipterus)*, *[Nanahughmilleria](/source/Nanahughmilleria)* and *Adelophthalmus*. The same also applies to *Parahughmilleria*, which lived during the same epoch as *Pruemopterus*, although the species *Parahughmilleria hefteri* (possibly a younger growth stage of the species *Parahughmilleria major*) is superficially similar to *Pruemopterus* in its streamlined body shape and the lateral epimera along the same segments of the opisthosoma. *Pruemopterus* can be distinguished from *Parahughmilleria hefteri* by several features, including its more centrally positioned and rounder eyes, its wider carapace, the epimera being much more prominent, and the telson being broader and more robust. Another difference between *Pruemopterus* and *Parahughmilleria* is that the opisthosomal segments of *Pruemopterus* are more or less constant in length, whereas they increase in length posteriorly in *Parahughmilleria*. The genus *[Unionopterus](/source/Unionopterus)*, probably an adelophthalmid, is fragmentarily known, which complicates comparisons, but is clearly different from *Pruemopterus* in its smaller eyes and the wider marginal rim of its carapace.[1]

Poschmann also noted in his description of the [type specimen](/source/Type_specimen) that there were also close similarities to the [Hughmilleriidae](/source/Hughmilleriidae) in the [Pterygotioidea](/source/Pterygotioidea) superfamily, though *Pruemopterus* differed from the genera in that family in having prominent lateral epimera on its opisthosomal segments (a feature for the most part missing among the hughmilleriids) and its eyes not being placed on the margin of the carapace.[1]

In a 2025 eurypterid monograph, James Lamsdell placed *Pruemopterus* in the family [Parahughmilleriidae](/source/Parahughmilleriidae) in Adelophthalmoidea, placing *Pruemopterus* as the sister taxon of *Parahughmilleria*.**[2]** The cladogram below follows the phylogenetic analysis of Lamsdell (2025).**[2]**

## Paleoecology

The deposits in which the *Pruemopterus* fossil was discovered are part of an Early Devonian fossil locality called the "Fossil-Lagerstätte Willwerath" that has yielded numerous early land plants, arthropods and vertebrates. Among the [chelicerates](/source/Chelicerates), to which the eurypterids belong, the Early Devonian deposits have yielded both [arachnids](/source/Arachnids)[1] (*[Devonotarbus hombachensis](/source/Devonotarbus)* and *[Xenarachne willwerathensis](/source/Xenarachne)*)[3] and early [xiphosurans](/source/Xiphosura) (genus *[Willwerathia](/source/Willwerathia)*). Eurypterids are especially diverse in these deposits, accounting for five genera in addition to *Pruemopterus*: *[Jaekelopterus](/source/Jaekelopterus)*, *[Rhenopterus](/source/Rhenopterus)*, *[Erieopterus](/source/Erieopterus)*, *Adelophthalmus* and *Parahughmilleria*.[1] *Pruemopterus* appears to have lived in non-marine aquatic environments. The Early Devonian eurypterid-yielding fossil sites in the Rhineland have been interpreted as having been part of a shallow aquatic environment with [brackish](/source/Brackish_water) to [fresh water](/source/Fresh_water),[4] such as an [estuary](/source/Estuary) or a [bay](/source/Bay). The [lithology](/source/Lithology) of the deposits in which *Pruemopterus* was discovered is composed of [lithified](/source/Lithification) gray [siltstone](/source/Siltstone).[3]

## See also

- [List of eurypterid genera](/source/List_of_eurypterid_genera)
- [Timeline of eurypterid research](/source/Timeline_of_eurypterid_research)

## References

1. Poschmann, Markus J. (2020). ["A new sea scorpion (Arthropoda, Eurypterida) from the Early Devonian of Willwerath (Rhineland-Palatinate, SW Germany)"](https://link.springer.com/article/10.1007%2Fs12542-020-00519-6). *[PalZ](/source/PalZ)*. **95**: 17–26. [doi:10.1007/s12542-020-00519-6](https://doi.org/10.1007/s12542-020-00519-6). [S2CID 221478876](https://api.semanticscholar.org/CorpusID:221478876)

1. Lamsdell, James C. (2025). "Codex Eurypterida: A Revised Taxonomy Based on Concordant Parsimony and Bayesian Phylogenetic Analyses". *Bulletin of the American Museum of Natural History*. **2025** (473): 55–56, 124–138. [doi:10.1206/0003-0090.473.1.1](https://doi.org/10.1206/0003-0090.473.1.1)

1. ["Willwerath (Mainz collection) (Devonian of Germany)"](https://paleobiodb.org/classic/basicCollectionSearch?collection_no=155775). *[Paleobiology Database](/source/Paleobiology_Database)*. Retrieved 22 January 2024.

1. Poschmann, Markus & Tetlie, O. Erik (2006). ["On the Emsian (Lower Devonian) arthropods of the Rhenish Slate Mountains: 5. Rare and poorly known eurypterids from Willwerath, Germany"](https://link.springer.com/article/10.1007/BF02990208). *Paläontologische Zeitschrift*. **80** (4): 325–343. [Bibcode:2006PalZ...80..325P](https://ui.adsabs.harvard.edu/abs/2006PalZ...80..325P). [doi:10.1007/BF02990208](https://doi.org/10.1007/BF02990208). [S2CID 129716740](https://api.semanticscholar.org/CorpusID:129716740)

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Adapted from the Wikipedia article [Pruemopterus](https://en.wikipedia.org/wiki/Pruemopterus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Pruemopterus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.