# Paucijaculum

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Cambrian genus of chaetognath

Paucijaculum Temporal range: Moscovian, ~311–307 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N Paucijaculum samamithion specimen from Mazon Creek Pit 11 Scientific classification Kingdom: Animalia Phylum: Chaetognatha Genus: †Paucijaculum Schram, 1973 Species: †P. samamithion Binomial name †Paucijaculum samamithion Schram, 1973

***Paucijaculum*** is an extinct genus of [chaetognath](/source/Chaetognath) from the [Carboniferous](/source/Carboniferous) age [Francis Creek Shale](/source/Mazon_Creek_fossil_beds) and [Carbondale Group](/source/Carbondale_Group) of [Illinois](/source/Illinois), United States.[2] It contains one species, ***Paucijaculum samamithion***.

## Discovery and naming

The holotype is **FMNH PE116** and it was discovered no later than 1972 inside an [ironstone](/source/Ironstone) concretion at Pit 11 at Mazon Creek.[3] [Schram](/source/Frederick_Schram) (1973) named and described *Paucijaculum samamithion* as the oldest known and first known fossil chaetognath;[3] this was accepted until *[Eognathacantha](/source/Eognathacantha)* was identified from the [Cambrian Stage 3](/source/Cambrian_Stage_3) in [China](/source/China).[4]

Additional specimens have been found in the [Carbondale Group](/source/Carbondale_Group) near [Essex, Illinois](/source/Essex%2C_Illinois).[5]

## Description

Closeup of the rounded tail fin of *Paucijaculum samamithion*

*Paucijaculum* grew up to 3 centimetres (1.2 in) long and had incipiently developed fins alongside a circular tail fin.[3]

Most specimens are poorly preserved and lack detail.[3]

## References

1. **[^](#cite_ref-Allison1987_1-0)** P. A. Allison (1987). "A new cephalopod with soft parts from the Upper Carboniferous Francis Creek Shale of Illinois, USA". *[Lethaia](/source/Lethaia)*. **20** (78): 117–121. [doi](/source/Doi_(identifier)):[10.1111/j.1502-3931.1987.tb02028.x](https://doi.org/10.1111%2Fj.1502-3931.1987.tb02028.x).

1. **[^](#cite_ref-2)** ["*Paucijaculum* Schram, 1973"](https://www.gbif.org/species/4632577). *GBIF*. Retrieved 9 February 2026.

1. ^ [***a***](#cite_ref-:0_3-0) [***b***](#cite_ref-:0_3-1) [***c***](#cite_ref-:0_3-2) [***d***](#cite_ref-:0_3-3) F. R. Schram. (1973). Pseudocoelomates and a nemertine from the Illinois Pennsylvanian. *Journal of Paleontology* 47:985-989

1. **[^](#cite_ref-4)** Chen, Jun-Yuan; Huang, Di-Ying (2002-10-04). ["A Possible Lower Cambrian Chaetognath (Arrow Worm)"](https://doi.org/10.1126/science.1075059). *Science*. **298** (5591): 187–187. [doi](/source/Doi_(identifier)):[10.1126/science.1075059](https://doi.org/10.1126%2Fscience.1075059). [ISSN](/source/ISSN_(identifier)) [0036-8075](https://search.worldcat.org/issn/0036-8075).

1. **[^](#cite_ref-5)** ["1" Fossil Arrow Worm (*Paucijaculum*) Pos/Neg- Illinois"](https://www.fossilera.com/fossils/1-0-fossil-arrow-worms-paucijaculum-pos-neg-illinois?srsltid=AfmBOop8lubm__iJ42v63zvqBAk03WtqwRphStQ0W1FZXtlyomeUMZsv). *FossilEra*. Retrieved 11 February 2026.

Taxon identifiers Paucijaculum Wikidata: Q138108412 GBIF: 4632577

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