Casterolimulus

{{Short description|Genus of horseshoe crab relatives}}

{{speciesbox

| fossil_range = Late Cretaceous

| parent_authority = Holland, Erickson & O'Brien, 1975

| taxon = Casterolimulus kletti

| authority = Holland, Erickson & O'Brien, 1975

| image = Casterolimulus.png

| image_caption = Casterolimulus kletti from the Fox Hills Formation

}}

Casterolimulus is an extinct genus of xiphosuran.{{cite journal |author=F. D. Holland Jr. |year=1975 |title=Casterolimulus: a new late Cretaceous generic link in limulid lineage |journal=Bulletins of American Paleontology |url=https://archive.org/details/bulletinsofameri287pale |volume=67 |issue=287 |pages=[https://archive.org/details/bulletinsofameri287pale/page/n278 235]–246}} It is known from the Late Cretaceous Fox Hills Formation of North America, and is believed to have lived in freshwater environments. It belongs to the family Limulidae, and is considered a close relative of Victalimulus, which is from the Early Cretaceous of Australia.{{Cite journal |last=Lamsdell |first=James C. |date=March 2021 |title=A new method for quantifying heterochrony in evolutionary lineages |url=https://www.cambridge.org/core/product/identifier/S0094837320000172/type/journal_article |journal=Paleobiology |language=en |volume=47 |issue=2 |pages=363–384 |doi=10.1017/pab.2020.17 |issn=0094-8373|doi-access=free }}