page_title: Rhenopteridae
section_title: Evolutionary history
hierarchical_section_title: Rhenopteridae / Evolutionary history
caption_attribution_description: English: Reconstruction of eurypterid Brachyopterus
context_page_description: The Rhenopteridae are a family of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". The family is the only family currently contained in the superfamily Rhenopteroidea, one of four superfamilies classified as part of the suborder Stylonurina.
  The family contains one of the earliest known eurypterids, Brachyopterus, known from the Middle Ordovician, and is the most primitive clade of stylonurine eurypterids. The last known members of the family went extinct during the Early Devonian.
context_section_description: The Rhenopterids first appeared during the Middle Ordovician as one of the earliest and most basal groups of Stylonurine eurypterids. Clear evolutionary trends can be observed in the carapaces of the rhenopterids. Basal rhenopterids possess broad carapaces narrowest at their base (as in Brachyopterus and Brachyopterella) whilst more derived rhenopterids have broad carapaces narrowest at the front and the most derived members possess narrower carapaces narrowest at the front (as in Rhenopterus). Kiaeropterus is unusual in its morphology and might represent a Silurian offshoot.
caption: Reconstruction of Brachyopterus, the earliest known rhenopterid.
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