Opabiniidae

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Extinct family of basal arthropods

title: "Opabiniidae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["prehistoric-arthropod-families", "dinocaridida"] description: "Extinct family of basal arthropods" topic_path: "general/prehistoric-arthropod-families" source: "https://en.wikipedia.org/wiki/Opabiniidae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct family of basal arthropods ::

| fossil_range = Middle Cambrian - Middle Ordovician, | image = 20220213 Opabiniidae Opabiniids.png | image_caption = Opabinia (top) and Utaurora (bottom) | taxon = Opabiniidae | authority = Walcott, 1912 | subdivision_ranks = Genera | subdivision = *Opabinia

Opabiniidae is an extinct family of marine stem-arthropods. Its type and best-known genus is Opabinia. It also contains Utaurora, and Mieridduryn. Opabiniids closely resemble radiodonts, but their frontal appendages were basally fused into a proboscis. Opabiniids are also distinguishable from radiodonts by setal blades covering at least part of the body flaps and serrated caudal rami. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/5/54/20210807_Opabiniidae_opabiniid_trunk_cross_section.png" caption="Cross section of the trunk of [[Utaurora]] and [[Opabinia"] ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/78/20220214_Opabiniidae_size.png" caption="Size comparison of [[Utaurora]] and [[Opabinia"] ::

History of study

Opabiniidae was named by Charles Doolittle Walcott in 1912, alongside its type species Opabinia. Walcott interpreted Opabiniidae as a family of anostracan crustaceans, most closely related to Thamnocephalidae. Opabinia was restudied in the 1970s, and reinterpreted as a stranger animal. Stephen Jay Gould referred to Opabinia as a "weird wonder", and an illustration of Opabinia prompted laughter when it was first revealed at a paleontological conference. In 2022, two more opabiniids were discovered, those being Utaurora and Mieridduryn.

Myoscolex from Emu Bay Shale is sometimes suggested to be an opabiniid, but morphological features supporting this interpretation are controversial.

References

Works cited

References

  1. Tamisiea, Jack. (8 February 2022). "One of Evolution's Oddest Creatures Finds a Fossilized Family Member - Opabinia, which swam the seas of Earth's Cambrian era some 500 million years ago, was not just a one hit wonder.". [[The New York Times]].
  2. (1997). "The Taphonomy and Affinities of the Problematic Fossil ''Myoscolex'' from the Lower Cambrian Emu Bay Shale of South Australia". Journal of Paleontology.
  3. Dzik, Jerzy. (2004). "Anatomy and relationships of the Early Cambrian worm Myoscolex". Zoologica Scripta.

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prehistoric-arthropod-familiesdinocaridida