1. Forum
  2. USENET
  3. sci.bio.paleontology

  • Shishania (obscure Cambrian organism)

    From erik simpson@eastside.erik@gmail.com to sci.bio.paleontology on Fri May 9 08:57:05 2025
    From Newsgroup: sci.bio.paleontology

    An article in Science https://www.science.org/doi/10.1126/science.adv4635

    Shishania is a chancelloriid and not a Cambrian mollusk

    Abstract
    The Cambrian evolutionary radiation is noted for its profusion of
    bizarre and unfamiliar body forms, many of which illuminate the early
    ancestry of major animal groups. The spine-covered fossil Shishania
    aculeata (Cambrian Stage 4, Yunnan, China) has been interpreted as intermediate between mollusks and their lophotrochozoan ancestors. Our
    new material challenges this interpretation. We propose taphonomic explanations for apparent molluscan features and instead identify
    prominent anatomical similarities to coeval chancelloriids from nearby
    strata. Our reinterpretation of Shishania as an early-diverging
    chancelloriid helps to consolidate a model for the early evolution of
    this enduringly problematic group of sponge-like metazoans.

    Typical of rapid evolutionary expansions into unpopulated or recently
    vacates ecospaces, Chancelloriids (and Shishania) are short-lived
    organisms of uncertain affinities. They have been linked to both
    sponges or halkieriids.
    --- Synchronet 3.21d-Linux NewsLink 1.2
  • From John Harshman@john.harshman@gmail.com to sci.bio.paleontology on Fri May 9 13:38:59 2025
    From Newsgroup: sci.bio.paleontology

    On 5/9/25 8:57 AM, erik simpson wrote:
    An article in Science https://www.science.org/doi/10.1126/science.adv4635

    Shishania is a chancelloriid and not a Cambrian mollusk

    Abstract
    The Cambrian evolutionary radiation is noted for its profusion of
    bizarre and unfamiliar body forms, many of which illuminate the early ancestry of major animal groups. The spine-covered fossil Shishania
    aculeata (Cambrian Stage 4, Yunnan, China) has been interpreted as intermediate between mollusks and their lophotrochozoan ancestors. Our
    new material challenges this interpretation. We propose taphonomic explanations for apparent molluscan features and instead identify
    prominent anatomical similarities to coeval chancelloriids from nearby strata. Our reinterpretation of Shishania as an early-diverging chancelloriid helps to consolidate a model for the early evolution of
    this enduringly problematic group of sponge-like metazoans.

    Typical of rapid evolutionary expansions into unpopulated or recently vacates ecospaces, Chancelloriids (and Shishania) are short-lived
    organisms of uncertain affinities.-a They have been linked to both
    sponges or halkieriids.

    And there's a big problem with fossils: you can't always tell a sponge
    from a lophotrochozoan.
    --- Synchronet 3.21d-Linux NewsLink 1.2