Re: Shishania (obscure Cambrian organism)

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.  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.