Chelatoida

Chelatoida is a term that has been used in some contexts to refer to a proposed group of aquatic, usually marine, animals characterized by a specific body plan and likely predatory habits. The concept originated from early interpretations of fossil evidence, particularly from the Ediacaran biota. Animals within this proposed group were often described as having a segmented, segmented body that was potentially flexible and capable of burrowing or swimming. Some theorized features included the presence of appendages for locomotion or feeding, and a distinct head region.

The term "chelatoida" is not widely accepted or used in mainstream paleontology or zoology today. Modern phylogenetic analyses, based on a broader range of fossil evidence and comparative anatomy, have generally not supported the existence of such a distinct, unified phylum or class. Instead, the organisms that were once considered potential members of Chelatoida are now often classified within existing groups or are recognized as representing diverse evolutionary experiments from the early Cambrian or late Precambrian periods. The challenges in definitively classifying these ancient life forms, due to the scarcity and often enigmatic nature of their fossilized remains, contribute to the fluid understanding of their relationships.