
Megacheira (from Ancient Greek μέγας (mégas), meaning "great", and χείρ (kheír), meaning "hand", also historically great appendage arthropods) is an extinct class of predatory arthropods defined by their possession of spined "great appendages". Their taxonomic position is controversial, with studies generally either considering them stem-group euarthropods, or stem-group chelicerates. The homology of the great appendages to the cephalic appendages of other arthropods is also controversial. Uncontested members of the group were present in marine environments worldwide from the lower Cambrian to
Megacheira (from Ancient Greek μέγας (mégas), meaning "great", and χείρ (kheír), meaning "hand", also historically great appendage arthropods) is an extinct class of predatory arthropods defined by their possession of spined "great appendages". Their taxonomic position is controversial, with studies generally either considering them stem-group euarthropods, or stem-group chelicerates. The homology of the great appendages to the cephalic appendages of other arthropods is also controversial. Uncontested members of the group were present in marine environments worldwide from the lower Cambrian to the upper Ordovician.
== Morphology ==
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).