Where does “chēlicera” come from?

chēlicera (New Latin) comes from Ancient Greek κέρας, from Proto-Hellenic *kérats.

Ancestry of “chēlicera”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	κέρας	horn; horn as a material, or anything made of...
2	Proto-Hellenic	*kérats	—