Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Late Ordovician (458–444 million years ago).[1] The earliest confirmed modern sharks (selachimorphs) are known from the Early Jurassic around 200 million years ago >
Quoting Wikipedia:
Shark-like chondrichthyans such as Cladoselache and Doliodus first appeared in the Devonian Period (419–359 million years), though some fossilized chondrichthyan-like scales are as old as the Late Ordovician (458–444 million years ago).[1] The earliest confirmed modern sharks (selachimorphs) are known from the Early Jurassic around 200 million years ago >
So, yes they appeared in the Devonian