"growl and bare the teeth," 1530, perhaps from Du. or Low Ger. snarren "to rattle," probably of imitative origin (cf. Ger. schnarren "to rattle," schnurren "to hum, buzz"). Meaning "speak in a harsh manner" first recorded 1693.
snarl
"to tangle, to catch in a snare or noose," late 14c., from a noun snarl "a snare, a noose" (late 14c.), probably a dim. of snare (1). The noun meaning "a tangle, a knot" is first attested c.1600.