What is the meaning of the suffix “‑don”?

What are the meaning and origin of the suffix ‑don, as in the words pteranodon and megalodon?

-odon (not just -don) means tooth. It is a variation of the suffix -odont, which comes from odon, which is Greek for tooth.

pter-anódōn means winged-toothless; megalodon means large-toothed. I learned Greek a while ago, and though I'm rusty, I recognized the words behind those names.

The suffix is not -don but -odon... Look at the etymology for "Ptenarodon":

ORIGIN modern Latin, from Greek pteron ‘wing’ + an- ‘without’ + odous, odont- ‘tooth.’

"Odont" still survives in Italian (I'm not aware about other languages), for example in the medical field "Odontoiatria" which treats about preventing/healing deseases that affect teeth, mandibles, gum, etc.