mastodon vs mastodont

mastodon and mastodont both are nouns.

Word	Noun	Adjective	Verb	Adverb
mastodon	Yes	No	No	No
mastodont	Yes	No	No	No

As nouns, mastodon and mastodont are synonyms defined as:

mastodon and mastodont: extinct elephant-like mammal that flourished worldwide from Miocene through Pleistocene times; differ from mammoths in the form of the molar teeth

mastodon (noun)	mastodont (noun)
extinct elephant-like mammal that flourished worldwide from Miocene through Pleistocene times; differ from mammoths in the form of the molar teeth	extinct elephant-like mammal that flourished worldwide from Miocene through Pleistocene times; differ from mammoths in the form of the molar teeth