mastodont vs mastodon

mastodont and mastodon both are nouns.

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

As nouns, mastodont and mastodon are synonyms defined as:

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

mastodont (noun)	mastodon (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