the first time the phrase "bites the dust" appears is in the rgveda (1.158.4-5) where the poet dirgatama has a prayer to the divine doctors and says ‘may the turning of the days not tire me, may the fires not burn me, may the wood-pyre not eat the earth, may the waters not swallow me’. there are disputes on what "bites the dirt" means in sayana’s commentary in the 14th century- which means the phrase had gone out of style in india at this time as most people began to be cremated instead of buried. but reading the padbandha, it's very clear that it refers to the wood-pyre eating earth, not the deceased human.