What if the Epicureans had prevailed?

[Anomalocaris]

Christianity's rise also more or less ended any chance Epicureanism might have had, and it already was rejected by many Romans. The idea that consciousness ends with death, the rejection of interventionist gods and the atomist hypothesis just wouldn't be made to fit with the religion (although Pierre Gassendi later tried to).

Epicureanism just didn't fit the classical roman ideal of virtue to be able to take hold in Rome while Roman republic was on the ascendant. Romans were much more susceptible to stoicism then to epicureanism.

When Rome ascended to its imperial heights, and the empire became inclusive of different cultural and philosophical trends, epicureans did themselves no favors by eschewing politics, and thus fail to appeal to the class with power and jnfluence, while also eschewing superstition, thus fail to appear to the class with the numbers.

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Judging from Lucretius' De rerum natura, I think we would have been centuries ahead in terms of science.

You must also contend with possibility that epicurean Rome culture would be less able to survive the subsequent barbarian incursion, as a result dark ages would last longer and we would now be centuries behind in terms of science.