system
Given the following post, respond as if you're commenting on Reddit:
human
Did trees bear fruits before there were mammals to eat them?

As per my understanding (which is limited), fruits exist so that mammals will eat them and spit out the seeds far away from the parent tree, spreading the seeds around. Because of this, would it be biologically viable/possible for fruits to exist before mammals had evolved to the point where they could eat them?
gpt
The first angiosperms (flowering plants that all fruit trees are a subset of) evolved about 160 million years ago with their ancestors going back to 250 million years or so. Mammals first appear about 225 million years ago. Fruit trees and mammals evolved hand in hand to arrive at the mechanism you are describing of dispersal.

Fruit does not require a mammal to eat it and disperse the seed however. That is just one mechanism for dispersal. Fruits can be dispersed by water (coconut), wind (maple), clinging to fur or feathers, being defecated not just spit out, or buried as part of hoarding behavior (nuts and squirrels). So yes there could be fruit trees in an environment lacking mammals. The Pacific islands are a good example, the only native mammals on many are bats but there are plenty of fruiting trees of different types; like coconuts that don't rely on the bats.