I couldn’t help but notice that the time photosynthesis is supposed to have evolved doesn’t line up with either the time when oxygen is supposed to have become an important element in the atmosphere, half a billion years later, or the time that fixed carbon begins showing up in the fossil record, which is much earlier, possibly over half a billion years. So, given the current interpretation of the fossil and geologic records, things don’t line up. They give a blasé explanation of why we don’t see oxygen until much later, but ignore why we see carbon with the distinct C13/C12 ratio diagnostic of fixation during photosynthesis much earlier.
It’s Darwinism, Tim. It doesn’t need to make sense. Just stay out of the way of the juggernaut.
You may also wish to read: Researchers say they have a “precise estimate” for the origin of photosynthesis. Botanist Margaret Helder writes to comment “The point to reflect on is what all those heterotrophs did for food prior to the appearance of the autotrophs. Any organic molecules in the environment would be quickly digested if there were only organisms around with no capacity to reduce carbon.”