This ask is not about dinosaurs, actually... before the evolution of grasses during the Cenozoic, what could have been the equivalent of grass-like ecosystems (prairies, savanna...) during the Mesozoic?
F E R N PRAIRIES
seriously, there were lots of different kinds of prairies. fern, horsetail, cycad, the list goes on. Basically, different kinds of low-lying plants would do the prairie thing in ecosystems where forests couldn't get a foothold.
but, there were a lot fewer of them than today. because grasses are kind of OP, and have their own photosynthesis system, so they are able to grow and take over many places that would have been forests before grasses took over. That doesn't mean there weren't prairies, but there were just less. and a lot of things were more scrubland than prairie, too.
It's honestly amazing how much grass has changed the ecology of the planet. they are the biggest bioengineers of the cenozoic after people...
