I suppose that quote could be interpreted in many different ways. The phrase "contest of evolution" in particular is mysterious: is the fall of the alien Lavos considered part of this contest, or is it not because it's a corrupting influence from outside the planet's nature? If it's the latter, then perhaps Lavos still fell in the Dragonian dimension, but the Reptites still managed to wipe the humans out and "continued to develop" by stealing their shelters, caverns, etc.
Of course it might perhaps be simplier to consider the link between the Ige Age and Lavos. If Lavos hadn't fall, the Reptites would have survived. The big and recurrent issue is the cryptical aspect of what those Chronopolitan ghosts say... I wish they could have talked more precisely.
Well, I'm not sure I myself totally believe in my theory, but I think it's at least worth remembering, because it gives Leah an actual reason for being there in El Nido, a reason which doesn't create a plot-hole moreover. If Leah were Ayla's mother from the Keystone dimension, this would bring the age-old Guardia paradox from CT all the way to CC (no Leah in Prehistory = no Ayla, no Guardia line). If this Leah is from the Dragonian dimension instead, everything is coherent: Leah is removed, thus Ayla is not born, the Reptites win the fight for life, and in the far future Dinopolis is created.
Thematically, this is also very interesting seeing that it ironically puts the Planet on the same level as all other "living" beings struggling for survival. The planet would have purposely screwed the Dragonian dimension in order to survive in the Keystone one.
In order to survive,
all living things in this world
fight desperately and
devour those they defeat...
Must one kill other living
things in order to survive?
Must one destroy another world
in order to allow one's own
world to continue?