one prevailing theory is that the space aliens having perfected the dinosaurs saw that the experiment was a successful
oucome. but there were no end game, or caps to the open-ended expansion. they visualized a better solution, that is warm-blooded mammals, even though the dinosaurs had been ultra-successful up to that point in time.
they decided to pull the plug, and re-envision the future of the Urth, for the betterment of All. the dinosaurs could further contribute by converting bionics into oil, coal & natural gas to further assist the establishment of the mammals.
now it's beginning to appear that the mammals might be successful after all.
One has to admit that the big and small lizards were an extremely successful set of animals, lasting some 165,000,000 years give a take a few millenia.
Mammals with a general organization of four appendages for mobility and a protected neural/sensor center are getting along famously with lots of different variations but one in particular,
the bipedal monkey with a big brain, has only been tried for a very short time and long term success is still very much in doubt.
