I mocked up some rules for a evolutionthread v2.
Evolution project v2
Past evolution project: http://www.newgrounds.com/bbs/topic/1209560/1
The basic idea is to take a creature and evolve it, it still has to reassemble the past creature for atleast 50%
Darwins evolution theory suggests Animals evolve into different species through natural selection. Animals that adapt to their predators, prey, environment, or find a better way to get food, have a bigger change of survival. Take this into account when designing a creature, so think function over form.
Take any past creature to evolve from, best take a recent one since the dated one are most likely to be extinguished.
Environments will change overtime, environment changes can be applied by the mods or anyone appointed by me or the mods. This will happen when too much of the same idea's come into play. note that you wont have to be too limited by an environments since there could also be things like hot springs, and mountain tops with everlasting snow.