Okay, Okay so I know my fair share of convergent evolution, foster rule etc. now I'm wondering because I have three creatures (a insect like creature a herbivore and carnivore I'll send images they have arthropod like characteristics but aren't arthropods except the tiny bugs) and they were the only animals on land how would they evolve if I treat them like Earth's mammal ancestor?
That said, the creatures they have evolved from an ancestor that had arthropod-like characteristics, but technically they are not arthropods that were found on earth. Some may have internal bones possible made of cartalege (a idea i had recently)besides the insects.
the continents on my planet split creating multiple environments, snow, desert, swamp and eventually come back together though there may be islands and on each one said creature was there (albeit one or two may not have made it to said island or just went extinct).
Would a huge diversity of creatures inevitably evolve from them or would they not change and stay relatively the same though with some minor differences due to environment?
Basically what I think I'm trying to say is can a species be really diverse like those of earth that evolved from one animal (an ancestor, a rodent I think or those mammal reptiles) but happen three times with creatures of different body structures and not face complications.