Is there a storybuilding device that can explain why alien worlds could possibly have similar creatures to that of Earth?
I can understand why stories set in alternate Earths and fantasy versions of Earth have the same animals with a few/lots of unique creatures.
But on a alien planet would it be a different story?
This question asked about if alien lifeforms would be Earth like in general. But it was closed as being 'unclear what you are asking'. It also concluded that convergent evolution would only result in life forms following the basic evolutionary paths, so we would recognise arm, head, mouth. They still wouldn't look like anything we would recognise as cat or dog. This further related question asked why 'sentient' aliens would be so similar to humans. But I am definitely not looking for alien humanoids (maybe their alien monkey predecessors). So this won't be relevant either: Justifying alien humanoids without convergent evolution. This is actually the most relevant, I think.
Say, the alien planet, planetX, is 'Earthlike'. Similar distance from the sun, similar day/night and seasonal cycles, similar atmospheric composition and climate dynamics. Let's ignore the niggling question on how life initially started for now. Once 'life' was started, could it evolve along similar trajectories?
Yes, there will obviously be differences, as the planetary history of PlanetX would be different to that of Earth's. eg a single mass extinction event wouldn't have wiped out 90% of all life in one swoop. Mammals as we know them might not have developed as we know it as maybe the dinosaurs where never wiped out. Then again, maybe the dinosaurs never achieved millions of years of dominance and maybe mammals evolved a lot sooner. Maybe we would have giant trilobites scurrying along (they are my favourite extinct critter).
How do I explain that an alien world, that has had no known contact with Earth before, has such similar and recognisable creatures and plantlife, such as horses, dogs, cats, whales, oaks, pines? with the obvious exception of those obviously alien creatures...
NOTE: I don't need any sentient human like creatures to evolve/have evolved. This is to explain the general alien wildlife and plantlife evolving along recognisable Earthlike paths.
If I can't use convergent evolution as a 'valid' reason...How do I explain that my world has Horses, and cattle, etc without reinventing the wheel? Evolve a super galaxy spanning deity that started it all? give lifeform's some sort of masterplan, that it will try follow as the environments and situations allow them too?
(reading between the lines: if you are worldbuilding on an alien planet, do you have to reinvent every single creature and plant to be 'different' and 'alien'?...)
EDIT I realise that alot of creatures and plantlife are the result of thousands of years of domestication. I can work around that.
I'm not looking for an identical 'horse' in everyway. Just that they appear similar and recognisable. I really don't mind of their internal structure is completely alien to our earth vets.
I think what I'm really asking is it possible (STORYWISE) to have creatures that have evolved on Earth in the past, that would appear alien to a modern day Earthlings, such as those awesome pictures in one of the answers below. But at the same time have more recognisably mammal type creatures.
Sort of like several evolutionary branches at once?! Follow some branches that were wiped out on Earth to get the 'aliens' EDIT