Translation:The elephant had decided he could bike.
I'm not sure why this was voted down, Royston, hence the lingot. I think you have light-heartedly raised an important point. Duo seems obsessed with rhinos, elephants and turtles. This gives rise to amusing and memorable sentences but misses opportunities to gradually (almost subliminally) expand everyday vocabulary. Of course, it is easy to compile a list of suitable words and commit them to memory, but isn't the point of Duolingo to minimise such drudgery?
I don't think the meaning is exactly the same, as far as I understand it, the difference would be that:
√ kon= was able to, general ability in the past
√ zouden kunnen= potential/hypothetical ability.
I think the confusion arises from the fact that in English both ideas can be conveyed with could.
Probably the moderators can explain this much better than me.