Angiosperms are flowering plants, so I'd say flowers and the parts of flowers are a pretty common characteristic.
Both humans and monkeys have this. A VERY long time ago Humans had very small "strings" of skin. This skin has evolved over time and now there is a bone left. Monkeys are technically un-evolved humans. Good thing they stuck around.
I would say the last option, the tilt of the axis/ rotation of the earth. Sorry if this is late, it says you asked a week ago. Hope this helps
