Complex sentence: The Ugandan red colobus like all colobus monkeys has thumbs which are so reduced in size they are almost absent, it is thought this feature may help in brachiation when moving through the canopy.
Split into simpler sentences: The Ugandan red colobus, like all colobus monkeys, has thumbs which are so reduced in size they are almost absent. It is thought this feature may help in brachiation when moving through the canopy.