Ride five types of animal in Chronopolis.
The easiest place to start is with a horse- there are several in stables scattered about Medieval England, but one is by the glowing door in the stables near the pig-jousting lanes.
Note that the actually pig-jousting doesn't count for the pig requirement here. Annoyingly. Scarabs are found in Ancient Egypt, between the Noir border and the temple of the four pharaohs.
There's a lone camel by the Sphinx's right elbow.
There's only one rideable sheep, and you'll have to shear it first. Find it by the smithy puzzle in Medieval England.
Pigs that will count for this achievement are the lost pigs from the farm right between Avengers Mansion and Wakanda.
Riding all five completes the challenge, and unlocks Captain America's Motorbike.
(The spores of Sakaar don't count).