But suddenly, out of nowhere, a giant mammoth foot stomped on Scrat, causing him to lose his grip on the acorn. Flattened by the massive weight, Scrat picked himself up as the mammoth walked off. Suddenly, another prehistoric mammal, a Brontohere stepped on him. Following him was another mammoth and a dodo bird. Another foot landed on Scrat, but this time, Scrat was stuck on it and was being carried away from his acorn. The foot belonged to a Macrauchenia, a prehistoric mammal that was part of an enormous migration of mammals heading away from the northern regions in search of warmer climates. An ice age had begun. This massive herd of mammals, consisting of Macrauchenia, Glyptodons, Palaeotherium, Prehistoric aardvarks and Brontotherium, was slowly travelling away from the snowy areas, migrating south to avoid a freezing cold front. Miles behind them was a glacier monument known as Glacier Pass, a large ice formation with a huge cut engraved in it, like an ice gorge. As this massive herd continued on, but, Suddenly, a large gasp erupted in the crowd of mammals. Everyone looked and to their shock, they saw a huge Wooly Mammoth stomping his way across the herd, going the opposite direction. Spooked, the mammals in his path frantically started moving out of the way. As this happened, the mammoth didn’t glance at what he was causing, nor did he seem to care. He kept stomping his way through the crowd, ignoring everyone around him. This mammoth, Manfred, had a grumpy expression on his face as he plowed through the crowd.