While Project Mesozoic was getting plenty of volunteers, there was also an influx of volunteers for Project Cenozoic. This was largely brought on by the deepening of winter and the dropping of temperature. As it got colder, more people were open to getting a warm fur coat to endure the winter. And there were enough people coming in to really get the Ice Age project started.
Martha's parents, Sidney and Brooke, were informed about the project during their visit to Animalia for Christmas. They weren't really the liveliest of people. They weren't bad parents, but they need to work up a bit of effort to do anything. Though complaining about how much hard work everything is was easy for them. Just traveling all the way to Lyre was irksome on its own. They had been toying the idea of joining Animalia for a while, though not wanting to become something too full of energy. Ground sloths seemed more their speed and it would certainly lead to a healthier lifestyle.
There were megafauna considered for becoming Animalians. The scientist at Horizon have looked at several species of prehistoric deer for instance. The Megaloceros (better known as the Irish Elk or Giant Deer) was considered for a time, but it was decided that it would be imprudent to recreate one until the northern Animalian colony was constructed because the gigantic antlers of the Irish Elk would make it took hard for an Animalian version to be able to move indoors. Rather, the smaller stag-moose was selected which resembled a modern moose in many ways except its muzzle was closer to that of a typical deer. For this ancient stag, a name going by the name of Stanley who had run into some trouble with the Mafia in his native Brooklyn and wanted to change his identity volunteered to be converted.
While some Ice Age mammals had a close resemblance to modern relatives, others were more radically different. The glyptodont was a Cenozoic ancestor of the armadillo, with a much larger shell. This shell was not flexible as modern armadillos', being one solid piece with a bony cap of armor on their heads that they couldn't withdraw and bony rings along their tails. Dory, who had signed up for Project Phoenix to treat her pronounced hunchback, was persuaded to join Project Cenozoic to resurrect the glyptodont. In particular, she wanted to become a Doedicurus, a subspecies that possessed a spiky mace-like tail club. After her conversion, Dory hooked up with Walter, mainly because of how similar the Doedicurus was to the Ankylosaurus in build. At least until either of them get a mate of their own species.
Wanda was certainly someone who deserved to join Animalia. She had been one of the firefighters who tried to help during the 9/11 attacks. She helped save plenty of lives, but she also seen several colleagues of hers die in the attempt and she herself got badly burned during the rescues. The scars she was left with were not just physical. The traumatic experience had left her with a crippling pyrophobia that made it all but impossible to help out with any further fire rescues. She had come to Lyre hoping to put some of her past behind her. When she heard about Project Cenozoic, she volunteered so she could become a species that could keep itself warm without having to need fire. As such, she became the first woolly rhinoceros Animalian. Once she's had time to adjust to her new body and hopefully some therapy sessions to help her heal her mental scars, she plans on joining the Rhino Guard, hoping that she'll be able to provide security at the northern Animalia colony when it was built.