Science Made Stupid is a hilarious parody of science.
At the end of the Creosote era, two new classes arose to challenge the ruling reptiles - birds and mammals.
The success of the birds was due in large part to their development of the feather. As you may recall from chapter 2, Galileo demonstrated that a feather falls more slowly than a lead weight. Being covered with feathers thus gave the birds a definite advantage over the flying reptiles, which were covered with lead weights.