For years, skeptics had raised the so-called temporal paradox: there were no feathered dinosaurs older than Archaeopteryx, so birds could not have arisen from dinosaurs.

多年以来，怀疑论者一直在提出所谓的时间悖论：即没有发现比始祖鸟更为古老的带羽毛恐龙，因此，鸟类不可能起源于恐龙。