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Paleontologists have long suspected that birds evolved not once, but multiple times from the feathered theropods of the Mesozoic Era (although it seems that only line of birds survived the K/T Extinction 65 million years ago and evolved into the modern variety). The discovery of Haplocheirus, an early genus in the line of bipedal dinosaurs known as "alvarezsaurs," helps confirm this theory: Haplocheirus predated Archaeopteryx by millions of years, yet it already had various bird-like features, such as feathers and clawed hands.
What makes Haplocheirus so important isn't only that it predated other feathered dinosaurs by millions of years, but that it sets the alvarezsaur family tree back a whopping 63 million years. Previously, these feathered theropods only dated back to the Cretaceous period, though paleontologists had long speculated that there should be at least some species from the late Jurassic.