Origin of avian flight Origin of avian flight Around 350 BCE, Aristotle and other philosophers of the time attempted to explain the aerodynamics of avian flight. Even after the discovery of the ancestral bird "Archaeopteryx" over 150 years ago, debates still persist regarding the evolution of flight. There are three leading hypotheses pertaining to avian flight: Pouncing Proavis model, Cursorial model, and Arboreal model. "Archaeopteryx", the oldest known ancestor of modern birds, could provide clues to the origin of avian flight. In March 2018, scientists reported that "Archaeopteryx" was likely capable of flight, but in a manner substantially different from that of modern birds.
Specimens of Archaeopteryx — limiting its ability to perch on branches and implying a terrestrial or trunk-climbing lifestyle. This has been interpreted as evidence of theropod ancestry. In 1988, Gregory S. Paul claimed to have found evidence of a hyperextensible second toe, but this was not verified and accepted by other scientists until the Thermopolis specimen was described. "Until now, the feature was thought to belong only to the species' close relatives, the deinonychosaurs." The Thermopolis Specimen was assigned to "Archaeopteryx siemensii" in 2007. The specimen is considered the most complete and well preserved "Archaeopteryx" remains yet. This specimen first came to light