Origin of birds mitochondrial uncoupling protein, UCP1, which is thermogenic. In mammals, UCP1 functions within brown adipose tissue to protect newborns against hypothermia. In modern birds, skeletal muscle serves a similar function and is presumed to have done so in their ancestors. In this view, bipedality and other avian skeletal alterations were side effects of muscle hyperplasia, with further evolutionary modifications of the forelimbs, including adaptations for flight or swimming, and vestigiality, being secondary consequences of two-leggedness. "Archaeopteryx" has historically been considered the first bird, or "Urvogel". Although newer fossil discoveries filled the gap between theropods and "Archaeopteryx", as well as the gap
Granger Archaeopteryx Granger Archaeopteryx The Granger Archaeopteryx is a British single-engined, tailless parasol monoplane designed and built in the late 1920s by two brothers, R.F.T. and R.J.T. Granger. The sole example built is currently under restoration for flight. The layout of the Archaeopteryx was inspired by the tailless swept-winged Westland-Hill Pterodactyl, itself derived from the aircraft of J. W. Dunne. These aircraft had been designed to resist stalling and to allow easy and safe recovery if they did. The Archaeopteryx follows the Dunne D.7 in being a parasol wing monoplane, however it differs in being the first aircraft of tailless swept configuration