Getting back the actual thread topic rather than the off topic posts.
- Light hollow bones ordered properly for flight to take place.
- Metabolic structure. Reptiles have the slowest, while Birds the fastest metabolism.
- Lung Structure. Terrestrial lungs have a two-directional flow structure. In birds however, air follows just one direction through the lungs. The structure of the lung in birds, and the functioning of the respiratory system are unique.
Actually therapods had hollow bones, their skeletons suggest a metabolic rate on par with mammals and birds and not only did they have flow-through lungs, so don't other archosaurs living today like crocodilians.
Similarity of Crocodilian and Avian Lungs Indicates Unidirectional Flow Is Ancestral for Archosaurs
- Physiological mechanisms to maintain an essentially constant body temperature.
Theropods are mesotherms.
Warm or Cold? Dinosaurs Had 'In-Between' Blood
- Feathers. From gene structure and organization, to development, morphogenesis and tissue organization, every feature is different in feathers and scales. Also the protein structure of bird feathers is unique among vertebrates.
Coelurasaurs had feathers.
First Dinosaur Tail Found Preserved in Amber
- Hip Structure. All dinosaurs fall into one of two major groups: A) "lizard-hipped" - their pubis bone is typically swept forward, B) "bird-hipped" - where the pubis juts backwards to join another bone called the ischium. However, birds are more closely related to the "lizard-hipped" dinosaurs, and would have to independently evolve the pubis bone facing backwards.
Maniraptorans evolved a bird shaped pelvis.
The Secret to Dinosaur Hip Shape
>> Among dinosaurs, the pubic bone shifted to a backwards-pointing position four times among maniraptoran dinosaurs - the group that contains favorites like
Velociraptor as well as birds - and once among ornithischians. <<
- Birds have a wishbone that includes a kneeled sternum bone, which is where the muscles attach to that are critical for flight.
Non-avian theropods had wishbones.
Wishbones and Dinosaurs
>> The anatomical structure we call the wishbone in birds is formed by the fusion of the two clavicles — what we call our collarbones. This anatomical structure was long thought unique to birds. But fossil discoveries of recent decades have shown that some kinds of dinosaurs also had wishbones. In particular, those dinosaurs known as
theropods: carnivorous dinosaurs that stood upright and walked — and ran — on two legs. This group includes mighty Tyrannosaurus rex, and the terrifying Velociraptors of
Jurassic Park.
This means the wishbone itself dates back more than 150 million years.
And there is now wide consensus among experts that this group of dinosaurs includes the direct ancestors of modern birds. (Not only did they have wishbones but, like birds, they likely incubated their eggs, had hollow bones, and were clad in feathers.) <<
Basically your entire laundry list not a problem because they had all evolved in theropods long before birds evolved.
