The modern bird a descendant of

The hands are spread out over the eggs as if to shelter them.

are birds dinosaurs yes or no

The skeleton of the animal is hunched up on a nest of eggs, like a brooding chicken. Nopcsa also proposed three stages in the evolution of flight.

Archaeopteryx

The facts are resoundingly in support of a maniraptoran origin for birds; certainly a theropodan origin at the very least. As the evogram shows, in the theropod lineage that would eventually lead to birds, the fifth digit e. One single well-preserved fossil bird unequivocably of Triassic age might shed some doubt on the theory of the maniraptoran affinities of birds. Modern birds have higher metabolisms than even the most agile Velociraptor ever had. Time passes, the environment changes An experienced fossil hunter, Li split the slab and beheld a creature unlike any he had seen. It might have helped drive miniaturization or vice versa. Scientists have located only ten intact fossilized skeletons of the earliest known bird, Archaeopteryx, which lived at the end of the Jurassic period, about million years ago.

Some bird-like fossils have been presented as Triassic birds, but so far have not held up under peer review. Despite their appearance, birds are more closely related to alligators than lizards are. A study comparing embryonic, juvenile and adult archosaur skulls concluded that bird skulls are derived from those of theropod dinosaurs by progenesisa type of paedomorphic heterochronywhich resulted in retention of juvenile characteristics of their ancestors.

The bony tail was reduced to a stump, and a spray of feathers at the tail eventually took on the function of improving stability and maneuverability. The facts are resoundingly in support of a maniraptoran origin for birds; certainly a theropodan origin at the very least.

Fragmentary remains of possible dromaeosaurs are also known from the Late Jurassic. The ratite birds, three of which are pictured in this article, are quite similar to theropod dinosaurs.

Well, not exactly.

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Dinosaur Institute