Archaeornithura is an extinct genus of ornithuromorphs
from the early Cretaceous period. It is known from two fossil specimens of a
single species, A. meemannae. The specimens have been dated to
the Hauterivian age, 130.7 million years ago, making A. meemannae the oldest known
ornithuromorph (the lineage that gave rise to modern birds, and
contains all living birds as well as many of their extinct relatives)
Archaeornithura had a moderately advanced plumage, fan-shaped tail feathers, a U-shaped furcula, highly fused wing apexes, and a well-developed alula – a projection on the front edges of the wings that is typically used to boost maneuverability during flight. Collectively, these traits mean that it shares many morphological features with a modern bird – more than found in any other bird of equivalent age. This suggests that ornithuromorpha diverged from other bird-like animals and dinosaurs earlier than previously thought. "The new bird is quite derived and has many advanced features of modern birds," said discoverer Wang Min.
It also suggests that key evolutionary advantages of birds – skilled flight and rapid growth in development – arose rapidly, and that habit specialization happened early in bird history. The species had long legs and feet similar to modern plovers, suggesting the it was a shore bird that waded into shallow water to feed. The species appears to have been adept at flying. Both known specimens of A. meemannae are excellently preserved, including substantial feathers. Some Archaeornithura feathers feature a central grove, a feature thought to arise from derived flight feathers. This feature was not previously known in ornithuromorpha, suggesting that modern feather morphology evolved separately within the Archaeopteryx lineage and a subset of the ornithuromorphs.
Phylogenetic analysis showed that Archaeornithura is closely related to more recent hongshanornithids, confirming that it is a valid family. Archaeornithura was shown to be the sister taxa of Tianyuornis, with fused metatarsals II–IV and the shape of outermost trabecula of the sternum in common. The specialized wading features of Archaeornithura suggest that the hongshanornithids originated in a semi-aquatic environment.
Description
Archaeornithura had a moderately advanced plumage, fan-shaped tail feathers, a U-shaped furcula, highly fused wing apexes, and a well-developed alula – a projection on the front edges of the wings that is typically used to boost maneuverability during flight. Collectively, these traits mean that it shares many morphological features with a modern bird – more than found in any other bird of equivalent age. This suggests that ornithuromorpha diverged from other bird-like animals and dinosaurs earlier than previously thought. "The new bird is quite derived and has many advanced features of modern birds," said discoverer Wang Min.
It also suggests that key evolutionary advantages of birds – skilled flight and rapid growth in development – arose rapidly, and that habit specialization happened early in bird history. The species had long legs and feet similar to modern plovers, suggesting the it was a shore bird that waded into shallow water to feed. The species appears to have been adept at flying. Both known specimens of A. meemannae are excellently preserved, including substantial feathers. Some Archaeornithura feathers feature a central grove, a feature thought to arise from derived flight feathers. This feature was not previously known in ornithuromorpha, suggesting that modern feather morphology evolved separately within the Archaeopteryx lineage and a subset of the ornithuromorphs.
Phylogenetic analysis showed that Archaeornithura is closely related to more recent hongshanornithids, confirming that it is a valid family. Archaeornithura was shown to be the sister taxa of Tianyuornis, with fused metatarsals II–IV and the shape of outermost trabecula of the sternum in common. The specialized wading features of Archaeornithura suggest that the hongshanornithids originated in a semi-aquatic environment.
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