Ornithuromorpha
Ornithuromorpha is a clade of birds within Avialae that includes all descendants of the most recent common ancestor of modern birds (Aves) and their close extinct relatives, excluding the Enantiornithes. In this sense, it represents the lineage leading to the crown group Aves, or Neornithes, and all of its extinct members. The name reflects a focus on “bird-form” lineage within the broader early bird radiation.
The fossil record of Ornithuromorpha spans the Late Jurassic to the Cretaceous, with many well-known examples
Key morphological trends within Ornithuromorpha include a shift toward a more derived, rigid skeletal structure, adaptations
Systematics within Ornithuromorpha are subject to ongoing study. Importantly, modern birds (Neornithes) are nested within this