Ornithothoraces

Ornithothoraces is an extinct group of birds that lived during the Mesozoic Era. The name Ornithothoraces literally translates to "bird chest," referring to the development of a prominent keel on the sternum, a characteristic feature of modern birds that serves as an anchor for flight muscles. This group is significant in avian evolution as it represents an early stage in the development of the avian skeleton, bridging the gap between non-avian dinosaurs and more modern bird forms.

Fossils attributed to Ornithothoraces exhibit a mosaic of traits. They possessed some dinosaurian features, such as a long bony tail and teeth in their jaws, but also displayed distinctly bird-like characteristics, most notably the fused clavicles forming a furcula or wishbone and the aforementioned keeled sternum. This combination of features suggests that Ornithothoraces were likely capable of some form of aerial locomotion, though the extent and efficiency of their flight are subjects of ongoing scientific debate.

The discovery of various Ornithothoraces species, such as Jeholornis and Sapeornis, primarily from the fossil-rich deposits of China, has provided crucial insights into the early diversification of birds. These finds have helped paleontologists understand the evolutionary transition from terrestrial, bipedal dinosaurs to flying avians. The Ornithothoraces represent a critical clade in understanding the origins of flight and the subsequent radiation of birds into the diverse array of species found today.