Concornis

Concornis is a genus of enantiornithine birds which existed during the early Cretaceous period, in the late Barremian age or about 125 million years ago, and its remains are known from the Calizas de La Huérguina Formation at Las Hoyas, Cuenca province, Spain. The single known species Concornis lacustris was described from remains of one individual skeleton which is not quite complete but bears feather impressions.

This was a smallish bird, measuring maybe 13 cm (12.5 in) without tail [1]. Its weight was probably some 75g or more, possibly over 100 g. Nothing is known about its skull, but it was almost certainly still toothed and somewhat snout-like as in its relatives. It was probably an accomplished flyer for its time, though perhaps not as nimble and somewhat lacking in stamina compared to modern birds. It is not known whether it had an alula and it must have possessed a long, narrow pygostyle not known to be associated with Neornithes-like rectrices. The legs were fairly long and neither dedicated to perching on branches nor to running on the ground; it had a large hallux as is generally absent in terrestrial birds.

Initially it was believed to be more primitive than Enantiornithes; these were at that time little-known and, as the primitive Iberomesornis was not yet considered to belong there either, contained only very advanced taxa. With more and more enantiornithine material becoming known, the placement of C. lacustris in this group was eventually verified. In fact, despite its early age, C. lacustris seems by no means primitive among the Enantiornithes.