Confuciusornithes

Confuciusornis

Several hundred examples of Confuciusornis have been found within a small area of China. Most are C. sanctus but a slender form C. dui has also been described. An
un-described fossil (DNO 088, see right) that seems to belong to this group and has recently been on tour in North America, mistakenly labeled as C. dui.

Changchengornis and Sapeornis may be close relatives (see Dinosauricon: http://dino.lm.com/images/.)

Like Archaeopteryx, Confuciusornis appears to be closely related to the dromaeosaurs but shows a few more bird-like characteristics. There is a sternal plate on the breast and there is a hint of a small keel on some specimens. The scapulas and coracoids are large and fused in an apparent attempt to strengthen the shoulder girdle. (see left.) The furcula or wishbone of Confuciusornis is simple, like that of Archaeopteryx but in Sapeornis there is a small hypocleideum where the fused clavicles meet.

The most outstanding feature of Confuciusornis is the massive humerus. Its great size suggests a specialized form of flight unknown in more recent lineages.

Confuciusornis is the earliest member of the Pygostylia. It and all subsequent birds have the vertebrae at the tip of the tail fused into a single mass. In Confuciusornis the pygostyle was simple and may not have had anything to do with flight (see the tail). Recently similar simple pygostyles have been found on dinosaurs (e.g. Nomingia, a relative of Chirostenotes).

Many of the fossils of Confuciusornis have included feather imprints. In modern birds the primaries are about half the length of the hand but in Confuciusornis the primary feathers were 2 or 3 times longer than the hand. They must have been exceptionally strong and are further evidence that Confuciusornis had an unusual flight style.

All of the bones suitable for the attachment of large flight muscles are in the shoulders while the rest of the skeleton is not much different from that of Archaeopteryx. When re-organized, the fossil of DNO 088 looks very much like that of a small terrestrial dinosaur (see left). The femur is particularly long and thin. In spite of its long legs, the toes of this animal are rather short and would not have provided support in soft mud. It may have been better designed to stalk through ground cover than to wade in soft mud.

Confuciusornis and its relatives must have carried one large mass of muscles on the shoulders to power the wings in flight and another on the hips for walking (see below). There is no sign of special structures to stiffen the skeleton between those muscle masses.