I'm curious about these particular dead birds. How the fuck did they end up with a major ball-and-socket joint being arse about?That's a pretty significant change, or seems like it anyway. Does anyone have an idea how and when this happened?
This refers to an anatomical feature - the articulation of the shoulder bones - which has a concave-convex socket joint that is the reverse of that of modern birds. Specifically, in enantiornitheans, the facet where the scapula (shoulder blade) meets the coracoid (the primary bone of the shoulder girdle in vertebrates other than mammals) is a convex knob and the corresponding point on the shoulder blade is concave and dish-shaped. In modern birds, the way the joint articulates is reversed.
http://www.clevelandshoulder.com/pdf/reverseShoulder.pdf(In case anyone's interested)
Quote from: Faid on March 07, 2017, 01:03:40 PMhttp://www.clevelandshoulder.com/pdf/reverseShoulder.pdf(In case anyone's interested)A quick google doesn't find any enantiornithines with a humeral head that looks like that. The coracoid is a bone that fits between the furcula (clavicle) and the scapula, about where the coracoid process is, but much bigger, and technically not homologous. Enantiornithines don't have a reversed shoulder girdle. That would be completely bizarre. They're talking about the joint between bones that make up the shoulder girdle, not the joint between that and the humerus.