|The origin and evolution of the pterosaur wing. A. Sphenodon. Note the shapes and positions of the two centralia B. Huehuecuetzpalli. The carpus was poorly ossifie. The radius contacts the ulna. C. Cosesaurus. The two centralia had migrated to the medial margin of the carpus. Tiny strands trail the forelimb. D. Sharovipteryx. The fingers grow longer. E. Longisquama. The trailing strands coalesce within a single membrane. Metacarpal IV torsion and finger folding begins. F, G and H. MPUM 6009. The wing finger further elongates as the rest of the manus shrinks.