Muraenosaurus [SEP] parent taxon
cervical vertebrae but display a broadened face of the centrum and a slight posterior incline in the neural spines. In the dorsal vertebrae the rib has been raised onto the neural arch. The neural spines have elongated anteroposteriorly and compressed vertically.
The pectoral girdle in "Muraenosaurus" is broader than in most plesiosaurs and helped to situate the animal as a member of "Cryptoclididae". The coracoids reach widths of nearly 14 inches. The forelimb is compressed mediolaterally when compared to the hind limb as well as limbs of other plesiosaurs.
Taxon in disguise
In bacteriology, a taxon in disguise is a species, genus or higher unit of biological classification whose evolutionary history reveals has evolved from another unit of similar or lower rank, making the parent unit paraphyletic. This happens when rapid evolution makes a new species appear radically different from the ancestral group, so that it is not (initially) recognised as belonging to the parent phylogenetic group, leaving the latter an evolutionary grade.
While the term is from bacteriology, parallel examples are found throughout the tree of