Mosasaurini

Mosasaurini is a extinct tribe of mosasaurine mosasaurs who lived during the Late Cretaceous and whose fossils have been found in North America, South America, Europe, Africa and Oceania, with questionable occurrences in Asia. They are highly derived mosasaurs, containing genera like Plotosaurus, having unique adaptations to fast swimming speeds, or Mosasaurus, which is among the largest known marine reptiles. The Mosasaurini form a clade of derived mosasaurine. The tribe contains one of the largest known mosasaur species, Mosasaurus hoffmannii, measuring over in length, but such a size is unusual within the tribe and even within the genus Mosasaurus in himself. Other large representatives are around long (like Plotosaurus, Eremiasaurus, Mosasaurus conodon and Mosasaurus beaugei) while others are even smaller, in a range of around long (like Mosasaurus missouriensis). The tribe was erected by Russell in 1967, stating that it is unified by having twelve or less pygal vertebrae and that the radius and ulna are widely separated by a bridge of carpalia on the distal border of the antebrachial foramen. But In a 1997 study, paleontologist Gorden Bell recovered Plotosaurus, which was formerly classified within another tribe called the Plotosaurini, as a sister genus to Mosasaurus. This rendered the Mosasaurini paraphyletic, which meant that it now contains a descendant lineage (Plotosaurini) that is not classified under it, and made its definition defunct. Paraphylys are forbidden in cladistics and so scientists must reclassify groups in order to eliminate such discrepancies if possible. Bell proposed that the Mosasaurini should be abandoned and that all members of the tribe should be incorporated into the Plotosaurini. While other scientists agree that a tribe containing Mosasaurus should be monophyletic, they argue that Mosasaurini should be the valid tribe. For example, in a 2012 study, Aaron LeBlanc, Caldwell, and Bardet argued that, while it is not necessarily invalid, abandoning Mosasaurini would not follow the general principle of the type genus carrying over to all ranks in a classification hierarchy, and that the original diagnostics of the Plotosaurini is outdated.