Mosasaurini

Mosasaurins Temporal range: Campanian-Maastrichtian, 82.7–66.0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skeleton of Mosasaurus (front view) in the Maastricht Natural History Museum.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Superfamily:	†Mosasauroidea
Family:	†Mosasauridae
Subfamily:	†Mosasaurinae
Tribe:	†Mosasaurini
Genera
†Mosasaurus †Moanasaurus †Eremiasaurus †Plotosaurus
Synonyms
Plotosaurini Russell, 1967

The Mosasaurini are a tribe of mosasaurine mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the tribe, known as "mosasaurins", have been recovered from North America, South America, Europe, Africa and Oceania, with questionable occurrences in Asia.^[1][2] The tribe contains the closely related genera Mosasaurus, Eremiasaurus, Plotosaurus and Moanasaurus. It has historically been more inclusive, on occasion including genera such as Plesiotylosaurus,^[3] Liodon and Clidastes,^[4] all of which are now seen as more basal mosasaurines.^[5]

Mosasaurins were highly derived predatory mosasaurs, containing genera like Plotosaurus, with unique adaptations towards fast swimming speeds and Mosasaurus itself, among the largest of the mosasaurs.

The etymology of the tribe derives from the genus Mosasaurus (Latin Mosa = "Meuse river" + Greek sauros = "lizard").

Description[]

Reconstruction of Plotosaurus bennisoni.

The Mosasaurini are a clade of derived mosasaurine mosasaurs. The tribe contains one of the largest known mosasaur species, Mosasaurus hoffmannii at over 12 meters in length, but it is notable that such a size is unusual within the tribe and even within the genus Mosasaurus itself. Other large mosasaurins are in a size range around 8 meters in length (such as Plotosaurus, Eremiasaurus and Mosasaurus conodon) whilst others are even smaller in a range of about 5–6 meters in length (such as Mosasaurus beaugei and Mosasaurus missouriensis).

The tribe was erected by Russell (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.^[4] 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.^[6] Paraphylys are forbidden in cladistics and so scientists must reclassify groups in order to eliminate such discrepancies if possible.^[7] 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.^[6]

A more recently suggested definition is a branch-based definition diagnosing the Mosasaurini as the most inclusive clade containing Mosasaurus hoffmannii but not Globidens dakotensis.^[8]

Species and taxonomy[]

Mosasaurini

• Mosasaurus
  • M. hoffmannii
  • M. missouriensis
  • M. conodon
  • M. lemonnieri
  • M. beaugei
• Moanasaurus
  • M. mangahouangae
• Eremiasaurus
  • E. heterodontus
• Plotosaurus
  • P. bennisoni
  • P. tuckeri (possibly synonymous with P. bennisoni)

References[]