Mosasaurinae

Mosasaurines Temporal range: Late Cretaceous,
Mounted skeleton of Mosasaurus conodon, Minnesota Science Museum
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Clade:	†Mosasauria
Family:	†Mosasauridae
Subfamily:	†Mosasaurinae Gervais, 1853
Type species
†Mosasaurus hoffmannii Mantell, 1829
Genera
†Amphekepubis †Clidastes †Dallasaurus †Gnathomortis †Goronyosaurus? †Jormungandr †Kourisodon †Liodon †Megapterygius †Plesiotylosaurus †Prognathodon †Stelladens †Thalassotitan †Globidensini †Carinodens †Globidens †Harranasaurus †Igdamanosaurus †Xenodens †Mosasaurini †Bentiabasaurus †Eremiasaurus †Plotosaurus †Moanasaurus †Mosasaurus

The Mosasaurinae are a subfamily of mosasaurs, a diverse group of Late Cretaceous marine squamates. Members of the subfamily are informally and collectively known as "mosasaurines" and their fossils have been recovered from every continent except for South America.

The lineage first appears in the Turonian and thrived until the K-Pg mass extinction at the end of the Maastrichtian. They ranged in size from some of the smallest known mosasaurs (Carinodens, 3–3.5 meters), to medium-sized taxa (Clidastes, 6+ meters), to the largest of the mosasaurs (Mosasaurus hoffmannii) potentially reaching about 13 m in length. Many genera of mosasaurines were either piscivorous or generalists, preying on fish and other marine reptiles, but one lineage, the Globidensini, evolved specialized crushing teeth, adapting to a diet of ammonites and/or marine turtles.

Though represented by relatively small forms throughout the Turonian and Santonian, such as Clidastes, the lineage diversified during the Campanian and had by the Maastrichtian grown into the most diverse and species-rich mosasaur subfamily.

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

Description

Skeleton of Clidastes liodontus mounted as if pursuing a fossil sea turtle

Russell (1967, pp. 123–124) defined the Mosasaurinae as differing from all other mosasaurs as follows: "Small rostrum present or absent anterior to premaxillary teeth. Fourteen or more teeth present in dentary and maxilla. Cranial nerves X, XI, and XII leave lateral wall of opisthotic through two foramina. No canal or groove in floor of basioccipital or basisphenoid for basilar artery. Suprastapedial process of quadrate distally expanded. Dorsal edge of surangular thin lamina of bone rising anteriorly to posterior surface of coronoid...At least 31, usually 42–45 presacral vertebrae present. Length of presacral series exceeds that of postsacral, neural spines of posterior caudal vertebrae elongated to form distinct fin. Appendicular elements with smoothly finished articular surfaces, tarsus and carpus well ossified." In his 1997 revision of the phylogeny of the Mosasauroidea, Bell (pp. 293–332) retained the Mosasaurinae as a clade, though he reassigned Russell's tribe Prognathodontini to the Mosasaurinae and recognized a new tribe of mosasaurines, the Globidensini.

The subfamily is generally recognised as containing two subdivisions, the tribes Globidensini (Globidens and its closest relatives) and Mosasaurini (Mosasaurus and its closest relatives). A third tribe, the Prognathodontini (Prognathodon and its closest relatives, such as Plesiotylosaurus), is also used on occasion. "Clidastini" or the adjective "clidastine" is also used sometimes, but generally refers to an adaptive grade close to and containing the genus Clidastes, rather than an actual clade.

Relationships

Cladogram of the Mosasaurinae modified from Longrich et al., 2022:

Mosasaurinae

Kourisodon Clidastes Globidensini Globidens simplex Globidens schumani Globidens phosphaticus Prognathodon rapax (=Ancylocentrum hungerfordi) Globidens alambamensis Globidens dakotensis Prognathodontini Gnathomortis Prognathodon overtoni Prognathodon saturator Thalassotitan atrox Prognathodon currii Prognathodon giganteus Prognathodon lutugini Prognathodon solvayi Mosasaurini Moanasaurus Mosasaurus mokoroa Mosasaurus conodon Plesiotylosaurus Plotosaurus Mosasaurus missouriensis Mosasaurus lemonnieri Mosasaurus hoffmannii Mosasaurus beaugei Mosasaurus maximus Liodon Mosasaurus sp. (MGGC 21876) "Magahouanga mosasaurine" Carinodens Xenodens

Further reading

• Kiernan, C. R. (2002). "Stratigraphic distribution and habitat segregation of mosasaurs in the Upper Cretaceous of western and central Alabama, with an historical review of Alabama mosasaur discoveries". Journal of Vertebrate Paleontology. 22 (1): 91–103. doi:10.1671/0272-4634(2002)022[0091:sdahso]2.0.co;2. S2CID 130280406.
• Williston, S. W. (1897). "Range and distribution of the mosasaurs with remarks on synonymy". Kansas University Quarterly. 4 (4): 177–185.