Plioplatecarpinae is a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...

s, a diverse group of Late

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

marine

squamates Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles; most members of which are commonly known as lizards, with the group also including snakes. With over 11,991 species, it is also the second-largest order ...

. Members of the subfamily are informally and collectively known as "plioplatecarpines" and have been recovered from all continents, though the occurrences in Australia remain questionable. The subfamily includes the genera '' Latoplatecarpus'', ''

Platecarpus ''Platecarpus'' ("oar wrist") is an extinct genus of aquatic lizards belonging to the mosasaur family, living around 84–81 million years ago during the middle Santonian to early Campanian, of the Late Cretaceous period. Fossils have been found ...

'', ''

Plioplatecarpus ''Plioplatecarpus'' is a genus of mosasaur lizard. Like all mosasaurs, it lived in the late Cretaceous period, about 73-68 million years ago. Discovery ''Plioplatecarpus'' has been found in many locations around the world (most mosasaurs were f ...

'' and '' Plesioplatecarpus''. Plioplatecarpines were small to medium-sized mosasaurs that were comparatively fast and agile compared to mosasaurs of other subfamilies. The first plioplatecarpines appear in the

Turonian The Turonian is, in the International Commission on Stratigraphy, ICS' geologic timescale, the second age (geology), age in the Late Cretaceous epoch (geology), Epoch, or a stage (stratigraphy), stage in the Upper Cretaceous series (stratigraphy), ...

and are among the oldest of mosasaurs, and the clade persists throughout the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

, a period of approximately 24 million years. The subfamily was seemingly heavily affected during a poorly understood middle-

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

mosasaur extinction event and its genera appear to have faced competition from mosasaurine mosasaurs during the Maastrichtian, leading to a decline in numbers and in diversity. The

etymology Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. ...

of this group derives from the genus ''Plioplatecarpus'' (

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''pleion'' = "more" +

''plate'' = "oar" +

''karpos'' = "wrist,

carpus In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known as the carpal ...

").

Description

In general, plioplatecarpines were short-skulled, short-bodied forms and were among the strongest swimming mosasaurs . Some workers have likened them to

pinniped Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant taxon, extant families Odobenidae (whose onl ...

s in their agility . Most forms were likely piscivores ("fish eaters"), though

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s (

belemnite Belemnitida (or belemnites) is an extinct order (biology), order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous (And possibly the Eocene). Unlike squid, belemnites had an internal skeleton that made up the cone ...

s) evidently formed an important part of the plioplatecarpine diet. Larger forms may have also fed upon smaller marine reptiles. At least one

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

evolved sturdy crushing teeth adapted to feeding on

shellfish Shellfish, in colloquial and fisheries usage, are exoskeleton-bearing Aquatic animal, aquatic invertebrates used as Human food, food, including various species of Mollusca, molluscs, crustaceans, and echinoderms. Although most kinds of shellfish ...

. The plioplatecarpines were medium-sized mosasaurs ranging from around 2.5 to 7.5 meters in length. Russell (1967, pp. 148Russell DA. 1967. Systematics and morphology of American mosasaurs. ''Peabody Museum of Natural History, Yale University, Bulletin'' 23.) defined the Plioplatecarpinae as follows: Small

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit ** podium * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ...

present or absent anterior to

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

ry teeth. Cranial nerves X, XI, XII leave lateral wall of opisthotic through single

foramen In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, artery, ...

. Canal or deep groove in floor of basioccipital and basispehnoid for basilar artery. Suprastapedial process of quadrate large, bluntly terminated and with parallel sides. Dorsal edge of surangular rounded and longitudinally horizontal...Twenty-nine or less presacral

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

present. Length of presacral series less than that of postsacral, neural spines of posterior

caudal Caudal may refer to: Anatomy * Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism * Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into th ...

vertebrae at most only slightly elongated, do not form an appreciable fin.

Haemal arch A haemal arch, also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the ha ...

es usually unfused to caudal

centra Centra is a convenience shop chain that operates throughout Ireland. The chain operates as a symbol group owned by Musgrave Group, the food wholesaler, meaning the individual shops are all owned by individual franchisees. The chain has three ...

. Appendicular elements lack smoothly finished articular surfaces." Plioplatecarpinae was given a phylogenetic definition by Jack Conrad in 2008 as "all taxa sharing a more recent common ancestor with '' Plioplatecarpus marshi'' than with '' Tylosaurus proriger'' or ''

Mosasaurus hoffmanni ''Mosasaurus'' (; "lizard of the Meuse River") is the type genus (defining example) of the mosasaurs, an extinct group of aquatic squamate reptiles. It lived from about 82 to 66 million years ago during the Campanian and Maastrichtian stages ...

''".

Phylogeny

Russell included two tribes, the Plioplatecarpini and Prognathodontini, the latter of which has been reassigned by BellBell GL. Jr. 1997. A phylogenetic revision of North American and Adriatic Mosasauroidea. pp. 293-332 In: Callaway JM, Nicholls EL, (eds.), ''Ancient Marine Reptiles'', Academic Press, 501 pp. to the

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

. Polcyn and Bell (2005, p. 322Polcyn MJ, Bell GL. Jr. 2005. ''Russellosaurus coheni'' n. gen., n. sp., a 92 million-year-old mosasaur from Texas (USA), and the definition of the parafamily Russellosaurina. ''Netherlands Journal of Geosciences'' 84 (3): 321-333.) have erected a more inclusive clade, the parafamily Russellosaurina, which includes the "subfamilies

Tylosaurinae The Tylosaurinae are a subfamily of mosasaurs,Williston, S. W. 1897. Range and distribution of the mosasaurs with remarks on synonymy. ''Kansas University Quarterly'' 4(4):177-185. a diverse group of Late Cretaceous marine squamates. Members of ...

and Plioplatecarpini and their sister-clade containing the genera ''

Tethysaurus ''Tethysaurus'' is an extinct genus of tethysaurine mosasauroid from the Early Turonian (Late Cretaceous) period. The only species is ''Tethysaurus nopcsai''. Discovery The name means "Tethys' lizard of Nopcsa", a reference to the Greek mythol ...

'', ''

Russellosaurus ''Russellosaurus'' is an extinct genus of tethysaurine mosasauroid from the Late Cretaceous of North America. The genus was described from a skull discovered in an exposure of the Arcadia Park Shale (lower Middle Turonian) at Cedar Hill, Dallas ...

'', and ''

Yaguarasaurus ''Yaguarasaurus'' is an extinct genus of mosasauroid from the Late Cretaceous (Turonian) period of Colombia, South America. The remains discovered (an articulated skull, some vertebrae and ribs) were defined as a new genus and species of mosasauri ...

''." The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below follows Simões et al. (2017) In their 2024 description of the Moroccan plioplatecarpine ''

Khinjaria ''Khinjaria'' (meaning "dagger") is an extinct genus of plioplatecarpine mosasaurid from the Late Cretaceous Ouled Abdoun Basin of Morocco. The genus contains a single species, ''K. acuta'', known from a partial skull and vertebra. ''Khinjaria ...

'', Longrich ''et al''. performed a

phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

, finding support for a clade of non-plioplatecarpin plioplatecarpines, named the Selmasaurini, which was recovered as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to Plioplatecarpini. Both clades were defined respectively as "all species closer to '' Selmasaurus russelli'' than '' Plioplatecarpus marshi'' or ''

Platecarpus tympaniticus ''Platecarpus'' ("oar wrist") is an extinct genus of aquatic lizards belonging to the mosasaur family, living around 84–81 million years ago during the middle Santonian to early Campanian, of the Late Cretaceous Period (geology), period. Fossils ...

''" and "all species closer to '' Plioplatecarpus marshi'' than to '' Selmasaurus russelli''". A similar clade was recovered by Strong ''et al.'' (2020) in their description of ''Gavialimimus''. The results of the analyses of Longrich ''et al''. are shown in the

below:

Species and taxonomy

Plioplatecarpinae * ''

Angolasaurus ''Angolasaurus'' ("Angola lizard") is an extinct genus of mosasaur. Definite remains from this genus have been recovered from the Turonian and Coniacian of Angola, and possibly the Coniacian of the United States, the Turonian of Brazil, and the M ...

'' ** ''A. bocagei'' * '' Ectenosaurus'' ** ''E. clidastoides'' ** ''E. tlemonectes'' ** ''E. shannoni'' * '' Sarabosaurus'' ** ''S. dahli'' * Selmasaurini ** '' Gavialimimus'' *** ''G. almaghribensis'' ** ''

Goronyosaurus ''Goronyosaurus'' is an extinct genus of marine lizard belonging to the mosasaur family. Fossils of ''Goronyosaurus'' are exclusively known from the Late Maastrichtian of the Iullemmeden Basin in West Africa, specifically the Dukamaje Formation o ...

'' *** ''G. nigeriensis'' **''

'' ***''K. acuta'' ** ''

Selmasaurus ''Selmasaurus'' is an extinct genus of marine lizard belonging to the mosasaur family. It is classified as part of the Plioplatecarpinae subfamily alongside genera like ''Angolasaurus'' and ''Platecarpus''. Two species are known, ''S. russelli'' ...

'' *** ''S. russelli'' *** ''S. johnsoni'' * Plioplatecarpini **'' Latoplatecarpus'' ***''L. nichollsae'' ***''L. willistoni'' **''

'' ***''P. tympaniticus'' **'' Plesioplatecarpus'' ***''P. planifrons'' **''

'' ***''P. primaevus'' ***''P. houzeaui'' ***''P. marshii'' *** ''P. peckensis''

References

{{Taxonbar, from=Q591005 Turonian first appearances Maastrichtian extinctions