Pliosauridae is a family of plesiosaurian marine reptiles from the Latest Triassic to the early

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

( Rhaetian to

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), ...

stages). The family is more inclusive than the archetypal short-necked large headed species that are placed in the subclade Thalassophonea, with early, primitive forms resembling other plesiosaurs with long necks. The largest thalassophonean pliosaurs reached , in length, with around a quarter of this length being the head. Thalassophonean pliosaurs represented the largest marine predators during their existence, spanning more than 80 million years. Pliosaurs went extinct during the early

and were subsequently replaced by the mosasaurs.

Taxonomy

Pliosauridae was formally named by Harry G. Seeley in 1874. Pliosauridae is a

stem-based taxon Phylogenetic nomenclature is a method of nomenclature for taxon, taxa in biology that uses phylogenetics, phylogenetic definitions for taxon names as explained below. This contrasts with Biological classification, the traditional method, by which ...

defined in 2010 (and in earlier studies in a similar manner) as "all taxa more closely related to '' Pliosaurus brachydeirus'' than to '' Leptocleidus superstes'', '' Polycotylus latipinnis'' or '' Meyerasaurus victor''". The family Brachauchenidae has been proposed to include pliosauroids which have very short necks and may include '' Brachauchenius'' and '' Kronosaurus''. However, modern

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analyses found that this group is actually 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 ...

of pliosaurids, and possibly even the "crown group" of Pliosauridae. Within Pliosauridae, there is a more derived clade called Thalassophonea. Thalassophonea was erected by Roger Benson and Patrick Druckenmiller in

2013 2013 was the first year since 1987 to contain four unique digits (a span of 26 years). 2013 was designated as: *International Year of Water Cooperation *International Year of Quinoa Events January * January 5 – 2013 Craig, Alask ...

. The

name A name is a term used for identification by an external observer. They can identify a class or category of things, or a single thing, either uniquely, or within a given context. The entity identified by a name is called its referent. A person ...

is derived from Greek ''thalassa'' (θάλασσα), "sea", and ''phoneus'' (φονεύς), "murderer". It is a

defined as "all taxa more closely related to '' Pliosaurus brachydeirus'' than to '' Marmornectes candrewi''". It includes the short necked and large headed taxa that typify the family. The following

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 ...

follows an analysis by Benson & Druckenmiller (2014).

References

External links

* {{Taxonbar, from=Q930029 Hettangian first appearances Turonian extinctions Sauropterygian families