Colossosauria is a clade of

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...

s from the latest

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

through the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger 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 ''creta'', the ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. The group was originally named by Bernardo González-Riga ''et al.'' in

2019 File:2019 collage v1.png, From top left, clockwise: Hong Kong protests turn to widespread riots and civil disobedience; House of Representatives votes to adopt articles of impeachment against Donald Trump; CRISPR gene editing first used to experim ...

and defined as the "most inclusive clade containing ''

Mendozasaurus neguyelap ''Mendozasaurus'' is a genus of titanosaurian sauropod dinosaur. It was a member of Titanosauria, which were massive sauropods that were common on the southern landmasses during the Cretaceous. It is represented by several partial skeletons from ...

'' but not ''

Saltasaurus loricatus ''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...

'' or '' Epachthosaurus sciuttoi''". The clade contains different taxa depending on the phylogenetic analysis used, in the defining paper the only subgroups were

Rinconsauria Rinconsauria is an extinct clade of giant titanosaurian sauropods known from the late Cretaceous period of Argentina. Systematics Rinconsauria was coined by Calvo et al. (2007) to include their new titanosaur ''Muyelensaurus'' and the previously ...

and

Lognkosauria Lognkosauria is a clade of giant long-necked sauropod dinosaurs within the clade Titanosauria. It includes some of the largest and heaviest dinosaurs known. Description Lognkosaurians can be distinguished from other titanosaurs by the wide and u ...

, but alternate phylogenies published previously had also included various similar titanosaurs such as ''

Aeolosaurus ''Aeolosaurus'' (; "Aeolus' lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. Like most sauropods, it would have been a quadrupedal herbivore with a long neck and tail. ''Aeolosau ...

'', ''

Bonitasaura ''Bonitasaura'' is a titanosaurian dinosaur hailing from uppermost layers of the Late Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén Group of the eastern Neuquén Basin, located in Río Negro Province, Northwestern Patagonia, Argenti ...

'', ''

Drusilasaura ''Drusilasaura'' is an extinct genus of possible lognkosaurian titanosaur sauropod dinosaur which lived during the late Cretaceous (Cenomanian-Turonian stage) of Santa Cruz Province of southern Patagonia, Argentina. ''Drusilasaura'' is known fr ...

'', ''

Overosaurus ''Overosaurus'' (meaning "Overo lizard", after the Cerro Overo locality) is an extinct genus of sauropod dinosaurs, containing only a single species, ''Overosaurus paradasorum''. This species lived approximately 86 to 84 million years ago during ...

'' and '' Quetecsaurus''. The phylogenetic analysis of González-Riga ''et al.'' (2019) placed Colossosauria as sister taxa to ''

Epachthosaurus ''Epachthosaurus'' (meaning "heavy lizard") was a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. It was a basal lithostrotian titanosaur. Its fossils have been found in Central and Northern Patagonia in South America. Discov ...

'', ''

Pitekunsaurus ''Pitekunsaurus'' is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Anacleto Formation of Neuquén, Argentina. It was described by L. Filippi and A. Garrido in 2008. The type species is ''P. macayai''. The generic name is d ...

'' and a larger clade including

Saltasauridae Saltasauridae (named after the Salta region of Argentina where they were first found) is a family of armored herbivorous sauropods from the Upper Cretaceous. They are known from fossils found in South America, Asia, North America, and Europe. Th ...

. Due to the labile position of ''Epachthosaurus'' in titanosaur phylogeny, Carballido and colleagues proposed a new definition for Colossosauria in 2022, as all taxa closer to ''

Patagotitan ''Patagotitan'' is a genus of titanosaurian sauropod dinosaur from the Cerro Barcino Formation in Chubut Province, Patagonia, Argentina. The genus contains a single species known from multiple individuals: ''Patagotitan mayorum'', first announce ...

'' than ''

Saltasaurus ''Saltasaurus'' (which means "lizard from Salta") is a genus of saltasaurid dinosaur of the Late Cretaceous period of Argentina. Small among sauropods, though still heavy by the standards of modern creatures, ''Saltasaurus'' was characterized by ...

''. This solidified the position of Colossosauria as the opposite clade to

Saltasauroidea Saltasauroidea is a superfamily of titanosaurs named by França and colleagues in 2016 based on their phylogenetic results, for a clade uniting Aeolosaurini and Saltasauridae, as well as the intermediate genera ''Baurutitan'', ''Diamantinasaurus'' ...

within

Eutitanosauria Eutitanosauria is a clade of titanosaurs, encompassing the more derived members of the group and characterized by the absence of the hyposphene-hypantrum articulation and possibly the presence of osteoderms. The group was first named by Sanz and c ...

, and stabilized all three groups based on derived members instead of the more problematic basal taxa like ''Epachthosaurus'' and ''Mendozasaurus''. While Rinconsauria and Lognkosauria were both suggested to be probable Colossosaur subgroups, the inconsistencies in titanosaur phylogenetic meant that no changes to either groups were proposed, leaving Colossosauria as probably also including unclassified taxa on the stem to either more restrictive group.

References

{{Taxonbar, from=Q77853179 Cretaceous dinosaurs Titanosaurs