Lithostrotian

Lithostrotians Temporal range: Early to Late Cretaceous, 120–66 Ma PreЄ Є O S D C P T J K Pg N
Life restorations of a pair of Saltasaurus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Order:	Saurischia
Suborder:	†Sauropodomorpha
Clade:	†Sauropoda
Clade:	†Titanosauria
Clade:	†Eutitanosauria
Clade:	†Lithostrotia Upchurch et al., 2004
Subgroups
†Antarctosaurus †Austroposeidon †Dreadnoughtus †Elaltitan †Isisaurus †Malawisaurus †Narambuenatitan † †Rukwatitan †Sarmientosaurus †Sonidosaurus †Tengrisaurus †Xianshanosaurus †Aeolosaurini †Lognkosauria †Nemegtosauridae †Saltasauridae

Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Unchurch et al. in 2004 as the most recent common ancestor of Malawisaurus and Saltasaurus and all the descendants of that ancestor. Lithostrotia is derived from the Ancient Greek lithostros, meaning "inlaid with stones", referring to the fact that many known lithostrotians are preserved with osteoderms. However, osteoderms are not a distinguishing feature of the group, as the two noted by Unchurch et al. include caudal vertebrae with strongly concave front faces (procoely), although the farthest vertebrae are not procoelous.

In 1895, Richard Lydekker named the family Titanosauridae to summarize sauropods with procoelous (concave on the front) caudal vertebrae. The name Titanosauridae has since been widely used, and was defined by Salgado and colleagues (1997), Gonzalaz-Riga (2003) and Salgado (2003) as node-based taxon. According to a proposal by Wilson and Upchurch (2003) looks today much of the research on the use of that name from: Wilson and Upchurch published a revision of the genus Titanosaurus and declare the type species Titanosaurus indicus as invalid because it is based only on two vertebrae of the tail, showing no diagnostically usable features. Consistently these authors consider ranking groups that are based on Titanosaurus as the nominal taxon, Titanosauridae, Titanosaurinae and Titanosauroidea - also considered invalid. In 2004 Upchurch and colleagues presented the new group Lithostrotia to describe the same group as Titanosauridae, but instead it was not based upon a specific taxon. The name Lithostrotia is not currently recognized by all researchers.

Upchurch and colleagues (2004) define the Lithostrotia as a node-based taxon that includes the last common ancestor of Malawisaurus and Saltasaurus and all descendants of that ancestor. According to this definition the Lithostrotia includes all forms that are more derived than Malawisaurus in phylogenies.

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