page_title: Lithostrotia
section_title: Systematics
hierarchical_section_title: Lithostrotia / Systematics
caption_attribution_description: Malawisaurus on Display at the Royal Ontario Museum
context_page_description: 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, although the farthest vertebrae are not procoelous.
context_section_description: Lithostrotia is a derived group of titanosaurs, excluding primitive forms such as Andesaurus and Phuwiangosaurus. The possibly equivalent clade Titanosauridae was positioned in a phylogenetic analysis by Calvo et al. (2007), where it included all titanosaurs apart from Andesaurus, though multiple primitive forms were not analyzed. Other phylogenies, by Unchurch et al. (2015), instead have found a few, non-lithostrotian titanosaurs, or nearly all non-brachiosaurid titanosauriformes within the group. Poropat et al. (2015) conducted a similar analysis to one of Unchurch et al. (2015). This analysis found that Andesaurus, Argentinosaurus and Epachthosaurus were within Titanosauria but outside Lithostrotia, and the latter group included Malawisaurus, Nemegtosaurus, Diamantinasaurus, Tapuiasaurus and Alamosaurus as basal lithostrotians outside Saltasauridae. The results of their analysis is shown below.
  Another phylogenetic analysis in 2016, partially reproduced below, found Diamantinasaurus as a non-lithostrotian titanosaur and the sister taxon of the contemporary Savannasaurus.
  The cladogram below follows Mocho et al. (2019) with the new subgroup called Lirainosaurinae.
caption: Malawisaurus skeleton, Royal Ontario Museum
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