DalinghesaurusLongidigitus-PaleozoologicalMuseumOfChina-May23-08

Shinisauria is a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

or evolutionary grouping of anguimorph lizards that includes the living Chinese crocodile lizard ''Shinisaurus'' and several of its closest extinct relatives. Shinisauria was named in 2008 as a stem-based taxon to include all anguimorphs more closely related to ''Shinisaurus'' than to any other lizard. Several recent phylogenetic analyses of lizard evolutionary relationships place Shinisauria in a

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

position within the clade Platynota, which also includes

monitor lizard Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recogn ...

s, helodermatids, and the extinct mosasaurs. Shinisaurians were once thought to be closely related to the genus ''

Xenosaurus ''Xenosaurus'' is a genus of lizards. ''Xenosaurus'' is the only extant genus in the family Xenosauridae with 13 species currently recognized."Xenosauridae" and "''Xenosaurus'' ". The Reptile Database. www.reptile-database.org. Also known as the ...

'', but they are now considered distant relatives within Anguimorpha. The fossil record of shinisaurians extends back to the

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 ...

with '' Dalinghosaurus'', which is from the

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

aged Yixian Formation of China. Two other extinct shinisaurians are currently known: ''

Bahndwivici ''Bahndwivici'' is an extinct genus of lizard known from a nearly complete and articulated skeleton discovered in rocks of the Green River Formation of Wyoming, United States. The skeleton is very similar to that of the modern Chinese crocodile ...

'' from the Eocene of Wyoming and ''

Merkurosaurus ''Merkurosaurus'' is an extinct genus of lizards from the Shinisauria that is known from the Late Oligocene of Germany, collected in 1999, and the Early Miocene Most Formation of the Czech Republic (west Bohemia) and the Wiesbaden Formation Ger ...

'' from the Late Oligocene of Germany and the Early Miocene of the Czech Republic. An indeterminate shinisaurian is known from an isolated tail found in the Eocene aged Messel pit in Germany.

References

Anguimorpha Tetrapod unranked clades {{lizard-stub