Plateosauria is a clade

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 of sauropodomorph dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s which lived during the Late Triassic

Late Triassic

The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...

 to the Late Cretaceous

Late Cretaceous

The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...

. The name Plateosauria was first coined by Gustav Tornier

Gustav Tornier

Gustav Tornier was a German zoologist and paleontologist.-Life and career:...

 in 1913. The name afterwards fell out of use until the 1980s, when a new generation of paleontologists began using the name again.

Plateosauria is a node-based taxon. In 1998, Paul Sereno

Paul Sereno

Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...

 defined Plateosauria as the last common ancestor of Plateosaurus engelhardti and Massospondylus carinatus, and its descendants. Peter Galton

Peter Galton

Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...

 and Paul Upchurch in 2004 used a different definition: the last common ancestor of Plateosaurus engelhardti and Jingshanosaurus xinwaensis, and its descendants. In their cladistic analysis the Plateosauria belonged to the Prosauropoda; an important subgroup were the Plateosauridae

Plateosauridae

Plateosauridae is a family of plateosaurian sauropodomorphs. Plateosaurids were early sauropodomorph dinosaurs which existed in Asia, Europe and South America during the Late Triassic period. Although several dinosaurs have been classified as plateosaurids over the years, a 2007 study by Adam M....

. In Galton's and Upchurch's study also Coloradisaurus

Coloradisaurus

Coloradisaurus is a genus of massospondylid sauropodomorph dinosaur. It lived during the Late Triassic period in what is now La Rioja Province, Argentina. It is known from the holotype PVL 5904, nearly complete skull...

, Euskelosaurus

Euskelosaurus

Euskelosaurus was a semi-bipedal dinosaur from the Late Triassic. It was a prosauropod that lived in the Late Triassic Period, in present-day South Africa, Lesotho, and Zimbabwe. It was first described by Thomas Henry Huxley in 1866 as Euskelesaurus brownii based on holotype BMNH R1625, limb and...

, Jingshanosaurus

Jingshanosaurus

Jingshanosaurus is a genus of prosauropod dinosaurs from the Early Jurassic. Its fossils, a nearly complete skeleton including the skull, were found near the town of Jingshan , Lufeng County, Yunnan Province, China, from which the name derives. First described in 1995, the type species is J....

, Massospondylus

Massospondylus

Massospondylus and ) is a genus of prosauropod dinosaur from the early Jurassic Period . It was described by Sir Richard Owen in 1854 from remains found in South Africa, and is thus one of the first dinosaurs to have been named...

, Mussaurus

Mussaurus

Mussaurus was a genus of herbivorous prosauropod dinosaur that lived in southern Argentina during the Late Triassic Period, about 215 million years ago...

, Sellosaurus, and Yunnanosaurus

Yunnanosaurus

Yunnanosaurus is a genus of prosauropod dinosaur from the Early to Middle Jurassic Period, a position in time that makes it one of the last prosauropods. It is closely related to Lufengosaurus...

proved to be plateosaurians.

However, recent cladistic

Cladistics

Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 analyses suggest that the clade Prosauropoda is a synonym

Synonym

Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

 of Plateosauridae

Plateosauridae

Plateosauridae is a family of plateosaurian sauropodomorphs. Plateosaurids were early sauropodomorph dinosaurs which existed in Asia, Europe and South America during the Late Triassic period. Although several dinosaurs have been classified as plateosaurids over the years, a 2007 study by Adam M....

 as both contain the same taxa by definition. Yates (2007), Yates et al. (2010), Pol et al. (2011), Novas et al. (2011) and others found the traditional Prosauropoda to be paraphyletic to sauropods and therefore Plateosauria includes the core group Sauropoda

Sauropoda

Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...

.

The following cladogram

Cladogram

A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...

 simplified after an analysis presented by Apaldetti and colleagues in 2011.
The following cladogram simplified after an analysis presented by Novas et al., 2011: