Unaysauridae 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, ...

of basal

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lon ...

s from the Late

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

and

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Diagnosis and systematics

Unaysauridae was defined by Müller ''et al.'' (2018) as the most inclusive clade including ''Unaysaurus tolentinoi'', but not ''

Plateosaurus engelhardti ''Plateosaurus'' (probably meaning "broad lizard", often mistranslated as "flat lizard") is a genus of Plateosauridae, plateosaurid dinosaur that lived during the Late Triassic Period (geology), period, around 214 to 204 timeline of the evolution ...

'' nor ''

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 ...

''. Members of Unaysauridae are diagnosed by a substantially expanded cranial part of the medial condyle of the astragalus, as well as a promaxillary fenestra. Unaysauridae is sister to Plateosauria, more derived than ''

Nambalia ''Nambalia'' is a genus of basal sauropodomorph dinosaur. It lived during the Late Triassic period (late Norian to earliest Rhaetian) in what is now Telangana, central India. It is known from the holotype ISI R273, parts 1–3, partially a ...

'', ''

Thecodontosaurus ''Thecodontosaurus'' ("socket-tooth lizard") is a genus of herbivorous basal sauropodomorph dinosaur that lived during the late Triassic period (Rhaetian age). Its remains are known mostly from Triassic "fissure fillings" in South England. ''The ...

'' ISI R277, ''

Pantydraco ''Pantydraco'' (where "panty-" is short for Pant-y-ffynnon, signifying ''hollow of the spring/well'' in Welsh, referring to the quarry at Bonvilston in South Wales where it was found) was a genus of basal sauropodomorph dinosaur from the Late Tri ...

'', and ''

Efraasia ''Efraasia'' (pronounced "E-FRAHS-ee-A") is a genus of basal sauropodomorph dinosaur. It was a herbivore which lived during the middle Norian stage of the Late Triassic, around 210 million years ago, in what is now Germany. It was named in 1 ...

''.Rodrigo Temp Müller; Max Cardoso Langer; Sérgio Dias-da-Silva (2018). "An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs". Biology Letters. 14 (11): 20180633. . ''Unaysaurus'' and ''Jaklapallisaurus'' had previously been assigned to

Plateosauridae Plateosauridae is a family of plateosaurian sauropodomorphs from the Late Triassic of Europe, Greenland, Africa and Asia. Although several dinosaurs have been classified as plateosaurids over the years, the family Plateosauridae is now restric ...

by prior authors.Fernando E. Novas; Martin D. Ezcurra; Sankar Chatterjee; T. S. Kutty (2011). "New dinosaur species from the Upper Triassic Upper Maleri and Lower Dharmaram formations of central India". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 101 (3–4): 333–349. . However, Beccari et al. (2021) questioned the validity of Unaysauridae in their description of '' Issi saaneq'' because it "''suffers from the missing data and fragmentary nature of specimens. For example, one synapomorphy of unaysaurids is related to the astragalus medial end length ratio to the anteroposterior length of the lateral end, a which has not been confirmed in'' U. tolentinoi'', whereas a second synapomorphy, the presence of a promaxillary fenestra, cannot be observed in'' J. asymmetrica ''which lacks the required cranial remains.''" Subsequently, their phylogenetic analysis recovered ''Unaysaurus'' and ''Macrocollum'' within Plateosauridae.

References

{{Taxonbar, from=Q59124438 Sauropodomorphs Norian first appearances Rhaetian extinctions Tetrapod unranked clades