Unaysauridae is a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

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 lo ...

s from the Late

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

and

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Diagnosis and systematics

Unaysauridae was defined by Müller ''et al.'' (2018) as the most inclusive clade including ''Unaysaurus tolentinoi'', but not '' Plateosaurus engelhardti'' nor '' Saltasaurus loricatus''. 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'', ''

Thecodontosaurus ''Thecodontosaurus'' ("socket-tooth lizard") is a genus of herbivorous basal sauropodomorph dinosaur that lived during the late Triassic period (Carnian? age). Its remains are known mostly from Triassic "fissure fillings" in South England. ''T ...

'' 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) is a genus of basal sauropodomorph dinosaur from the Late T ...

'', and ''

Efraasia ''Efraasia'' (pronounced "E-FRAHS-ee-A") is a genus of basal (phylogenetics), 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 Germ ...

''. ''Unaysaurus'' and ''Jaklapallisaurus'' had previously been assigned to Plateosauridae by prior authors. 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 Dinosaur families Late Triassic dinosaurs