''Thadeosaurus'' is an
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
diapsid
Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ago ...
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
belonging to the family
Younginidae
Younginidae is an extinct family of neodiapsid reptiles from the Late Permian and Early Triassic. In a phylogenetic context, younginids are near the base of the clade Neodiapsida. Younginidae includes the species ''Youngina capensis'' from the La ...
. Fossils have been found in the
Lower Sakamena Formation (
Sakamena Group Sakamena is a village near Betroka in the region of Anosy in Madagascar.
Sakamena is also the name of a Permian sedimentary geological formation that has yielded many vertebrate fossil, including Triadobatrachus (the first lissamphibian), Claudio ...
) of the
Morondava Basin
Morondava Basin is one of the major sedimentary basins of Madagascar. It encompasses the large Tsimiroro heavy oil field and giant Bemolanga
Bemolanga is a large oil sands deposit in the onshore Morondava Basin of Madagascar. The deposit was ...
,
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
in
1981
Events January
* January 1
** Greece enters the European Economic Community, predecessor of the European Union.
** Palau becomes a self-governing territory.
* January 10 – Salvadoran Civil War: The FMLN launches its first major offensiv ...
, and date to the late
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
to the early
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 ...
period.
Description
![Thadeosaurus Scale](https://upload.wikimedia.org/wikipedia/commons/6/67/Thadeosaurus_Scale.svg)
''Thadeosaurus'' was a
lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia alt ...
-like animal, with a remarkably long tail that comprised about two thirds of the animal's total length of . It also had long toes, especially on the hind legs, which would have given it a powerful stride, since the toes would still touch the ground while the foot was being raised. Combined with a strong
breast bone to increase the strength in the forelimbs, this means that ''Thadeosaurus'' was probably a good runner.
Below is a
cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
from Reisz ''et al.'' (2011) showing the
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
position of ''Thadeosaurus'' among other early diapsids:
References
Prehistoric neodiapsids
Prehistoric reptile genera
Lopingian reptiles of Africa
Early Triassic reptiles of Africa
Changhsingian genus first appearances
Induan genus extinctions
Fossils of Madagascar
Permian Madagascar
Triassic Madagascar
Fossil taxa described in 1981
{{permian-reptile-stub