''Megalancosaurus'' is a

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 extinct reptile from the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

Dolomia di Forni Formation and

Zorzino Limestone The Calcare di Zorzino, Italian for Zorzino Limestone is a Late Triassic (Norian) geological formation in Italy (Cene, Lombardy, Cene and ).Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

, and one of the best known drepanosaurids. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''M. preonensis''; a translation of the animal's scientific name would be "long armed reptile from the Preone Valley."

Anatomy

''Megalancosaurus'' was fairly small, its adult length was only about 25 centimeters (10 inches). It was built like a

chameleon Chameleons or chamaeleons (family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 202 species described as of June 2015. The members of this family are best known for their distinct range of colors, bein ...

and probably lived a similar

arboreal Arboreal locomotion is the Animal locomotion, locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. Th ...

lifestyle, feeding on insects and other small animals. Even its feet were chameleon like, with two toes being opposed to the remaining three. The tail is long, prehensile, and bears a strange claw-like organ made of fused vertebrae at its end. Its shoulders formed a

withers The withers is the ridge between the shoulder blades of an animal, typically a quadruped. In many species, it is the tallest point of the body. In horses and dogs, it is the standard place to measure the animal's height. In contrast, cattle ar ...

that would have served as an attachment site for especially strong muscles. Some specimens have an opposable digit on the feet. Because not all members of the species appear to bear this digit, it has been speculated that it is an instance of

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, only being possessed by whichever sex needed a stronger grip on the branch during

copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetrat ...

. The head of ''Megalancosaurus'' is superficially very birdlike. The skull was roughly 30 mm long and 12 mm tall. The eyes were large and the snout was narrow. Towards the tip of the snout were two small premaxillary teeth, which were separated by a diastema from at least 22 small maxillary teeth. The orbits were directed anteriorly, suggesting that ''Megalancosaurus'' had good binocular vision. It has been proposed that ''Megalancosaurus'' was capable of gliding, though while not fully ruled out it has largely been dismissed.Renesto, S. (2000). Bird-like head on a chameleon body: new specimens of the enigmatic diapsid reptile Megalancosaurus from the Late Triassic of Northern Italy. Rivista Italiana di Paleontologia e Stratigrafia (Research In Paleontology and Stratigraphy), 106(2).

History

''Megalancosaurus preonensis'' was first described in 1980. Its discoverers interpreted it as an archosaur, based in part on the belief that it had an antorbital fenestra. In 1994, two specimens originally thought to be juveniles of ''

Drepanosaurus ''Drepanosaurus'' (; "sickle lizard") is a genus of arboreal (tree-dwelling) reptile that lived during the Triassic Period. It is a member of the Drepanosauridae, a group of diapsid reptiles known for their prehensile tails. ''Drepanosaurus'' wa ...

'' were assigned to the species. This discovery led to the realization that it was a drepanosaurid. Since then, it has been regarded as one of the most derived members of the group.

Related genera

* '' Dolabrosaurus'' * ''

'' * ''

Hypuronector ''Hypuronector'' is a genus of extinct drepanosaur reptile from the Triassic Period that lived in what is now New Jersey. The etymology of the name translates as "deep-tailed swimmer from the lake," in reference to its assumed aquatic habits hypo ...

'' * '' Vallesaurus''

References

External links

Hairy Museum of Natural History page on simosaurs
{{Taxonbar, from=Q3079302 Drepanosaurs Late Triassic reptiles of Europe Fossils of Italy Fossil taxa described in 1981 Prehistoric reptile genera