Telmatosaurus (meaning “marsh lizard”) is a genus belonging to basal hadrosauromorph dinosaurs from the Late Cretaceous. It was a small hadrosaur that was about five meters (16 feet) long, and was found in the present-day Romania.

Franz Nopcsa, Public domain, via Wikimedia Commons

The comparatively tiny dimension of Telmatosaurus with 5m in length and an estimated weight of half a ton is explained as an example of dwarfism insular.

In 1895, a group of peasants presented Ilona Nopcsa, child of the lord with a skull of a dinosaur they discovered at the estate Sacele in the district of Hunedoara (then known as Hunyad) located in Transylvania. Ilona had an older brother named Ferenc Or Franz of Felso-Szilvas. He was moved by the discovery to study paleontology in the University of Vienna. In 1899, Nopcsa christened his skull Limnosaurus transsylvanicus. The name is derived from the Greek limne, limne, “swamp”, a reference to the alleged swamp-dwelling habits of the hadrosaurs. The exact name was used to refer to Transylvania. Then Nopcsa realized that the name Limnosaurus had been previously utilized in the name of Othniel Charles Marsh in 1872 to refer to the species of crocodilian (later classified as Pristichampsus) which is why in 1903 Nopcsa changed the name of the Telmatosaurus genus. Telma again means “marsh”. In 1910, Barnum Brown, not aware of the name Nopcsa’s substitute was able to name the Genus Hecatasaurus however this was a junior synonym.

The Holotype, BMNH B.3386, was discovered within the Hateg Basin in a layer of the Sanpetru Formation that dates to the Maastrichtian approximately 70 million years ago. in the past part of Hateg Island, one of the islands in the European Archipelago. It is comprised of a skull and lower jaws.

In 1915, Nopcsa identified his species as belonging into the genus Orthomerus and identified it being an Orthomerus transsylvanicus. Since the 1980s, Orthomerus has been considered as a nomen dubium. This led to a revival of name Telmatosaurus. The fragmentary material of hadrosauroids that comes from Spain, France and Germany which was previously attributed to Orthomerus in the past, is nowadays identified as Telmatosaurus, however it is difficult to establish; this applies to the majority of Romanian eggs and fragments.

Source: Wikipedia