Halticosaurus (pron.:"HAL-tick-oh-SORE-us") is a dubious genus of theropod dinosaur from the late Triassic period (middle Norian stage, around 215.6–208 million years ago). It is known from a single fragmentary fossil specimen of the species H. longotarsus, found in the Middle Stubensandstein formation of what is present-day Germany[1] The only known specimen was poorly preserved and may have been put together from bones of unrelated animals. Further research would be required to determine which of the bones belonged together, and what kind of theropod Halticosaurus was. However, most of the bones have been lost. For these reasons, Halticosaurus is considered to be a nomen dubium.[2]
The name Halticosaurus comes from the Greek words altikos (αλτικος) meaning "good at jumping"/"nimble" and sauros (σαυρος) meaning "lizard"; thus "nimble lizard". Halticosaurus was described and named by Friedrich von Huene[3] in 1908 and the type species is Halticosaurus longotarsus.
Halticosaurus longotarsus, is known from the holotype SMNS 12353, which consists of partial jaw bones and teeth, incomplete neck, back, hip and tail vertebrae, a partial humerus, two partial femora, and fragments of an ilium and a metatarsal. The specimen was discovered in the Middle Stubensandstein Member of the Löwenstein Formation in Baden-Württemberg, Germany. It was recovered by A. Burrer, G. Mayer, and E. Fraas in 1902,[4] at the Burrerschen Quarry, in gray/blue marl that was deposited during the Norian stage of the Triassic period, approximately 215-212 million years ago. The specimen is currently housed in the collection of the State Museum of Natural History Stuttgart in Stuttgart, Germany. von Huene named Halticosaurus orbitoangulatus in 1932 on the basis of a mangled skull also from the Middle Stubensandstein,[5] but it is now considered to have belonged to the indeterminate loricatan archosaur Apatosuchus.[6] He also named Halticosaurus lilliensterni in 1934,[7] but it became the new genus Liliensternus in 1984.[8]
According to Welles (1984) H. longotarsus could be distinguished from the similar species Liliensternus liliensterni based on the following features:[8]
In 1992, Michael Benton noted that the skull was 18 inches (46 cm) long but was lightly built, with large fenestrae. The legs of the specimen were strong, and its arms were relatively short. Benton estimated that Halticosaurus would have been about 5.5 m (18.0 ft) long.[9]
However, the fossil material used by these previous researchers was later found to be mixed together with the remains of other animals, including a sauropodomorph (Sellosaurus gracilis). In 2000, Rauhut and Hungerbühler re-examined the fossil material and concluded that only the two partial femora could be reliably referred to H. longotarsus.[2]