| Halticosaurus | |
|---|---|
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Halticosauridae Bock, 1952 |
| Genus: | †Halticosaurus Huene, 1908 |
| Species: | †H. longotarsus |
| Binomial name | |
| †Halticosaurus longotarsus Huene, 1908 | |
Halticosaurus (pron.:"HAL-tick-oh-SORE-us") is adubiousgenus oftheropoddinosaur from thelate Triassic period (middleNorianstage, around 215.6–208 million years ago). It is known from a single fragmentary fossil specimen of the speciesH. longotarsus, found in theMiddle Stubensandstein formation of what is present-dayGermany[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 theropodHalticosaurus was. However, most of the bones have been lost. For these reasons,Halticosaurus is considered to be anomen dubium.[2]
The nameHalticosaurus comes from theGreek wordsaltikos (αλτικος) meaning "good at jumping"/"nimble" andsauros (σαυρος) meaning "lizard"; thus "nimble lizard".Halticosaurus was described and named byFriedrich von Huene[3] in1908 and thetype species isHalticosaurus longotarsus.
Halticosaurus longotarsus, is known from theholotypeSMNS 12353, which consists of partialjaw bones and teeth, incomplete neck, back, hip and tailvertebrae, a partialhumerus, two partialfemora, and fragments of anilium and ametatarsal. The specimen was discovered in theMiddle Stubensandstein Member of theLöwenstein 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 theNorian stage of the Triassic period, approximately 215-212 million years ago. The specimen is currently housed in the collection of theState Museum of Natural History Stuttgart in Stuttgart,Germany. von Huene namedHalticosaurus 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 indeterminateloricatanarchosaurApatosuchus.[6] He also namedHalticosaurus lilliensterni in 1934,[7] but it became the new genusLiliensternus in 1984.[8]
According to Welles (1984)H. longotarsus could be distinguished from the similar speciesLiliensternus 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 largefenestrae. The legs of the specimen were strong, and its arms were relatively short. Benton estimated thatHalticosaurus 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 toH. longotarsus.[2]
In 1908, Huene originally assigned this genus broadly to Dinosauria, and after additional analysis in 1909 he assignedHalticosaurus to Saurischia.[3][10] In 1952, Bock observed enough unique skeletal features to assign it to its own familyHalticosauridae. Welles (1984) and Chatterjee (1987) later agreed with this classification.[8][11] Over the years there was an effort to referHalticosaurus toPodokesauridae by paleontologists like Simmons (1965), Ostrom (1978), Battail (1986) and Carroll (1988). In their attempt at phylogenetic analysis, Norman (1990) and later, Rauhut and Hungerbuhler (2000) concluded thatHalticosaurus was indeterminate because the available material is too poorly preserved.[2]
A second species, based on a partial skullSMNS 12353b was assigned to this genus as cf.Halticosaurus orbitoangulatus in 1932.[5] In 2000, Rauhut and Hungerbuhler reassigned this material to the genusSaltoposuchus, acrocodylomorph, based on the morphology of the teeth and theantorbital fenestra in the skull.[2] A new genus name,Apatosuchus, was created for this specimen by Hans-Dieter Sues and Rainer R. Schoch in2013 when they realized that it represented a primitiveloricatan archosaur rather than a dinosaur or a crocodylomorph, as a result of further preparation of the specimen.[6]
A third species,H. liliensterni, was reclassified asLiliensternus by Welles.[8] Mortimer (2011) noted that between 1934 and 1984,Liliensternus was incorrectly considered to be a species ofHalticosaurus.[12]
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