Halticosaurus
| Halticosaurus Temporal range: Late Triassic,
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | Neotheropoda Bock, 1952 |
| Family: | †Halticosauridae Bock, 1952 |
| Genus: | †Halticosaurus Huene, 1908 |
| Type species | |
| †Halticosaurus longotarsus Huene, 1908
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| Synonyms[1] | |
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Tanystrosuchus Species Synonymy
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Halticosaurus (pron.:"HAL-tick-oh-SORE-us") is a genus of theropod dinosaur from the Late Triassic period (middle Norian stage, around 208 million years ago). It was a coelophysoid found in the Middle Stubensandstein formation of what is present-day Germany. Some researchers considered Halticosaurus the same genus as Liliensternus, but Samuel Welles (1984) found differences in the femoral head and the anterior trochanter.
Etymology
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[2] in 1908 and the type species is Halticosaurus longotarsus.
Description
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 This material was found to be mixed in with the remains of a prosauropod dinosaur, Sellosaurus gracilis. Rauhut and Hungerbuhler (2000) reassessed the type material and concluded that only the two partial femora can be reliably referred to this genus.[3] The hip bone has only two fused sacral vertebrae, a basal condition. The presence of a five-fingered hand represents the primitive condition of dinosaurs.[4] Benton (1992) noted that its skull was 18 inches long but was lightly built, featuring large fenestrae. The legs of Halticosaurus were strong as its arms were relatively short. Estimates suggest that Halticosaurus was about 5.5 m (18.0 ft) long.[4]
Classification and phylogeny
In 1908, Huene originally assigned this genus broadly to Dinosauria, and after additional analysis in 1909 he assigned Halticosaurus to Saurischia.[2][5] In 1952, Bock observed enough unique skeletal features to assign it to its own family Halticosauridae. Welles (1984) and Chatterjee (1987) later agreed with this classification.[6][7] Over the years there was an effort to refer Halticosaurus to Podokesauridae 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 that Halticosaurus was indeterminate because the available material is too poorly preserved,[3] but Welles (1984) was able to demonstrate that morphological differences exist between Halticosaurus and comparable taxa such as Dilophosaurus and Liliensternus, and that this genus has a suite of characters that distinguish it from other theropod dinosaurs.[6]
Reclassified species
A second species, based on a partial skull SMNS 12353b was assigned to this genus as cf. Halticosaurus orbitoangulatus. In 2000, Rauhut and Hungerbuhler reassigned this material to the genus Saltoposuchus, a crocodylomorph, based on the morphology of the teeth and the antorbital fenestra in the skull.[3][8] A new generic name Apatosuchus was erected for this specimen by Hans-Dieter Sues and Rainer R. Schoch in 2013 when it was realized that it represented a basal loricatan archosaur rather than a dinosaur or a crocodylomorph, as a result of further preparation of the specimen.[9]
A third species, H. liliensterni, was reclassified as Liliensternus by Welles.[6] Mortimer (2011) noted that between 1934 and 1984, Liliensternus was incorrectly considered to be a species of Halticosaurus.[10]
Distinguishing anatomical features
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group.
According to Welles (1984) Halticosaurus can be distinguished based on the following features, all of which differ from those of Liliensternus liliensterni:[6]
- the dentary is shallower and is pointed more anteriorly
- shorter and taller mid cervical vertebrae are present
- a sharp ventral keel is present on the mid-cervical vertebrae
- the sacral centra are narrower
- lower third sacral vertebra
- a more distally placed anterior trochanter
- the presence of smaller distal condyles on metatarsal II which extend less far proximally on shaft
Paleoecology
Provenance and occurrence
The genus Halticosaurus was discovered in the Middle Stubensandstein Member of the Löwenstein Formation in Baden-Wurttemberg, Germany. The remains of the holotype of Halticosaurus SMNS 12353 were recovered by A. Burrer, G. Mayer, E. Fraas in 1902, 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 housed in the collection of the State Museum of Natural History Stuttgart in Stuttgart, Germany. Another specimen assigned to Halticosaurus was collected by O. Jaekel in 1909, at the Trossingen Formation in Germany in sediments deposited during the Rhaetian stage of the Triassic period, approximately 208 to 201 million years ago.
Fauna and Habitat
Studies suggest that the paleoenvironment of the Middle Stubensandstein Member was an alluvial plain with a semi-arid to sub-humid climate in the land-locked South German Keuper Basin. This formation has produced the remains of rausuchids like Teratosaurus, phytosaurs like Nicrosaurus and the dinosaurs Dolichosuchus, Tanystropheus posthumus, Efraasia, Plateosaurus (=Sellosaurus), and Procompsognathus.[3][11]
References
- ^ Olshevsky, G. (1991). "A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia" (PDF). Mesozoic Meanderings 2. San Diego: 196.
- ^ a b Huene, 1908. Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse [The dinosaurs of the European Triassic formations with consideration of occurrences outside Europe]. Geologische und Palaeontologische Abhandlungen Suppl. 1(1), 1-419.
- ^ a b c d Rauhut, O.M.W. and Hungerbuhler, A. (2000) "A review of European Triassic theropods". Gaia 15: 75-88.
- ^ a b Benton, M. (1992). Dinosaur and other prehistoric animal factfinder. 1st American ed. New York: Kingfisher Books. Chicago / Turabian.
- ^ Huene, 1909. Skizze zu einer Systematik und Stammesgeschichte der Dinosaurier [Sketch of the systematics and origins of the dinosaurs]. Centralblatt für Mineralogie, Geologie und Paläontologie. 1909, 12-22.
- ^ a b c d Welles, 1984. Dilophosaurus wetherilli (Dinosauria, Theropoda), osteology and comparisons. Palaeontographica. Beiträge zur Naturgeschichte der Vorzeit. Abteilung A: Paläozoologie, Stratigraphie 185 p. 85-180.
- ^ S. Chatterjee. 1987. A new theropod dinosaur from India with remarks on the Gondwana-Laurasia connection in the Late Triassic. Gondwana 6: Stratigraphy, Sedimentology and Paleontology, G. D. McKenzie (ed.), Geophysical Monographs 41:183-189
- ^ Glut, D. F., 2003, Dinosaurs, the Encyclopedia, Supplement 3: McFarland & Company, Inc., 726pp.
- ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1111/zoj.12038 , please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi=10.1111/zoj.12038instead. - ^ Mortimer, Mickey (2012). "Coelophysoidea".
- ^ E. Fraas. 1907. Aetosaurus crassicauda n. sp. nebst Beobachtungen über das Becken der Aetosaurier [Aetosaurus crassicauda n. sp. together with observations on the pelvis of aetosaurs]. Mitteilungen aus dem Königlichen Naturalien-Kabinett zu Stuttgart 42:101-109
