Sarahsaurus
| Sarahsaurus | ||||||||
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Sarahsaurus skull fossil |
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| Temporal occurrence | ||||||||
| Lower Jurassic ( Sinemurian to Pliensbachian ) | ||||||||
| 199.3 to 182.7 million years | ||||||||
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Sarahsaurus | ||||||||
| Rowe , Sues & Reisz , 2010 | ||||||||
| Art | ||||||||
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Sarahsaurus is a genus of primitive sauropodomorphic dinosaurs that lived in the Lower Jurassic North America. Fossils of the so far only species Sarahsaurus aurifontanalis have been found in the Kayenta Formation near Gold Springs in Arizona .
So far, the remains of three individuals have been found: The holotype specimen consists of a fragmentary skull and the almost complete residual skeleton, while a second specimen includes an almost complete skull and a third specimen includes an almost complete residual skeleton. Sarahsaurus can be distinguished from other sauropodomorphs by an opening (foramen) in the pubis and by a phalangeal formula of the hand skeleton of 2-3-4-2-2.
Sarahsaurus was named by Timothy B. Rowe, Hans-Dieter Sues, and Robert R. Reisz in 2010 and is the third known original genus of sauropodomorphic dinosaur from North America.
description
Sarahsaurus was a little over 4 m long and weighed about 110 kg. Like other basal sauropodomorph dinosaurs, it had a long neck with a head small in relation to its torso and a long muscular tail. The arms were significantly shorter than the legs, but very strong. The hand, about the size of a human, was very strong and had large claws. A large difference in length between the fore and hind limbs indicates a pure two-leggedness in related "prosauropods". However, when viewed from the side , the thigh bones of Sarhasaurus were straight and not curved, as is typical of the much larger and four-legged sauropods.
Site and excavation
Sarahsaurus holotype and the finds assigned in the first description come from the middle third of the 'Silty Facies' of the Kayenta Formation (Glen Canyon Group). The site is located in northeast Arizona on the northern edge of the basin drained by the Gold Spring Wash, near the Grand Canyon. The finds come from the Lower Jura (Sinemur – Pliensbach).
etymology
The generic name Sarahsaurus honors Sarah Butler, who raised a large amount for the "Dino Pit", an interactive exhibition at the Austin Nature and Science Center , through a fundraising she directed . The "Dino Pit" was co-founded by Timothy Rowe, one of the authors who described Sarahsaurus . Rowe promised Ms. Butler that if she raised $ 1 million that she would name a dinosaur after her. The second component of the generic name goes back to the Greek sauros / σαῦρος , "lizard", "salamander"
The species name aurifontanalis , formed from aurum ( Latin for "gold") and fontanalis (Latin for "from the source") refers to the site near the town of Gold Springs in Arizona.
Type material and systematic classification
Type material
In the original description, Rowe et al. in addition to the holotype, two other individuals are identified as referred specimens. The holotype is an incomplete skull with associated almost complete skeleton of an adult animal and has the collection number TMM 43646-2 of the Texas Natural Science Center. Premaxillaries, frontals, quadruates and the cranium are preserved from the skull. Most of the postcranial skeleton was found in the natural composite. The amalgamation of the various skull bones with one another, as well as that of the neural arches with the vertebral bodies along the entire spine and that of the ribs in the pelvic area and on the tail with their associated vertebrae indicate that the animal was fully grown.
The assigned find TMM 43646-3 is a post- cranial skeleton from the same site as the holotype . The Museum of Comparative Zoology at Harvard University houses MCZ 8893, an almost complete skull with a lower jaw and some fragments of vertebrae and leg bones. This specimen shows open sutures on the skull and was therefore not fully grown.
Taxonomy
The position of Sarahsaurus in the family tree of the Sauropodomorpha cannot be clearly determined. Two different data matrices result in drastically different positions: using the Yates matrix results in a position at the base of the Sauropodomorpha for Sarahsaurus , as a sister group to the Plateosauria plus Riojasaurus and Ruehleia . The Upchurch, Barrett, and Galton matrix, on the other hand, places Sarahsaurus as a basal sauropod . This discrepancy is due to the fact that the result based on the Yates matrix was falsified by homoplasias (convergence), which is also supported by the temporal and spatial distribution of the basal prosauropods. A position at the base of the Sauropoda, on the other hand, seems more credible and less affected by methodological problems.
Paleobiology
Not much is known about the way of life of Sarahsaurus . The set of teeth typical of " prosauropods " indicates, in analogy to similar genera, that the animals were herbivores, but possibly also ate small vertebrates and insects.
Individual evidence
- Jump up ↑ Brian Crafts: New Strong-Handed Dinosaur May Shatter Assumptions. In: National Geographic Daily News. Entry dated October 6, 2010, accessed August 9, 2010.
- ↑ a b c d e f g h Timothy B. Rowe , Hans-Dieter Sues , Robert R. Reisz: Dispersal and diversity in the earliest North American sauropodomorph dinosaurs, with a description of a new taxon. In: Proceedings of the Royal Society. Series B: Biological Sciences. Vol. 278, No. 1708, 2011, ISSN 0950-1193 , pp. 1044-1053, doi : 10.1098 / rspb.2010.1867 .
- ↑ a b Sarahsaurus aurifontanalis, A New Sauropodomorph. In: Palaeoblog. Entry from October 15, 2010, accessed August 8, 2014.
- ^ Heinrich Mallison: The Digital Plateosaurus I: Body Mass, Mass Distribution, and Posture Assessed by Using CAD and CAE on a Digitally Mounted Complete Skeleton. In: Palaeontologia Electronica. Vol. 13, No. 2, 2010, ISSN 1094-8074 , p. 8A, online .
- ↑ Fritz Cl. Werner : Word elements of Latin-Greek technical terms in the biological sciences (= Suhrkamp-Taschenbuch 64). Suhrkamp, Frankfurt am Main 1972, ISBN 3-518-06564-5 , p. 364.
- ^ Adam M. Yates: The first complete skull of the Triassic dinosaur Melanorosaurus Haughton (Sauropodomorpha: Anchisauria). In: Paul M. Barrett , David J. Batten (Eds.): Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (= Special Papers in Palaeontology. Vol. 77). The Palaeontological Association, London 2007, ISBN 978-1-4051-6933-2 , pp. 9-55.
- ^ Paul Upchurch , Paul M. Barrett, Peter M. Galton: A phylogenetic analysis of basal sauropodomorph relationships: Implications for the origin of sauropod dinosaurs. In: Paul M. Barrett, David J. Batten (Eds.): Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (= Special Papers in Palaeontology. Vol. 77). The Palaeontological Association, London 2007, ISBN 978-1-4051-6933-2 , pp. 57-90, abstract .
- ↑ Peter M. Galton : Cranial anatomy of the prosauropod dinosaur Plateosaurus from the Knollenmergel (Middle Keuper, Upper Triassic) of Germany. I. Two complete skulls from Trossingen / Württ. With comments on the diet. In: Geologica et Palaeontologica. Vol. 18, 1984, ISSN 0072-1018 , pp. 139-171.
- ^ Paul M. Barrett: Prosauropod dinosaurs and iguanas: speculations on the diets of extinct reptiles. In: Hans-Dieter Sues (Ed.): Evolution of herbivory in terrestrial vertebrates. Perspectives from the fossil record. Cambridge University Press, Cambridge et al. 2000, ISBN 0-521-59449-9 , pp. 42-78, doi : 10.1017 / CBO9780511549717.004 .
