Titanosauriformes
| Titanosauriformes | ||||||||||
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Live reconstruction of the original titanosauriform Euhelopus |
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| Temporal occurrence | ||||||||||
| Middle Jurassic to Upper Cretaceous ( Bathonian to Maastrichtian ) | ||||||||||
| 168.3 to 66 million years | ||||||||||
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Titanosauriformes | ||||||||||
| Salgado et al. , 1997 |
The Titanosauriformes are a group of sauropod dinosaurs, which includes the Brachiosauridae , the Titanosauria and some original forms such as Euhelopus . They are classified along with Camarasaurus and related forms within the Macronaria group .
Possibly the oldest representative of the Titanosauriformes is Lapparentosaurus from the Middle Jurassic ( Bathonium , about 168.3 million years ago) - however, the classification of this genus within the Titanosauriformes is only provisional. The Titanosauria as the last group of the Titanosauriformes did not become extinct until 66 million years ago along with all other non-avian dinosaurs at the Cretaceous-Tertiary border . Fossils have been found all over the world, with the exception of Antarctica .
features
General
The limbs of original titanosauriformes such as Brachiosaurus and Euhelopus were longer than those of other sauropods. In addition, the front legs were significantly elongated relative to the hind legs, which is due, among other things, to an elongated metatarsus . In Brachiosaurus , the front legs were even longer than the rear legs. Thanks to these adjustments, the shoulder was at a greater height, which increased the maximum grazing height. These original titanosauriformes could therefore have specialized in higher-lying food sources - in contrast to the Diplodocoidea , which showed short front legs and thus a deeper shoulder, which probably means that these sauropods mainly took up low-growing vegetation. While Brachiosaurus and Euhelopus were often reconstructed in the past with a giraffe-like, almost vertically stretched neck, a more recent study suggests that the neck was kept approximately horizontal in a neutral position. In the more derived (more modern) titanosaurs, the titanosaurs, the limbs were shortened and much more robust.
Within the Titanosauriformes there is a trend towards a wider leg position. For example, the thigh bone (femur) of derived titanosaurs is splayed outwards by about 10 °, while this bone was oriented vertically in other sauropod groups. This development can also be recognized on the basis of fossil tracks: footprints of sauropods can be divided into two groups - the "narrow- lane" type, Parabrontopodus , which probably shows the original constellation of more primitive sauropod groups, and the "broad-lane" type, Brontopodus , which shows the Constellation especially with titanosaurs and possibly other Macronarians shows. The first adjustments to an additional leg position can already be found in Brachiosaurus .
Synapomorphies
The Titanosauriformes can be differentiated from other groups by different, commonly derived characteristics ( synapomorphies ). The presence or absence of these characteristics determines whether a genus is classified within the Titanosauriformes or not. Commonly derived features can be found, for example, in the vertebral arches of the middle caudal vertebrae, which were positioned on the front half of the vertebral bodies. In all other sauropods and theropods , the vertebral arches are located in the middle of the caudal vertebrae. Furthermore, the claw of the first finger was either reduced or missing, as with most Titanosauria. Further important jointly derived features can be found in the pelvic bones: The anterior (anterior) process (pubic peduncle) on the underside of the ilium (ilium) was perpendicular to the axis of the sacrum (sacrum). The iliac bone showed in the anterior (pre-acetabular) half an enlarged and upwardly directed club-like crest, which led to the fact that the iliac bone showed its highest point in the anterior half, and not immediately above the joint socket ( acetabulum ), as in more original sauropods. The upper half of the thigh bone shows a large, lateral hump.
Systematics
definition
The taxon Titanosauriformes was established in 1997 by Leonardo Salgado and colleagues. These authors define the Titanosauriformes as a node-based definition , which includes the last common ancestor of Brachiosaurus brancai , Chubutisaurus insignis and the Titanosauria as well as all descendants of this ancestor. Paul Sereno (1998, 2005) proposes a new definition that only uses the well-known reference genera Saltasaurus and Brachiosaurus . According to this definition, the Titanosauriformes include the last common ancestor of Brachiosaurus brancai and Saltasaurus loricatus as well as all descendants of this ancestor.
External system
The Titanosauriformes are classified within the Macronaria group. Some authors lead another group within the Macronaria, which is superordinate to the Titanosauriformes, the Camarasauromorpha . The Macronaria form together with the Diplodocoidea ( Diplodocidae , Dicraeosauridae and Rebbachisauridae ) the group Neosauropoda .
The following system was simplified according to Upchurch and colleagues, 2004:
| Sauropoda |
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Internal system
The Titanosauriformes can generally be divided into two groups, the Brachiosauridae , which includes Brachiosaurus and Giraffatitan , as well as the Titanosauria , which are assigned to genera such as Saltasaurus , Rapetosaurus or Opisthocoelicaudia . Some researchers have additional groups that are not recognized by many other researchers. These include the Euhelopodidae , which is said to include Euhelopus , and the Huanghetitanidae , which was established in 2006 and which is said to include the genus Huanghetitan .
Sereno and Wilson (1998) described a new, superordinate group within the Titanosauriformes, the Somphospondyli , which is said to include the Titanosauria and Euhelopus . However, this group is not accepted by some researchers.
The following system was simplified according to Wilson (2002):
| Titanosauriformes |
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Individual evidence
- ^ Gregory S. Paul: The Princeton Field Guide To Dinosaurs , 2010. ISBN 978-0-691-13720-9 , pp. 200-213 Online
- ↑ a b Paul Sereno: Titanosauriformes. (No longer available online.) In: Taxon Search. Archived from the original on February 24, 2012 ; Retrieved October 4, 2010 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ A b c Matthew T. Carrano: The Evolution of Sauropod Locomotion - morphological diversity of a secondarily quadrupedal radiation . In: Rogers, Wilson (Ed.): The Sauropods: Evolution and Paleobiology . University of California Press, 2005, ISBN 0-520-24623-3 .
- ↑ Kent A. Stevens, J. Michael Parrish: Digital Reconstructions of Sauropod Dinosaurs and Implications for Feeding . In: Rogers, Wilson (Ed.): The Sauropods: Evolution and Paleobiology . University of California Press, 2005, ISBN 0-520-24623-3 .
- ↑ Jeffrey A. Wilson, Matthew T. Carrano: Titanosaurs and the origin of "wide-gauge" trackways: a biomechanical and systematic perspective on sauropod locomotion . In: Paleobiology . tape 52 , no. 2 , 1999, p. 252-267 .
- ^ A b Leonardo Salgado, Rodolfo Anibal Coria, Jorge Orlando Calvo: Evolution of Titanosaurid Sauropods. I: Phylogenetic Analysis Based on the Postcranial Evidence . In: Ameghiniana . tape 34 , no. 1 , 1997, ISSN 0002-7014 , p. 3-32 .
- ↑ a b Upchurch, Barrett, Dodson: Sauropoda . In: Weishampel, Dodson, Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, 2004, ISBN 0-520-24209-2 , pp. 259-322 .
- ↑ H. You, D. Li, L. Zhou, Q. Ji: Huanghetitan liujiaxiaensis. a New Sauropod Dinosaur from the Lower Cretaceous Hekou Group of Lanzhou Basin, Gansu Province, China . In: Geological Review . tape 52 , no. 5 , 2006, p. 668-674 .
- ↑ Jeffrey A. Wilson, Paul C. Sereno: Early Evolution and Higher-level Phylogeny of Sauropod Dinosaurs . In: Journal of Vertebrate Paleontology . 18, addition to number 2, 1998.
- ↑ Jeffrey A. Wilson: Sauropod dinosaur phylogeny: critique and cladistic analysis . In: Zoological Journal of the Linnean Society . tape 136 , 2002, pp. 217-276 .
