Sauroposeidon

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Sauroposeidon
Outline reconstruction of Sauroposeidon and the position of the four cervical vertebrae. Size comparison to humans.

Outline reconstruction of Sauroposeidon and location of the four cervical vertebrae. Size comparison to humans.

Temporal occurrence
Lower Cretaceous ( Aptian to Middle Albian )
126.3 to 107.5 million years
Locations
Systematics
Dinosaur (dinosauria)
Sauropods (Sauropoda)
Macronaria
Titanosauriformes
Brachiosauridae
Sauroposeidon
Scientific name
Sauroposeidon
Wedel , Cifelli & Sanders , 2000
Art
  • Sauroposeidon proteles Wedel, Cifelli & Sanders, 2000
Cervical vertebrae 5 to 8, holotype of Sauroposeidon
Drawing reconstruction of the series of vertebrae of the holotype

Sauroposeidon is a genus of sauropod dinosaur from the Lower Cretaceous North America. The genus is placed in the group of Brachiosauridae and is closely related to the well-known Jurassic genera Brachiosaurus and Giraffatitan .

From Sauroposeidon merely a series of four very large is cervical vertebra known, the greatest of these is 1.4 meters long. These are the longest vertebrae of any known vertebrate . The fossils of this dinosaur were recovered in rural Oklahoma (USA) in 1994 and scientifically described for the first time in 2000 as the new genus and species Sauroposeidon proteles . The existence of sauroposeidon in the Lower Cretaceous shows that large sauropods survived the transition from the Jurassic to the Cretaceous. Because of the sparse tradition, one can only speculate about the anatomy and way of life of the species. Like all sauropods, however, Sauroposeidon probably fed on plants.

features

anatomy

Compared to other sauropods, the Brachiosauridae had relatively long necks, short tails and slender and long limbs. They differed from all other sauropods by their elongated front legs, which led to a raised shoulder and gave the animals a giraffe-like appearance. Different groups of sauropods developed particularly long cervical spine independently of one another , on the one hand by lengthening the cervical vertebrae and on the other hand by transforming the anterior vertebrae into cervical vertebrae. Brachiosaurids retained the original number with 13 cervical vertebrae and lengthened the individual vertebrae. Of Sauroposeidon only the middle portion of the neck is known from the fifth to the eighth cervical vertebrae. The vortices are similar to those of other brachiosaurids such as the late Jurassic genera Brachiosaurus and Giraffatitan , but show a number of specialized, advanced features that other brachiosaurids lack.

Description of the vertebrae

The elongation of the cervical vertebrae found in all brachiosaurids was extremely pronounced in Sauroposeidon . The vertebral bodies were more than five times longer than they were tall. The vertebral body of the eighth cervical vertebra (C8) was about 1.25 meters long in this animal with a total length of 1.4 meters. This bone was almost a third longer than the C8 in Giraffatitan , so Sauroposeidon had the longest vertebral bones of all known vertebrates.

The vertebrae are extremely light thanks to air-filled cavities and internal chambers - this recess in the bones is known as pneumatization. In the living animal, the cavities and chambers were probably filled with air sacs that were connected to the airways. The external appearance of the vertebrae is characterized by large, bowl-like pits (fossae), which are separated from one another by thin bone bridges (laminae). These pits have drastically reduced the bone mass of the vertebrae, the cross-section of the vertebrae is similar to that of an I-beam . The size of the pits is significantly larger than that of related genera: the lateral pits of the vertebral bodies extend to the rear end, and the spinous processes are also deeply hollowed out.

Internally, the vortices are completely spared by small, irregularly shaped air-filled chambers (pneumatic camellae). These chambers are only separated from each other by thin bony partitions (septa), which vary in thickness from less than one to three millimeters. In contrast, the corresponding vertebrae in Brachiosaurus and Giraffatitan are mostly hollowed out by large cavities (pneumatic cameras), and only partially by the significantly smaller Camellae.

The vertebrae and their neck ribs are preserved. These were also greatly elongated and ran back along the underside of the spine, with the cervical rib of each vertebra overhanging the two following vertebrae. The longest preserved cervical rib arises from the sixth cervical vertebra and measures 3.42 meters.

Systematics

Sauroposeidon is considered a close relative of the Upper Jurassic genera Giraffatitan and Brachiosaurus . Direct comparisons are currently only possible with Giraffatitan , as there are no cervical vertebrae that can undoubtedly be attributed to Brachiosaurus . Important common features between Sauroposeidon and Giraffatitan can be found on the spinous processes: These did not sit in the middle of the vertebra, but were shifted forward. In addition, the middle cervical spine showed an abrupt, step-like increase in the spinous processes between the sixth and seventh cervical vertebrae. The spinous process of the sixth cervical vertebra further away from the body was still low, while that of the seventh cervical vertebra closer to the body was considerably higher and exceeded the height of the vertebral body. Other common features, such as the general shape of the vertebrae and the long cervical ribs, have developed independently of one another in different groups of sauropods.

The genera Sauroposeidon , Giraffatitan and Brachiosaurus are grouped together by many researchers as Brachiosauridae . A number of other representatives were assigned to this group, but all of them are very little known. The Brachiosauridae form - like the Titanosauria - a group within the Titanosauriformes .

Sauropods are only passed down from the Lower Cretaceous North America through very sparse remains and for the most part belonged to relatively small and short-necked representatives. However, Wedel and colleagues (2000) point to a single, poorly preserved cervical vertebra from the Cloverly formation (specimen number YPM 5294), which could possibly belong to sauroposeidon or to a closely related genus. The vertebra belonged to a young animal, is 47 centimeters long and shows a length-to-height ratio similar to that of Sauroposeidon . The expression of one of the laminae is also reminiscent of this genus. This finding also shows that cervical vertebrae could already have been greatly elongated in animals of a young age.

Research history and naming

Location of the site in southwest Atoka County (Oklahoma).

The only find came from the Arnold family farm land in southwest Atoka County , about 20 kilometers west of Antlers in rural Oklahoma . This farm and the adjacent grounds of McLeod Prison have long been known for their dinosaur fossils; among other things, the type material of the Acrocanthosaurus described in 1950 comes from this area. The vertebrae were discovered by Bobby Cross, a prison officer charged with training sniffer dogs. His work took Cross regularly throughout the prison grounds, where he had already found significant dinosaur fossils, including complete skeletons of Tenontosaurus .

While examining a slope on the premises of the adjacent Arnold family farm, from which fossils of Tenontosaurus had already been recovered, Cross noticed in May 1994 the remains of Sauroposeidon scented out of the rock . Cross informed the Oklahoma Museum of Natural History about the new find, which organized two excavations in May and August 1994 to retrieve the fossils. For the transport, the series of vortices wrapped in a plaster of paris had to be cut into three parts, the largest of these parts weighed approximately three tons. The subsequent preparation of the fossil in the museum took three years to complete.

Finally, in 2000, sauroposeidon was scientifically described by paleontologists Mathew Wedel , Richard Cifelli and Kent Sanders . In the same year, a more extensive publication followed on the anatomy, the relationships and the paleobiology of this dinosaur. The researchers chose the name Sauroposeidon ( Greek sauros - "lizard"; Greek Poseidon - the god of earthquakes in Greek mythology ) to emphasize the size of this animal. The second part of the species name (Gr. Proteles - "perfected before the end") indicates the advanced structure of the vertebrae and the late appearance of this sauropod in the uppermost layers of the Lower Cretaceous, before sauropod fossils from layers of the early Upper Cretaceous in North America and Europe largely disappear. While this hiatus was previously interpreted as a temporary regional extinction of the sauropods, today it is assumed that it is solely due to a lack of fossil conservation.

Paleohabitat, geology of the site and taphonomy

Sauroposeidon comes from the Antlers Formation , a formation mainly made up of sand and clay stones, which was deposited in the Aptian and Albian during the Lower Cretaceous . This formation is open in parts of Oklahoma, Texas and Arkansas - the narrow and elongated distribution area of ​​the formation traces the former course of the Gulf Coast. At the time of the deposition, this coast was believed to have been dominated by forests, river deltas , lagoons and bayous . Apart from the Sauroposeidon fossils, sauropods of the formation are only known from undetermined, very fragmentary remains. The most common herbivore was the ornithopod Tenontosaurus . Predatory dinosaurs include the dromaeosaurs Deinonychus and the large carnosaurs Acrocanthosaurus . In addition to dinosaurs, crocodiles like Goniopholis , pterosaurs like Istiodactylus , mammals like Gobiconodon as well as turtles and fish have been passed down.

The location is officially documented under the designation OMNH locality V821. It opens up sandstones that are believed to belong to the upper part of the middle section of the Antlers Formation, which at this point is estimated to be about 150 meters thick . Other finds from this site include teeth from Deinonychus , remains of a small crocodile and a Tenontosaurus skeleton; these fossils were found about 20 meters from the Sauroposeidon fossil.

What happened to the rest of the skeleton is unknown. The four vertebrae were found to be anatomically connected on the right side. The neck ribs have remained in their original position, indicating that the vertebrae were covered in sediment when they were still surrounded by flesh and muscle. Neck ribs of the missing, preceding vertebrae are not present, which indicates that the neck was not simply broken apart, but rather pulled apart. Although the site was subjected to a detailed investigation and further excavations, no further evidence of the sauroposeidon skeleton was found in 2005 .

Paleobiology

height

Body measurements are based on comparisons with closely related and better known species. Mathew Wedel and colleagues (2000) indicate that the cervical vertebrae between 25 and 33% longer than the respective cervical vertebrae in the Berlin Museum of Natural History issued holotype -Exemplars of Giraffatitan . The latter skeleton shows a neck length of 9 meters. If the proportions of Sauroposeidon's neck resembled those of Giraffatitan's , it would have been 11.25 to 12 meters long.

Estimates of total length and weight are subject to a significant degree of inaccuracy because no bones of the trunk are known. Mathew Wedel and colleagues (2000, 2005) note that the cervical vertebrae are significantly longer than those of Giraffatitan , but only show a slightly larger diameter. These researchers therefore suspect that Sauroposeidon was only 10 to 15% larger than Giraffatitan , but had a significantly longer neck in proportion. The total length of the body could therefore have been 28 meters, with the shoulder 6 or 7 meters high and the neck 17 or 18 meters high, perhaps up to 20 meters. At the same time, these researchers put their estimates into perspective: For example, the sauropod Mamenchisaurus would have shown an extremely long neck in combination with a relatively small trunk, which means that the trunk may not have increased in size to the same extent as the neck. Thus it is even possible that Sauroposeidon was smaller than the Berlin Giraffatitan specimen. Another estimate by Kenneth Carpenter gives a body length of 34 meters.

Meanwhile, body weight estimates are fraught with even greater uncertainty, especially since the extent of the airbag system is unknown. The average of five different weight estimates of the Berlin Giraffatitan skeleton is 40 tons. If Sauroposeidon's physique was similar to that of Giraffatitan , based on this average, its weight can be estimated at 50 to 60 tons. However, the researchers note that the neck was much slimmer than Giraffatitan's , and that this may also be true of the torso - in this case, Sauroposeidon may have even weighed less than the Berlin Giraffatitan specimen.

Posture and function of the neck

The posture of the neck in brachiosaurids is controversial - various interpretations range from an almost vertical to a horizontal posture. Mathew Wedel and colleagues (2000) argue against a vertical neck posture, since such a posture would have required a strong curvature of the neck base, for which there is no evidence - on the contrary, the lowest cervical vertebrae of a Giraffatitan find were found in a straight line. Instead, the neck of brachiosaurids like Sauroposeidon was pointed upwards. The researchers also find that the mean cervical sequence in both Giraffatitan and Sauroposeidon shows an abrupt decrease in the height of the spinous processes towards the head . The high spinous processes of the lower cervical vertebrae offered the back muscles an enlarged lever arm , which enabled this neck section to be held upright. The lack of high spinous processes in the cervical vertebrae further away from the body would, however, indicate a more horizontal posture of this cervical section. Thus the neck would have assumed a slight S-curve.

Mathew Wedel and colleagues (2000) also discuss the function of the greatly elongated neck of sauroposeidon . One possible advantage of a very long neck would be the accessibility of food sources that were not available to other herbivores - thus the neck could have been developed as a result of competitive pressure from other herbivores. Wedel and colleagues believe this scenario is unlikely, since the next largest herbivore of the Antlers formation, the ornithopod Tenontosaurus , could only graze at a maximum height of three meters, while Sauroposeidon was possibly able to reach heights of up to 18 meters. Instead, the researchers note that the elongated neck resulted in an increased reach, which allowed more food to be taken in without moving the body. Thus, the elongated neck could have counteracted the restriction in mobility that a life in the woods would have meant for such a large animal.

literature

  • Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Sauroposeidon proteles, a new sauropod from the early Cretaceous of Oklahoma. In: Journal of Vertebrate Paleontology. Vol. 20, No. 1, 2000, ISSN  0272-4634 , pp. 109-114, doi : 10.1671 / 0272-4634 (2000) 020 [0109: SPANSF] 2.0.CO; 2 .
  • Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, ISSN  0567-7920 , pp. 343-388, online .
  • Mathew J. Wedel, Richard L. Cifelli: Sauroposeidon: Oklahoma's Native Giant. In: Oklahoma Geology Notes. Vol. 65, No. 2, 2005, ISSN  0030-1736 , pp. 40-57

Web links

Commons : Sauroposeidon  - collection of images, videos and audio files

Individual evidence

  1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. 2010, ISBN 978-0-691-13720-9 , p. 203, online .
  2. ↑ a b c d e Mathew J. Wedel, Richard L. Cifelli: Sauroposeidon: Oklahoma's Native Giant. In: Oklahoma Geology Notes. Vol. 65, No. 2, 2005, pp. 40-57, here pp. 45-59: Discovery and Description of Sauroposeidon , digitized (PDF; 2.15 MB) .
  3. ^ A b Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Sauroposeidon proteles, a new sauropod from the early Cretaceous of Oklahoma. In: Journal of Vertebrate Paleontology. Vol. 20, No. 1, 2000, pp. 109-114, here p. 110: Systematic Paleontology.
  4. ^ Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 352-359: Morphological description.
  5. ^ A b c Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Sauroposeidon proteles, a new sauropod from the early Cretaceous of Oklahoma. In: Journal of Vertebrate Paleontology. Vol. 20, No. 1, 2000, pp. 109-114, here pp. 110-111: Description.
  6. ^ A b Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Sauroposeidon proteles, a new sauropod from the early Cretaceous of Oklahoma. In: Journal of Vertebrate Paleontology. Vol. 20, No. 1, 2000, pp. 109-114, here pp. 112-113: Functional Morphology.
  7. ^ A b Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here p. 352: Systematic Paleontology.
  8. ^ Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 359-365: Vertebral internal structure.
  9. ↑ Michael P. Taylor: A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914). In: Journal of Vertebrate Paleontology. Vol. 29, No. 3, 2009, pp. 787-806, here pp. 789, 798, doi : 10.1671 / 039.029.0309 .
  10. ^ Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 373-374: Brachiosauridae.
  11. ^ A b Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 365, 371-372: Systematics and affinities.
  12. ^ A b c Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 350-351: Geology and taphonomy.
  13. ^ Philip D. Mannion, Paul Upchurch : A re-evaluation of the 'mid-Cretaceous sauropod hiatus' and the impact of uneven sampling of the fossil record on patterns of regional dinosaur extinction. In: Palaeogeography, Palaeoclimatology, Palaeoecology. Vol. 299, No. 3/4, 2011, ISSN  0031-0182 , pp. 529-540, doi : 10.1016 / j.palaeo.2010.12.003 .
  14. ^ Mathew J. Wedel, Richard L. Cifelli: Sauroposeidon: Oklahoma's Native Giant. In: Oklahoma Geology Notes. Vol. 65, No. 2, 2005, pp. 40-57, here pp. 43-45: The Antlers Formation and its dinosaurs.
  15. ^ A b c Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 374-376: Size estimates.
  16. ^ Mathew J. Wedel, Richard L. Cifelli: Sauroposeidon: Oklahoma's Native Giant. In: Oklahoma Geology Notes. Vol. 65, No. 2, 2005, pp. 40-57, here pp. 52-55: Flesh on the bones.
  17. ↑ Thomas R. Holtz Jr .: Dinosaurs. The most complete, up-to-date encyclopedia for dinosaur Lovers of all Ages. Random House, New York NY 2007, ISBN 978-0-375-82419-7 .
  18. ↑ Kenneth Carpenter : Biggest of the Big: A critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. In: John R. Foster, Spencer G. Lucas (eds.): Paleontology and geology of the Upper Jurassic Morrison formation (= New Mexico Museum of Natural History & Science. Bulletin. 36, ISSN  1524-4156 ). New Mexico Museum of Natural History & Science, Albuquerque NM 2006, pp. 131-138, here p. 133, online .
  19. ^ Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 382-383: Air sac systems.
  20. ↑ P. Martin Sander , Andreas Christian, Marcus Clauss, Regina Fechner, Carole T. Gee, Eva-Maria Griebeler, Hanns-Christian Gunga , Jürgen Hummel, Heinrich Mallison, Steven F. Perry, Holger Preuschoft, Oliver WM Rauhut , Kristian Remes , Thomas Tütken, Oliver Wings, Ulrich Witzel: Biology of the sauropod dinosaurs: the evolution of gigantism. In: Biological Reviews. Vol. 86, No. 1, 2011, ISSN  0006-3231 , pp. 117–155, here p. 128: Bauplan and skeletal anatomy , doi : 10.1111 / j.1469-185X.2010.00137.x .
  21. ^ A b Mathew J. Wedel, Richard L. Cifelli, R. Kent Sanders: Osteology, paleobiology, and relationships of the sauropod dinosaur Sauroposeidon. In: Acta Palaeontologica Polonica. Vol. 45, No. 4, 2000, pp. 343-388, here pp. 376-382: Neck posture and biomechanics.
This version was added to the list of articles worth reading on September 18, 2012 .