Sauroposeidon

The first fossils classified as Sauroposeidon were four neck vertebrae discovered in rural Oklahoma, not far from the Texas border, in a claystone outcrop that dates the fossils to about 110 million years ago (mya). This falls within the Early Cretaceous Period, specifically between the Aptian and Albian epochs. These vertebrae were discovered in May 1994 at the Antlers Formation in Atoka County, Oklahoma by dog trainer Bobby Cross and secured by Dr. Richard Cifelli and a team from the Oklahoma Museum of Natural History in May 1994 and August 1994. Initially the fossils were believed to be simply too large to be the remains of an animal, and due to the state of preservation, believed to be tree trunks. In fact, they are the longest such bones known in dinosaurs. Thus, the vertebrae were stored until 1999, when Dr. Cifelli gave them to a graduate student, Matt Wedel, to analyze as part of a project. Upon their realization of the find's significance, they issued a press release in October 1999, followed by official publication of their findings in the Journal of Vertebrate Paleontology in March 2000. The new species was named S. proteles, and the holotype is OMNH 53062. It garnered immediate media attention leading to some sources calling it inaccurately the largest dinosaur ever. The generic name comes from sauros (Greek σαύρος for "lizard"), and Poseidon (Ποσειδών), the sea god in Greek mythology, who is also associated with earthquakes, that facet styled as Ennosigaios or Enosikhthōn, "Earthshaker". This is a reference to the notion that a sauropod's weight was so great that the ground shook as it walked.The specific descriptor proteles also comes from the Ancient Greek πρωτέλης and means "perfect before the end", which refers to ''Sauroposeidon's'' status as the last and most specialized giant sauropod known in North America, during the Early Cretaceous. In 2012, numerous other sauropod remains that had been known for decades under various different names were also classified in the genus Sauroposeidon. The name Paluxysaurus was based on the specimen FWMSH 93B-10-18, a partial skull including an associated left maxilla, nasal, and teeth. Other bones from the quarry included a partial neck of seven vertebrae, thirteen vertebrae from the back and 30 from the tail, and examples of all limb and girdle bones except some hand and foot bones. It was distinguished from all other sauropods by vertebral details, and has various morphological differences in other bones compared to other sauropods of the Early Cretaceous of North America. The genus was limited to the bonebed remains; for example, the partial skeleton from Wise County known as Pleurocoelus sp. (SMU 61732) is not referred to Paluxysaurus; instead that specimen is the holotype of Astrophocaudia slaughteri D'Emic 2012, another somphospondylan sauropod. There are differences in the remains of P. sp. and Paluxysaurus, but they cannot be distinguished with confidence. In 2012, re-analysis of these specimens in light of additional Sauroposeidon remains led paleontologists D'Emic and Foreman to conclude that Paluxysaurus was the same animal as Sauroposeidon, and thus a junior synonym of S. proteles. ==Description==

The original Sauroposeidon find was composed of four articulated, mid-cervical vertebrae (numbers 5 to 8), with the in place. The vertebrae are extremely elongated, with the largest one having an overall length of , making it the longest sauropod neck vertebra on record. The cervical ribs were remarkably long as well, with the longest measurable rib (on vertebra 6) measuring – about 18% longer than the longest rib reported for Giraffatitan, but exceeded in length by the cervical ribs of Mamenchisaurus. ''Sauroposeidon's'' shoulder height has been estimated at based on an interpretation of the animal as a brachiosaurid. Estimates of its total possible length have ranged from to . The mass of Sauroposeidon is estimated at . While the vertebrae of Sauroposeidon are 25–33% longer than Giraffatitan', they are only 10–15% larger in diameter. This means that while Sauroposeidon probably has a larger body than Giraffatitan its body is smaller in comparison to the size of its neck, so it did not weigh as much as a scaled-up Giraffatitan. By comparison, Giraffatitan might have weighed . This estimate of the Giraffatitan is an average of several different methodologies. However, Sauroposeidon has a gracile neck compared to Giraffatitan. If the rest of the body turns out to be similarly slender, the mass estimate may be too high. This could be similar to the way the relatively robust Apatosaurus weighs far more than the longer but much slimmer Diplodocus. In addition, it is possible that sauropods may have had an air sac system, like those in birds, which could reduce all sauropod mass estimates by 20% or more. ==Paleoecology==

and Sauroposeidon'' Sauropods, which include the largest terrestrial animals of all time, were a very wide-ranging and successful group. They first appeared in the Early Jurassic and soon spread across the world. By the time of the late Jurassic, North America and Africa were dominated by the diplodocids and brachiosaurids and, by the end of the Late Cretaceous, titanosaurids were widespread (though only in the southern hemisphere). Between these periods, in the Early Cretaceous, the fossil record is sparse. Few specimens have been found in North America from that time and those specimens that do exist are often fragmentary or represent juvenile members of their species. Most of the surviving sauropods at the time were also shrinking in size to a mere in length, and maybe , which makes the discovery of an extremely specialized super-giant like Sauroposeidon very unusual. Sauroposeidon lived on the shores of the Gulf of Mexico, which ran through Oklahoma at that time, in a vast river delta similar to the Mississippi delta today. This paleoenvironment, which has been preserved in the Antlers Formation, also stretches from southwest Arkansas through southeastern Oklahoma and into northeastern Texas. This geological formation has not been dated radiometrically. Scientists have used biostratigraphic data and the fact that it shares several of the same genera as the Trinity Group of Texas, to surmise that this formation was laid down during the Aptian and Albian stages of the Early Cretaceous Period, approximately 110 mya. The area preserved in this formation was a large floodplain that drained into a shallow inland sea. Several million years later, this sea would expand to the north, becoming the Western Interior Seaway and dividing North America in two for nearly the entire Late Cretaceous period. The paleoenvironment of Sauroposeidon consisted of tropical or sub-tropical forests, river deltas, coastal swamps, bayous and lagoons, probably similar to that of modern-day Louisiana. There were few predators which could attempt to attack a full-grown Sauroposeidon, but juveniles were likely to be preyed on by the contemporary Acrocanthosaurus atokensis (a carnosaur slightly smaller than a Tyrannosaurus), which likely were the apex predators in this region, and the small dromaeosaur Deinonychus antirrhopus. Sauroposeidon also shared its paleoenvironment with other dinosaurs, such as the sauropod Astrodon (Pleurocoelus) and the most common dinosaur in this region, the ornithopod Tenontosaurus. Other vertebrates present during this time included the amphibian Albanerpeton arthridion, the reptiles Atokasaurus metarsiodon and Ptilotodon wilsoni, the cartilaginous fish Hybodus buderi and Lissodus anitae, the ray-finned fish Gyronchus dumblei, the crocodilians Goniopholis, Bernissartia, and Paluxysuchus, and the turtles Glyptops and Naomichelys. Possible indeterminate bird remains are also known from the Antlers Formation. The fossil evidence suggests that the gar Lepisosteus was the most common vertebrate in this region. The early mammals known from this region included Atokatheridium boreni and Paracimexomys crossi. ==References==