Puertasaurus

The holotype and only known specimen of Puertasaurus reuili was discovered in the Santa Cruz Province of southern Patagonia, Argentina. The remains were recovered in Cerro Los Hornos, near the La Leona River, and were reported from the Cerro Fortaleza Formation (which, at the time, was referred to as the Pari Aike Formation). The holotype was discovered in a grey sandstone lens that also preserved the carbonized remains of cycads and conifers. It was given the specimen number of MPM 10002, and consists of four vertebrae, specifically one cervical, one dorsal, and two (about 3% of the skeleton). Of this material, only the dorsal vertebra was complete. Most of the cervical vertebra was preserved, but only the centra of the caudal vertebrae are known. Puertasaurus reuilli was described by the paleontologists Fernando Novas, Leonardo Salgado, Jorge Calvo, and Federico Agnolin in 2005, and was named after the fossil hunters Pablo Puerta and Santiago Reuil, who discovered the holotype in January 2001 and prepared it afterwards. Its discovery was announced in July 2006, at the Argentine Museum of Natural Sciences in Buenos Aires. Puertasaurus was the first discovered giant titanosaur that preserved cervical vertebrae. ==Description==

Size based on related taxa Due to a lack of better material, the size of Puertasaurus is difficult to estimate. Novas estimated the new species was approximately long and weighing between . This would place it as one of the largest dinosaurs, only rivaled in size by its relative Argentinosaurus, which has been estimated at up to in length and in mass. The discovery of the more complete Futalognkosaurus revealed that these previous estimates were likely too high, and suggested that giants such as Puertasaurus and Argentinosaurus were probably less than long. In 2012, Thomas Holtz estimated Puertasaurus to have been potentially long and 72.5-80 tonnes (80-88 short tons). In 2013, the entire neck was estimated to have been approximately long by Mike Taylor and Matt Wedel. Later the same year, Scott Hartman made a reconstruction that suggests a total length of , slightly shorter than other estimates. In 2016, Gregory S. Paul estimated a length of and a weight of at least . In 2017, paleontologist José Carballido and his colleagues estimated its mass at roughly , which was lighter than Patagotitan, a more complete giant sauropod. Vertebrae Of the four vertebrae preserved in the holotype, the largest is the dorsal vertebra (thought to be a second dorsal vertebra), measuring tall and wide. This is the broadest sauropod vertebra known, and two-thirds of its width is made up of the huge (structures projecting from the side of the vertebra), which are heavily expanded and have very deep bases, forming wing-like structures when viewed from the front. In other titanosaurs, such as Dreadnoughtus, they are far less wide and deep. The zygapophyseal articulations, which connect two adjacent vertebrae, are located on the lower part the neural arch. The and (processes on the side of the vertebra) are strongly laterally projected. The cervical vertebra lacks (large cavities) and was not very pneumatic. The length of the restored centrum is estimated to be long based on other titanosaurs. ==Classification==

'', temporarily exhibited at the Museum Koenig Puertasaurus is differentiated from other sauropods based on a unique combination of features. These features consist of the heavily expanded neural spines on the cervical vertebrae, which result in the neural spines being wider than the vertebral body, strong dorsolateral (high on the side) ridges on these neural spines, robust spinoprezygapophyseal laminae (projections in front of the neural spine) on the posterior cervical vertebrae, anterior dorsal vertebrae that are very short from front to back, and the animal's giant size. }} ==Paleoecology==

, a dinosaur from the same formation as Puertasaurus'' Puertasaurus is from the Late Cretaceous Period of southern Patagonia. However, which formation it was derived from and its geological age have been disputed, because of the inconsistent stratigraphic nomenclature of southern Patagonia. It was originally reported as being from the Pari Aike Formation, and Maastrichtian in age. The Pari Aike Formation was subsequently reassigned to the Mata Amarilla Formation and reinterpreted as being from the Cenomanian to Santonian. The Cerro Fortaleza Formation represents a terrestrial ecosystem. The presence of paleosols and lignite suggests a humid environment with high amounts of rainfall and a high water table. Avulsion surfaces, histosols, carbonaceous fossil roots, and silicified wood all provide evidence of a low-lying forested landscape with poor drainage. Non-dinosaurian fauna known from the formation include crocodilians, turtles, bony fish, and lamniform sharks. ==References==