Paluxysaurus

Paluxysaurus (meaning "Paluxy lizard", in reference to the town of Paluxy, Texas, and the Paluxy River) is a genus of basal titanosauriform sauropod dinosaur from the late Aptian or early Albian-age (around 112 million years old) Lower Cretaceous Twin Mountains Formation of Hood County, Texas, USA. It is known from the remains of at least four individuals found in a bonebed.

Classification
Peter J. Rose, who described the genus, performed a cladistic analysis that suggested Paluxysaurus formed a clade with Brachiosaurus, which would make it a brachiosaurid. The clade, though, is only supported by a single characteristic: a "relatively transversely broad femur at mid-shaft". Whether or not it is a brachiosaurid, Paluxysaurus appears to be a basal titanosauriform.

Discovery and history
Sauropod bones and trackways have long been known from the Paluxy River area, usually referred to the genus Pleurocoelus, including partial skeletons (particularly from the Glen Rose Formation, above the Twin Mountains Formation). In the mid 1980s, students from the University of Texas at Austin discovered a bonebed on a ranch in Hood County, but early work stopped in 1987. The quarry was reopened in 1993 and has been worked since then, by parties from Southern Methodist University, the Fort Worth Museum of Science and History, and Tarleton State University. All sauropod remains appear to come from the same genus of sauropod. Petrified logs are also known from the site. The discovery site was fluvial when its rocks were being deposited, with channel sands and muds, and concretions of calcite-cemented sandstone containing fossils. Following excavation and preparation of the majority of the fossils, the sauropod has been named Paluxysaurus.

Paluxysaurus is based on FWMSH 93B-10-18, an associated left maxilla and nasal, and teeth. Other bones from the quarry include 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 is 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 has so far been limited to the bonebed remains; for example, the partial skeleton from Wise County known as Pleurocoelus sp. (SMU 61732) is not referred to Paluxysaurus. There are differences in the remains of P. sp. and Paluxysaurus, but they cannot be distinguished with confidence.

Paleoecology and paleobiology
Like other sauropods, Paluxysaurus would have been a large, quadrupedal herbivore, eating plants with a small head on a long neck.