in the lower Morrison Formation. More fragmentary remains have also been referred to the species. A re-evaluation by Robert T. Bakker in 1998 found it to be more primitive, so Bakker coined the new generic name Eobrontosaurus, derived from Greek , "dawn", and Brontosaurus. The cladogram below is the result of an analysis by Tschopp, Mateus, and Benson (2015). The authors analyzed most diplodocid type specimens separately to deduce which specimen belonged to which species and genus. Palaeobiology Posture and locomotion Historically, sauropods like Brontosaurus were believed to be too massive to support their own weight on dry land, so theoretically they must have lived partly submerged in water, perhaps in swamps. Recent findings do not support this, and sauropods are thought to have been fully terrestrial animals. Diplodocids like Brontosaurus are often portrayed with their necks held high up in the air, allowing them to browse on tall trees. Though some studies have suggested that diplodocid necks were less flexible than previously believed, other studies have found that all tetrapods appear to hold their necks at the maximum possible vertical extension when in a normal, alert posture, and argue that the same would hold true for sauropods barring any unknown, unique characteristics that set the soft tissue anatomy of their necks apart from that of other animals. Trackways of sauropods like Brontosaurus show that the average range for them was around per day, and they could potentially reach a top speed of . The slow locomotion of sauropods may be due to the minimal muscling or recoil after strides. Various uses have been proposed for the single claw on the forelimb of sauropods. They were suggested to have been for defence, but the shape and size of them makes this unlikely. Other predictions were that it could be for feeding, but the most probable is that the claw was for grasping objects like tree trunks when rearing. Physiology James Spotila et al. (1991) suggest that the large body size of Brontosaurus and other sauropods would have made them unable to maintain high metabolic rates, as they would not be able to release enough heat. However, temperatures in the Jurassic were 3 degrees Celsius higher than present. They assumed that the animals had a reptilian respiratory system. Wedel found that an avian system would have allowed them to dump more heat. Some scientists have argued that the heart would have