NEBULASAURUS

Despite sounding like an interstellar gas cloud, Nebulasaurus is a sauropodomorph dinosaur. In fact, it's a eusauropod (true sauropod), no less. Its name means "misty cloud lizard", which is a crafty play on the Nebula theme and refers to the mountainous Chinese Province of Yunnan — "southern cloudy province" — where it was discovered. Unfortunately, most of its remains have disappeared in a puff of cloudy smoke, and palaeontologists scouring the Zhanghe Formation home of Nebulasaurus have so far failed to find a single scrap to bolster a partial, albeit well-preserved, neurocranium, aka the braincase or brainpan: the portion of the skull that protects the brain.

Three other sauropodomorphs are known from Yunnan, though none of them own a braincase, which would be problematic if not for the fact that this particular body part is so willing to cooperate with scientists. The braincase of basal non-sauropod sauropodomorphs (represented in this area by Yunnanosaurus youngi) and the noodle-necked mamenchisaurids (represented in this area by Eomamenchisaurus yuanmouensis and Yuanmousaurus jiangyiensis) are choc-a-bloc with features that define their entire clan. But those very features are all absent in Nebulasaurus, which makes it a unique and standalone critter by process of elimination.

Although meagre, the remains of Nebulasaurus sport several features found in highly derived neosauropods, which is unusual given their Mid-Jurassic age and lowly position on the Sauropoda branch of the dinosaurian family tree. Thus, Nebulasaurus represents a previously unknown group of primitive Asian eusauropods with some characteristics that were ahead of their time. But regardless, they were extinct by the dawn of the Late Jurassic, while mamenchisaurids went on to dominate.

The closest relative of Nebulasaurus seems to be Africa's Spinophorosaurus which is unusual in having spiked osteoderms, probably from the tail, similar to those that form the thagomizer of stegosaurs.