Huashanosaurus

MEANING: Huashan Mountain lizard

PERIOD: Early - Middle Jurassic

CONTINENT: Asia

Huashanosaurus is a basal sauropod dinosaur that lived from the Early to Middle Jurassic periods of what is now China. It was a long-necked herbivore which still exhibited many basal traits of the earlier sauropodomorphs, while transitioning to obligate quardupedality. Huashanosaurus grew to approximately 12 m in length, and weighed around 10 t.

Abstract from paper: We report a new eusauropod dinosaur, Huashanosaurus qini gen. et sp. nov., based on a partial skeleton recovered from a bed in the Lower to Middle Jurassic Wangmen Formation (Fm.) from Huqiu Quarry near Mingjiang River, Ningming County, Guangxi Zhuang Autonomous Region, southern China. The new taxon can be diagnosed by the following autapomorphies: posterior process of the ulna hook-shaped; the cross-section of the proximal part of the ulna crescent-shaped; groove structure present at the posterodistal surface of the fibula. Phylogenetic analysis reveals that H. qini is later-diverging than the Middle Jurassic Shunosaurus. Previous work showed that the Wangmen Fm. is early Early Jurassic in age whereas the new eusauropod discovery indicates that the Wangmen Fm. is probably somewhat younger Early–Middle Jurassic in age. The find increases the diversity of Jurassic eusauropods in China.

Huashanosaurus is from the Early to Middle Jurassic. The Jurassic Period, the second period of the Mesozoic Era, spanned from about 201 to 145 million years ago. It followed the Triassic-Jurassic extinction event, which cleared the way for new groups of organisms to rise and diversify - especially the dinosaurs. This extinction, likely caused by massive volcanic activity related to the breakup of the supercontinent Pangea, triggered climate shifts and widespread ecological upheaval. In the aftermath, the Early Jurassic began as a time of recovery and opportunity, where surviving lineages began to spread into newly vacated ecological roles.

During the Early Jurassic, Pangea was still largely intact, but rifting had begun in earnest, especially in the northern hemisphere. This led to the formation of new coastlines and the early stages of the Atlantic Ocean. Global climates were warm and relatively stable, with no evidence of polar ice. In many regions, lush forests of ferns, cycads, ginkgoes, and conifers flourished. These plants formed the backbone of early Jurassic ecosystems and provided food for a growing diversity of herbivorous dinosaurs.

The Middle Jurassic, spanning from approximately 174 to 163 million years ago, was a period of increasing tectonic activity and evolutionary innovation. By this time, the supercontinent Pangaea had begun to split more significantly, with Laurasia in the north and Gondwana in the south drifting apart. This movement created new coastlines, shallow seas, and rift valleys that fostered diverse ecosystems. The climate remained generally warm and humid, promoting the spread of lush vegetation, including ferns, cycads, and conifers, which blanketed much of the land and supported a wide variety of herbivorous dinosaurs.

Though less well known than the Late Jurassic, the Middle Jurassic was an important evolutionary chapter. Several major dinosaur groups began to diversify, including the stegosaurs and more derived long-necked sauropods that would later dominate the landscape. Theropods also continued to evolve, giving rise to new lineages like the megalosaurids and the early ancestors of more derived carnivores. Fossil evidence from this interval is relatively scarce compared to later stages, but what we do have paints a picture of an increasingly complex world, setting the stage for the iconic ecosystems of the Late Jurassic.

Huashanosaurus is a basal sauropod. Sauropods are saurischian dinosaurs that had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Brachiosaurus, Diplodocus, Apatosaurus and Brontosaurus.

The oldest known unequivocal sauropod dinosaurs are known from the Early Jurassic, and by the Late Jurassic (150 million years ago), sauropods had become widespread. By the Late Cretaceous, one group of sauropods, the titanosaurs, had replaced all others and had a near-global distribution. This group included the largest animals ever to walk the earth. Estimates vary, but the largest titanosaurs are estimated at upward of around 40 m, and weighing 100 t, or possibly even more.

As with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilized remains of sauropods have been found on every continent, including Antarctica.