Wudingloong

MEANING: Wuding County dragon

PERIOD: Early Jurassic

CONTINENT: Asia

Wudingloong is the earliest diverging, and oldest sauropodomorph dinosaur known from East Asia. Typical of basal sauropodomorphs, or "prosauropods," it was a bipedal herbivore with a long neck. Wudingloong was a fairly small prosauropod at approximately 4 m in length, and weighing around 400 kg.

Abstract from paper: A new dinosaur assemblage from the Lower Jurassic at Wande Town, Wuding County, Yunnan Province, China is discovered recently. Here a new sauropodomorph from this site, Wudingloong wui gen. et sp. nov., is described on the basis of a partial skeleton. Wudingloong is different from other non-sauropodiform sauropodomorphs particularly in having an ascending ramus of the maxilla excavated by triangular antorbital fossa, distinct ventral keel on the middle cervical centra, a slender humerus with a flat and low humeral head, a gracile metacarpal V with the proximal end as wide as the distal end, and a large and robust ungual of manual digit I. Wudingloong was excavated from the lowest Lower Jurassic Yubacun Formation, which is the lowest dinosaur bone bed in East Asia. Both the phylogenetic analysis and stratigraphic horizon indicate that Wudingloong represents the earliest-diverging and stratigraphically oldest sauropodomorph dinosaur discovered in East Asia so far. The discovery of this new taxon provides further evidence that the southwestern China sauropodomorph assemblage is one of the most taxonomically diverse and morphologically disparate in the pre-Toarcian Early Jurassic worldwide, represented by various taxa from near the base of the Massopoda to non-sauropodan sauropodiforms.

Wudingloong is from the Early 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.

Dinosaurs, which had first appeared in the Late Triassic, truly began to establish dominance during this time. Early sauropods like began evolving larger body sizes and more efficient quadrupedal locomotion, paving the way for the giants of the Late Jurassic. Theropods such filled the role of medium-to-large predators, while small ornithischians scurried below the forest canopy. Although these groups were still relatively primitive compared to their later descendants, the foundations of major Mesozoic lineages were already being laid in the Early Jurassic. The period set the stage for an explosion of diversity and gigantism that would characterize the rest of the Jurassic world.

Wudingloong is a basal sauropodomorph. Sauropodomorpha is the larger group that contains the long-necked sauropod dinosaurs. Basal sauropodomorphs, often informally referred to as "prosauropods," were early members of the lineage that eventually gave rise to the massive quadrupedal herbivores. These early sauropodomorphs thrived during the Late Triassic and Early Jurassic periods and represent some of the first large-bodied plant-eaters to evolve within Dinosauria. They were generally medium-sized, with long necks, small heads, and leaf-shaped teeth suited for a herbivorous or omnivorous diet.

Unlike their gigantic descendants, most basal sauropodomorphs were primarily bipedal, though some likely used all four limbs when moving slowly or feeding. Their forelimbs were shorter than their hindlimbs, and many had grasping hands with large claws - features that suggest a degree of versatility in both locomotion and feeding behavior. Fossil evidence of these dinosaurs has been found across much of Pangea, showing they were among the earliest dinosaur groups to achieve a widespread distribution. Though often overshadowed by the sauropods they gave rise to, these early forms played a crucial role in the rise of large-bodied herbivores and the overall success of dinosaurs in the Mesozoic.