Jinchuanloong

MEANING: Jinchuan dragon

PERIOD: Middle Jurassic

CONTINENT: Asia

Jinchuanloong is a relatively basal sauropod that measured an estimated 10 m in length. Sauropod skulls typically don't preserve well in the fossil record, but Jinchuanloong is known mainly from the skull, and parts of the neck and tail. Like all sauropods, Jinchuanloong was a quadrupedal herbivore that used its long neck to reach the vegetation that it fed on.

Abstract from paper: Sauropod dinosaurs were gigantic quadrupedal herbivores. They range from Early Jurassic to Late Cretaceous and have been found on all continents. The rich sauropod faunas in the Middle and Late Jurassic of China are mainly from southern or western China. Here, we describe a non-neosauropod eusauropod from the Middle Jurassic Xinhe Formation of Gansu Province, northwestern China, based on an associated partial skeleton that includes a nearly complete skull with mandible, the five anteriormost cervical vertebrae appressed with the skull and the posterior 29 articulated caudal vertebrae. It can be diagnosed as a new taxon Jinchuanloong niedu gen. et sp. nov. based on several cranial and postcranial autapomorphies. In Jinchuanloong, the posterior margin of the external naris lies in front of the posterior margin of the antorbital fenestra, similar to that in basal eusauropods, and the base of the maxillary ascending process presents a foramen, similar to that in neosauropods. The finding of Jinchuanloong adds diversity and helps elucidate the evolution of the sauropods in East Asia.

Jinchuanloong is from the Middle Jurassic. 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.

Jinchuanloong is a 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.