Scientists in China have recently discovered a new species of gigantic sauropod dinosaur named Tongnanlong zhimingi. This dinosaur lived ~147 million years ago, in the Late Jurassic, in the Sichuan Basin of southwestern China.
Where and How It Was Found
The fossil, catalogued as the holotype, was dug up at a construction site in the Tongnan District of Chongqing. It was found in sandstone and mudstone layers of the Suining Formation, which is generally dated to the Late Jurassic.
“Anatomical and phylogenetic analysis demonstrate that Tongnanlong is a mamenchisaurid eusauropod. This discovery increases the taxonomic diversity of mamenchisaurid. It strengthens the idea that Mamenchisauridae was a non-endemic clade that radiated widely in Asia and Africa during the Middle-Late Jurassic.”, wrote the scientists in their paper describing Tongnanlong, published in Scientific Reports last month
The specimen was excavated from a quarry. It includes three dorsal (back) vertebrae, six caudal (tail) vertebrae, parts of the shoulder blade and collarbone, and fragments of the bones of the hind limbs.
A true giant of Asia
Scientists estimate that this dinosaur was enormous, measuring at about 25 to 26 meters (82 to 85 feet) long. They wrote that the “huge-sized scapula and coracoid also indicate that the specimen belongs to an extremely gigantic individual with a body length approaching about 25 ~ 26 m.” Given that it owns the biggest scapula so far known, it might be the biggest maenchisaurid so far.
Scapula and coracoid in lateral view
Its length places it close to the Dreadnoughtus, a giant sauropod from Patagonia. Though it remains smaller than Titanosaurus, Argentinosaurus and other heavyweights, it is among the largest dinosaurs in the world. It is also one of the largest dinosaurs known from Asia.
Sauropods were the largest terrestrial dinosaurs that ever existed – think long neck and massive bodies supported by pillar-like legs. They first evolved in the Late Triassic, and achieved a global distribution by the Middle Jurassic, before going extinct along with the rest of the dinosaurs at the end of the Late Cretaceous. More than 150 genera have been identified, including over 20 genera from the Jurassic period in China.
The Existence of Tongnanlong Challenges Isolation Theories
The Scientists write that the sauropods from the Middle-Late Jurassic Sichuan Basin are considered an endemic group of dinosaurs, differing from their contemporaneous sauropod cousins from the rest of Pangaea. This distribution is called the “East Asian Isolation” hypothesis, which occurred during the Jurassic to Early Cretaceous.
However, this discovery challenges the “East Asian Isolation” hypothesis by providing more phylogenetic analyses and studies of neosauropod dinosaurs from China. The paper supports the idea that they were distributed globally during the Middle Jurassic.