Evrim Yazgin
Cosmos science journalist
A fossil skull found in northwestern China belongs to a rare group of dinosaurs that is an early member of a lineage of sauropods not related to better-known species such as Brachiosaurus and Apatosaurus.
Sauropods were the largest land animals of all time. They had distinctive small heads, and long necks and tails. Sauropods could eat more than 200kg of plant matter every day – the largest species could have grown to 70–100 tonnes.
This dinosaur group was at its most diverse and prominent during the late Jurassic period – 201 to 143 million years ago (mya). Sauropods died out at the end of the Cretaceous period 66 mya along with all the dinosaurs which didn’t evolve into birds.
How sauropods emerged, and how they reached such gigantic sizes, are evolutionary mysteries.
Sauropods would have evolved from “sauropodomorphs” which lived in the late Triassic period (252–201 mya), such as Mbiresaurus – a 230-million-year-old dinosaur of which a fossil was found in 2022.
Early Jurassic sauropod evolution saw the development of different clades within the group.
Most of the most well-known sauropods belong to a group called Neosauropoda which sits within a broader group called Eusauropods and includes almost all long-necked dinosaurs except the very earliest forms of sauropodomorphs.
Non-Neosauropoda fossils in the Eusauropod group are very rare. Complete skulls are even rarer.
Palaeontologists conducting work in China report the discovery of a near-complete non-Neosauropoda Eurosauropod skull in a paper published in Scientific Reports. The fossil dates to the Middle Jurassic, about 165 to 168 mya.
Along with the skull are more than 30 vertebrae. The fossils were found in the Xinhe Formation about 1,200km west of Beijing. The specimen belongs to a species unknown to science and has been named Jinchuanloong niedu after the Jinchuan District where it was discovered.
The palaeontologists compared Jinchuanloong to other East Asian sauropods and found a combination of primitive features along with those present in later sauropod species.
Unfused arches in the vertebrae and skull features suggest that the individual discovered was a juvenile or subadult when it died. In life, this animal would have been about 10m long, suggesting adults grew much larger.
“The discovery of Jinchuanloong niedu enriches the diversity of early diverging sauropods and provides additional information to help understand the evolutionary history of sauropods in northwest China,” the authors write.
