Exceptionally long neck Lijiangosaurus yongshengensis It contained 42 cervical vertebrae, according to a research team led by paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences.
Reconstruction of nothosaurs around 240 million years ago, revealing the hidden diversity of southwest China: Lijiangosaurus yongshengensis (center), Notosaurus yangjuanensis (top left), Notosaurus luopingensis (top right), Brevicaudosaurus jiyangshanensis (bottom left) and Lariosaurus hongguoensis (bottom right). Image credit: Kelai Lee.
Lijiangosaurus yongshengensis lived in the Middle Triassic seas between 247 and 241 million years ago.
The ancient creature was a species nothosaurustreasure Marine sauropterygian reptiles.
Nothosaurs could grow up to 7 m (23 ft) in length and swim using four paddle-like limbs.
They had flattened skulls with a network of thin, conical teeth that were used to catch fish and squid.
“Sauropterygians arose as a major clade of marine reptiles during the Early to Middle Triassic and persisted as key components of the Mesozoic marine ecosystem for approximately 180 million years,” said lead author Dr. Qinghua Shan and colleagues.
“Early sauropterygian divergences include placodonts, pachypleurosaurs, nothosaurs, and early pistosaurs.”
“Plesiosaurs, an emblematic group of extinct reptiles, represent a late divergence from Pistosauria of a clade within Sauropterygia.”
“Nothosaurs are equated with notosaurs in systematic paleontology, which covers not only the family Nothosauridae (Nothosaurus And Lariosaurus), but also other species of Notosaurus.”
“Despite numerous described species, nothosaurids show less diversity at the genus level and anatomical morphology compared to other sauropterygian subgroups.”
“The body size of nothosaurs is generally larger than that of pachypleurosaurs, but smaller than that of pistosaurs, including plesiosaurs.”
Lijiangosaurus yongshengensis had a small skull and a body length of over 2.5 m (8 ft).
It developed an exceptionally long neck with 42 cervical vertebrae, twice as many as most sauropterygian peers.
“Plesiosaurs are typically characterized by incredibly long necks,” the paleontologists said.
“Despite the secondary development of short necks in some later plesiosaur species, early plesiosaurs and their Triassic ancestors, early pistosaurs, possess impressively elongated necks, with a number of cervical vertebrae greater than 30 suggested as a synapomorphy of early pistosaurs and plesiosaurs.”
“Following this traditional view, in our study we consider only a neck with more than 30 cervical vertebrae to be a long or elongated neck.”
“This iconic plesiosaur character is characteristic of secondary marine tetrapods, while other members, such as ichthyosaurs, thalattosuchus, mosasaurs and cetaceans, have short necks and are more fish-like.”
Fossilized skeleton Lijiangosaurus yongshengensis was found in a previously unknown locality of the Early Middle Triassic Beiya Formation in China's Yunnan Province near the eastern Tibetan Plateau and northern Myanmar.
“This site is different from previously documented fossil-rich regions in southwest China around the border between Yunnan and Guizhou provinces,” the researchers said.
Lijiangosaurus yongshengensis represents the earliest known sauropterygian reptile with an exceptionally long neck and 42 cervical vertebrae.
“Our discovery shows that excessive cervical elongation, developing more than 30 cervical vertebrae, arose in sauropterygians before the appearance of plesiosaurs and their pistosaur ancestors,” the scientists said.
“Moreover, Lijiangosaurus yongshengensis “has a unique type of accessory intervertebral articulation compared to other reptiles, and we associate this structure with reduced body undulation.”
“This discovery increases the known diversity of accessory intervertebral articulations in reptiles and highlights the high plasticity of the vertebral column early in sauropterygian evolution.”
teams paper appears in the magazine Communication biology.
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W. Wang etc.. 2025. Earliest long-necked sauropterygian. Lijiangosaurus yongshengensis and the plasticity of vertebral evolution in sauropterygian marine reptiles. Commun Biol 8, 1551; two: 10.1038/s42003-025-08911-1
