The remarkably long neck of Lijangosaurus johnschengensis. The research team, led by paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, identified 42 cervical vertebrae at the site.
Reconstruction of nososaurs from approximately 240 million years ago showcases previously hidden diversity in southwestern China: Lijangosaurus johnschengensis (center), Nososaurus janjuanensis (top left), Nososaurus luopingensis (top right), Brevicaudosaurus janshanensis (bottom left), and Lariosaurus hongoensis (bottom right). Image credit: Kelai Li.
Lijangosaurus johnschengensis thrived in the mid-Triassic oceans between 247 and 241 million years ago.
The following ancient creatures belong to the Notosaurus clade of marine sauropterygian reptiles.
Nososaurs could reach lengths of up to 7 meters (23 feet) and swam using four paddle-like limbs.
They possessed flat skulls with a network of slender conical teeth specialized for catching fish and squid.
“Sauropterygia emerged as a dominant marine reptile clade in the Early to Middle Triassic, maintaining its significance for approximately 180 million years within the Mesozoic marine ecosystem,” stated lead author Dr. Xiang Qinghua and colleagues.
“Early diverging sauropterygians include placodonts, pachysaurids, nososaurs, and early pistosaurs.”
“The iconic group known as plesiosaurs represents a clade that diverged later from pistosaurs within the suborder Pterosauria.”
“Nososauridae represents the systematic paleontological equivalent of nososaurids and encompasses more than just nososaurids (nososaurus and lariosaurus) as well as other nososaur species.”
“Although numerous species have been described, nososaurs show low diversity at the genus level and in anatomical morphology relative to other sauropterygian subgroups.”
“Typically, nososaurs are larger than pachypleurosaurs but smaller than pistosaurs, including plesiosaurs.”
The skull of Lijangosaurus johnschengensis was small, while its body extended over 2.5 meters (8 feet) in length.
It evolved an extraordinarily long neck with 42 cervical vertebrae, twice the number seen in most sauropterygians of its time.
“Plesiosaurs are generally recognized for their surprisingly long necks,” noted the paleontologists.
“Despite some late-diverging plesiosaur species exhibiting short necks, early plesiosaurs and their Triassic ancestors, early pistosaurs, featured impressively elongated necks with more than 30 cervical vertebrae, indicating a conformational lineage between early pistosaurs and plesiosaurs.”
“In line with this traditional understanding, we consider only necks with more than 30 cervical vertebrae as long or elongated necks in our research.”
“This distinctive feature of plesiosaurs is unmatched among secondary marine quadrupeds; in contrast, other leading marine animals like ichthyosaurs, thalatoids, mosasaurs, and cetaceans typically possess shorter necks and exhibit more fish-like traits.”
The fossilized skeleton of Lijangosaurus johnschengensis was unearthed in a previously unidentified Early Middle Triassic zone of the Beiya Formation in Yunnan Province, China, near the eastern Tibetan Plateau and northern Myanmar.
“This location differs from previously documented fossil-rich regions in southwestern China along the Yunnan-Guizhou border,” the researchers remarked.
Lijangosaurus johnschengensis marks the earliest known instance of a sauropterygian reptile with an exceptionally long neck featuring 42 cervical vertebrae.
“Our findings demonstrate that extreme cervical elongation, defined as possessing more than 30 cervical vertebrae, emerged in sauropterygians prior to the arrival of plesiosaurs and their pterosaur ancestors,” the scientists concluded.
“Moreover, Lijangosaurus johnschengensis shows a unique type of accessory facet joint differing from other reptiles, which is believed to reduce body undulation.”
“This discovery enhances our understanding of the variety of accessory facet joints in reptiles and underscores the high degree of spinal flexibility during the early evolution of sauropterygians.”
The team’s paper is published in the journal Communications Biology.
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W. Wang et al. 2025. The oldest long-necked sauropterygians, Lijangosaurus johnschengensis: Plasticity of vertebral evolution in sauropterygian marine reptiles. Communications Biology August 1551. doi: 10.1038/s42003-025-08911-1
Source: www.sci.news
