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A newly discovered marine reptile fossil in China is prompting paleontologists to re-evaluate the timeline of long-necked sea creature evolution.The remarkably well-preserved skeleton of Lijiangosaurus yongshengensis, dating back to the Middle Triassic period, boasts an unusually elongated neck-composed of 42 vertebrae-challenging previous understandings of how and when this adaptation emerged. The find, detailed in the journal Communications Biology, offers a potentially crucial missing link in the evolutionary history of iconic plesiosaurs and other sauropterygians.
A newly discovered marine reptile fossil from China is challenging established timelines for the evolution of long-necked sea creatures. Paleontologists have identified the specimen as Lijiangosaurus yongshengensis, a find that suggests the development of extremely elongated necks in these reptiles began earlier than previously thought.
Lijiangosaurus yongshengensis lived during the Middle Triassic period, approximately 247–241 million years ago. The reptile belongs to the nothosaur group, which is part of the larger clade called Sauropterygia – a group of marine reptiles that dominated ocean ecosystems for nearly 180 million years.
Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, describe Sauropterygia as emerging as a major group of marine reptiles in the early to mid-Triassic, and remaining a key component of Mesozoic marine ecosystems for around 180 million years.
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What is a Nothosaur?
Nothosaurs are characterized by their streamlined bodies and four paddle-like limbs. They could reach lengths of up to 7 meters (approximately 23 feet), with flat skulls and sharp teeth adapted for catching fish or squid. This discovery adds to our understanding of the diversity of early marine reptiles and their adaptations to aquatic life.
Dr. Qinghua Shang and his team explain that nothosaurs were generally larger than pachypleurosaur, but smaller than pistosaur and plesiosaur.
Evolutionarily, nothosaurs represent a step towards the emergence of plesiosaurs—the iconic long-necked reptiles of the dinosaur era.
Despite numerous identified species, experts note that the morphological diversity of nothosaurs is relatively low compared to other sauropterygian groups.
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An Extremely Long Neck: 42 Vertebrae
The most striking feature of Lijiangosaurus yongshengensis is its exceptionally long neck, composed of 42 cervical vertebrae—double the number found in most contemporary marine reptiles. The reptile measured over 2.5 meters (approximately 8.2 feet) in total length, with a relatively small head.
Paleontologists clarify that, in their study, a “long neck” is defined as one with more than 30 vertebrae. With 42 vertebrae, Lijiangosaurus isn’t just “long”—it’s extreme.
“Plesiosaurs are typically known for their remarkably long necks… Lijiangosaurus exhibits this iconic character much earlier than plesiosaurs and their pistosaur ancestors evolved,” the researchers wrote.
They also emphasize that the ability to develop such a long neck was a unique adaptation. Other marine reptile groups, such as ichthyosaurs and mosasaurs, as well as marine mammals like whales and dolphins, generally had shorter necks.
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The Lijiangosaurus fossil was discovered in a new location within the Beiya Formation, near the eastern Tibetan Plateau and northern Myanmar. This location differs from the well-known fossil areas along the Yunnan–Guizhou provincial border that previously served as a center for Triassic reptile discoveries.
The find is particularly significant because this fossil is the earliest known sauropterygian to exhibit an extremely long neck, indicating that this extreme adaptation arose earlier than previously believed. This discovery could reshape our understanding of marine reptile evolution.
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Unique Vertebral Structure for Body Stability
In addition to its long neck, Lijiangosaurus also possesses additional articulations between its vertebrae not found in other reptiles. “We assessed that this structure helped reduce body waves during swimming,” the scientists stated.
This suggests the adaptation may have helped the reptile maneuver through the water more efficiently—a previously unknown biomechanical innovation.
The discovery of Lijiangosaurus provides new insights into the early evolution of Triassic marine reptiles, demonstrating the plasticity and experimental nature of the vertebrate skeleton in the early period following the Permian mass extinction—when many animal groups rapidly evolved to fill vacant marine ecological niches.
The scientists concluded: “This discovery adds to the known diversity of vertebral structures in reptiles, and highlights the high evolutionary flexibility of the vertebra in early sauropterygians.”
The complete research was published in the journal Communications Biology.
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