2023-09-10 02:26:23
New research suggests that plesiosaurs, marine reptiles known for their long necks, developed these unique features over five million years, about 250 million years ago. Plesiosaurs quickly evolved their distinctive long necks, evolving over five million years, a recent study that presents a new ancestor, Chosaurus xiangensis, has revealed. Research shows that plesiosaurs evolved their distinctive long necks in a remarkably short time. These long necks are thought to have been used to catch fast-moving fish, and they evolved rapidly over five million years, about 250 million years ago. The findings, recently published in the journal BMC Ecology and Evolution, and conducted by scientists in China and the United Kingdom, show that a species known as pachypleurosaurus lengthened its neck primarily by adding new vertebrae. This species had 25 vertebrae, while some Late Cretaceous plesiosaurs such as Elasmosaurus had up to 72 years of age, and its neck was five times as long as its proboscis. Origins and new discoveries These creatures first appeared in the early Trias, just four million years after the end-Permian mass extinction, which led to the disappearance of nearly 90% of species on Earth. This period was characterized by rapid transformations following this catastrophic event. In this study, researchers describe a new ancestor of short-necked plesiosaurs called Chosaurus xiangensis from the Lower Triassic of Hubei Province, China. Its neck began to lengthen, but it was only half the length of its torso, compared to 80% or more in its later relatives. Image showing rapid evolution rates and samples. Research suggests that plesiosaurs, marine reptiles known for their long necks, developed these unique features over five million years, about 250 million years ago. Credit: Chi-Ling Liu “We were lucky to find two complete skeletons of this new monster,” said Chi-Ling Liu of China’s Wuhan University of Geosciences, who led the project. “It is small in size, less than half a meter long, but it is close in lineage to a large group of marine reptiles called Sauropterygia. “Our new reptile, Chaosaurus, is a pachypleurosaur, part of a group of very important small marine predators of the Triassic. At first I wasn’t really sure if it was a pachypleurosaur, because its neck seemed very short. Context and comparisons Dr Li Tian, also from China’s Wuhan University of Geosciences, who co-supervised the project, said: ‘The fossils come from the Nanchang-yuan’an fauna in Hubei. “This has been studied extensively in recent years as one of the oldest groups of Triassic marine reptiles. We have high-quality radiometry showing that the animals date back to 248 million years ago. Collaborating Professor Michael Benton, University of Bristol School of Earth Sciences, said: “The end-Permian mass extinction was the largest mass extinction ever recorded, and only one in twenty species survived. “The Lower Triassic was a period of recovery and marine reptiles evolved very rapidly at this time, most of which were predators of shrimp, fish and other sea creatures. They appeared just after the extinction, so we know that their rates of change were very rapid in the new post-crisis world. » “The basipleurosaur,” Professor Qing Long, co-supervisor of the Wuhan Center for the Chinese Geological Survey, said, “The organisms were able to lengthen their necks mainly by adding new vertebrae.” “Normally, vertebrates like reptiles and mammals (and us), we have seven cervical vertebrae. Chausaurus actually had 17, while later pachypleurosaurs had 25. Some late Cretaceous plesiosaurs like Ismosaurus were 72 years old, and their neck was five times the length of their torso. With so many vertebrae, these long necks must have been super-eels and may have lashed their necks to catch fish prey while keeping the body stable. Diverse evolutionary tactics Dr Tom Stubbs from the Open University in the UK added: “Not all long-necked animals do it in the same way. Giraffes, for example, retain the standard seven cervical vertebrae, but each one is very long, allowing them to reach tree heights. Flamingos also have a long neck that allows them to reach water to feed, thanks to their long legs. They have additional vertebrae, up to twenty, but each one is also long. Dr Ben Moon, also from the University of Bristol, added: “Our study shows that pachypleurosaurs doubled their neck length over five million years, and then the rate of increase slowed.” “They probably achieved an ideal neck length for their lifestyle. “We think that as small predators, they probably fed mainly on shrimp and small fish, so their ability to sneak into a small swarm and then glide through the water, pointing their head toward the prey in a fast swim, was an excellent survival tool but there may have been additional costs to having a longer neck.” Much, so it settled at a length equal to the length of the torso. Reference: “Rapid neck elongation in Sauropterygia (Reptilia: Diapsida) revealed by a new basal pachypleurosaur from the Lower Triassic of China” by Qi-Ling Liu, Long Cheng, Thomas L. Stubbs, Benjamin C. Moon, Michael J. Benton and Li Tian, 31 Aug 2023, BMC Ecology and Evolution.doi: 10.1186/s12862-023-02150-s
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