Evolutionary Biologists Say Recently Discovered Fossils Show the Transition of a Reptil from Earth Life to Marine Life


Vadasaurus herzogi

Credit: Mick Ellison Used with permission from the American Museum of Natural History

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Using modern research equipment on a 155-million-year-old reptile fossil, scientists at Johns Hopkins and the American Museum of Natural History report that they have filled in some important clues to animal evolution. which once roamed the earth and was transformed into aquatic life.

A report on recent discoveries about the reptile, Vadasaurus herzogi, will be available online in the Nov. 8 issue of Royal Science Open Science, and it has been suggested that some animal forms of leg length, including elongated, such as the whip tail, and triangular-shaped head, are well suited to aquatic life, while its large branches it is associated with land -loving species.

Vadasaurus, which is the Latin term for “wading lizard,” discovered in limestone holes near Solnhofen, Germany, part of a shallow sea that has long been explored for many fossil finds.

The well-preserved fossil is in the American Museum of Natural History in New York, where the work of unlocking the secrets of its evolution fell to the museum’s research partner. Gabriel Bever, Ph.D., who is also an assistant professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine, and Mark Norell, Ph.D., is the head of the museum’s paleontology division.

“The anatomical and behavioral characteristics of modern groups of living things have accumulated over a long period of time,” says Bever. “There are many things that can be taught to us about the history of evolution, including the order in which shapes evolve and their adaptive role in a changing environment.”

“Any hour we get a fossil like this that’s very well protected, and it’s so important to understand a significant environmental shift, it’s so important,” Norell said. “It’s so important,” he added, “that we can consider Vadasaurus to be Archeopteryx of rynchocephalians. ”

According to Bever, their work adds to the list of sea creatures whose ancestors were vertebrates that lived on land. They include modern whales, seals, and sea snakes, and ancient (and now extinct) species of ichthyosaurs, mosasaurs, and plesiosaurs.

Bever said their study offers evidence that Vadasaurus, probably an adult it died, can be attributed in its anatomy to a small group of marine species called pleurosaurs, which have long been thought to have terrestrial roots. Pleurosaurs lived during the Jurassic period, 185 to 150 million years ago. Tuna-like creatures have shortened limbs that may be used for guidance rather than pushing water. To date, fossils of only three ancient species of pleurosaurs have been discovered.

It uses two kinds of statistical algorithms and reconstructions of evolutionary “trees,” Bever and Norell say. Vadasaurus and pleurosaurs are part of a much larger line of reptiles called Rhynchocephalia. Like the sea -loving pleurosaurs, Vadasaurus’ the skull is a triangular shape, an adaptation found among many streamlined, aquatic animals, such as most fish, eels and whales. An elongated snout, common in marine animals, has teeth away from the body for trapping fish.

By examining the shape and structure of Vadasaurus’ skull, Bever and Norell also concluded Vadasaurus’ the sting is likely to be a quick, side -to -side movement, compared to the slower, more vigorous sting typical of many land -dwelling animals.

About 155 million years ago, Vadasaurus’ The tail starts to lengthen like most modern marine animals, like Bever, but not to the size of a 5-foot pleurosaur. Vadasaurus, they found, there are 24 pre-Sacal vertebrae, running from the head to the beginning of the tail, while the pleurosaurus has more than 50 posterior vertebrae.

Despite the appearance of water, Vadasaurus retains some features that are frequently found among land vertebrates. For example, Vadasaurus there are still large branches, in relation to the size of its body, expected to be a reptile living on the ground. Bever guessed that Vadasaurus its limbs are not used for water propulsion, but to drive. As he said Vadasaurus can swim like a modern sea snake, moving on its spinal column with an indestructible form of motion.

“Our data shows that Vadasaurus an early cousin of the pleurosaur, ”Bever said. “And these two reptiles have something to do with the modern tuatara.” The modern tuatara is a land lizard -like reptile that inhabits the coastal islands of New Zealand and it is the only remaining rhynchocephalian species still on Earth.

Bever tells a complete history of the evolution of Vadasaurus will require additional data and fossil finds.

“We don’t know exactly what time it is Vadasaurus spending land versus water. It may be that the animal is making water adaptations for other reasons, and that these changes have been beneficial for aquatic life, ”Bever said.

the Johns Hopkins Center for Functional Anatomy and Evolution examined the relationships between anatomy, behavior and evolution of vertebrates. Bever’s laboratory focuses on how genes, development, morphology, and the fossil record both produce and inform the main patterns of vertebrate evolution.

Funding for this research was provided by the American Museum of Natural History and the Johns Hopkins University School of Medicine.



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