Mosasaurs, an extinct group of aquatic squamate reptiles, adapted to a very different environment during the Late Cretaceous period, as discovered by a group of scientists. These marine predators have been known to hunt in the salty oceans, but now they have found that these mammoths adapted to a freshwater environment and even fed on dinosaurs. IFL Science reported that when Trissa Ford came across a Tyrannosaurus rex tooth in Hell Creek, North Dakota, in 2022, the careful digging led the group to another tooth. Dig leader Dr Clint Boyd knew it didn't belong to a T. rex, and reached out to marine reptile expert Dr Nathan Van Vranken of Eastern West Virginia Community and Technical College. He confirmed that it had come from a mosasaur of the Prognathodontini subfamily.&nbsp;This was strange since Hill Creek had never had an ocean, nor a salty lake. Hell Creek is almost 2,000 kilometres from the ocean, and &nbsp;Dr Melanie During, of Uppsala University, who helped the team solve the mystery, says the tooth had remained in the same place. There had also never been any saltwater source in the region. Her analysis revealed that this mosasaur was a descendant of a species that had adapted to living in river water. The study is published in BMC Zoology.Also Read: <a href="https://www.wionews.com/science/this-giant-blue-dragon-monster-haunted-prehistoric-waters-of-the-pacific-ocean-72-million-years-ago-669185">A giant blue dragon mosasaur roamed the Pacific waters 72 million years ago</a><h2>Mosasaurs adapted to live in rivers</h2>Scientists have always believed that mosasaurs lived in salty waters. This is because the Western Interior Seaway, which divided North America into two parts, was connected to both the Arctic Ocean and the Gulf of Mexico, and was presumably salty. Mosasaurs inhabited this waterway, which meant they were thriving in saltwater. However, it underwent a huge change at the end of the dinosaur era. Dr Melanie told the publication that mountains were forming at this time and the San Andreas fault was very active, leading the continent to lift upwards. The Seaway got blocked from both sides, cutting off access to the oceans. Gradually, rainwater flushed out all the salt, effectively turning the Hill Creek region into a network of rivers. &nbsp;This shows the mosasaurs underwent a major adaptation.Also Read: <a href="https://www.wionews.com/science/sea-monster-that-lived-85mn-years-ago-on-dry-land-that-was-once-an-ocean-760391">Sea monster lived 85mn years ago on Texas dry land that was once an ocean</a>&nbsp;She compared the mosasaurs to Australia’s giant saltwater crocodiles, which adapted to freshwater. Since the latter moved to also being able to live on land, could the mosasaurs also have done the same? She thinks it is possible.&nbsp;

Mosasaurs underwent a major lifestyle change during the late Cretaceous period and adapted to living in a completely new environment. Researchers found a tooth that led them to find something shocking about these giants.

Mosasaurs, an extinct group of aquatic squamate reptiles, adapted to a very different environment during the Late Cretaceous period, as discovered by a group of scientists. These marine predators have been known to hunt in the salty oceans, but now they have found that these mammoths adapted to a freshwater environment and even fed on dinosaurs. IFL Science reported that when Trissa Ford came across a Tyrannosaurus rex tooth in Hell Creek, North Dakota, in 2022, the careful digging led the group to another tooth. Dig leader Dr Clint Boyd knew it didn't belong to a T. rex, and reached out to marine reptile expert Dr Nathan Van Vranken of Eastern West Virginia Community and Technical College. He confirmed that it had come from a mosasaur of the Prognathodontini subfamily. This was strange since Hill Creek had never had an ocean, nor a salty lake. Hell Creek is almost 2,000 kilometres from the ocean, and Dr Melanie During, of Uppsala University, who helped the team solve the mystery, says the tooth had remained in the same place. There had also never been any saltwater source in the region. Her analysis revealed that this mosasaur was a descendant of a species that had adapted to living in river water. The study is published in BMC Zoology. Also Read: A giant blue dragon mosasaur roamed the Pacific waters 72 million years ago Mosasaurs adapted to live in rivers Scientists have always believed that mosasaurs lived in salty waters. This is because the Western Interior Seaway, which divided North America into two parts, was connected to both the Arctic Ocean and the Gulf of Mexico, and was presumably salty. Mosasaurs inhabited this waterway, which meant they were thriving in saltwater. However, it underwent a huge change at the end of the dinosaur era. Dr Melanie told the publication that mountains were forming at this time and the San Andreas fault was very active, leading the continent to lift upwards. The Seaway got blocked from both sides, cutting off access to the oceans. Gradually, rainwater flushed out all the salt, effectively turning the Hill Creek region into a network of rivers. This shows the mosasaurs underwent a major adaptation. Also Read: Sea monster lived 85mn years ago on Texas dry land that was once an ocean She compared the mosasaurs to Australia’s giant saltwater crocodiles, which adapted to freshwater. Since the latter moved to also being able to live on land, could the mosasaurs also have done the same? She thinks it is possible.

Mosasaurs underwent a major lifestyle change during the late Cretaceous period and adapted to living in a completely new environment. Researchers found a tooth that led them to find something shocking about these giants.

T. rex tooth leads scientists to make a shocking discovery about brute that ate dinosaurs

Beneath what is now a Lowe’s parking lot just off Route 55 in Mantua Township, New Jersey, lies a remarkable fossil site, soon to be the Edelman Fossil Park &amp; Museum. The site sits atop a layer of sediment known as the extinction layer, marking the boundary between the Cretaceous and Paleogene periods some 66 million years ago. This layer is evidence of the asteroid impact that ended the age of dinosaurs. Geologists and palaeontologists have uncovered more than 1,00,000 fossils to date, representing over 100 species, including marine reptiles, fish, turtles, and sharks. The quarry beneath the future museum provides a preserved ecosystem capturing the final moments of Cretaceous marine life.<h3>The Mosasaur and Ancient Seas</h3>Among the most striking finds are mosasaur bones, large marine predators that once ruled the shallow seas covering what is now southern New Jersey. These creatures could reach lengths of up to 50 feet, and their remains give scientists insight into marine biodiversity just before the end-Cretaceous mass extinction. The sediments around the fossils show that this region was submerged under the Atlantic Seaway, a warm shallow sea teeming with life. The fossil-rich marl layers include not just mosasaurs, but also marine crocodiles, sea turtles, and many invertebrates. A recent feature by Energy Reporters highlights that the fossils uncovered at Edelman Fossil Park are changing our understanding of the last days of the dinosaurs.&nbsp;The site had long been known for its fossil potential before becoming an official museum. Dr Kenneth Lacovara, founding executive director of Edelman Fossil Park &amp; Museum, led efforts to transform the former quarry into a public science and education facility. The museum officially opened in March 2025. It is located on ‘66 Million Mosasaur Way’ in Mantua, New Jersey. Visitors can take part in fossil digs, guided tours, and interactive programmes. The public aspect is central: this is one of the few places in the eastern United States with an open quarry where amateurs and school groups can help uncover fossils.<h3>Why It Matters</h3>This discovery reshapes our understanding of the end-Cretaceous marine world. The density and diversity of fossils in the extinction layer help fill in details about which species survived until the very end, which perished, and how ecosystems collapsed and rebounded in the wake of global catastrophe. The site also emphasises how fossil evidence can lie hidden under modern development, only to be revealed by careful geological and palaeontological study.&nbsp;

Geologists and palaeontologists have uncovered more than 1,00,000 fossils to date, representing over 100 species, including marine reptiles, fish, turtles, and sharks. The quarry beneath the future museum provides a preserved ecosystem capturing the final moments of Cretaceous marine life.

Beneath what is now a Lowe’s parking lot just off Route 55 in Mantua Township, New Jersey, lies a remarkable fossil site, soon to be the Edelman Fossil Park & Museum. The site sits atop a layer of sediment known as the extinction layer, marking the boundary between the Cretaceous and Paleogene periods some 66 million years ago. This layer is evidence of the asteroid impact that ended the age of dinosaurs. Geologists and palaeontologists have uncovered more than 1,00,000 fossils to date, representing over 100 species, including marine reptiles, fish, turtles, and sharks. The quarry beneath the future museum provides a preserved ecosystem capturing the final moments of Cretaceous marine life. The Mosasaur and Ancient Seas Among the most striking finds are mosasaur bones, large marine predators that once ruled the shallow seas covering what is now southern New Jersey. These creatures could reach lengths of up to 50 feet, and their remains give scientists insight into marine biodiversity just before the end-Cretaceous mass extinction. The sediments around the fossils show that this region was submerged under the Atlantic Seaway, a warm shallow sea teeming with life. The fossil-rich marl layers include not just mosasaurs, but also marine crocodiles, sea turtles, and many invertebrates. A recent feature by Energy Reporters highlights that the fossils uncovered at Edelman Fossil Park are changing our understanding of the last days of the dinosaurs. The site had long been known for its fossil potential before becoming an official museum. Dr Kenneth Lacovara, founding executive director of Edelman Fossil Park & Museum, led efforts to transform the former quarry into a public science and education facility. The museum officially opened in March 2025. It is located on ‘66 Million Mosasaur Way’ in Mantua, New Jersey. Visitors can take part in fossil digs, guided tours, and interactive programmes. The public aspect is central: this is one of the few places in the eastern United States with an open quarry where amateurs and school groups can help uncover fossils. Why It Matters This discovery reshapes our understanding of the end-Cretaceous marine world. The density and diversity of fossils in the extinction layer help fill in details about which species survived until the very end, which perished, and how ecosystems collapsed and rebounded in the wake of global catastrophe. The site also emphasises how fossil evidence can lie hidden under modern development, only to be revealed by careful geological and palaeontological study.

Geologists and palaeontologists have uncovered more than 1,00,000 fossils to date, representing over 100 species, including marine reptiles, fish, turtles, and sharks. The quarry beneath the future museum provides a preserved ecosystem capturing the final moments of Cretaceous marine life.

50-foot fossil predator from dinosaur age found beneath US shopping centre

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T. rex tooth leads scientists to make a shocking discovery about brute that ate dinosaurs

50-foot fossil predator from dinosaur age found beneath US shopping centre