Latest news with #Cretaceous-Paleogene
Yahoo
24-06-2025
- Science
- Yahoo
Fossils from giant possum-like mammal that lived 60 million years ago found in Texas
Paleontologists have found fossilized remains of a giant possum-like mammal that lived 60 million years ago. The fossils, found at Big Bend National Park in Texas, belong to a group of ancient near-marsupials from the Paleocene period that scientists call Swaindelphys, according to a paper published last week in the Journal of Vertebrate Paleontology. MORE: Fossils found in North America reveal new species of 'very odd' sea monster: Scientists The prehistoric species, called Swaindelphys solastella, was "gigantic" compared to other Swaindelphys at the time but are actually about the size of a modern hedgehog, according to the researchers. "I compared them to a lot of other marsupials from around the same time period to see what they're most closely related to," said Kristen Miller, a doctoral student at The University of Kansas' Biodiversity Institute and Natural History Museum and lead author of the paper, said in a statement. At first, the paleontologists thought the fossils belonged to a group of metatherians -- or marsupial-like mammals -- from the Cretaceous period that survived the Cretaceous-Paleogene extinction, the mass extinction event believed to have wiped dinosaurs from the planet 66 million years ago. But additional analysis revealed that the specimens belonged to a "surprisingly large" new species of Swaindelphys. "Not only are they the largest metatherians from this time period, but they're also the youngest and located at the most southern latitude," Miller said. MORE: What paleontologists learned from fossils of a 3-eyed predator that lived 500 million years ago The new fossil is the largest marsupial -- in terms of body and size -- found so far in North America from the Paleocene period, Chris Beard, senior curator with KU's Biodiversity Institute, said in a statement. "Since everything is bigger in Texas, this is perhaps not surprising," Beard said. "I call them 'primatomorphans,'" Beard said. "They're not, technically speaking, primates, but they're very close to the ancestry of living and fossil primates. These marsupials are probably ecological analogues of early primates." The researchers' work is aimed at uncovering some of the smaller and harder-to-find fossil mammals that lived at Big Bend at the time, Beard said. MORE: Scientists discover 'legless, headless wonder' that predated the dinosaurs The paleontologists are also interested in the differences in the kinds of fossils found in more northern regions, such as Wyoming and Alberta, Canada. "North of that ancient divide, we see the classic Bighorn Basin taxa in their expected time periods," Miller said said. "But south of that, in river drainages that originate in the central Rockies and areas farther to the south, things start to go a little wacky." More research into Swaindelphys solastella, as well as new fieldwork in Big Bend, is planned.
24-06-2025
- Science
Fossils from giant possum-like mammal that lived 60 million years ago found in Texas
Paleontologists have found fossilized remains of a giant possum-like mammal that lived 60 million years ago. The fossils, found at Big Bend National Park in Texas, belong to a group of ancient near-marsupials from the Paleocene period that scientists call Swaindelphys, according to a paper published last week in the Journal of Vertebrate Paleontology. The prehistoric species, called Swaindelphys solastella, was "gigantic" compared to other Swaindelphys at the time but are actually about the size of a modern hedgehog, according to the researchers. "I compared them to a lot of other marsupials from around the same time period to see what they're most closely related to," said Kristen Miller, a doctoral student at The University of Kansas' Biodiversity Institute and Natural History Museum and lead author of the paper, said in a statement. At first, the paleontologists thought the fossils belonged to a group of metatherians -- or marsupial-like mammals -- from the Cretaceous period that survived the Cretaceous-Paleogene extinction, the mass extinction event believed to have wiped dinosaurs from the planet 66 million years ago. But additional analysis revealed that the specimens belonged to a "surprisingly large" new species of Swaindelphys. "Not only are they the largest metatherians from this time period, but they're also the youngest and located at the most southern latitude," Miller said. The new fossil is the largest marsupial -- in terms of body and size -- found so far in North America from the Paleocene period, Chris Beard, senior curator with KU's Biodiversity Institute, said in a statement. "Since everything is bigger in Texas, this is perhaps not surprising," Beard said. "I call them 'primatomorphans,'" Beard said. "They're not, technically speaking, primates, but they're very close to the ancestry of living and fossil primates. These marsupials are probably ecological analogues of early primates." The researchers' work is aimed at uncovering some of the smaller and harder-to-find fossil mammals that lived at Big Bend at the time, Beard said. The paleontologists are also interested in the differences in the kinds of fossils found in more northern regions, such as Wyoming and Alberta, Canada. "North of that ancient divide, we see the classic Bighorn Basin taxa in their expected time periods," Miller said said. "But south of that, in river drainages that originate in the central Rockies and areas farther to the south, things start to go a little wacky." More research into Swaindelphys solastella, as well as new fieldwork in Big Bend, is planned.
Forbes
29-04-2025
- Science
- Forbes
Life At Impact Site Of Dinosaur-Killing Asteroid Recovered Surprisingly Fast
At the Cretaceous-Paleogene transition 66 million years ago, an asteroid about 10 kilometers in diameter struck a shallow sea in what is today Southeast Mexico. The impact formed the Chicxulub crater, which is around 200 kilometers wide and one kilometer deep. The impact would have thrown trillions of tons of dust into the atmosphere, blocking the sunlight and cooling the Earth's climate significantly. Entire ecosystems collapsed and the impact caused the extinction of 75 percent of all species, including all non-avian dinosaurs. At the impact site every life form was virtually wiped out, but just 30,000 years later marine life flourished thanks to a hydrothermal system created by the asteroid shattering the seafloor. In 2016, an international team of researchers retrieved over 829 meters of cores from within the crater. A new study based on chemical traces and microfossils found in the cores presents evidence that marine life returned to the site of the crater less than a decade after the impact. This rapid recovery was likely helped by a hydrothermal system created by the asteroid impact and a steady supply of nutrients in the crater environment. "After the asteroid impact, the Gulf of Mexico records an ecological recovery process that is quite different from that of the global ocean, as continuous hydrothermal activity has created a unique marine environment," says study lead author Honami Sato, an assistant professor at Japan's Kyushu University. The study hinges on a chemical element called osmium, a metallic element common in asteroids. The researchers found evidence that osmium from the remains of the asteroid buried kilometers beneath the impact crater was continuously released in the Gulf of Mexico as hot water moved beneath the shattered seafloor and up toward the surface. The researchers analyzed the chemical composition of sediments covering the crater to determine the extent of the hydrothermal system and how long the enrichment of osmium lasted. Microfossils preserved in the same sediments allowed the scientists to reconstruct how species diversity changed after the impact. The results show that as the hydrothermal system ceased releasing osmium from the asteroid, the types of marine life living at the crater site changed. When the hydrothermal system was releasing osmium, the dominant plankton were species living in high-nutrient environments. When the osmium returned to pre-impact levels, the plankton changed to species adapted to low-nutrient environments. This finding indicates that the ecosystem was no longer being sustained by the nutrients from the hydrothermal system being released into the overlying ocean. Likely the system was buried to deep by sediments accumulating over time in the basin formed by the impact. "This study reveals that impact cratering events, while primarily destructive, can in some cases also lead to significant hydrothermal activity," concludes coauthor Steven Goderis, a research professor at the Vrije Universiteit Brussel, Belgium. "In the case of Chicxulub, this process played a vital role in the rapid recovery of marine ecosystems." The study,"Prolonged 187Os/188Os excursion implies hydrothermal influence after the Chicxulub impact in the Gulf of Mexico," was published in the journal Nature Communications. Additional material and interviews provided by the University of Texas at Austin.
Yahoo
13-03-2025
- Science
- Yahoo
How mammals avoided being eaten by dinosaurs
Early mammals had dark inconspicuous fur and only came out at night until dinosaurs became extinct, scientists believe. A study of colouration of mammals that lived in the Mesozoic era – around 150 million years ago – shows that none had developed the array of patterns and colours seen today and were a dark and dusky greyish-brown shade. The colours are similar to the hue of nocturnal animals, such as moles, mice, rats and bats. Experts say the findings support the hypotheses that early mammals were largely nocturnal and coloured to camouflage them from meat-eating dinosaurs and other predators. After dinosaurs became extinct approximately 66 million years ago, mammals were able to come out during the day and evolve the spots, stripes and brighter colours exhibited by many creatures today, experts believe. Dr Matthew Shawkey, associate professor of biology at the University of Ghent, said: 'Evidence suggests that most mammals were nocturnal in the Jurassic/Cretaceous, perhaps to avoid being eaten by dinosaurs. 'It is likely that the extinction of the dinosaurs enabled mammals to take on new habits, including daytime activity, as they were no longer threatened by dinosaurs. 'Mammals rapidly diversified and spread into new niches previously occupied by dinosaurs.' The findings were only possible because scientists have recently discovered that melanosomes – the cell machinery responsible for pigmentation – can be preserved in fossils. Scientists looked at the melanosomes from 116 living mammals and compared them to the fossilised versions from six types of Mesozoic mammals from around 158 million years ago to see which fur had the closest match. The results stand in stark contrast to the varied melanosome structures found in feathered dinosaurs, early birds, and pterosaurs. There also appeared to be no difference in coat colour between male and female mammals. Writing in the journal Science, the authors said: 'Samples taken from different integumentary locations of each fossil resulted in uniformly dark brown colour, with no evidence of colour patterns such as striping, spots, or counter-shading as seen in extant mammals. 'A nocturnal lifestyle may have enabled these species to avoid predation by diurnal carnivores and, furthermore, may have helped them to survive mass extinction. Darker hairs could help small mammaliaforms to reduce heat loss through insulation 'Our results suggest that the melanosome variation and colour expansion seen in extant mammals may have occurred during their rapid radiation and diversification after the Cretaceous-Paleogene extinction.' Researchers believe that the high melanin content in their fur could have been beneficial for thermoregulation and providing mechanical strength for protection. Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.
Telegraph
13-03-2025
- Science
- Telegraph
How mammals avoided being eaten by dinosaurs
Early mammals had dark inconspicuous fur and only came out at night until dinosaurs became extinct, scientists believe. A study of colouration of mammals that lived in the Mesozoic era – around 150 million years ago – shows that none had developed the array of patterns and colours seen today and were a dark and dusky greyish-brown shade. The colours are similar to the hue of nocturnal animals, such as moles, mice, rats and bats. Experts say the findings support the hypotheses that early mammals were largely nocturnal and coloured to camouflage them from meat-eating dinosaurs and other predators. After dinosaurs became extinct approximately 66 million years ago, mammals were able to come out during the day and evolve the spots, stripes and brighter colours exhibited by many creatures today, experts believe. Dr Matthew Shawkey, associate professor of biology at the University of Ghent, said: 'Evidence suggests that most mammals were nocturnal in the Jurassic/Cretaceous, perhaps to avoid being eaten by dinosaurs. 'It is likely that the extinction of the dinosaurs enabled mammals to take on new habits, including daytime activity, as they were no longer threatened by dinosaurs. 'Mammals rapidly diversified and spread into new niches previously occupied by dinosaurs.' The findings were only possible because scientists have recently discovered that melanosomes – the cell machinery responsible for pigmentation – can be preserved in fossils. Scientists looked at the melanosomes from 116 living mammals and compared them to the fossilised versions from six types of Mesozoic mammals from around 158 million years ago to see which fur had the closest match. The results stand in stark contrast to the varied melanosome structures found in feathered dinosaurs, early birds, and pterosaurs. There also appeared to be no difference in coat colour between male and female mammals. Writing in the journal Science, the authors said: 'Samples taken from different integumentary locations of each fossil resulted in uniformly dark brown colour, with no evidence of colour patterns such as striping, spots, or counter-shading as seen in extant mammals. 'A nocturnal lifestyle may have enabled these species to avoid predation by diurnal carnivores and, furthermore, may have helped them to survive mass extinction. Darker hairs could help small mammaliaforms to reduce heat loss through insulation 'Our results suggest that the melanosome variation and colour expansion seen in extant mammals may have occurred during their rapid radiation and diversification after the Cretaceous-Paleogene extinction.'
