All posts tagged: palaeontology

A worm that lived half a billion years ago preferred turning right

A worm that lived half a billion years ago preferred turning right

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Spriggina floundersi worms that bent to the right are preserved as fossils that bend to the left Scott Evans/AMNH A 555-million-year-old worm had a predilection for turning right, possibly indicating the oldest known example of handedness. Although these worms lacked limbs and so couldn’t be considered left- or right-handed in the way that we understand, the development of a tendency to favour one side over another is evidence of an advanced nervous system. It remains a feature of free-living mobile life today, but until this discovery, it wasn’t thought to have emerged until the Cambrian Period, which began around 541 million years ago. Scott Evans at the American Museum of Natural History in New York and his colleagues analysed 100 fossil specimens of a small flatworm-like creature, Spriggina floundersi, collected in South Australia over recent decades. These animals lived during the Ediacaran Period, when multicellular life first became widespread. It preceded the Cambrian explosion, when animal life diversified dramatically and many groups of animals first appeared. Spriggina lived in what was, half a billion years …

Remarkable fossils rewrite the story of how animals conquered the land

Remarkable fossils rewrite the story of how animals conquered the land

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A fossil baby embolomere from Mazon Creek, Illinois Arjan Mann A set of exquisitely preserved 300-million-year-old fossils suggests that early four-limbed vertebrates did not undergo a metamorphosis between their juvenile and adult stages, challenging conventional ideas about the evolution of life on land. “We have for a very long time assumed that these animals were broadly amphibian-like, and that this life cycle would have bridged the gap between life in the water and life on land,” says Jason Pardo at the Field Museum of Natural History in Chicago. Today’s reptiles, birds, mammals and amphibians belong to a group called tetrapods, which evolved from lobe-finned fish around 390 million years ago. But almost nothing was known about the early developmental stages of these ancestral lobe-finned fish, says John Long at Flinders University in Adelaide, Australia. Pardo and his colleague Arjan Mann, also at the Field Museum, examined a collection of fossils that were unearthed between the 1960s and 1990s at the Mazon Creek fossil site, south-west of Chicago. The preserved animals lived 307 million to 309 …

Frozen squirrel scat preserves ancient DNA from hundreds of species

Frozen squirrel scat preserves ancient DNA from hundreds of species

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Arctic ground squirrels gather food from a wide variety of sources and store it in burrows Government of Yukon A rich and complex ecosystem stretching back 700,000 years that included woolly mammoths, bison, horses and big cats has been unveiled thanks to DNA preserved in frozen faeces. Arctic ground squirrels (Urocitellus parryii) are rodents about 40 centimetres long, found in cold regions of both North America and Siberia. These areas were joined by a land bridge in the past, with the whole region being known as Beringia. “The squirrels hibernate for about eight months of the year and in the four months that they’re conscious, they really need to get out there and eat and bring as many resources as they can back to their burrow,” says Tyler Murchie at the Hakai Institute in Campbell River, Canada. This means their burrows often contain a wealth of faecal pellets and food caches, which makes the animals like “natural archivists”, says Murchie. To see what might be stored in this archive, he and his colleagues looked at preserved …

Dinosaur-killing Chicxulub asteroid impact site stayed hot for millions of years

Dinosaur-killing Chicxulub asteroid impact site stayed hot for millions of years

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Illustration of the Chicxulub asteroid impact, which took place 66 million years ago MARK GARLICK/Science Photo Library/Getty Images The asteroid strike that wiped out the dinosaurs hit with such force that it took at least 8 million years for the impact site to cool down, creating a warm underground ecosystem where microscopic life thrived. The Chicxulub asteroid, which collided with Earth 66 million years ago at what is now Mexico, is thought to have been as large as 15 kilometres in diameter. The strike caused so much climate chaos that it wiped out three-quarters of species on Earth. All the dinosaurs except the ancestors of birds became extinct and a nuclear winter gripped the planet for at least 15 years. Its effects were also felt deep underground. “The Chicxulub impact was big enough to cause deformation at least 35 kilometres under the surface of the Earth, detectable using geophysical surveys,” says Annemarie Pickersgill at the University of Glasgow, UK. The impact melted about 10,000 cubic kilometres of rock, she says. The combination of melted rock …

We may finally know why dinosaurs like T. rex evolved tiny arms

We may finally know why dinosaurs like T. rex evolved tiny arms

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Tyrannosaurus rex wasn’t the only predatory dinosaur with small arms ROGER HARRIS/Getty Images/SCIENCE PHOTO LIBRARY With jaws like these, who needs big arms? A new analysis suggests dinosaurs like Tyrannosaurus rex had shrunken forelimbs because their massive, powerful heads became their primary tool for killing large prey, rendering their arms redundant. It is an evolutionary approach that five different lineages of large theropod dinosaurs took independently. Researchers are well aware that a number of large, predatory theropods followed a trend towards bigger bodies, bigger heads and smaller, shorter arms over time. But it wasn’t known why this pattern repeated across multiple predatory dinosaur families, scattered across the globe and separated by many millions of years, says Charlie Scherer at University College London. There was also little understanding of how the bones in their ever-heftier skulls changed as their arms became proportionally smaller. “This paper tackles one of the big evolutionary questions in theropod dinosaurs,” says Andre Rowe at the University of Bristol, UK, who wasn’t involved with the research. Scherer and his colleagues compiled data …

Extinct relative of koalas discovered in Western Australia

Extinct relative of koalas discovered in Western Australia

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An artist’s impression of the Western Australian koala WA Museum Australia was once home to a second species of koala that lived only in the west of the continent, where it became extinct around 30,000 years ago. Today, there is only one koala species: Phascolarctos cinereus. It is found almost exclusively in eucalyptus forests in eastern Australia and is threatened by habitat loss, disease, collisions with cars and predation by introduced species. Numerous koala fossils, aged between 137,000 and 31,000 years old, have been collected in Western Australian caves over the past century. Until now, however, there wasn’t enough material to conclude that the remains were from a different species. In the past 25 years, more fossils have become available to researchers, including skulls donated by the family of late speleologist Lindsay Hatcher, who discovered numerous ancient remains during his expeditions in caves in the south-west of Western Australia. “Amongst the donation was a koala skull in very good condition,” says Kenny Travouillon at the Western Australian Museum. “Upon examination of that skull, we noticed …

Largest ever octopus was great white shark of invertebrate predators

Largest ever octopus was great white shark of invertebrate predators

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A reconstruction of the giant octopus Yohei Utsuki/Department of Earth and Planetary Sciences, Hokkaido University While dinosaurs ruled the land, Cretaceous oceans were home to a fierce and enormous octopus species that may have reached up to 19 metres in length, rivalling the size of the largest predators of the time, including sharks and marine reptiles like plesiosaurs and mosasaurs. These octopuses were active predators, says Yasuhiro Iba at Hokkaido University in Japan. “They could be thought of as the orcas or great white sharks of the invertebrate world – large, intelligent and highly effective apex predators,” says Iba. “These were animals over 10 metres long, with long arms, powerful jaws capable of crushing hard structures and probably advanced behaviour.” Iba and his colleagues looked at 27 large, fossilised octopus jaws dating to between 100 million and 72 million years that had been collected in Japan and Vancouver Island, Canada. A dozen of the octopus jaws were new to science and were locked inside rocks, says Iba. They became visible only when the researchers used …

Hidden fossils reveal secrets of oceans before major mass extinction

Hidden fossils reveal secrets of oceans before major mass extinction

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One of the radiolarian fossils found inside the rock sample Courtesy of Jonathan Aitchison A tiny pellet of ancient rock, a mere half the size of a grain of rice, has yielded 20 microscopic fossils representing eight different species, including one that is entirely new to science. The discovery will enhance our understanding of the second-largest known mass extinction. It also shows how new analytical techniques are unlocking parts of the fossil record that have previously gone overlooked. Jonathan Aitchison at the University of Queensland, Australia, and his colleagues extracted the pellet from a rock that was collected in late 2018 from the Sichuan basin in China, about 300 kilometres south of Xian. The rock is445 million years old, which means it formed just before the Late Ordovician mass extinction – the second most severe to have occurred over the past 500 million years. Inside the pellet, they found eight different species of radiolarians, which are single-celled plankton that make their shells from silica. Radiolarians are still found throughout the oceans today. The fossils found …

Surprise fossil discoveries push back the evolution of complex animals

Surprise fossil discoveries push back the evolution of complex animals

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Artist’s reconstruction of the ancient ocean ecosystem preserved in the Jiangchuan biota Xiaodong Wang A huge and beautifully preserved suite of fossils discovered in China has cast doubt on the idea that complex life flourished dramatically during a rapid burst of evolution known as the Cambrian explosion. This event, spanning roughly 541 million to 513 million years ago, is when most of the animal groups alive today are thought to have first appeared, along with a bizarre array of evolutionary experiments that later went extinct. In the preceding period, known as the Ediacaran, it was thought that life was much less complex. But that is contradicted by the new fossil site in Yunnan province, known as the Jiangchuan biota, which includes more than 700 fossils dating from 554 to 537 million years ago. “The discovery shows that Cambrian-type animal communities did not appear suddenly, but already had clear foundations and transitional forms by the end of the Ediacaran,” says Gaorong Li at Yunnan University in Kunming, China, who led the team behind the discovery. Ross …

Fossils discovered in Egypt may be the closest ancestor of all apes

Fossils discovered in Egypt may be the closest ancestor of all apes

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Artist’s reconstruction of Masripithecus moghraensis, an ape that lived around 17 million years ago Mauricio Antón/Professor Hesham Sallam A newly discovered ape species that lived around 17 million years ago suggests that the first apes may have evolved in North Africa, not East Africa as previously thought. In 2023 and 2024, at the Wadi Moghra archaeological site in northern Egypt, Shorouq Al-Ashqar at Mansoura University, Egypt, and her colleagues found teeth and jawbones from two ancient apes in deposits dated to approximately 17 million to 18 million years old. Altogether, the team found four specimens, including the front of a mandible, or jawbone, along with two molar teeth found next to it, belonging to one individual. The other fossil is a separate mandibular fragment, with no tooth crowns, from another individual. Al-Ashqar and her colleagues think the animal, named Masripithecus moghraensis, is the closest known ancestor of all living great apes, including humans, gorillas and chimpanzees, and lesser apes such as gibbons and siamangs. Apes are distinguished from monkeys because they do not have tails. …