Latest news with #Gondwana
The Independent
29-05-2025
- General
- The Independent
Scientists solve mystery of Antarctic mountain range hidden for 500 million years
Have you ever imagined what Antarctica looks like beneath its thick blanket of ice? Hidden below are rugged mountains, valleys, hills and plains. Some peaks, like the towering Transantarctic Mountains, rise above the ice. But others, like the mysterious and ancient Gamburtsev Subglacial Mountains in the middle of East Antarctica, are completely buried. The Gamburtsev Mountains are similar in scale and shape to the European Alps. But we can't see them because the high alpine peaks and deep glacial valleys are entombed beneath kilometres of ice. How did they come to be? Typically, a mountain range will rise in places where two tectonic plates clash with each other. But East Antarctica has been tectonically stable for millions of years. Our new study, published in Earth and Planetary Science Letters, reveals how this hidden mountain chain emerged more than 500 million years ago when the supercontinent Gondwana formed from colliding tectonic plates. Our findings offer fresh insight into how mountains and continents evolve over geological time. They also help explain why Antarctica's interior has remained remarkably stable for hundreds of millions of years. A buried secret The Gamburtsev Mountains are buried beneath the highest point of the East Antarctic ice sheet. They were first discovered by a Soviet expedition using seismic techniques in 1958. Because the mountain range is completely covered in ice, it's one of the least understood tectonic features on Earth. For scientists, it's deeply puzzling. How could such a massive mountain range form and still be preserved in the heart of an ancient, stable continent? Most major mountain chains mark the sites of tectonic collisions. For example, the Himalayas are still rising today as the Indian and Eurasian plates continue to converge, a process that began about 50 million years ago. Plate tectonic models suggest the crust now forming East Antarctica came from at least two large continents more than 700 million years ago. These continents used to be separated by a vast ocean basin. The collision of these landmasses was key to the birth of Gondwana, a supercontinent that included what is now Africa, South America, Australia, India and Antarctica. Our new study supports the idea that the Gamburtsev Mountains first formed during this ancient collision. The colossal clash of continents triggered the flow of hot, partly molten rock deep beneath the mountains. As the crust thickened and heated during mountain building, it eventually became unstable and began to collapse under its own weight. Deep beneath the surface, hot rocks began to flow sideways, like toothpaste squeezed from a tube, in a process known as gravitational spreading. This caused the mountains to partially collapse, while still preserving a thick crustal 'root', which extends into Earth's mantle beneath. Crystal time capsules To piece together the timing of this dramatic rise and fall, we analysed tiny zircon grains found in sandstones deposited by rivers flowing from the ancient mountains more than 250 million years ago. These sandstones were recovered from the Prince Charles Mountains, which poke out of the ice hundreds of kilometres away. Zircons are often called 'time capsules' because they contain minuscule amounts of uranium in their crystal structure, which decays at a known rate and allows scientists to determine their age with great precision. These zircon grains preserve a record of the mountain-building timeline: the Gamburtsev Mountains began to rise around 650 million years ago, reached Himalayan heights by 580 million years ago, and experienced deep crustal melting and flow that ended around 500 million years ago. Most mountain ranges formed by continental collisions are eventually worn down by erosion or reshaped by later tectonic events. Because they've been preserved by a deep layer of ice, the Gamburtsev Subglacial Mountains are one of the best-preserved ancient mountain belts on Earth. While it's currently very challenging and expensive to drill through the thick ice to sample the mountains directly, our model offers new predictions to guide future exploration. For instance, recent fieldwork near the Denman Glacier on East Antarctica's coast uncovered rocks that may be related to these ancient mountains. Further analysis of these rock samples will help reconstruct the hidden architecture of East Antarctica. Antarctica remains a continent full of geological surprises, and the secrets buried beneath its ice are only beginning to be revealed. Jacqueline Halpin is an Associate Professor of Geology at the University of Tasmania. Nathan R. Daczko is a Professor of Earth Science at Macquarie University.
The Independent
28-05-2025
- Science
- The Independent
Secrets of ‘polar dinosaur' forest home revealed for first time in 120 million years
Roughly 140 million to 100 million years ago, the piece of land that is modern day Australia was located much further south on Earth. In fact, what is now Victoria was once within the polar circle, up to 80 degrees south of the equator and shrouded in darkness for months at a time. Despite these harsh conditions, dinosaurs thrived here, leaving behind evidence of their existence at various palaeontological sites. For decades, scientists have come to these sites to study the rocks containing the bones of these ancient creatures in order to better understand them. My new research with palynologist Barbara Wagstaff, published in Alcheringa, builds on existing knowledge by using plant fossils from bone-bearing sites in the region to explain how the forests these dinosaurs lived in evolved – and, for the first time, illustrating them in detail. One of the warmest periods on Earth The Early Cretaceous epoch – between roughly 140 million and 100 million years ago – represents one of the warmest periods in the last half a billion years of Earth's history. The sustained warmth was a result of increased volcanic activity, which released large quantities of carbon dioxide into the atmosphere. The sustained warmth resulted in no polar ice caps, high sea levels and flooded continents. The geographic distribution of land masses was also very different back then. The supercontinent Gondwana, in which most of the southern continents we know today were clumped into a single landmass, had only just started to break apart. At the time, southernmost Australia was in the polar circle. The dinosaurs that lived in this region are known as 'polar dinosaurs'. They included small ornithopods (plant-eaters with beaks and cheeks full of teeth) and therapods (carnivorous and predatory dinosaurs). Building a picture of ancient plants For decades, palaeontologists have been studying rocks from Victorian sites. To establish the age of the recovered dinosaur bones, we've needed the expertise of palynologists – palaeontologists who study microscopic fossil spores and pollen produced by plants. Palynologists identified key species that they dissolved out of rocks. They deduced the dinosaur bones ranged in age from 130 to 100 million years old. At the same time, they were carefully recording all the microscopic spores and pollen they saw in the slides to build a picture of the plants through the Early Cretaceous period. A planet-altering transition The transition from a world without flowers to one with flowers has fascinated scientists for centuries, most famously Charles Darwin who labelled them 'an abominable mystery'. More importantly, it also forever changed our planet. Shortly after their first appearance, approximately 132 million years ago, albeit in the southern portion of the supercontinent Laurasia, we see an explosive radiation of flowering plants not only in our new record from Victoria, but also globally. What fuelled the evolution and rapid global expansion of flowering plants that dominate the Australian landscape today? Our new research suggests warmer conditions helped flowering plants migrate across the globe and colonise understorey habitats shortly after evolving. Increased competition also contributed to the turnover in understorey flora, with flowering plants outcompeting lycophytes in rapidly colonising braided river channels after flooding events. The appearance of flowering plants in the landscape resulted in the extinction of numerous understorey plants (in particular ferns) with a long fossil record. As a result, by 100 million years ago, the forests of Victoria included an open conifer-dominated forest canopy. The subcanopy beneath was made up of seed ferns and ferns. Flowering plants and ferns featured in the understorey, alongside liverworts, hornworts, lycophytes and sphagnum-like mosses. Diversifying in a warming world High carbon dioxide levels in the past made the planet warmer. This is consistent with what's happening today. As a result of these warmer conditions, cool-temperate forests thrived in the polar circle. For flowering plants, the warmer conditions provided an opportunity to diversify in an increasingly warm world. However, not all plants adapted to the warming world, with many understorey floras, including ferns, becoming extinct. The fossil record provides crucial insights into how life will respond to predicted future climate conditions because these have occurred before in Earth's history. Knowing this history is crucial to our response to the current climate change challenge. Some exciting places to visit to see fossils in Australia include Eric the Red West dig site in the Otway Ranges, Inverloch's Dinosaur Dreaming dig site in Victoria, the Dinosaur Trail along the Queensland towns of Hughenden, Richmond and Winton, and sauropod footprints in Western Australia at Gantheaume Point.
The Independent
28-05-2025
- General
- The Independent
Breakthrough after mysterious mountain range found buried beneath Antarctica's ice
Have you ever imagined what Antarctica looks like beneath its thick blanket of ice? Hidden below are rugged mountains, valleys, hills and plains. Some peaks, like the towering Transantarctic Mountains, rise above the ice. But others, like the mysterious and ancient Gamburtsev Subglacial Mountains in the middle of East Antarctica, are completely buried. The Gamburtsev Mountains are similar in scale and shape to the European Alps. But we can't see them because the high alpine peaks and deep glacial valleys are entombed beneath kilometres of ice. How did they come to be? Typically, a mountain range will rise in places where two tectonic plates clash with each other. But East Antarctica has been tectonically stable for millions of years. Our new study, published in Earth and Planetary Science Letters, reveals how this hidden mountain chain emerged more than 500 million years ago when the supercontinent Gondwana formed from colliding tectonic plates. Our findings offer fresh insight into how mountains and continents evolve over geological time. They also help explain why Antarctica's interior has remained remarkably stable for hundreds of millions of years. A buried secret The Gamburtsev Mountains are buried beneath the highest point of the East Antarctic ice sheet. They were first discovered by a Soviet expedition using seismic techniques in 1958. Because the mountain range is completely covered in ice, it's one of the least understood tectonic features on Earth. For scientists, it's deeply puzzling. How could such a massive mountain range form and still be preserved in the heart of an ancient, stable continent? Most major mountain chains mark the sites of tectonic collisions. For example, the Himalayas are still rising today as the Indian and Eurasian plates continue to converge, a process that began about 50 million years ago. Plate tectonic models suggest the crust now forming East Antarctica came from at least two large continents more than 700 million years ago. These continents used to be separated by a vast ocean basin. The collision of these landmasses was key to the birth of Gondwana, a supercontinent that included what is now Africa, South America, Australia, India and Antarctica. Our new study supports the idea that the Gamburtsev Mountains first formed during this ancient collision. The colossal clash of continents triggered the flow of hot, partly molten rock deep beneath the mountains. As the crust thickened and heated during mountain building, it eventually became unstable and began to collapse under its own weight. Deep beneath the surface, hot rocks began to flow sideways, like toothpaste squeezed from a tube, in a process known as gravitational spreading. This caused the mountains to partially collapse, while still preserving a thick crustal 'root', which extends into Earth's mantle beneath. Crystal time capsules To piece together the timing of this dramatic rise and fall, we analysed tiny zircon grains found in sandstones deposited by rivers flowing from the ancient mountains more than 250 million years ago. These sandstones were recovered from the Prince Charles Mountains, which poke out of the ice hundreds of kilometres away. Zircons are often called 'time capsules' because they contain minuscule amounts of uranium in their crystal structure, which decays at a known rate and allows scientists to determine their age with great precision. These zircon grains preserve a record of the mountain-building timeline: the Gamburtsev Mountains began to rise around 650 million years ago, reached Himalayan heights by 580 million years ago, and experienced deep crustal melting and flow that ended around 500 million years ago. Most mountain ranges formed by continental collisions are eventually worn down by erosion or reshaped by later tectonic events. Because they've been preserved by a deep layer of ice, the Gamburtsev Subglacial Mountains are one of the best-preserved ancient mountain belts on Earth. While it's currently very challenging and expensive to drill through the thick ice to sample the mountains directly, our model offers new predictions to guide future exploration. For instance, recent fieldwork near the Denman Glacier on East Antarctica's coast uncovered rocks that may be related to these ancient mountains. Further analysis of these rock samples will help reconstruct the hidden architecture of East Antarctica. Antarctica remains a continent full of geological surprises, and the secrets buried beneath its ice are only beginning to be revealed. Jacqueline Halpin is an Associate Professor of Geology at the University of Tasmania. Nathan R. Daczko is a Professor of Earth Science at Macquarie University.
CNN
22-05-2025
- Science
- CNN
Tiny clawed tracks left in ancient mud are the oldest reptile footprints
Distinct clawed footprints found on a slab of 356 million-year-old rock from Australia suggest that reptile relatives appeared between 35 million and 40 million years earlier than previously believed. The tracks also push back the origin of amniotes, a group that includes reptiles, birds and mammals, and provide new evidence about how animals transitioned from existing solely in the seas to living on land. Amniotes represent a crucial part of the transition from aquatic to terrestrial life because they were the only tetrapods, or four-limbed creatures, that evolved to reproduce on land. Previously, the oldest body fossils and footprints associated with amniotes were dated to 318 million years ago in Canada. But the new findings, published on May 14 in the journal Nature, challenge such long-held assumptions and signal that the transformation of tetrapods living in water to living on land likely occurred much more rapidly than scientists thought. 'I'm stunned,' said study coauthor Per Erik Ahlberg, professor of evolution and developmental biology at Uppsala University in Sweden, in a statement. 'A single track-bearing slab, which one person can lift, calls into question everything we thought we knew about when modern tetrapods evolved.' The location of the discovery indicates that Australia, once a central part of the ancient southern supercontinent of Gondwana that also included present-day Africa, South America, Arabia, Madagascar, Antarctica and India, may be the ideal place to look for more amniote and reptile fossils — and where they originated, according to the study authors. The rock slab, found by amateur paleontologists and study coauthors Craig Eury and John Eason in the Snowy Plains Formation in Victoria, Australia, appears to show two sets of tracks from the same animal that represent the earliest clawed footprints ever discovered. The shape of the feet is similar to a modern water monitor's, and though the animal's exact size is unknown, it may have resembled a small goanna-like creature about 80 centimeters (31 inches) in length, said lead study author John Long, strategic professor in paleontology at Flinders University. Asian water monitors are large lizards native to South and Southeast Asia, while goannas are large lizards commonly found in Australia. Hooked claws, a key feature specific to reptiles, might have enabled the primitive tetrapod to dig and climb trees. The animal that made the footprints is the oldest known reptile and oldest known amniote, Ahlberg said. And it's helping scientists crack the code on how tetrapods evolved. 'Our new find implies that the two main evolutionary lines leading to modern tetrapods — one, the line to modern amphibians, and two, the line leading to reptiles, mammals and birds — diverged from each other much earlier in time than previously thought, likely back in the Devonian Period about 380 million years ago,' Long said. Prior to this finding, the Devonian Period was believed to be a time of primitive fishlike tetrapods and 'fishapods' like Tiktaalik, which exhibited traits of fish and early tetrapods and began to explore shorelines in limited ways. But the new study reveals a diversity of large and small tetrapods, some aquatic and others largely or entirely terrestrial, likely lived at the same time. 'One of the implications of our research is that tetrapod diversity at this time was higher, and included more advanced forms, than had been thought,' Ahlberg wrote in an email. It's crucial to understand when life shifted from being entirely aquatic to terrestrial because it is one of the biggest steps in the evolution of life, Long said. This transition showed that animals were no longer dependent on living in or near water. The transition occurred partly because amniotes evolved to reproduce with hard-shelled, rather than soft-shelled, eggs. 'The vertebrates' move onto land was an important part, and within that a key step was the evolution of the amniotic egg in the immediate common ancestors of reptiles and mammals,' Ahlberg said. 'So these events form a key episode in our own ancestry as well as the history of the planet.' The new study pushes the origin of amniotes much deeper into the Carboniferous Period, 299 million to 359 million years ago, which allows a much greater length of time for the diversification of early reptiles, said Stuart Sumida, president of the Society of Vertebrate Paleontology and professor of biology at California State University, San Bernardino. Sumida, who wrote an accompanying article to release with the study, did not participate in the new research. Long has been studying ancient fish fossils from the Mansfield district, where the slab was found, since 1980. 'The Mansfield area has produced many famous fossils, beginning with spectacular fossil fishes found 120 years ago, and ancient sharks. But the holy grail that we were always looking for was evidence of land animals, or tetrapods, like early amphibians. Many had searched for such trackways but never found them — until this slab arrived in our laboratory to be studied,' he said. Fossils from the Mansfield district have shed light on how sexual organs might have first evolved in ancient armored fish. Now, the researchers want to know what else lived in Gondwana alongside the ancient reptile they found. The findings have inspired researchers to broaden the search for fossils of the earliest amniotes, and their close relatives, to the southern continents, Sumida said. 'Most of the skeletal fossil discoveries of the earliest amniotes are known from continents derived from the northern components of Pangea,' Sumida said in an email. 'Discoveries there suggested that amniote origins might be in those regions. It seems clear to me now that we must now expand our search for Early Carboniferous localities in Australia, South America, and Africa.'
CNN
22-05-2025
- Science
- CNN
Tiny clawed tracks left in ancient mud are the oldest reptile footprints
Distinct clawed footprints found on a slab of 356 million-year-old rock from Australia suggest that reptile relatives appeared between 35 million and 40 million years earlier than previously believed. The tracks also push back the origin of amniotes, a group that includes reptiles, birds and mammals, and provide new evidence about how animals transitioned from existing solely in the seas to living on land. Amniotes represent a crucial part of the transition from aquatic to terrestrial life because they were the only tetrapods, or four-limbed creatures, that evolved to reproduce on land. Previously, the oldest body fossils and footprints associated with amniotes were dated to 318 million years ago in Canada. But the new findings, published on May 14 in the journal Nature, challenge such long-held assumptions and signal that the transformation of tetrapods living in water to living on land likely occurred much more rapidly than scientists thought. 'I'm stunned,' said study coauthor Per Erik Ahlberg, professor of evolution and developmental biology at Uppsala University in Sweden, in a statement. 'A single track-bearing slab, which one person can lift, calls into question everything we thought we knew about when modern tetrapods evolved.' The location of the discovery indicates that Australia, once a central part of the ancient southern supercontinent of Gondwana that also included present-day Africa, South America, Arabia, Madagascar, Antarctica and India, may be the ideal place to look for more amniote and reptile fossils — and where they originated, according to the study authors. The rock slab, found by amateur paleontologists and study coauthors Craig Eury and John Eason in the Snowy Plains Formation in Victoria, Australia, appears to show two sets of tracks from the same animal that represent the earliest clawed footprints ever discovered. The shape of the feet is similar to a modern water monitor's, and though the animal's exact size is unknown, it may have resembled a small goanna-like creature about 80 centimeters (31 inches) in length, said lead study author John Long, strategic professor in paleontology at Flinders University. Asian water monitors are large lizards native to South and Southeast Asia, while goannas are large lizards commonly found in Australia. Hooked claws, a key feature specific to reptiles, might have enabled the primitive tetrapod to dig and climb trees. The animal that made the footprints is the oldest known reptile and oldest known amniote, Ahlberg said. And it's helping scientists crack the code on how tetrapods evolved. 'Our new find implies that the two main evolutionary lines leading to modern tetrapods — one, the line to modern amphibians, and two, the line leading to reptiles, mammals and birds — diverged from each other much earlier in time than previously thought, likely back in the Devonian Period about 380 million years ago,' Long said. Prior to this finding, the Devonian Period was believed to be a time of primitive fishlike tetrapods and 'fishapods' like Tiktaalik, which exhibited traits of fish and early tetrapods and began to explore shorelines in limited ways. But the new study reveals a diversity of large and small tetrapods, some aquatic and others largely or entirely terrestrial, likely lived at the same time. 'One of the implications of our research is that tetrapod diversity at this time was higher, and included more advanced forms, than had been thought,' Ahlberg wrote in an email. It's crucial to understand when life shifted from being entirely aquatic to terrestrial because it is one of the biggest steps in the evolution of life, Long said. This transition showed that animals were no longer dependent on living in or near water. The transition occurred partly because amniotes evolved to reproduce with hard-shelled, rather than soft-shelled, eggs. 'The vertebrates' move onto land was an important part, and within that a key step was the evolution of the amniotic egg in the immediate common ancestors of reptiles and mammals,' Ahlberg said. 'So these events form a key episode in our own ancestry as well as the history of the planet.' The new study pushes the origin of amniotes much deeper into the Carboniferous Period, 299 million to 359 million years ago, which allows a much greater length of time for the diversification of early reptiles, said Stuart Sumida, president of the Society of Vertebrate Paleontology and professor of biology at California State University, San Bernardino. Sumida, who wrote an accompanying article to release with the study, did not participate in the new research. Long has been studying ancient fish fossils from the Mansfield district, where the slab was found, since 1980. 'The Mansfield area has produced many famous fossils, beginning with spectacular fossil fishes found 120 years ago, and ancient sharks. But the holy grail that we were always looking for was evidence of land animals, or tetrapods, like early amphibians. Many had searched for such trackways but never found them — until this slab arrived in our laboratory to be studied,' he said. Fossils from the Mansfield district have shed light on how sexual organs might have first evolved in ancient armored fish. Now, the researchers want to know what else lived in Gondwana alongside the ancient reptile they found. The findings have inspired researchers to broaden the search for fossils of the earliest amniotes, and their close relatives, to the southern continents, Sumida said. 'Most of the skeletal fossil discoveries of the earliest amniotes are known from continents derived from the northern components of Pangea,' Sumida said in an email. 'Discoveries there suggested that amniote origins might be in those regions. It seems clear to me now that we must now expand our search for Early Carboniferous localities in Australia, South America, and Africa.'
