Latest news with #tetrapods
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.'
Gizmodo
14-05-2025
- Science
- Gizmodo
355-Million-Year-Old Footprints Just Rewrote Reptilian History
The origin of four-limbed animals known as tetrapods was thought to be fairly straightforward: Fish flopped onto land in the Devonian, evolved, and eventually diversified into the reptiles, birds, mammals, and other creatures that cover the Earth today. But now, a slab of sandstone small enough to be carried by a single person has thrown that tidy timeline into chaos. The slab is from southeastern Australia and dates to about 355 million years ago, shortly after the end of the Devonian. Discovered by two amateur paleontologists (co-authors of a new study describing the find), the rock preserves a set of remarkable footprints: long-toed impressions with unmistakable claw marks. These trace fossils now represent the oldest clawed tetrapod tracks ever found. 'The key impact is that it pushes an important part of the tetrapod evolutionary tree—in essence, all the branches that go below the reptile-mammal split (also known as the amniote crown-group node)—back in time,' said Per Ahlberg, a researcher at Uppsala University and the lead author of the study, in an email to Gizmodo. Ahlberg explained that although scientists agree tetrapods evolved in the Devonian, those early creatures were believed to be fish-like, only beginning to adapt to life on land. The researchers published a Nature study today describing the fossils and their significance for the tree of life. 'If we already have reptiles at the beginning of the Carboniferous, which is what our Australian trackways indicate, that can't be true,' Ahlberg said. 'When I saw this specimen for the first time, I was very surprised,' said co-author Grzegorz Niedźwiedzki, also a researcher at Uppsala University. 'After just a few seconds I noticed that there were clearly preserved claw marks.' Claws are significant. They're a signature of early amniotes—the group that includes reptiles, birds, and mammals. Other tetrapods, like early amphibians or so-called 'fishapods' such as Tiktaalik, didn't have them. Which means the creature that made the fossilized tracks was likely a primitive reptile—and it was scurrying around much earlier than anyone expected. 'It collides head-on with the often-repeated claim that Tiktaalik and similar 'fishapods' were not only closely related to tetrapods (which they were), but actual tetrapod antecedents or even ancestors,' Ahlberg said. 'In fact, they lived long after the earliest tetrapods, and if our branch-length inferences are correct Tiktaalik was more or less contemporary with the tetrapod crown-group node!' In other words, the appearance of reptiles—and by extension, the evolutionary branch that leads to humankind—gets pushed back by 35 million years. The team's conclusions also mean that the split between amniotes and amphibians had to happen even earlier. By combining DNA-based family trees with fossil dates, the team found that the crown-group node likely lies way back in the Devonian—contemporary with Tiktaalik. That suggests advanced tetrapods were already on the scene while Tiktaalik was figuring out how to prop itself up. Currently, the claw print fossil slab 'represents the entire fossil record of tetrapods from the earliest Carboniferous of Gondwana—a gigantic supercontinent comprising Africa, South America, Antarctica, Australia and India,' said Ahlberg in an Uppsala release. 'Who knows what else lived there?' The key for the team now is more fieldwork—in Australia and elsewhere—that could yield more clues about the early amniotes that occupied Gondwana. More footprints would be good, Ahlberg said, but body fossils would be even better.
