Ancient footprints from Australia reveal earliest-known reptile
The fossilized footprints, apparently made on a muddy ancient river bank, include two trackways plus one isolated print, all displaying hallmark features of reptile tracks including overall shape, toe length and associated claw marks, researchers said. They appear to have been left by a reptile with body dimensions similar to those of a lizard, they said.
The footprints reveal that reptiles existed about 35 million years earlier than previously known, showing that the evolution of land vertebrates occurred more rapidly than had been thought.
"So this is all quite radical stuff," said paleontologist Per Ahlberg of the University of Uppsala in Sweden, who led the study published on Wednesday in the journal Nature.
The Australian footprints were preserved in a sandstone slab measuring about 14 inches (35 cm) across that was found on the banks of the Broken River near the town of Barjarg in the state of Victoria.
The story of land vertebrates started with fish leaving the water, a milestone in the evolution of life on Earth. These animals were the first tetrapods - meaning "four feet" - and they were the forerunners of today's terrestrial vertebrates: amphibians, reptiles, mammals and birds. Footprints in Poland dating to about 390 million years ago represent the oldest fossil evidence for these first tetrapods, which lived an amphibious lifestyle.
These creatures were the ancestors of all later land vertebrates. Their descendants split into two major lineages - one leading to today's amphibians and the other to the amniotes, a group spanning reptiles, mammals and birds. The amniotes, the first vertebrates to lay eggs on land and thus finally break free of the water, cleaved into two lineages, one leading to reptiles and the other to mammals. Birds evolved much later from reptile ancestors.
The Australian footprints each are approximately 1-1.5 inches (3-4 cm) long. They appear to have been left by three individuals of the same reptile species, with no tail drag or body drag marks. No skeletal remains were found but the footprints offer some idea of what the reptile that made them looked like.
"The feet are rather lizard-like in shape, and the distance between hip and shoulder appears to have been about 17 cm (6.7 inches). Of course we don't know anything about the shape of the head, the length of the neck or the length of the tail, but if we imagine lizard-like proportions the total length could have been in the region of 60 cm to 80 cm (24 to 32 inches)," Ahlberg said.
"In terms of its overall appearance, 'lizard-like' is probably the best guess, because lizards are the group of living reptiles that have retained the closest approximation to the ancestral body form," Ahlberg added.
The modest size of the earliest reptiles stands in contrast to some of their later descendants like the dinosaurs.
This reptile probably was a predator because plant-eating did not appear until later in reptilian evolution. The bodies of herbivorous reptiles tend to be big and clunky, whereas this one evidently was lithe with long, slender toes, Ahlberg said.
The researchers also described newly identified fossilized reptile footprints from Poland dating to 327 million years ago that broadly resemble those from Australia. Those also are older than the previous earliest-known evidence for reptiles - skeletal fossils from Canada of a lizard-like creature named Hylonomus dating to around 320 million years ago, as well as fossil footprints from about the same time.
The reptile that left the Australian footprints lived during the Carboniferous Period, a time when global temperatures were similar to today's, with ice at Earth's poles but a warm equatorial region. Australia at the time formed part of the ancient supercontinent Gondwana and lay at the southern edge of the tropics. There were forests, partly composed of giant clubmoss trees.
"The tracks were left near the water's edge of what was probably quite a large river, inhabited by a diversity of big fishes," Ahlberg said.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Straits Times
a day ago
- Straits Times
Ethiopian fossils reveal new species in human evolutionary lineage
Researchers have unearthed tooth fossils in Ethiopia dating to about 2.65 million years ago of a previously unknown species in the human evolutionary lineage, one that lived in the same time and place as the earliest-known member of the genus Homo to which our own species belongs. The scientists discovered in the Ledi-Geraru research project area of northeastern Ethiopia's Afar Region 10 teeth - six molars, two incisors, one premolar and one canine - that they concluded belonged to a new Australopithecus species. The teeth came from two individuals. Until now, six species of the genus Australopithecus, an important early human ancestor that displayed a mix of ape-like and human-like traits, were known from fossils at various African sites. The researchers said the newly found teeth bore traits indicating they belonged to a seventh species. A genus is a group of closely related species that share similar characteristics. For example, lions and tigers are from the same genus but represent different species. The scientists also discovered three other teeth dating to 2.59 million years ago that had traits showing they belonged to the oldest-known species of Homo, one that was first revealed by a jawbone unearthed in the same vicinity in 2013. Scientists have not yet assigned names to the Australopithecus and Homo species represented by these 13 teeth because of the incomplete nature of the fossil remains. Our species Homo sapiens is the most recent member of the Homo genus, first appearing roughly 300,000 years ago in Africa before later spreading worldwide. The new dental fossils provide insight into a poorly understood period in human evolution. The close age of the teeth suggests that this newly identified Australopithecus species coexisted in this region with the early Homo species, raising questions about whether they competed for the same resources. The teeth also indicate that there were four hominins - as species in the human evolutionary lineage are known - that inhabited East Africa at the time. Previous fossils showed that another Australopithecus species and a species of Paranthropus, a hominin possessing a specialized skull adapted for heavy chewing, lived in East Africa during this time. An additional Australopithecus species also inhabited southern Africa, bringing the number of hominins then on the continent to five. The presence of these contemporaneous hominins illustrates the complicated nature of the human evolutionary process. "This reinforces the idea that the story of human evolution is not of a single lineage changing slowly through time," said University of Nevada, Las Vegas paleoanthropologist Brian Villmoare, lead author of the research published on Wednesday in the journal Nature. "Rather, the pattern of human evolution is similar to that of other organisms, repeatedly branching into multiple species throughout the fossil record, many of whom lived at the same time," Villmoare added. The researchers are seeking clues about the nature of any interaction between the Australopithecus and Homo species represented by the 13 teeth. "We are currently analyzing teeth to see if we can tell if they ate the same thing," said Arizona State University paleoecologist and project co-director Kaye Reed. If so, they may have fought over resources, Reed said. Crude stone tools dating to about the same time were previously discovered nearby, Reed said, probably made by the Homo species. The researchers determined the age of the teeth using a technique that dated feldspar crystals contained in volcanic ash in the sediments where they were discovered based on radioactive decay of the element argon. The Afar Region, one of Earth's hottest and lowest places, is an arid expanse of badlands. But at the time of these species, rivers flowed across a vegetated landscape into shallow lakes in a landscape populated by a splendid array of animals. These included giraffes, horses, pigs, elephants, hippos and antelopes as well as predators such as saber-toothed cats and hyenas. Homo is generally thought to have descended from a species of Australopithecus, though the exact species and the timing have been a matter of debate. Australopithecus eventually died out. Australopithecus includes the famous fossil Lucy, who was a member of the species Australopithecus afarensis who lived approximately 3.18 million years ago. Lucy's remains were discovered in 1974, also in the Afar Region. The newly discovered teeth had characteristics that showed they did not belong to Lucy's species, the researchers said. "This new Australopithecus species is in no way some 'missing link,' and we actually don't think that it was necessarily ancestral to any known species," Villmoare said. "Species arose and many went extinct," Reed said. "Each find is a piece of the puzzle that puts human evolution into a twiggy tree, rather than a linear graphic." REUTERS
CNA
a day ago
- CNA
Ethiopian fossils reveal new species in human evolutionary lineage
Researchers have unearthed tooth fossils in Ethiopia dating to about 2.65 million years ago of a previously unknown species in the human evolutionary lineage, one that lived in the same time and place as the earliest-known member of the genus Homo to which our own species belongs. The scientists discovered in the Ledi-Geraru research project area of northeastern Ethiopia's Afar Region 10 teeth - six molars, two incisors, one premolar and one canine - that they concluded belonged to a new Australopithecus species. The teeth came from two individuals. Until now, six species of the genus Australopithecus, an important early human ancestor that displayed a mix of ape-like and human-like traits, were known from fossils at various African sites. The researchers said the newly found teeth bore traits indicating they belonged to a seventh species. A genus is a group of closely related species that share similar characteristics. For example, lions and tigers are from the same genus but represent different species. The scientists also discovered three other teeth dating to 2.59 million years ago that had traits showing they belonged to the oldest-known species of Homo, one that was first revealed by a jawbone unearthed in the same vicinity in 2013. Scientists have not yet assigned names to the Australopithecus and Homo species represented by these 13 teeth because of the incomplete nature of the fossil remains. Our species Homo sapiens is the most recent member of the Homo genus, first appearing roughly 300,000 years ago in Africa before later spreading worldwide. The new dental fossils provide insight into a poorly understood period in human evolution. The close age of the teeth suggests that this newly identified Australopithecus species coexisted in this region with the early Homo species, raising questions about whether they competed for the same resources. The teeth also indicate that there were four hominins - as species in the human evolutionary lineage are known - that inhabited East Africa at the time. Previous fossils showed that another Australopithecus species and a species of Paranthropus, a hominin possessing a specialized skull adapted for heavy chewing, lived in East Africa during this time. An additional Australopithecus species also inhabited southern Africa, bringing the number of hominins then on the continent to five. The presence of these contemporaneous hominins illustrates the complicated nature of the human evolutionary process. "This reinforces the idea that the story of human evolution is not of a single lineage changing slowly through time," said University of Nevada, Las Vegas paleoanthropologist Brian Villmoare, lead author of the research published on Wednesday in the journal Nature. "Rather, the pattern of human evolution is similar to that of other organisms, repeatedly branching into multiple species throughout the fossil record, many of whom lived at the same time," Villmoare added. The researchers are seeking clues about the nature of any interaction between the Australopithecus and Homo species represented by the 13 teeth. "We are currently analyzing teeth to see if we can tell if they ate the same thing," said Arizona State University paleoecologist and project co-director Kaye Reed. If so, they may have fought over resources, Reed said. Crude stone tools dating to about the same time were previously discovered nearby, Reed said, probably made by the Homo species. The researchers determined the age of the teeth using a technique that dated feldspar crystals contained in volcanic ash in the sediments where they were discovered based on radioactive decay of the element argon. The Afar Region, one of Earth's hottest and lowest places, is an arid expanse of badlands. But at the time of these species, rivers flowed across a vegetated landscape into shallow lakes in a landscape populated by a splendid array of animals. These included giraffes, horses, pigs, elephants, hippos and antelopes as well as predators such as saber-toothed cats and hyenas. Homo is generally thought to have descended from a species of Australopithecus, though the exact species and the timing have been a matter of debate. Australopithecus eventually died out. Australopithecus includes the famous fossil Lucy, who was a member of the species Australopithecus afarensis who lived approximately 3.18 million years ago. Lucy's remains were discovered in 1974, also in the Afar Region. The newly discovered teeth had characteristics that showed they did not belong to Lucy's species, the researchers said. "This new Australopithecus species is in no way some 'missing link,' and we actually don't think that it was necessarily ancestral to any known species," Villmoare said. "Species arose and many went extinct," Reed said. "Each find is a piece of the puzzle that puts human evolution into a twiggy tree, rather than a linear graphic."
Straits Times
4 days ago
- Straits Times
Scientists find possible artefacts of oldest known Wallacean prehistoric humans in Indonesia
Sign up now: Get ST's newsletters delivered to your inbox Archaeologists from Australia and Indonesia found the small, chipped tools, used to cut little animals and carve rocks, under the soil in the region of Soppeng in South Sulawesi. SOPPENG, Indonesia – Scientists have found a series of stone tools on Indonesia's Sulawesi island they say may be evidence of humans living 1.5 million years ago on islands between Asia and Australia, the earliest known humans in the Wallacea region. Wallacea is a region in Eastern Indonesia including several islands such as Sulawesi, Lombok, Flores, Timor, Sumbawa that lie between Borneo and Java and Australia and New Guinea. The region is named for the naturalist Alfred Russel Wallace who studied the fauna and flora of the area. Archaeologists from Australia and Indonesia found the small, chipped tools, used to cut little animals and carve rocks, under the soil in the region of Soppeng in South Sulawesi. Radioactive tracing of these tools and the teeth of animals found around the site were dated at up to 1.48 million years ago. The findings could transform theories of early human migrations, according to an article the archaeologists published in the journal Nature in August. The earliest Wallacean humans, pre-historic persons known as Homo Erectus, were thought to have only settled in Indonesia's Flores island and Philippines' Luzon island around 1.02 million years ago, as they were thought to be incapable of distant sea travel, proving the significance of the Sulawesi findings in theories of migration. 'These were artefacts made by ancient humans who lived on the earth long before the evolution of our species, Homo Sapiens,' said Professor Adam Brumm, lead archaeologist from Griffith University in Queensland, Australia. 'We think Homo Erectus somehow got from the Asian mainland across a significant ocean gap to this island, Sulawesi, at least 1 million years ago,' said the professor, whose contributions to the field span 21 years of grant-funded research in Indonesia. REUTERS
