A groundbreaking discovery in Victoria, Australia, has pushed back the known date of the emergence of reptile-like animals with claws by over 35 million years, revealing a pivotal moment in evolutionary history.
The discovery of a 356-million-year-old fossil slab in Victoria, Australia, has rewritten the history of animals transitioning from water to land. The three sets of tracks, featuring five-fingered hands and hooked claws, have shed new light on the earliest four-legged creatures.
Fossils found in sedimentary rocks provide evidence of ancient 'terrestrial life' dating back over 3.5 billion years.
The oldest known fossils are stromatolites, layered structures created by cyanobacteria in shallow water.
As the Earth's atmosphere changed, more complex life forms emerged, such as multicellular organisms and plants.
Fossil records show that these early life forms adapted to various environments, including terrestrial ecosystems.
The discovery of 'ancient' terrestrial life has significantly contributed to our understanding of evolution and the history of life on Earth.
A New Window into Evolutionary History
The find is significant because it pushes back the previously known date of the emergence of reptile-like animals with claws. These early tetrapods are thought to be ancestors of birds, reptiles, and mammals, including humans. The fossil tracks were dated to around 356 million years ago, making them over 35 million years older than the previous oldest clawed fossils found in Nova Scotia, Canada.
The evolution of reptiles dates back to over 320 million years ago during the Carboniferous period.
The first reptiles, such as Hylonomus lyelli, were small, lizard-like creatures that lived on land.
Over time, they developed into various groups, including snakes, lizards, and turtles.
Reptiles evolved from amphibians and are characterized by their scaly skin, laying eggs, and being cold-blooded.
Today, there are over 10,000 known species of reptiles, ranging in size, shape, and behavior.
Clues to the Early Reptile’s Existence
The tracks themselves provide crucial evidence of the early reptile’s existence on land. According to John Long, a researcher at Flinders University, the five-fingered hands and hooked claws are ‘beautiful‘ and ‘a dead giveaway‘ that this was an amniote, or creature whose young develop inside amniotic fluid. This category includes reptiles, mammals, and humans.
The presence of these features rules out the possibility that the animal was an amphibian, which were thought to be the first four-legged land animals. Amphibians have young that pass through a larval stage, forcing them to return to water rather than living their whole life cycle on land. The early amphibians also lacked well-developed claws at the end of their fingers and feet.
A Turning Point in Evolution
The discovery of these ancient tracks marks a significant turning point in evolution. With hard shell eggs, amniotes were no longer bound to reproduce in water but could invade dry land and establish new continents. This was a crucial moment in the development of life on Earth.
The evolutionary process has been marked by several significant milestones.
The emergence of single-celled organisms around 3.5 billion years ago laid the foundation for life on Earth.
The development of multicellular organisms, such as sponges and cnidarians, occurred approximately 2.1 billion years ago.
The Cambrian explosion, which took place around 541 million years ago, saw a rapid diversification of animal species.
The evolution of vertebrates began around 530 million years ago with the emergence of fish-like creatures.
The development of tetrapods, or four-legged animals, occurred approximately 360 million years ago.
While some researchers are cautious about the interpretation of the fossil evidence, others believe that the tracks demonstrate advanced terrestrial locomotion. However, there is ongoing debate about whether the claws are true claws or just pointed digits. Further analysis is needed to confirm the findings and shed more light on the evolution of these early reptile-like animals.
- newscientist.com | Fossil tracks rewrite history of animals leaving water to live on land
