Buzz
To achieve the breathtaking variety of life on Earth, nature had to overcome a myriad of challenges over billions of years of evolution. New environments needed to be explored, and entirely new life forms had to be developed to take advantage of the resources made available. Since humanity began to examine the vast history of life on our planet through the lens of paleontology and geology, we've uncovered several key moments in the evolution of life on Earth.
10. The First Humans The Omo Remains
Humanity's ancestry stretches far back, but who were the earliest modern humans, similar to the ones we know today? The Omo I and II fossils could hold the answer. These two partial skulls, uncovered in Ethiopia in 1967, have recently been confirmed to be an astonishing 195,000 years old, making them the oldest known anatomically modern humans. While there is some debate about Omo II, Omo I is widely accepted as a true example of modern human anatomy. In fact, scientists now believe that Homo sapiens evolved around 200,000 years ago, suggesting that the Omo fossils were among the first true humans to walk the Earth.
What do the two skulls imply? Beyond confirming the emergence of humanity in Africa, they have added complexity to one of the greatest puzzles of human evolution. Cultural markers such as musical instruments, needles, and ornaments are only known to exist around 50,000 years ago. Complex tools like harpoons also appear after that period, although simpler stone tools predate this by much. So, if fully modern humans were present 200,000 years ago, why did it take them another 150,000 years to create anything resembling culture?
9. The First Bird Protoavis
It is now established that birds evolved from dinosaurs, and many dinosaurs were actually covered in feathers. This leads to the question: when does a creature stop being considered a dinosaur and start being classified as a bird? For years, paleontologists placed species like Archaeopteryx (pictured) and Confuciusornis—small, feather-covered animals capable of flight, tree climbing, and running—at the transition point. Additionally, Confuciusornis is recognized for having a true beak, giving it an edge over others in the race for the title of the earliest true bird.
However, there is an even older contender for the title of first bird. Protoavis lived around 220 million years ago, a full 80 million years before its closest rival. Discovered in Texas by paleontologist Sankar Chatterjee, it is argued that Protoavis is even more closely related to modern birds than Archaeopteryx. If true, this would challenge our entire understanding of avian evolution. While the prevailing theory suggests that birds evolved from coelurosaurian dinosaurs, Protoavis predates these dinosaurs, making such a theory difficult to reconcile. If Protoavis is truly a bird, it suggests that birds may have evolved elsewhere.
But don't rush to revise the textbooks, as the identification of Protoavis as a bird has sparked significant controversy. The fossil was poorly preserved when Chatterjee discovered it, leading many paleontologists to argue that it is actually a combination of bone fragments from different species, which Chatterjee may have mistakenly reconstructed into a plausible skeleton. Others point out that there is no solid reason to consider Protoavis the ancestor of modern birds. Instead, it may be a case of convergent evolution, where two unrelated species independently developed similar features.
8. The First Species to Walk on Land Tiktaalik and Pneumodesmus
Part fish, part frog, and part alligator, Tiktaalik was the platypus of the Devonian period, thriving in shallow waters around 375 million years ago. Discovered in Canada in 2004, Tiktaalik is considered a key transitional species between aquatic vertebrates and the first land animals. It possessed several important adaptations, including ribs to support its body, lungs for breathing air, a movable neck, and eyes positioned on top of its head like a crocodile. Tiktaalik also had proto-legs, evolving halfway from fins, enabling it to push along riverbeds. However, its 'legs' likely lacked the mobility required for full terrestrial locomotion, and it probably remained in the shallows, occasionally scrambling on mud flats.
While vertebrates like Tiktaalik struggled to adapt to land, they were actually preceded by a millipede species known as Pneumodesmus, which lived around 428 million years ago. Despite its small size—only about 1 centimeter (0.4 inches)—Pneumodesmus was the first known creature to truly inhabit land. As the oldest air-breathing organism we know, it had tiny spiracles, or breathing openings, on its body, allowing it to breathe in air. Pneumodesmus stands as one of nature’s most successful early experiments, paving the way for all subsequent land animals.
7. The First True Reptile Hylonomus Lyelli
Reptiles were the first vertebrates to fully adapt to life on land, even reproducing outside of aquatic environments. This remarkable achievement makes them quite extraordinary, and the tiny creature known as Hylonomus lyelli may just be the most extraordinary of them all. Measuring only 20 centimeters (8 inches) in length, Hylonomus lyelli is the oldest confirmed reptile species, dating back at least 310 million years. Likely an insect-eater, this lizard-like animal was discovered in 1860, preserved within a tree trunk in Nova Scotia.
However, since 1860, two contenders for the title of the first reptile have emerged. Westlothiana and Casineria are both slightly older than Hylonomus lyelli, with ages of 338 million years and 335 million years, respectively. But there is still debate among scientists about whether either species should be classified as a true reptile, as both share certain amphibian characteristics, suggesting they may have relied on a stable water source for survival and reproduction. For now, Hylonomus lyelli retains its title.
6. The Oldest Known Flying Creature Rhyniognatha Hirsti
Flight as a mode of movement demands an intricate design (low body mass with a strong frame) and considerable energy from powerful wing muscles. The earliest creature capable of flight was, in fact, the oldest known insect, Rhyniognatha hirsti. This minuscule insect existed around 400 million years ago, showing that flight is far from a recent evolutionary development.
Rhyniognatha hirsti was first discovered in 1928 within Devonian-era rocks. However, its fossil went largely overlooked for nearly 75 years until biologist Michael Engel stumbled upon it in a drawer at London’s Natural History Museum. Upon seeing the remarkable specimen, Engel was stunned, and this reaction came before he realized just how ancient the insect truly was.
Since its rediscovery, researchers have meticulously examined its remains, confirming that the tiny insect possessed wings and was almost certainly capable of flight. However, there is still some uncertainty regarding which insect family it belonged to. Regardless, this fossil remains an extraordinary discovery, and ongoing studies will likely shed more light on the earliest known pioneer of flight.
5. The First Flowering Plants Potomacapnos and Amborella
While most people associate plants with flowers, the reality is that flowers are a relatively recent addition in the grand scheme of evolution. Before flowers emerged, plants reproduced via spores for hundreds of millions of years. Interestingly, scientists are still unsure why flowers evolved in the first place, as they are fragile and require significant energy to produce. This energy could potentially be better spent on growing seeds or increasing height. Furthermore, non-flowering plants have no counterparts to flowers, leaving scientists puzzled as to how they came about in the first place. This mystery led Darwin to famously call the origin of flowers 'an abominable mystery.'
The earliest known fossils of flowering plants date back to the Cretaceous period, around 115 to 125 million years ago. Among the oldest is Potomacapnos, a surprisingly complex plant that bears resemblance to modern poppies. The complexity found in early fossils suggests that flowers evolved quickly, reaching a form similar to what we see today rather than gradually over time. However, drawing definitive conclusions is challenging, as flowers are delicate and seldom preserved in fossil form.
Some answers may lie in a rare shrub that grows only on the Pacific island of New Caledonia. Amborella trichopoda (pictured) is the last surviving member of the Amborellales. Around the beginning of the Cretaceous period, the Amborellales diverged from non-flowering plants, becoming the oldest surviving order of flowering plants. Later, two other orders emerged: the Nymphaeales, which gave rise to modern water lilies, and the Austrobaileyales, from which all other flowering plants evolved. Since the Amborellales appeared first, Amborella trichopoda is considered the closest living relative to the original flowering plants. By comparing it to the Austrobaileyales, scientists can gain insights into the traits of the first flowering plants and those that evolved later.
4. The Earliest Mammal Hadrocodium Wui
The earliest known mammal was a small creature, similar in size and appearance to a modern-day mouse or shrew. Discovered in China in 2001, Hadrocodium wui measured only centimeters (1.4 inches) in length and weighed a mere 2 grams. Its diet and lifestyle likely resembled that of present-day shrews, as its teeth included specialized fangs designed for slicing through insects.
So, what sets Hadrocodium apart as a mammal rather than a therapsid (a mammal-like reptile from the Mesozoic era)? For one, its relatively large brain compared to its size, as well as the fact that its middle-ear bones were distinct from its jaw—an important evolutionary distinction between mammals and reptiles. Hadrocodium’s design was notably modern, particularly in its advanced sense of smell.
What truly makes Hadrocodium wui remarkable, however, is its age. Dating back 195 million years, Hadrocodium lived long before some of the most famous dinosaurs, including the stegosaurus, diplodocus, and tyrannosaurus. In fact, the mighty tyrannosaurus was much closer to our time than it was to Hadrocodium wui.
3. The Oldest Life-Form
Identifying the oldest life-form is a surprisingly complicated task, as early life was so basic that it’s difficult to pinpoint it precisely. For example, rocks found near Pilbara, Australia, were once believed to contain traces of a purple, ocean-dwelling microbial community estimated to be nearly billion years old. This would have been the oldest known life on Earth, generating much excitement—until recent tests confirmed that these 'microfossils' were actually strange mineral formations caused by hydrothermal activity. In other words, they were never living organisms.
A similar case occurred in South Africa, where tiny tubes discovered in rocks were initially interpreted as evidence of 3.4-billion-year-old bacteria. However, later research revealed these tubes were simply natural structures formed by volcanic processes. Despite these misinterpretations, the search for the oldest known fossils continues, with the Strelley Pool Formation in Australia now providing carbon-rich 'bag-shaped bodies' that are considered strong evidence of ancient microbial life. At 3.43 billion years old, these deposits are only 20 million years younger than the Pilbara microfossils were once thought to be.
Interestingly, some evidence suggests that the organisms found in the Strelley Pool may have been photosynthetic, meaning they survived by converting light into energy. While no direct fossil evidence has been found, it is widely believed that the earliest bacteria were chemolithotrophs, organisms that obtained their energy by consuming rocks. Photosynthetic bacteria likely evolved later, implying that these early bacteria predated the Strelley Pool organisms by a substantial margin.
2. The Earliest True Dinosaur Nyasasaurus Parringtoni
The dinosaurs’ dominance began after the catastrophic Permian extinction, which occurred about 250 million years ago and wiped out nearly 90% of all life on Earth, including 95% of marine species and most of the planet’s trees. This event paved the way for the rise of the dinosaurs.
The oldest confirmed true dinosaur is Nyasasaurus parringtoni, a species discovered in Tanzania in the 1930s but only definitively dated in 2011. So far, only a handful of bones from this species have been identified—leaving scientists unsure whether it was a carnivore or herbivore, and whether it walked on two legs or not.
Despite the uncertainties, we do know that Nyasasaurus parringtoni was relatively small, standing just 1 meter (3 feet) tall and weighing between 18 and 60 kilograms (40–135 lbs). It’s far from the iconic image of a dinosaur, but an examination of its bones suggests it was a fast-growing creature, a key indicator of being warm-blooded—an essential characteristic of dinosaurs. For now, the scientific community is eager to find more fossils to determine the exact family of dinosaurs it belongs to.
1. The First Tree Wattieza
Trees have long been and continue to be vital in shaping Earth’s atmosphere. Without their ability to transform carbon dioxide into oxygen, life on Earth, as we understand it, would be unsustainable. The arrival of the first forests had a profound impact on our ecosystem, cooling the planet and establishing the conditions we now take for granted. Therefore, the appearance of trees marks one of the most significant evolutionary milestones in history.
The oldest known tree species is Wattieza, a 397-million-year-old plant resembling a modern palm tree that likely reached a height of around 10 meters (30 feet). Wattieza existed some 140 million years before the dinosaurs, spreading across the planet long before the first vertebrates made their way onto land. It reproduced by spores, much like modern ferns and fungi. Although the species is now extinct, a 180-kilogram (400 lb) fossil was discovered in New York in 2004, providing crucial insight into how forests came to dominate terrestrial ecosystems.
