Approximately 100 million years in the past, our beloved Earth sported an entirely different visage. Absent were the humans, and the planet was under the rule of some rather intimidating creatures – the dinosaurs. These were no ordinary dinosaurs; they were colossal, towering over even the loftiest buildings, boasting jaws with the power to shatter bones in the blink of an eye, and the swiftness to sprint at an astonishing 90 kilometers per hour. They were true behemoths, reigning over Earth for an astounding span of 170 million years. However, a fateful day arrived when something occurred, an event that would wipe them from the face of the planet. What precisely transpired, and how? Let`s delve into this mystery.
“As it draws nearer to our planet, Earth’s gravitational pull grows stronger,” rendering its impending arrival invisible to those on the surface.
Ladies and gentlemen, the term ‘Dinosaur’ finds its origins in the Greek language, stemming from the words ‘Denios,’ meaning ‘Terrible,’ and ‘Sauros,’ meaning ‘Lizard’ – quite literally, ‘Terrible Lizard.’ This term first graced the pages of history in 1841 when the first dinosaur fossils were unearthed. A British scientist by the name of Richard Owen was the one who introduced the word ‘dinosaur.’ At the time, people possessed limited knowledge of these ancient creatures and their appearances. Consequently, the initial depictions of dinosaurs bore little resemblance to our contemporary understanding.
One of the earliest discovered fossils was that of the Megalosaurus, and when you examine the initial illustrations, they differ significantly from the images we have today. Over subsequent decades, as researchers uncovered more information about dinosaurs, these depictions were refined to portray a more realistic image. Today, over 10,000 dinosaur fossils have been excavated by paleontologists across the globe, leading to the identification of over 900 distinct species. It’s truly exciting to think about the prospect of discovering more fossils.
Interestingly, from 2003 to 2022, an average of 45 new dinosaur species have been identified each year. This demonstrates that the work of paleontologists is far from complete. In fact, consider the images of newly discovered dinosaur species from the past year. Among them is a rather peculiar dinosaur found in Chile, boasting a blade-like tail weapon and a beak for a mouth, aptly named Stegouros Elengassen.
As of today, our knowledge of dinosaurs is quite extensive. However, let’s embark on our journey starting from the very beginning, millions of years ago. Scientists estimate that the first dinosaurs emerged approximately 230-240 million years ago, with the oldest dinosaur fossils discovered thus far dating back to 231.4 million years ago in Africa. During this era, Earth bore little resemblance to its current form. All the continents we recognize today – Asia, Africa, Australia, Europe – were conjoined into a single supercontinent known as Pangaea. Scientists believe that Pangaea’s arrangement resembled the continents we know today. This was a time of arid, dry climates with minimal rainfall, labeled the Triassic Period and the dawn of dinosaur emergence.
During this epoch, the dinosaurs differed greatly from our preconceived notions. They were notably smaller in size, with the average dinosaur of that era measuring merely around 2 meters in length. For instance, the Eoraptor, a dinosaur from this period, is considered the ancestor of later dinosaurs. The dominant creatures of this era were enormous reptiles, some of which might be considered rather endearing, such as one believed to be the ancestor of all turtles.
However, Earth underwent significant transformations as it approached the end of the Triassic period, roughly 201 million years ago. The supercontinent Pangaea began to fragment, a process that, although I use the term “suddenly,” took place over thousands of years in the grand timescale of millions of years. Fissures appeared in the supercontinent, accompanied by substantial volcanic eruptions along these fault lines. These eruptions unleashed a deluge of carbon dioxide and sulfur dioxide into the atmosphere, triggering severe global warming. The entry of sulfur dioxide and aerosols into the atmosphere blocked sunlight, leading to localized cooling. When carbon dioxide and sulfur dioxide mixed with water, the oceans’ acidity levels increased, setting off rapid and drastic climate changes. The implications of these transformations made survival increasingly difficult for the species of the era.
Most of the reptiles and other species from that period were cold-blooded creatures, ill-equipped to cope with dramatic shifts in temperature. Dinosaurs, however, shared a similarity with humans in that they were warm-blooded, making them better suited to endure these climatic fluctuations. These volcanic eruptions and climatic shifts persisted for around 600,000 years, pushing most other species to the brink of extinction. As a result, the sole survivors on Earth were the dinosaurs, crocodiles, turtles, and early mammals. This cataclysmic event is known as the Triassic-Jurassic Extinction Event.
And so, the Triassic period drew to a close, and the Jurassic period dawned. For those who might find the name familiar, it was the inspiration behind the famous “Jurassic Park” films. The term “Jurassic” is a reference to this specific period. The Jurassic period spanned from approximately 201 million to 145 million years ago. During this era, dinosaurs ascended to become the dominant species on the planet. Through the course of evolution, some grew to impressive sizes. For example, some of the early Titanosaurs, inhabitants of this period around 160 million years ago, could weigh up to a colossal 15,000 kilograms and measure up to 15 meters in length.
The Jurassic period also marked the emergence of dinosaurs capable of flight, exemplified by Archaeopteryx, one of the earliest feathered dinosaurs, which bore a resemblance to the birds we see today. During this period, Pangaea began its division into two smaller supercontinents: Laurasia and Gondwanaland. This period has gained notoriety thanks to the “Jurassic Park” films. However, the subsequent era, the Cretaceous period, bore witness to the true flourishing of the dinosaurs.
The Cretaceous period was particularly prolific, leading to a surge in the diversity of dinosaur species. This was the era when we encountered some of the most iconic dinosaurs, including the ever-famous Tyrannosaurus rex (T-Rex), which thrived towards the conclusion of the Cretaceous period, around 65-68 million years ago. Although there is some debate among researchers, most believe that T-Rex did not exist during the Jurassic period. It is intriguing to note the irony that the “Jurassic Park” film series used the T-Rex as its logo. The Cretaceous period stood as the longest epoch in the age of dinosaurs, commencing around 145 million years ago and concluding approximately 65 million years ago.
During this epoch, the two supercontinents, Laurasia and Gondwanaland, began to break apart, gradually shaping the continents into forms that resemble what we see on the world map today. The Cretaceous period was a time when numerous new species of dinosaurs emerged, including raptors, armored dinosaurs, giant herbivores, and formidable carnivores. Among them, the Titanosaurs, such as the Argentinosaurus, could weigh up to a staggering 77 tonnes.
This period also saw the development of numerous flowering plants, and Earth’s climate was notably warmer. Sea levels rose, and almost every kind of dinosaur one can imagine proliferated.
Inhabiting this era were various dinosaurs, including raptors, armored dinosaurs, enormous herbivores, and formidable carnivores. Among them, the Titanosaurus stood as one of the largest terrestrial creatures ever known, while the Argentinosaurus could weigh up to a staggering 77 tonnes. The iconic T-Rex, believed to be the apex predator of its time, reached lengths of up to 40 feet and possessed the most powerful jaws of any known animal. Notably, the evolution of grass, which we commonly associate with Earth, commenced a mere 70 million years ago. Therefore, when envisioning the Earth in the narrative I’ve been sharing, it’s important not to picture a world covered in grass; other plant varieties existed.
Around 68 million years ago, both the T-Rex and Triceratops evolved, marking a notable point in history. It’s intriguing to note that we are closer in time to the existence of the T-Rex than it was to the Jurassic Period, with a span of 80 million years separating the two, whereas only 68 million years stand between us and the T-Rex.
Another intriguing species of dinosaurs that existed at the time were the Ornithomimids, which bore a resemblance to ostriches and ranked among the fastest dinosaurs, capable of sprinting at speeds of up to 80 km/hr. In terms of flight, the Quetzalcoatlus reigned as the largest flying dinosaur, boasting an impressive wingspan measuring 10-11 meters. This was indeed a prosperous era for dinosaurs, with the climate favoring their existence and the evolution of new species taking place. Furthermore, there was no other species to compete with them, allowing them to rule over Earth effortlessly.
However, this golden age came to an abrupt end when a colossal asteroid, measuring approximately 10-15 kilometers in diameter, hurtled towards Earth and collided with it 66 million years ago. The asteroid was traveling at an astounding speed of 30 kilometers per second, equivalent to 150 times the velocity of a jet airliner. Specifically, it struck the Yucatan Peninsula in Mexico, the same region that would later give rise to the Mayan civilization and historic wonders such as Chichen Itza.
The impact of the asteroid generated a massive crater with a diameter of 180 kilometers, releasing energy at an astonishing rate, equivalent to 100 teratonnes of TNT, which is a staggering 1 billion times the energy produced by the atomic bombs dropped on Hiroshima and Nagasaki. The impact led to the disintegration of everything within its vicinity. The impact expelled vast amounts of soil into the atmosphere, heating the land and causing scorching dust to rain down across distant areas.
Global temperatures skyrocketed by several degrees for hours, causing the incineration of all creatures within thousands of kilometers. It is believed that only small animals survived the initial blast by taking refuge underground, in water, caves, or within large tree trunks.
Nevertheless, the initial impact was just the beginning. Subsequent shock waves, heat pulses, wildfires spanning thousands of kilometers of forest, and enormous tsunamis ensued. It’s conjectured that an immediate tsunami, with waves towering to 2 kilometers in height, struck the shores.
Can you fathom the sheer magnitude of a 2-kilometer-tall tsunami wave?
Volcanic eruptions rekindled, acid rain fell, and earthquakes rocked the Earth. The immediate consequences were exceptionally lethal. You might think that on the opposite side of the Earth, where the impact didn’t reach, some animals could have survived. However, the long-term repercussions were even more deadly.
The fine dust particles thrown into the atmosphere blocked sunlight for the following year worldwide, triggering a nuclear winter. Temperatures plummeted dramatically, and for an estimated three years, Earth was encased in a deep freeze. This calamity killed numerous plants and animals as the absence of sunlight prevented photosynthesis. Plants withered, depriving herbivorous creatures of sustenance, and ultimately, even carnivorous animals starved due to the absence of prey. This chain reaction unraveled, and only small omnivorous creatures such as mammals, lizards, turtles, and some birds managed to endure by scavenging on dead dinosaurs, decaying plants, and fungi. This led to the release of carbon and sulfur into the atmosphere, causing sunlight to be significantly diminished for several thousand years.
And it didn’t stop there; acid rain continued for thousands of years. Once the nuclear winter came to an end, the dust settled, and sunlight graced the Earth again. However, a significant amount of carbon dioxide had already been released into the atmosphere, resulting in intense global warming. Consider this, my friends – a single asteroid altered Earth’s history for thousands of years.
With a few exceptions aside, no terrestrial four-legged creatures weighing over 25 kilograms managed to survive this catastrophic event. All terrestrial dinosaurs were wiped out, along with the plant and animal species that had once thrived on Earth. Over 75% of species faced extinction.
At this juncture, the Cretaceous period concluded, giving way to the Paleogene period. But it wasn’t the end; instead, this event presented an opportunity for other animal species to rise. The dinosaurs, Earth’s rulers, were no more, paving the way for the evolution of mammals in the wake of the dinosaurs’ extinction.
Mammals stepped in to fill the ecological void left by the dinosaurs, and it was during this period that the evolution of horses, whales, bats, and primates occurred. The Paleogene era also saw the emergence of several snakes and smaller lizards. Remarkably, the only group of dinosaurs to survive were the flying dinosaurs, which gradually evolved into the birds we recognize today. That’s right, the birds you observe soaring through the skies today share ancestry with these flying dinosaurs, most closely linked to chickens and ostriches.
This genetic relationship between birds and dinosaurs is supported by numerous studies. Indeed, the closest living relative of the fearsome T-Rex is believed to be a chicken, illustrating the fascinating connection between birds and these prehistoric creatures. As for the asteroid’s impact site and the dating of this cataclysmic event, these details are supported by the presence of a rare mineral – iridium. Scientists have identified deposits of iridium at select locations on Earth, offering evidence of the asteroid strike and its occurrence approximately 66 million years ago.
A high concentration of iridium is found on Earth’s surface, which is indeed a rare mineral within the Earth’s composition. This anomaly is explained by the fact that comets and asteroids, bearing a substantial iridium content, are responsible for this occurrence. When scientists subjected the iridium layer to carbon dating, they determined that it dates back to 66 million years ago, marking the period of the asteroid impact that dispersed this mineral across the planet.
Despite the immense impact of the asteroid, you might wonder why the crater it left isn’t more visible. However, the passage of 66 million years has caused considerable alterations in the Earth’s geography due to the relentless movement of continents. The asteroid’s crater is concealed within the Yucatan Peninsula, where numerous excavation expeditions have confirmed the event’s actual occurrence and the precise location.
The crater’s position is clearly marked on the map, with one half submerged beneath the sea and the other half on land. This impact’s real-world manifestation can be observed in the cenotes of the Mexican region. These picturesque sinkholes exhibit a distinct pattern, forming a ring around the asteroid’s crater. These cenotes have evolved into popular tourist attractions where visitors can partake in swimming activities. Collectively, these cenotes form the world’s most extensive underground cave system.
When contemplating the ramifications of a current asteroid impact, it’s reasonable to question if it could result in human extinction. Indeed, such an event poses a legitimate threat. Near Earth Asteroids, or NEAs, are the class of asteroids that might impact Earth in the foreseeable future. Agencies like NASA diligently monitor and track these NEAs to calculate their trajectories and assess the potential for Earth impact.
As of April 2022, more than 28,000 NEAs have been identified, including over 800 with diameters of 1 kilometer or more, underscoring the potential hazard they pose. However, there’s no need for immediate alarm because scientific advancements enable the precise prediction of their paths and the estimation of the probability of impact. Furthermore, strategies are in place to mitigate potential threats, as demonstrated by NASA’s DART space mission, launched in 2021 (Double Asteroid Redirection Test). This mission entailed colliding a spacecraft with an asteroid to alter its trajectory. The success of this test on an asteroid not on a collision course with Earth highlights the feasibility of such efforts if an asteroid were to threaten Earth in the future.
Nonetheless, the danger of asteroid impact isn’t the only peril humanity faces. The asteroid strike that extinguished the dinosaurs is categorized as the fifth mass extinction event in Earth’s history. However, scientists believe that the sixth mass extinction event has already commenced, and it is driven by human activities.
This ongoing event is known as the Holocene Extinction Event. Over the last 100-200 years, human-induced factors, such as deforestation and pollution of the oceans and atmosphere, have precipitated an unprecedented loss of biodiversity. Biologists concur that this constitutes a mass extinction event with the extinction rate exceeding the natural rate by more than 100 to 1,000 times.
Human actions have disrupted the habitats of many species, pushing thousands of mammals, birds, reptiles, and amphibians into the endangered category or causing their outright extinction. To combat this devastation, a United Nations Convention on Biological Diversity Meeting was convened in Japan in 2010, where 20 biodiversity targets were established with a deadline of 2020. Unfortunately, only six of these targets were partially met. In January 2020, a new initiative, akin to the Paris Agreement, was launched to prevent biodiversity and ecosystem collapse, setting a deadline for 2030. Its objectives include designating 30% of land and oceans as protected areas and reducing pollution by at least 50%. Scientists have suggested that the ongoing extinctions must be limited to 20 or fewer species per year.
The ultimate success of these endeavors remains to be seen, but they are critically important. If plant and animal species continue to go extinct as they have in previous extinction events, it may become impossible for humans to survive. Intriguingly, humans, as per scientific estimations, emerged a mere 300,000 years ago in Africa. This is in stark contrast to the reign of the dinosaurs, which persisted as Earth’s dominant species for an astounding 174 million years. Humans, by comparison, have been present for only 300,000 years, which is merely 600 times shorter than the reign of the dinosaurs.
Whether humans can surpass the record set by dinosaurs or face extinction before reaching one million years depends largely on collective efforts to preserve the planet. The right answer hinges on these collective endeavors.
