The Late Cretaceous period was the last great age of the dinosaurs.
Hundreds of giant reptilian species populated the supercontinent Pangea.
Armored herbivores battled against ferocious, bipedal predators.
Avian dinosaurs soared through the skies, and aquatic reptiles ruled the Earth’s rivers
and oceans; but why don’t giant reptiles from the Cretaceous exist in the world today?
Spanning 79 million years ago, the Cretaceous was the third geological period in the Mesozoic
Era; but long before the Cretaceous period, our prehistoric planet was already teeming
with dinosaurs.
The Triassic and Jurassic periods stimulated tremendous evolutionary growth, rearing diverse
populations of giant, reptilian species.
Many direct ancestors of Cretaceous dinosaurs evolved during the Triassic and Jurassic,
as well as mammals and the first flying vertebrates.
At the beginning of the Jurassic period, the Earth did experience a major extinction, known
as the Tr-J Extinction Event.
Nearly a third of aquatic organisms, like plesiosaurus and ancient mollusks, disappeared;
however, dinosaurs remained the rulers of the Earth.
Their dynasty matured through the Jurassic period and into the Early Cretaceous.
145 million years ago, when the Cretaceous period began, our planet was changing rapidly.
All seven of the world’s current major landmasses were joined together in one supercontinent
called Pangea.
Here, creatures roamed freely from North America to Australia, but the Earth’s crust was
moving; and Pangea was breaking apart.
The Americas drifted west.
Eurasia moved east, and vast oceans developed in the spaces between.
The world was no longer a single, interconnected system.
Instead, distinct landmasses with individual climates and topographies developed unique
ecosystems, bearing hundreds of new species, including angiosperms, insects, and some of
the largest dinosaurs to ever walk the Earth.
In North and South America, Titanosaurs, the last of the giant sauropods, reached their
long necks to feast on the tallest trees.
Titanosaurs weighed over 90 tons and stretched over 100 feet long.
The largest among them, the Argentinosaurus, was the heaviest dinosaur in recorded history,
weighing about 110 tons.
Though gentle giants, these dinosaurs intimidated predators with their overwhelming size and
strength.
Though shorter and lighter, another giant herbivore called Triceratops lived in the
Western United States.
Triceratops were armed with three horns on their faces and bony frills on the backs of
their heads.
These massive creatures outweighed African elephants and wielded enough power to fight
and kill carnivores like Tyrannosaurus.
Like modern-day rams and oxen, these humongous herbivores clashed with members of their own
species, smashing their horns and frills together in Earth-shaking battles for dominance and
territory.
Triceratops was not the only herbivore with armor during the Cretaceous Period.
In the United States and parts of Canada, Ornithischians like the Ankylosaurus had rows
of wedge-shaped bones protruding like spikes from their bodies.
On their tails, Ankylosaurus wielded massive clubs to shatter the bones of other dinosaurs.
Herbivores like Triceratops and Ankylosaurus could easily defend themselves, so predators
had to fight tooth and nail for every meal; but few apex predators were more successful
than Tyrannosaurus, “the tyrant king” of the dinosaurs.
This bipedal predator grew over 40 feet long and 20 feet tall, and they hunted in the grasslands
of North America and Asia.
Scientists estimate that Tyrannosaurus had the strongest bite of any living thing on
the planet.
With their crushing jaws, Tyrannosaurus wrestled and killed herbivores of all shapes and sizes.
But Tyrannosaurus wasn’t the largest predator during the Cretaceous period.
Lurking in the rivers and swamps of North Africa, Spinosaurus was a semi-aquatic carnivore
that fed on ancient sharks and giant fish called Coelacanths, which exist in the world
today.
With a narrow snout, long arms, and a sleek body, Spinosaurus grew up to 52 feet long;
that’s over 12 feet longer than the average Tyrannosaur.
Spinosaurus gets its name from a bony protrusion that formed a sail on its back.
With their sails fully extended, Spinosaurus nearly doubled its height, intimidating their
prey and other predators.
Tyrannosaurus terrorized prehistoric grasslands and plains.
Spinosaurus attacked anything too close to the water’s edge; even the skies were patrolled
by airborne dinosaurs called Pterosaurs.
These menacing, flying reptiles were the first animals, excluding insects, to evolve powered
flight.
Often mistaken for oversized birds, Pterosaurs were ruthless predators that dominated the
skies during the Cretaceous period.
Some pterosaurs were larger than modern-day fighter jets, swooping down on mammals and
smaller dinosaurs.
During the Late Cretaceous, Pangea drifted further apart and new oceans formed in the
gaps between each continent; but these bodies of water were as dangerous as the land and
the sky.
Many larger aquatic predators died out during the Tr-J Extinction Event; however, one ferocious
carnivore still lurked beneath the waves.
Mosasaurus was a crocodile-jawed apex predator, stretching up to 58 feet long and well-adapted
to its marine environment.
Preying on sharks and dinosaurs, Mosasaurus was a deep-sea terror, reminiscent of sea
monsters in myths and legends.
While the Cretaceous period was dominated by a frightening cast of reptilian giants,
the longest-lasting species were anything but giant or terrifying.
They weren’t club-swinging herbivores or toothy predators but a myriad of plants, insects,
and small mammals.
Ancient insect hives, created by Triassic wasps 207 million years ago, were discovered
in the petrified forests of Arizona.
From these ancient insects, the first bees evolved during the Cretaceous period, preceding
the evolution of flowering plants.
The oldest flowering plant is a distant relative of the black pepper plant, estimated to be
at least 122 million years old.
Nurtured by a radical growth of floral diversity, populations of pollinators, along with ants,
grasshoppers, aphids, and termites, skyrocketed during the Late Cretaceous.
Feeding on insects and flowers, rodents and marsupials also thrived during the last age
of the dinosaurs.
Hiding in burrows, nests, and dark corners of the forests, the ancestors of modern-day
mammals were ignored by the larger dinosaurs stomping over their heads.
In the Late Cretaceous, 100-ton reptiles shook the Earth, but at the same time, a diverse
tapestry of unsuspecting species was transforming the globe.
Of course, 65 million years ago, our global ecosystem changed forever.
At the end of the Cretaceous, a mass extinction, known as the Cretaceous-Tertiary or K-T Extinction
Event, wiped out nearly every non-avian dinosaur and three quarters of all life on Earth.
Most likely, an asteroid struck the Yucatan peninsula in modern-day Mexico.
Dust and debris launched into the atmosphere and blocked the sun’s rays from lighting
or warming the Earth’s surface, thereby limiting the growth of life-giving plants.
Toxic clouds of vaporized rock suffocated most dinosaur species.
The only survivors were plants, like ferns and magnolias, small creatures, like insects
and rodent-like animals, and the many species of fungi that grew on decaying organic matter.
These species flourished for the remainder of the Mesozoic Era and evolved into the millions
of plants and animals we know today.
While the dinosaurs disappeared 65 million years ago, these giant reptiles were legendary,
unforgettable creatures, unrivaled in power, size, and ferocity.
Today, their relatives and descendants, like birds, roam the Earth, but the Cretaceous
remains the one and only Age of Monsters.