252 million years ago, ancient life on Earth suffered a serious blow
from a deadly combination of heat and low oxygen. 95% of all marine species perished, and
two-thirds of terrestrial species vanished. It was a cataclysm so severe that it looked
like the end of all life on planet Earth. But as the saying goes, life finds a way, and the most well-known prehistoric creatures
would rise on Earth - The Dinosaurs. If you love dinosaurs, then get
ready to see your favorites, how they evolved, and how they would
rule the Earth for millions of years. [LOGO] The extinction event of the Permian-Triassic
era 252 million years ago marked the beginning of the Mesozoic Era of the Triassic,
Jurassic, and Cretaceous period, which lasted 186 million years. The Great
Dying, which lasted 200,000 years, marked the beginning of the Mesozoic Era which included
the Triassic, Jurassic, and Cretaceous periods. During the Triassic era, there was one vast
supercontinent called Pangaea, which was mostly vast deserts with a hot and dry climate
surrounded by a huge ocean called Panthalassa. Dinosaurs would first begin to evolve
during the mid to late Triassic period. When we talk about dinosaurs, we immediately
imagine towering and thundering animals, like Tyrannosaurus rex. But, new research shows
that the dinosaurs, and their pterosaur relatives, evolved from extremely small ancestors. Proof of
this theory was discovered in Madagascar when a newly discovered reptile species was found.
Named Kongonaphon kely or ‘tiny bug slayer’, it lived some 237 million years ago and stood
just 10 centimeters tall [4-inches]. It is one of the first small animals found from the
root of the Ornithodira family tree, and is an important discovery. The ‘miniaturization event’
in which it lived served as a survival strategy for early ornithodirans, and wear on its teeth
showed the tiny creature preyed on insects. This eliminated the need for them to compete with
their relatives for meat. Furthermore, research of this tiny dinosaur relative showed that feathers
and other fuzzy skin coverings, found on the later true dinosaurs and pterosaurs, likely
originated to protect the tiny dino ancestors from the extreme climate of the mid to late
Triassic period when the first dinosaurs evolved. The Triassic marked the rise of the reptiles,
mainly the archosaurs or ‘ruling lizards’, and therapsids or ‘mammal-like
reptiles’. For reasons unknown, the archosaurs had an evolutionary edge, muscling
out their mammal-like cousins and evolving by the mid to late Triassic into the first true
dinosaurs, such as Eoraptor and Herrerasaurus. Dinosaurs were divided into two main branches:
saurischian, which means ‘lizard-hipped', and ornithischian, or ‘bird-hipped’ dinosaurs.
Eoraptor was at the root of the Saurischian family tree. It was only 91 centimeters long [3-feet] and
weighed about 11 kilograms [25 lbs]. It had long legs that allowed it to run fast, and its front
paws had sharp claws that helped it to grab prey. Herrerasaurus was more advanced in evolution than
the Eoraptor because it had a joint in its lower jaw. It had a large skull, and its jaws were armed
with the sharp teeth of a carnivore. It averaged in length from 3 to 6 meters [10 to 20 feet] and
had five fingers on each paw with blunt claws. Staurikosaurus was another early true dinosaur
that was about 2 meters long [6.5 feet] with a large skull as long as its femur, and there were
13-14 sharp teeth in its upper and lower jaws. It has short front paws with five fingers.
It had long hind legs that allowed it to run fast. Staurikosaurus was a predator that weighed
about 30 kilograms [66-lbs] And although this dinosaur was kind of small, it probably
had no trouble dealing with larger prey. Eoraptor, Herrerasaurus, and Staurikosaurus
are prime examples of the rapid evolution of predatory dinosaurs 225 million years ago. But at the same time, the first plant eating
[herbivorous] dinosaurs appeared in the fossil record. Pisanosaurus was a 1 meter
[3.3 feet] dinosaur that weighed 2 to 9 kilograms [5-20 lbs] and had closely spaced
teeth forming a continuous edge for grinding plant matter. By the late Triassic period,
there were at least 15 different dinosaurs. During the Jurassic period, Earth’s climate
changed from hot and dry to a much more humid and subtropical climate. Forests of ferns, cycads,
and conifers began to cover the planet, and the air was warm, moist, with tropical breezes. During
the beginning of this period, the breakup of the supercontinent Pangaea continued and accelerated.
Laurasia, the northern half of the continent, broke up into North America and Eurasia. The
southern half called Gondwana began to break up during the mid-Jurassic. The eastern parts;
Antarctica, Madagascar, India, and Australia, split off from the western half of Africa and
South America. New oceans flooded the spaces in between. Huge mountains rose on the seafloor
and pushed sea levels higher onto the continents. It was all this water that created the humid and
subtropical climate. Deserts began to turn green, palm tree-like cycads, and conifer trees
such as the araucaria and pine were abundant. The oceans became full of diverse and abundant
life. And at the top of the ocean food chain were the marine reptiles; the Plesiosaurs with
their long necks and paddle finned flippers. Among them were giant marine crocodiles, sharks,
and rays. Ichthyosaurs, squid-like cephalopods, coil-shelled ammonites, sponges, snails,
and mollusks were abundant in the ancient oceans. Coral reefs grew and expanded quickly
in the warm waters, and microscopic plankton increased rapidly to the point that they
may have turned parts of the ocean red. The earliest known bird, Archaeopteryx,
took to the skies in the late Jurassic, likely evolved from an early Coelurosaurian
dinosaur. Archaeopteryx had to compete for airspace with pterosaurs, flying reptiles
that had been buzzing the skies since the late Triassic. Meanwhile, insects such
as leafhoppers and beetles were abundant, and many of Earth's earliest mammals
scurried around the feet of dinosaurs. It was at this time that the dinosaurs
began making their mark in a huge way… literally. Small quadrupedal plant-eating
dinosaurs gradually evolved into multi-ton giants. The plant-eating sauropod named
Brachiosaurus was 16 meters tall [52 feet] and stretched out to around 26 meters [85 feet]
long, and could weigh as much as 25 tons! Another herbivorous sauropod giant named Diplodocus was 27
meters [90 feet] long and weighed between 30 to 50 tons. The sheer size of these dinosaur giants may
have stopped the attacks of a bulky meat-eating dinosaur that walked on two powerful legs who also
lived during this time; the ominous Allosaurus. This huge carnivore ranged in size from 7 to 12
meters long [25 - 40 feet], weighed nearly 2 tons, and had 16 sharp teeth in its upper and lower
jaw. And like many predatory dinosaurs of the Mesozoic Era, Allosaurus constantly grew, shed,
and replaced its three to four inch teeth. And this dinosaur was fast. Models suggest that
Allosaurus could run up to 34 kilometers per hour [21 mph]. Fossil evidence shows that Allosaurus
preyed on Stegosaurus, and the plant-eating dinosaur fought back, punching holes right through
Allosaurus’ bones with its spiky clubbed tail. It could be why Stegosaurus had a pretty long run and
survived all the way up to the late Cretaceous. But there were new predators that would come along
that were as equally terrifying as the Allosaurus. The North American Tyrannosaurus rex measured
could grow to 12.5 meters long [40 feet] and weigh up to 8 to 10 tons, although now some say
it might have weighed half of these estimates. But the T-rex wasn’t alone in the meat-eating
dinosaur category. In fact, it was either outclassed or equal to two other sharp toothed
monsters; the South American Giganotosaurus which had the same type of build and weighed 9 tons, and
the 10 ton northern African Spinosaurus. Still, the T-rex was a mean and nasty predator, if not
downright unhygienic. Experts believe that shards of rotten, bacteria-laden meat was constantly
lodged in its closely packed teeth, which gave the animal a ‘septic bite’ that would eventually be
fatal to its wounded prey. Of course, this process would have taken at least several days or weeks,
and another T-Rex would probably reap the rewards. Scientists examining a T-rex skull determined
it had the bite force of between 1,500 to 5,000 pounds per square inch, and could take bites of
flesh in the 225 kilogram [500 pounds] range. But Tyrannosaurus rex, like Allosaurus,
had problems with prey itself. It lived in the same region and time period
as some armored plant-eating dinosaurs. One of the most iconic dinosaurs
next to T-Rex has to be Triceratops, which means ‘three-horned face’. All Triceratops
had three-horned skulls. Two massive horns were above the eye sockets and one smaller horn was
over the nose. Weighing around 6.5 to 13 tons, the biggest Triceratops was 9 meters
[30 feet] long from nose to tail. The tips of their shoulders were 3
meters [9.8 feet] off the ground. Triceratops had teeth arranged in ‘dental
batteries’, and each individual tooth was stacked in a vertical column of three to five teeth. These
formed rows with 36 to 40 tooth-loaded columns. This means that a single Triceratops could have
800 teeth at its disposal. It had a narrow beak, and powerful jaws that allowed it to
grind down tough vegetation and trees. It is one of the last non-avian dinosaurs
to evolve at the end of the Cretaceous. Ankylosaurus is another of the most famous armored
dinosaurs. It was the largest ankylosaurid, and the last of its kind – it is thought to have
lived right up to the end of the Cretaceous Period The body of Ankylosaurus was covered in
bony plates. It had a beak and teeth, and four horns that projected backwards from its
head. Its tail ended in a club, which provided protection from predators. This would have
been useful, since Ankylosaurus lived alongside Tyrannosaurus rex and other meat eating predators.
At some point during the middle of the Creataceous period, dinosaurs from the Ornithopod
family evolved into the popular Hadrosaur or duck-billed dinosaurs. They were large,
oddly shaped, low-slung vegetation eaters with tough beaks on their snouts, which
were used for shredding vegetation. These dinosaurs are believed to have lived in
herds and were capable of walking on two legs. Sauropods became even bigger by the Late
Cretaceous period. You may have thought that Brachiosaurus and Diplodocus were big. But by
the time the late Creatacous period rolled around, there was another dinosaur that existed, which
could possibly be the biggest land animal that has ever walked the Earth; Argentinosaurus.
This behemoth could be 30 to 40 meters in length [100 to 130 feet] and weigh between 50 and
100 tons. It was a member of the Titanosauria, the dominant group during the Creataceous period and
was a herbivore like its earlier sauropod cousins. There was also a strange new breed of dinosaur
that lived 20 million years before they all went extinct. They are called Pachycephalosaurus,
or Bone-Headed Dinosaurs, and have a bizarre looking skull with horns on the snout and around
the base of the skull. These could have been used to fight off the last of the big predators, or
even to show dominance over their own species. Of course, there are more than 700 different
dinosaurs that have been found so far, but not enough time to
cover them all in one video. There are some dinosaurs that lived in the
colder regions when they were further south and within the Antarctic Circle during the
Cretaceous. During this time there could have been some snow and ice and temperatures as low as -10c
[14°F] during the three month long dark winters. There were a variety of different dinosaurs
living in this polar zone. In 2014, a skull section and upper and lower jaw bones were
found of a miniature T-rex called Nanuqsaurus hoglundi. It is believed that many dinosaurs
had feathers to protect them from the elements, and this tiny T-rex cousin, which was about
6 meters long [20 feet] It is now believed that all species of Tyrannosaurus rex had
feathers to protect them from the elements, and Nanuqsaurus was no different. Other dinosaurs
like the horned and duck-billed dinosaurs, along with other small feathery
predators, parrot-like oviraptors, and a small herbivore named Leaellynasaura
lived in the polar region as well. But their time would soon come to an end… Everyone talks about how dramatically the
dinosaurs went extinct, but judging by the whopping 165 million years they survived, they
just might be the most successful vertebrate animals to ever exist on planet Earth. In fact,
some dinosaur relatives are still around on the planet today. Modern-day birds are, in fact,
descendants of feathered dinosaurs. And you might be surprised to learn that crocodiles
are the closest living relatives to birds, as they shared a common ancestor. The two groups
are the only known survivors of the Archosaurs. We all know what happened to the dinosaurs,
and if you missed our video on The Day The Dinosaurs Went Extinct, we’ll put
a link in the description for you. Please let us know in the comments what
you thought about the video, and tell us what you’d like to see next. Stay tuned for
more cool videos, and thanks for watching!
