Getty Images
Dinosaurs became extinct at the K-T boundary — the dividing line between the Cretaceous and Tertiary periods. The end of the Cretaceous marks the end of the dinosaurs, while the beginning of the Tertiary marks the rise of mammal life on Earth.
Dinosaurs aren't the only things that died out at the K-T boundary. About 50 percent of the species on Earth became extinct, including many other large reptiles, like pterosaurs and plesiosaurus, as well as lots of plant species and marine animals.
Advertisement
Other life forms, such as ferns, flourished by taking advantage of the sudden abundance of natural resources.
Scientists have proposed several theories to explain dinosaurs' extinction. There's not much physical evidence for some of them.
For example, one theory is that dinosaurs were allergic to flower pollen — flowering plants and bees evolved together during the late Cretaceous period. However, flowering plants existed for millions of years before the dinosaurs died out.
Another theory is that mammals, which began to proliferate at the end of the Cretaceous period, ate dinosaurs' eggs. But considering the number of whole fossil egg specimens, this seems unlikely.
Then there's the Alvarez hypothesis. In 1980, Luis and Walter Alvarez proposed that comets or asteroids had hit the Earth, causing massive shock waves, debris clouds and other devastation. There's a lot of evidence to support this hypothesis.
One is a layer of a mineral called iridium, which exists in many locations on the planet at depths equated with the end of the Cretaceous period. Iridium is more common in space debris than on Earth, so the huge impact of an object from space could have caused this effect.
"" Satellite image of the Chicxulub impact site.NASA
Perhaps the biggest support for this hypothesis is the Chicxulub crater. This is a massive asteroid crater off the coast of the Yucatán Peninsula. Based on measurements of sediments and analysis of the surrounding rock, scientists estimate that the asteroid that caused the crater was between 8.7 miles (14 kilometers) in diameter.
This would have caused exactly the kind of devastation described in the Alvarez hypothesis. A team of three researchers even believes to have discovered the identity of the asteroid itself. Using mathematical models, the group narrowed the field to the Baptistina cluster, a group of asteroids created by a large impact beyond the orbit of Mars [source: Sky & Telescope].
According to the Alvarez theory, the extinction of the dinosaurs was catastrophic and extrinsic, meaning it came from outside of the Earth. However, other theories suggest that the mass extinction was intrinsic and gradual.
One idea is that volcanoes in what is now India experienced massive eruptions just before the end of the Cretaceous. These eruptions filled the air with carbon dioxide and sulfur, changing the climate and damaging plant and animal life.
The changing face of the planet may have also played a role. As the continents moved, ocean currents would have changed the weather patterns in different parts of the world. Various forms of life may have been unable to survive these changes.
The best explanation for what happened to the dinosaurs may be a combination of intrinsic and extrinsic theories — an asteroid impact combined with geological changes and volcanic eruptions. There are also indications that dinosaurs were becoming less diverse before the end of the Cretaceous period.
But regardless of the cause, not everything on Earth died at the K-T boundary. Frogs, mollusks and crocodilians survived, and so did birds.
Advertisement
There are many stories about dinosaurs that we have heard. They existed long before our time, and there are no dinosaurs left today. There are a lot of interesting and fascinating facts about dinosaurs that have been presented in movies and articles about them. We can better understand the history of our planet by studying the stories of dinosaurs.
Discover our collection of dinosaur lamps if you are passionate about dinosaurs and would like to buy a gift for yourself or a child.
Life on Earth emerged 3770 million years ago, according to the latest data, and evolution has left countless living organisms behind. Dinosaurs, for example, have evolved into new species while others have disappeared.
During the Mesozoic Era (251 MYA. to 65 MYA.) there were three major periods: the Triassic, Jurassic, and Cretaceous. During these periods, dinosaurs were the dominant terrestrial vertebrates on our planet. This was a group of extremely diverse reptiles that are thought to have virtually disappeared during the Cretaceous-Tertiary mass extinction that ended the Mesozoic era.
There are dinosaurs still alive today: science explains
Are dinosaurs still alive today? Yes, there are still dinosaurs living among us today, but they are different from the ones that existed millions of years ago.
Reptiles of the modern age are not dinosaurs
Popular culture has taken it upon itself to recreate dinosaurs as reptile-like animals, especially because of the scales. There is, however, a difference between the two families.
There was a time when reptiles and dinosaurs coexisted, but that does not mean they were the same species. Since they differ in physical and genetic characteristics, they cannot be considered relatives.
Today’s reptiles are the result of a long evolutionary process that allowed them to adapt and survive.
You might believe that today’s reptiles are descendants of dinosaurs because of the image of dinosaurs, but this is not true.
Which dinosaurs are still alive today?
Would you like to know if there is still a Dinosaur alive today? There are descendants of these animals today, but they are not scaly like reptiles. Birds are their closest relatives. A Tyrannosaurus Rex for example is closer to a chicken or turkey than a crocodile or turtle.
According to scientific findings, birds and dinosaurs share a common bond that survived extinction, evolved, and produced offspring today.
It is not just that birds evolved from dinosaurs, but that all birds are dinosaurs, according to paleontologist Aki Watanabe of the American Museum of Natural History.
The lineage could be compared to that of humans and primates who share a common ancestor, and in a way, humans are primates.
Dinosaurs also had feathers
Dinosaurs like the
big Stegosaurus
for example didn’t have much scientific evidence when they first appeared in popular culture. Furthermore, dinosaurs in movies had to look scary, regardless of their scientific inaccuracies.
Some species, including Tyrannosaurus rex, have feathers similar to modern birds, called proto-feathers.
Since dinosaurs couldn’t fly, scientists believe feathers appeared on their bodies to regulate temperature or display themselves for mate or defense purposes.
Dinosaurs and birds have other common characteristics
Dinosaurs and birds also share other characteristics, such as: a fast metabolism, hollow bones that make them lighter, and furculas, which are bones exclusive to birds and theropods. You’ve probably seen these bones in chickens. They’re called wishbones.
In addition, both species have relatively large brains for their body sizes.
Contrary to what movies have depicted, dinosaurs probably looked more like birds than reptiles.
Every bird, no matter how small or common, is part of an evolutionary lineage that has survived for millions of years.
Modern day animals that lived with the dinosaurs
Millions of years ago, dinosaurs ruled the planet, but there were also other animals that inhabited the planet, some of which have evolved and survived millennia of change.
Sharks
Throughout history, sharks have survived by doing what they do best: hunting. They have managed to remain exactly the same as they were millions of years ago because their bodies haven’t evolved much. Even though their size has decreased considerably, their ferocity has not.
Echidnas
A mammal that emerged in the Cenozoic era and has survived thanks to its defenses and adaptations to the terrain, it is one of the first mammals on Earth.
It is a species of anteater with a very long snout that feeds mainly on insects and is protected from predators by dozens of spikes all over its body.
Caimans
The alligator, along with the crocodile, was among the animals that lived with the dinosaurs. They had to change just a little because they could measure twice as much as today, but their structure and feeding habits were the same as today, and they were a very common species at the time.
In addition, it was the most feared due to its ability to move on land as well as in water.
Bees
For millions of years, bees have pollinated flowers around the world. Taking care of them is essential for our planet because some regions of the planet are disappearing, and this could be a major issue.
crabs
The fact that crabs lived alongside dinosaurs might not seem so strange if we discuss it. As we can see from their armored appearance, they have a very similar anatomy to the animals of their time.
The size has been reduced, as in many species, because of the size of the prey they eat, but they still have hard bodies to protect themselves.
65 million years is a long time for giant dinosaurs to live and die without leaving any fossils. The dinosaurs did not all go extinct, scientifically speaking. Many of us see dinosaurs every day, and some even have them in their homes. Modern birds are descendants of dinosaurs.