Why did the huge animals like dinosaurs become extinct

By James "Zach" Zacharias, Senior Curator of Education and History What is an extinction event? Most people do not realize that paleontologists and scientists have created certain criteria for extinction events. These events are characterized by a sharp change in the abundance of multi-cellular organisms and a widespread decrease in the Earth’s biodiversity. Most of the diversity and biomass on Earth is microbial and difficult to measure so these events are limited to easily observable biologically complex components of the biosphere. Scientists have established three criteria for a major extinction event. The first is that the event must be worldwide. Animals must be affected over the entire globe not just regionally. Second, an extinction event must happen very quickly in a short geologic time scale. Finally, one-third of all existing species must disappear. What is remarkable is that after these catastrophic events new life, new species, and new ecosystems emerge to fill the void very quickly. There have been five major such extinction events referred to as the “Big Five.” The first extinction event goes back 444 million years ago to the Paleozoic era. The second was the Ordovician where 86% of all life on Earth was eliminated. This was followed by the Devonian extinction event 375 million years ago were 75% of life went extinct. The biggest extinction event was the devastating End-Permian extinction event 251 million years ago where 96% of all species disappeared. The ...

Author • Caitlin Syme PhD Candidate, Vertebrate Palaeontology, The University of Queensland Disclosure statement Caitlin Syme does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment. Partners It crash-landed near Mexico. It shook the ground. It made big waves in the sea. Any animals and plants that were nearby would have gotten squashed or washed away! The asteroid made lots of dust and dirt and rocks to fly up into the air. All that dust and dirt covered the planet and made the sky dark. There were many forest fires too. Before the asteroid hit Earth, there were lots of volcanoes erupting in what we now call India. They made smoke, and ash, and gases fill up the air. We are not sure if the asteroid then hitting Earth made more volcanoes erupt. Maybe it was just very bad timing. From cold to hot It was so dusty and dark that the warm sunshine couldn’t reach the ground. This made the Earth very cold. But after the dust settled and the sun came out, the Earth got very hot indeed. The sea creatures, plants, and land animals didn’t like that very much. The plants probably had a hard time growing. The plant-eating animals ran out of plants to eat, and then the animals that ate other animals also ran out of food. So it became very hard for dinosaurs to survive. But it’s still really hard to know for sure exactly why the dinosaur...

While there are several controversial explanations, the leading theory for the actual 'kill mechanism' is that a 10km-wide asteroid smashed into Earth, leaving a crater 180km across at Chicxulub in Mexico. A thermal pulse from heated debris spread across the globe, while the force of collision – equivalent to millions of atomic bombs – created shockwaves that triggered earthquakes, then tsunamis and wildfires. The impact launched a vast dust cloud into the atmosphere, which coincided with gas released from volcanic activity and blocked-out the sun for years. That led to a nuclear winter and limited photosynthesis, which ultimately powers most life, and that in turn caused a collapse of our planet's ecosystems. The Cretaceous–Paleogene extinction event took place approx. 66 millions years ago. © Getty Did all dinosaurs go extinct? Not quite – because birds are living dinosaurs! To distinguish birds – the class Aves – from prehistoric reptiles, extinct groups are known as 'non-avian dinosaurs'. They were the dominant terrestrial vertebrates of the Mesozoic era (252-66 MYA) throughout the Triassic, Jurassic and Cretaceous periods. Because the fifth extinction occurred at the boundary between the Cretaceous (K) and subsequent Palaeogene (Pg) period, it's also called the end-Cretaceous or K-Pg event. Other reptiles commonly mistaken for dinosaurs went extinct during the event, including the winged pterosaurs and aquatic plesiosaurs and mosasaurs. What is a dinosaur? The word 'd...

Key Takeaways • Major extinction events from Earth's ancient past are linked by the same mystery: Why did certain organisms die off while others survived? • Two recent studies aimed to answer that question through different techniques, including isotopic analysis and machine learning. • The research revealed several potential explanations for why certain animals survived extinction events, including seasonal factors and the levels of genetic variation within species. About 65 million years ago, a massive asteroid slammed into Earth, darkening the sky and killing a large number of animals, including the dinosaurs. But for some reason, certain creatures survived, like mammals, crocodiles, birds, and turtles. Although shrouded in death, the catastrophe allowed the rise of mammals, resulting in a huge explosion of their diversity and number. Similarly, 250 million years ago, the world saw the worst mass extinction event in history: the End-Permian Extinction. Also known as the Great Dying, the event was caused by a series of volcanic eruptions that killed off three-fourths of the animals on land, and even more in the oceans. But again, some animals survived. These two events are linked by a mystery: In mass extinctions, why do some animals perish while others survive? Recently, two separate teams looked into these two extinction events to understand what allows a species to survive when the world is dying around them. The end of the dinosaurs To understand the extinction event...

A misconception commonly portrayed in popular books and media is that all the dinosaurs died out at the same time—and apparently quite suddenly—at the end of the Faunal changes During the 160 million years or so of the It is important to note that extinction is a normal, universal occurrence. Mass extinctions often come to mind when the term extinction is mentioned, but the normal background extinctions that occur throughout Because the Why Do Animals Have Tails? The It was not only the dinosaurs that disappeared 66 million years ago at the Cretaceous–Tertiary, or K–T, boundary (also referred to as the Cretaceous–Paleogene, or K–Pg, boundary). Many other organisms became extinct or were greatly reduced in abundance and Whatever factors caused it, there was undeniably a major, worldwide biotic change near the end of the Cretaceous. But the extermination of the dinosaurs is the best-known change by far, and it has been a puzzle to paleontologists, geologists, and biologists for two centuries. Many One important question is whether the extinctions were

An artist's impression of the dinosaur-killing asteroid impact that created Chicxulub crater. (Image credit: NASA) Other research, coauthored by Stanford geophysicist Sonia Tikoo-Schantz, suggests the crater from the giant asteroid impact linked to the dinosaur extinction some 66 million years ago may have “The fossil record is our only archive of past extinction events,” Stanford paleobiologist Jonathan Payne Many scientists say a sixth mass extinction is Even When species vanish, This collection covers how scientists are deciphering the mysteries and mechanisms of extinction and survival in Earth’s deep past and painting an increasingly detailed picture of life now at the brink. Scroll down for extinction research news and insights spanning Last updated: April 29, 2021 Media Mention | November 2017 Humans didn’t outsmart the Neanderthals. We just outlasted them. “It’s not that Neanderthals were these brutish, wide-shouldered, sort of advanced apes that roamed the land until we came over and beat them,” Stanford evolutionary biologist Oren Kolodny tells The Washington Post. “It’s more that it was a companion hominin species that was Media Mention | September 2019 Earth has survived extinctions before, it’s humans who are fragile A new scientific study co-led by Malcom Hodgskiss, a PhD student in Geological Sciences at Stanford, and "actual events reminded us this week that the Earth endures. It’s us, all the living things that inhabit it for a while, who are fragile; and ...

Many giant animals roamed the Earth after non-avian dinosaurs went extinct. Illustration by Emily Lankiewicz / Dmitry Bogdanov via Wikipedia under CC BY-SA 3.0 / Dmitry Bogdanov via Wikipedia under CC BY-SA 3.0 / Pagodroma721 via Wikipedia under CC BY-SA 4.0 / Sergiodlarosa via Wikipedia under CC BY-SA 4.0 / public domain Dinosaurs have always seemed larger than life. They lived during a time when almost everything seemed bigger—titanic herbivores stretching more than 80 feet long were not uncommon, and nine-ton carnivores had to feast on hundreds of pounds of flesh each day to survive. This popular view of the Age of Dinosaurs overlooks the innumerable small species that lived alongside Stegosaurus and Triceratops, just as we’re surrounded by insects, birds, rodents and other small animals today. It also falsely frames the end of this era as an end to the heyday of gigantism—but that’s only an illusion. Life didn’t shrink after the end of the Cretaceous. Long past the Age of Dinosaurs, Earth saw the evolution of impressive birds, snakes, crocodiles, rhinos and more, including the largest animals of all time. While the broader story of life on Earth may best be told through the diminutive and meek creatures that are often overlooked, here are ten animals that underscore the fact that remarkable body size was not just the domain of the dinosaurs. Barylambda A restoration of Barylambda Barylambda, an herbivorous beast that lived in western North America between 50 million an...

A misconception commonly portrayed in popular books and media is that all the dinosaurs died out at the same time—and apparently quite suddenly—at the end of the Faunal changes During the 160 million years or so of the It is important to note that extinction is a normal, universal occurrence. Mass extinctions often come to mind when the term extinction is mentioned, but the normal background extinctions that occur throughout Because the How Do We Know That Dinosaurs May Have Had Feathers? The It was not only the dinosaurs that disappeared 66 million years ago at the Cretaceous–Tertiary, or K–T, boundary (also referred to as the Cretaceous–Paleogene, or K–Pg, boundary). Many other organisms became extinct or were greatly reduced in abundance and Whatever factors caused it, there was undeniably a major, worldwide biotic change near the end of the Cretaceous. But the extermination of the dinosaurs is the best-known change by far, and it has been a puzzle to paleontologists, geologists, and biologists for two centuries. Many One important question is whether the extinctions were

An artist's impression of the dinosaur-killing asteroid impact that created Chicxulub crater. (Image credit: NASA) Other research, coauthored by Stanford geophysicist Sonia Tikoo-Schantz, suggests the crater from the giant asteroid impact linked to the dinosaur extinction some 66 million years ago may have “The fossil record is our only archive of past extinction events,” Stanford paleobiologist Jonathan Payne Many scientists say a sixth mass extinction is Even When species vanish, This collection covers how scientists are deciphering the mysteries and mechanisms of extinction and survival in Earth’s deep past and painting an increasingly detailed picture of life now at the brink. Scroll down for extinction research news and insights spanning Last updated: April 29, 2021 Media Mention | November 2017 Humans didn’t outsmart the Neanderthals. We just outlasted them. “It’s not that Neanderthals were these brutish, wide-shouldered, sort of advanced apes that roamed the land until we came over and beat them,” Stanford evolutionary biologist Oren Kolodny tells The Washington Post. “It’s more that it was a companion hominin species that was Media Mention | September 2019 Earth has survived extinctions before, it’s humans who are fragile A new scientific study co-led by Malcom Hodgskiss, a PhD student in Geological Sciences at Stanford, and "actual events reminded us this week that the Earth endures. It’s us, all the living things that inhabit it for a while, who are fragile; and ...

Author • Caitlin Syme PhD Candidate, Vertebrate Palaeontology, The University of Queensland Disclosure statement Caitlin Syme does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment. Partners The Conversation UK receives funding from these organisations View the full list It crash-landed near Mexico. It shook the ground. It made big waves in the sea. Any animals and plants that were nearby would have gotten squashed or washed away! The asteroid made lots of dust and dirt and rocks to fly up into the air. All that dust and dirt covered the planet and made the sky dark. There were many forest fires too. Before the asteroid hit Earth, there were lots of volcanoes erupting in what we now call India. They made smoke, and ash, and gases fill up the air. We are not sure if the asteroid then hitting Earth made more volcanoes erupt. Maybe it was just very bad timing. From cold to hot It was so dusty and dark that the warm sunshine couldn’t reach the ground. This made the Earth very cold. But after the dust settled and the sun came out, the Earth got very hot indeed. The sea creatures, plants, and land animals didn’t like that very much. The plants probably had a hard time growing. The plant-eating animals ran out of plants to eat, and then the animals that ate other animals also ran out of food. So it became very hard for dinosaurs...