Episode KT. Extinction of dinosaurs and 85% of species following a meteorite impact at Chicxulub, Yucatan (early Cenozoic)

The land corridor connecting Europe and Africa is submerging. Animal migrations toward Europe continue from the De Geer Corridor, which connects it to North America. Various species of crocodiles and dinosaurs arrive from there, but most of them cannot acclimate to the polar conditions of the De Geer Corridor. For example, Tyrannosaurus rex and Triceratops (at different times) never crossed the corridor.

First plants of the Platanaceae family (plane trees)

Third peak of dinosaur diversification

Tyrannosaurus rex, one of the most evolved dinosaurs

Hadrosaurs and Triceratops

South America. The Cronopio dentiacutus, a type of saber-toothed squirrel, is spreading. This is the oldest evidence of mammals on the South American continent.

The toad species Alytidae appears in Europe, which will dominate the continent for the next 100 million years, overcoming every catastrophe.

The gene for epsilon and gamma globin, two of the eight human globins, is formed.

The southern part of Africa (the last 1600 km) is starting to rise; in 100 million years it will rise by 1.5 km, without any apparent tectonic activity.

The Indonesian plate is starting to sink, dragging Northern Australia with it. In 100 million years, it will sink 200 meters.

Insects are among the dominant species on the planet

Approximate estimated time of appearance of Saturn’s rings.

Titanosaurs (family Saurischia)

The first flowers (angiosperms) appear, which exploit another successful living species: insects.

First species of angiosperm plants, that is, with flowers and seeds all in one

Cretaceous (Mesozoic period, Secondary era)

Archaeopteryx, the first birds

The first snakes appear

The first bees evolve. But honeybees, or Apis, do not appear for another 125 million years.

Second peak of dinosaur diversification

The first species of ants: similar to today’s, they spread along with flowering plants. They quickly multiplied. Today, it is estimated that there are about 10 trillion ants on the planet, and they weigh slightly more than the combined weight of all human beings.

Toarcian turnover extinction due to ocean acidification. This is not one of the six major mass extinctions, but it is still a significant event.

Diplodocus (family Saurischia)

First species of insects with wings

Jurassic (Mesozoic period, Secondary era): the first forms of birds appear

First peak of dinosaur diversification

The Fourth Mass Extinction occurred at the end of the Triassic, 200 million years ago, with the extinction of 80% of species. The Third Mass Extinction occurred at the end of the Permian, 251 million years ago, when 96% of species became extinct. The Second Extinction occurred during the Late Devonian, 375 million years ago, when 75% of living species became extinct. The First Extinction occurred 444 million years ago, with a mass extinction (80-90%) of living species, at the end of the Ordovician. The Fifth Extinction occurred at the KT Boundary, or end of the Cretaceous, 66 million years ago, with the extinction of 76% of species, including ammonites and non-avian dinosaurs. The Sixth Extinction is the current one, caused by Homo sapiens since prehistoric times.

Crocodiles are among the dominant species in swamps

Volcanoes rise in the mid-Atlantic

Sharks are among the dominant species in the seas and oceans

First Pterosaurs (flying reptiles); the oldest finds were found in Cene – Val Seriana, near Bergamo

Dinosaurs rule the planet

The Sun begins its current, nearly circular, orbit around the Milky Way

First Therapsids, reptile ancestors of mammals

80 species of ichthyosaurs thrive in the oceans

First woody plants: first trees (Cycadaceae family)

Plesiosaurs rule the seas

Large (95%) mass extinction of living species (Permian/Triassic, early Mesozoic)

Meteorite falls in Bedout crater in northwestern Australia, 190km in diameter

Triassic (Mesozoic period, Secondary era): reptiles dominate the planet and the first mammals appear

massive release of CO2, likely due to extreme volcanism in the Siberian Traps, raised the planet’s temperature by an average of 10°C and acidified the oceans. In just 100,000 to 200,000 years, 90% of species were completely wiped out. The warming oceans favored bacteria that produced hydrogen sulfite, which is poisonous to most other life forms. The ocean must have appeared purple, with sulfurous bubbles releasing poisonous gas under a greenish sky. An apocalyptic scenario. What followed has long puzzled scientists. The planet became lethal and remained so for 5 million years. Scientists at the University of Leeds in England and the China University of Geosciences have speculated that the cause may lie in a climatic tipping point: the collapse of tropical forests. The Permian extinction event is unique “because it is the only one in which all plants died.”

violent volcanic eruption: the Siberian Traps gave rise to what is now Siberia. Coal deposits ignite. The eruption and devastation continue for 900,000 years. The impact on life is tremendous: it will be another 25 million years before coal and diversification are found again. In total, 3 million cubic kilometers of lava are erupted. 96% of marine life and 70% of land life become extinct, including all 30,000 species of trilobites and 97% of ammonites.

Glaciation

Last common ancestor between humans and birds

Odonata, which includes dragonflies, were the first order of insects to acquire wings. It was a successful form. Dragonflies still have virtually the same shape as they did back then. In the Carboniferous, they were just larger: up to 75 cm in wingspan (Meganeura monyi).

First reptiles

First seeded plants (Gymnosperms)

Ammonites thrive in the seas

Carboniferous (Paleozoic period, Primary era)

First terrestrial amphibians

The Second Extinction occurred during the Late Devonian, 375 million years ago, when 75% of living species became extinct. The First Extinction occurred 444 million years ago, a mass extinction (80-90%) of living species, at the end of the Ordovician. The Third Extinction occurred at the end of the Permian, 251 million years ago, when 96% of species became extinct. The Fourth Extinction occurred at the end of the Triassic, 200 million years ago, with the extinction of 80% of species. The Fifth Extinction occurred at the KT Boundary, or end of the Cretaceous, 66 million years ago, with the extinction of 76% of species, including ammonites and non-avian dinosaurs. The Sixth Extinction is the current one, caused by Homo sapiens since prehistoric times.

In the Devonian and Carboniferous periods, the oxygen level in the atmosphere was as high as 35% (today it is 20%), allowing animals to grow to large sizes in a short time.

Devonian (Paleozoic period, Primary era)

Glaciation

Silurian (Paleozoic period, Primary era)

First species of spiders

First insect species (without wings: millipedes and spiders are among the first)

Mass extinction (80-90%) of living species. This is the End-Ordovician Extinction, the First Mass Extinction. The Second Extinction is the Late Devonian, 375 million years ago, when 75% of living species became extinct. The Third is the End-Permian, 251 million years ago, when 96% of species became extinct; the Fourth is the End-Triassic, 200 million years ago, with the extinction of 80% of species. The Fifth is the KT Boundary, or End-Cretaceous, 66 million years ago, with the extinction of 76% of species, including ammonites and non-avian dinosaurs. The Sixth is the current extinction, caused by Homo sapiens since prehistoric times.

The massive emission of oxygen by plants dramatically increases the element’s presence in Earth’s atmosphere. The number of minerals and compounds on Earth expands from 250 to 1,500 due to the turbulence of plate tectonics, and then to about 4,500 thanks to oxygen compounds (such as the salts and acids it produces). And if we count the compounds directly generated by life, this diversity expands to over 5,000. The advent of human technology will further expand this number.

First plants on land

The jawless fish Eriptychius americanus already has an articulated skull. It was discovered in Colorado’s Harding Sandstone Formation in 2023 AD and is the oldest 3D fossil evidence of the cranial anatomy of a primitive vertebrate, according to a study in the journal Nature. The skull arrangement of E. americanus was unlike anything seen in living vertebrates or the fish’s extinct relatives, with unfused cartilage sections—some symmetrical, some not—at the front of the head and surrounding the mouth, olfactory organs, and eyes. “This fossil fills a gap in our knowledge of the evolution of the vertebrate head,” said paleobiologist Lauren Sallan, assistant professor in the macroevolution unit at the Okinawa Institute of Science and Technology Graduate University in Japan. “This gap was partly due to the fact that the Ordovician ancestors of jawed fishes were relatively rare and mostly confined to very shallow marine waters. After death, the remains of these early fishes, including Eryptychius, were usually destroyed by waves, and we find mostly pieces of them,” said Sallan, who researches the origins of marine biodiversity and was not involved in the study.

double asteroid strikes the paleocontinent Baltic (which at the time was near South Africa). It hits what is now Sweden, above Stockholm. At the time, the area is 500 meters below sea level. The impact creates a crater 7.5 kilometers across and another 700 meters in diameter. The waters open up in a gigantic tsunami that leaves the center of the main crater dry for over 100 seconds. The discovery was made in 2015 by Swedish scientist Erik Sturkell.

Earth may have had rings for a period of 20-40 million years, approximately 460-480 million years ago. This would at least explain a number of factors, including an increase in meteorite impacts, all in an equatorial belt, and an episode of drastic temperature drops, or rather, an extreme cooling of the climate.

Ordovician (Paleozoic period, Primary era): plants begin to invade the land

First corals: they are among the oldest life forms (or better yet, ecosystems) on Earth.