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This is good evidence for the continental drift because if all of the continents are together the animals could travel anywhere but when the continents split some of the animals were stuck on continents that don't have the right resources for them. So they died off and then left fossils.

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The Mesozoic era was 65 million years ago. The Cretaceous period is a small time slot in the Mesozoic era that was 66 million years ago. 

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The Mesozoic era was 65 million years ago. The Cretaceous period is a small time slot in the Mesozoic era that was 66 million years ago. 

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(Image: © AMNH/J. Brougham)

The Cretaceous Period was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago.

In the early Cretaceous, the continents were in very different positions than they are today. Sections of the supercontinent Pangaea were drifting apart. The Tethys Ocean still separated the northern Laurasia continent from southern Gondwana. The North and South Atlantic were still closed, although the Central Atlantic had begun to open up in the late Jurassic Period. By the middle of the period, ocean levels were much higher; most of the landmass we are familiar with was underwater. By the end of the period, the continents were much closer to modern configuration. Africa and South America had assumed their distinctive shapes; but India had not yet collided with Asia and Australia was still part of Antarctica.

(Image credit: USGS)

Cretaceous Period plants

One of the hallmarks of the Cretaceous Period was the development and radiation of the flowering plants. The oldest angiosperm fossil that has been found to date is Archaefructus liaoningensis, found by Ge Sun and David Dilcher in China. It seems to have been most similar to the modern black pepper plant and is thought to be at least 122 million years old.

It used to be thought that the pollinating insects, such as bees and wasps, evolved at about the same time as the angiosperms. It was frequently cited as an example of co-evolution. New research, however, indicates that insect pollination was probably well established before the first flowers. While the oldest bee fossil was trapped in its amber prison only about 80 million years ago, evidence has been found that bee- or wasp-like insects built hive-like nests in what is now called the Petrified Forest in Arizona.

These nests, found by Stephen Hasiotis and his team from the University of Colorado, are at least 207 million years old. It is now thought that competition for insect attention probably facilitated the relatively rapid success and diversification of the flowering plants. As diverse flower forms lured insects to pollinate them, insects adapted to differing ways of gathering nectar and moving pollen thus setting up the intricate co-evolutionary systems we are familiar with today.

There is limited evidence that dinosaurs ate angiosperms. Two dinosaur coprolites (fossilized excrements) discovered in Utah contain fragments of angiosperm wood, according to an unpublished study presented at the 2015 Society of Vertebrate Paleontology annual meeting. This finding, as well as others, including an Early Cretaceous ankylosaur that had fossilized angiosperm fruit in its gut, suggests that some paleo-beasts ate flowering plants.

Moreover, the shape of some teeth from Cretaceous animals suggests that the herbivores grazed on leaves and twigs, said Betsy Kruk, a volunteer researcher at the Field Museum of Natural History in Chicago.

Cretaceous Period animals

During the Cretaceous Period, more ancient birds took flight, joining the pterosaurs in the air. The origin of flight is debated by many experts. In the "trees down" theory, it is thought that small reptiles may have evolved flight from gliding behaviors. In the "ground up" hypothesis flight may have evolved from the ability of small theropods to leap high to grasp prey. Feathers probably evolved from early body coverings whose primary function, at least at first, was thermoregulation.

(Image credit: Eduard Solà Vázquez)

At any rate it is clear that avians were highly successful and became widely diversified during the Cretaceous. Confuciusornis (125 million to 140 million years ago) was a crow-size bird with a modern beak, but enormous claws at the tips of the wings. Iberomesornis, a contemporary, only the size of a sparrow, was capable of flight and was probably an insectivore. [ Image Gallery: Avian Ancestors: Dinosaurs That Learned to Fly]

By the end of the Jurassic, some of the large sauropods, such as Apatosaurus and Diplodocus, went extinct. But other giant sauropods, including the titanosaurs, flourished, especially toward the end of the Cretaceous, Kruk said.

Large herds of herbivorous ornithischians also thrived during the Cretaceous, such as Iguanodon (a genus that includes duck-billed dinosaurs, also known as hadrosaurs), Ankylosaurus and the ceratopsians. Theropods, including Tyrannosaurus rex, continued as apex predators until the end of the Cretaceous.

K-Pg extinction event

About 65.5 million years ago, nearly all large vertebrates and many tropical invertebrates became extinct in what was clearly a geological, climatic and biological event with worldwide consequences. Geologists call it the K-Pg extinction event because it marks the boundary between the Cretaceous and Paleogene periods. The event was formally known as the Cretaceous-Tertiary (K-T) event, but the International Commission on Stratigraphy, which sets standards and boundaries for the geologic time scale, now discourages the use of the term Tertiary. The "K" is from the German word for Cretaceous, Kreide.

In 1979, a geologist who was studying rock layers between the Cretaceous and Paleogene periods spotted a thin layer of grey clay separating the two eras. Other scientists found this grey layer all over the world, and tests showed that it contained high concentrations of iridium, an element that is rare on Earth, but common in most meteorites, Kruk said in a class she co-taught on Coursera.org.

Also within this layer are indications of "shocked quartz" and tiny glass-like globes called tektites that form when rock is suddenly vaporized then immediately cooled, as happens when an extraterrestrial object strikes the Earth with great force.

The Chicxulub (CHEEK-sheh-loob) crater in the Yucatan dates precisely to this time. The crater site is more than 110 miles (180 kilometers) in diameter and chemical analysis shows that the sedimentary rock of the area was melted and mixed together by temperatures consistent with the blast impact of an asteroid about 6 miles (10 km) across striking the Earth at this point.

When the asteroid collided with Earth, its impact triggered shockwaves, massive tsunamis and sent a large cloud of hot rock and dust into the atmosphere, Kruk said. As the super-heated debris fell back to Earth, they started forest fires and increased temperatures.

"This rain of hot dust raised global temperatures for hours after the impact, and cooked alive animals that were too large to seek shelter," Kruk said in the class. "Small animals that could shelter underground, underwater, or perhaps in caves or large tree trunks, may have been able to survive this initial heat blast."

Tiny fragments likely stayed in the atmosphere, possibly blocking part of the sun's ray for months or years. With less sunlight, plants and the animals dependent on them would have died, Kruk said. Furthermore, the reduced sunlight would have lowered global temperatures, impairing large active animals with high-energy needs, she said.

"Smaller, omnivorous terrestrial animals, like mammals, lizards, turtles, or birds, may have been able to survive as scavengers feeding on the carcasses of dead dinosaurs, fungi, roots and decaying plant matter, while smaller animals with lower metabolisms were best able to wait the disaster out," Kruk said.

There is also evidence that a series of huge volcanic eruptions at the Deccan traps, located along the tectonic border between India and Asia, began just before the K-Pg event boundary. It is likely that these regional catastrophes combined to precipitate a mass extinction.

Cretaceous Period climate

The world was a warmer place during the Cretaceous period. The poles were cooler than the lower latitudes, but "overall things were warmer," Kruk told Live Science. Fossils of tropical plants and ferns support this idea, she said.

Animals lived all over, even in colder areas. For instance, Hadrosaurus fossils dating to the Late Cretaceous were uncovered in Alaska.

When the asteroid hit, the world likely experienced so-called "nuclear winter," when particles blocked many of the sun's rays from hitting Earth.
Additional resources Additional reporting by Staff Writer Laura Geggel. Follow her on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+.

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Cretaceous Period: Animals, Plants & Extinction Event

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(Image: © AMNH/J. Brougham) The Cretaceous Period was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago.

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Why is this good evidence for a continental drift?

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Why is this good evidence for a continental drift?

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This is good evidence because they calculated all the land erosion and made a model of what the continents look like before and they connected them and made the one continent

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Alfred Wegner , Found the Seirra Nevadas and Andes mountains, by the theories of the earth being a molten ball of lava, with the plates moving and folding on each other, were a cooling and heating process with the earths crust. He also hypothesised on India moving up north into Asia, forming the Himalayas.

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Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific. The fit is even more striking when the submerged continental shelves are compared rather than the coastlines.

In 1912 Alfred Wegener (1880-1930) noticed the same thing and proposed that the continents were once compressed into a single protocontinent which he called Pangaea (meaning "all lands"), and over time they have drifted apart into their current distribution. He believed that Pangaea was intact until the late Carboniferous period, about 300 million years ago, when it began to break up and drift apart. However, Wegener's hypothesis lacked a geological mechanism to explain how the continents could drift across the earth's surface as he proposed.

Searching for evidence to further develop his theory of continental drift, Wegener came across a paleontological paper suggesting that a land bridge had once connected Africa with Brazil. This proposed land bridge was an attempt to explain the well known paleontological observation that the same fossilized plants and animals from the same time period were found in South America and Africa. The same was true for fossils found in Europe and North America, and Madagascar and India. Many of these organisms could not have traveled across the vast oceans that currently exist. Wegener's drift theory seemed more plausible than land bridges connecting all of the continents. But that in itself was not enough to support his idea. Another observation favoring continental drift was the presence of evidence for continental glaciation in the Pennsylvanian period. Striae left by the scraping of glaciers over the land surface indicated that Africa and South America had been close together at the time of this ancient ice age. The same scraping patterns can be found along the coasts of South America and South Africa.

Wegener's drift hypothesis also provided an alternate explanation for the formation of mountains (orogenesis). The theory being discussed during his time was the "Contraction theory" which suggested that the planet was once a molten ball and in the process of cooling the surface cracked and folded up on itself. The big problem with this idea was that all mountain ranges should be approximately the same age, and this was known not to be true. Wegener's explanation was that as the continents moved, the leading edge of the continent would encounter resistance and thus compress and fold upwards forming mountains near the leading edges of the drifting continents. The Sierra Nevada mountains on the Pacific coast of North America and the Andes on the coast of South America were cited. Wegener also suggested that India drifted northward into the asian continent thus forming the Himalayas.

Wegener eventually proposed a mechanism for continental drift that focused on his assertion that the rotation of the earth created a centrifugal force towards the equator. He believed that Pangaea originated near the south pole and that the centrifugal force of the planet caused the protocontinent to break apart and the resultant continents to drift towards the equator. He called this the "pole-fleeing force". This idea was quickly rejected by the scientific community primarily because
the actual forces generated by the rotation of the earth were calculated to be insufficient to move continents. Wegener also tried to explain the westward drift of the Americas by invoking the gravitational forces of the sun and the moon, this idea was also quickly rejected. Wegener's inability to provide an adequate explanation of the forces responsible for continental drift and the prevailing belief that the earth was solid and immovable resulted in the scientific dismissal of his theories.

In 1929, about the time Wegener's ideas began to be dismissed, Arthur Holmes elaborated on one of Wegener's many hypotheses; the idea that the mantle undergoes thermal convection. This idea is based on the fact that as a substance is heated its density decreases and rises to the surface until it is cooled and sinks again. This repeated heating and cooling results in a current which may be enough to cause continents to move. Arthur Holmes suggested that this thermal convection was like a conveyor belt and that the upwelling pressure could break apart a continent and then force the broken continent in opposite directions carried by the convection currents. This idea received very little attention at the time.

Not until the 1960's did Holmes' idea receive any attention. Greater understanding of the ocean floor and the discoveries of features like mid-oceanic ridges, geomagnetic anomalies parallel to the mid-oceanic ridges, and the association of island arcs and oceanic trenches occurring together and near the continental margins, suggested convection might indeed be at work. These discoveries and more led Harry Hess (1962) and R.Dietz (1961) to publish similar hypotheses based on mantle convection currents, now known as "sea floor spreading". This idea was basically the same as that proposed by Holmes over 30 years earlier, but now there was much more evidence to further develop and support the idea.

background music: from Mozart's requiem (K626)

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Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific.

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In Norway, there is an Arctic forest. There are fossilized tropical tree trunks. Researches think that they got there because millions of years ago when all of the continents were together, the continents split and the animals were on the continents that are no longer by the equator.

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Svalbard, Norway is known for it's splendid Arctic scenery, frigid weather and polar bears. But it wasn't always like this. In a study published recently in Geology, researchers announce the discovery of a fossilized tropical forest in Svalbard.

Chris Berry and other researchers from Cardiff University found tropical tree stumps--the remains of an ancient tropical forest--during field work in the frigid latitudes.

380 million years ago, the continents were in vastly different places. The solid part of the Earth that we live on is broken into sections called tectonic plates. Over time, these plates move, pushed around by the Earth's mobile interior. Svalbard was near the equator 380 million years ago. (Watch this great animation to see where your home was back then.)

The fossilized tree stumps found by the researchers were lycopsids, early trees that are related to club moss.

Scientists think that the explosive growth of these trees during this period helped to reduce the amount of carbon dioxide in the atmosphere.

"During the Devonian Period, it is widely believed that there was a huge drop in the level of carbon dioxide in the atmosphere, from 15 times the present amount to something approaching current levels," Berry said in a statement. "The evolution of tree-sized vegetation is the most likely cause of this dramatic drop in carbon dioxide because the plants were absorbing carbon dioxide through photosynthesis to build their tissues, and also through the process of forming soils."

Today, Svalbard's frigid temperatures have made it very attractive to biologists, who took advantage of the cool climate to refrigerate the Doomsday Seed Vault, a repository of seed samples from around the world. The first withdrawal from the vault was made this year in response to the ongoing conflict in Syria, and surely more will come soon as climate change continues to impact both wild plants and agricultural crops around the world.

"It's amazing that we've uncovered one of the very first forests in the very place that is now being used to preserve the Earth's plant diversity," Berry said.

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Fossilized Tropical Forests Found In Arctic

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Svalbard, Norway is known for it's splendid Arctic scenery, frigid weather and polar bears. But it wasn't always like this. In a study published recently in Geology, researchers announce the discovery of a fossilized tropical forest in Svalbard. Chris Berry and other researchers from Cardiff University found tropical tree stumps--the remains of an ancient tropical forest--during field work in the frigid latitudes.

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In the pangea North America, south america, and Africa were connected. What is now Europe was connected to North America.

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The Sierra Nevada mountains and Andes mountains were once together, but plate tectonics shifted them with the contraction theory 

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The Sierra Nevada mountains and Andes mountains were once together, but plate tectonics shifted them with the contraction theory 

# data[].attributes.attachment_link.readable_text
Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific. The fit is even more striking when the submerged continental shelves are compared rather than the coastlines.

In 1912 Alfred Wegener (1880-1930) noticed the same thing and proposed that the continents were once compressed into a single protocontinent which he called Pangaea (meaning "all lands"), and over time they have drifted apart into their current distribution. He believed that Pangaea was intact until the late Carboniferous period, about 300 million years ago, when it began to break up and drift apart. However, Wegener's hypothesis lacked a geological mechanism to explain how the continents could drift across the earth's surface as he proposed.

Searching for evidence to further develop his theory of continental drift, Wegener came across a paleontological paper suggesting that a land bridge had once connected Africa with Brazil. This proposed land bridge was an attempt to explain the well known paleontological observation that the same fossilized plants and animals from the same time period were found in South America and Africa. The same was true for fossils found in Europe and North America, and Madagascar and India. Many of these organisms could not have traveled across the vast oceans that currently exist. Wegener's drift theory seemed more plausible than land bridges connecting all of the continents. But that in itself was not enough to support his idea. Another observation favoring continental drift was the presence of evidence for continental glaciation in the Pennsylvanian period. Striae left by the scraping of glaciers over the land surface indicated that Africa and South America had been close together at the time of this ancient ice age. The same scraping patterns can be found along the coasts of South America and South Africa.

Wegener's drift hypothesis also provided an alternate explanation for the formation of mountains (orogenesis). The theory being discussed during his time was the "Contraction theory" which suggested that the planet was once a molten ball and in the process of cooling the surface cracked and folded up on itself. The big problem with this idea was that all mountain ranges should be approximately the same age, and this was known not to be true. Wegener's explanation was that as the continents moved, the leading edge of the continent would encounter resistance and thus compress and fold upwards forming mountains near the leading edges of the drifting continents. The Sierra Nevada mountains on the Pacific coast of North America and the Andes on the coast of South America were cited. Wegener also suggested that India drifted northward into the asian continent thus forming the Himalayas.

Wegener eventually proposed a mechanism for continental drift that focused on his assertion that the rotation of the earth created a centrifugal force towards the equator. He believed that Pangaea originated near the south pole and that the centrifugal force of the planet caused the protocontinent to break apart and the resultant continents to drift towards the equator. He called this the "pole-fleeing force". This idea was quickly rejected by the scientific community primarily because
the actual forces generated by the rotation of the earth were calculated to be insufficient to move continents. Wegener also tried to explain the westward drift of the Americas by invoking the gravitational forces of the sun and the moon, this idea was also quickly rejected. Wegener's inability to provide an adequate explanation of the forces responsible for continental drift and the prevailing belief that the earth was solid and immovable resulted in the scientific dismissal of his theories.

In 1929, about the time Wegener's ideas began to be dismissed, Arthur Holmes elaborated on one of Wegener's many hypotheses; the idea that the mantle undergoes thermal convection. This idea is based on the fact that as a substance is heated its density decreases and rises to the surface until it is cooled and sinks again. This repeated heating and cooling results in a current which may be enough to cause continents to move. Arthur Holmes suggested that this thermal convection was like a conveyor belt and that the upwelling pressure could break apart a continent and then force the broken continent in opposite directions carried by the convection currents. This idea received very little attention at the time.

Not until the 1960's did Holmes' idea receive any attention. Greater understanding of the ocean floor and the discoveries of features like mid-oceanic ridges, geomagnetic anomalies parallel to the mid-oceanic ridges, and the association of island arcs and oceanic trenches occurring together and near the continental margins, suggested convection might indeed be at work. These discoveries and more led Harry Hess (1962) and R.Dietz (1961) to publish similar hypotheses based on mantle convection currents, now known as "sea floor spreading". This idea was basically the same as that proposed by Holmes over 30 years earlier, but now there was much more evidence to further develop and support the idea.

background music: from Mozart's requiem (K626)

# data[].attributes.attachment_link.description
Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific.

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Paleoclimatic data is data extracted from natural resources from tree rings, ice cores, corals, and ocean and lake sediments

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Paleoclimatology data are derived from natural sources such as tree rings, ice cores, corals, and ocean and lake sediments. These proxy climate data extend the archive of weather and climate information hundreds to millions of years. The data include geophysical or biological measurement time series and some reconstructed climate variables such as temperature and precipitation.

NCEI provides the paleoclimatology data and information scientists need to understand natural climate variability and future climate change. We also operate the World Data Service for Paleoclimatology, which archives and distributes data contributed by scientists around the world.

# data[].attributes.attachment_link.description
Paleoclimatology data are derived from natural sources such as tree rings, ice cores, corals, and ocean and lake sediments. These proxy climate data extend the archive of weather and climate information hundreds to millions of years. The data include geophysical or biological measurement time series and some reconstructed climate variables such as temperature and precipitation.