Between 65 and 145 million years ago amazon quiz years ago, the Amazon River flowed towards the Pacific Ocean in the opposite direction it flows today. This change is believed to be a result of the tectonic changes that occurred at the end of the Cretaceous period. This amazon quiz can be played from the app only.
Dinosaurs
The Late Triassic through the Early Jurassic was dinosaurs’ heyday. This is when the first ceratopsian and pachycepalosaurid dinosaurs appeared and when the bird lineage diverged from its flightless theropod ancestors. Also, during the Late Jurassic, the breakup of the world-continent Pangea began to speed up, increasing regional differences in flora and fauna.
Fierce predatory dinosaurs scavenged and hunted for meat. Crocodiles and turtles flourished. Lizards, snakes, birds, and pterosaurs sailed the skies, while mammals ran along the ground. Plant-eating dinosaurs grew body armour to protect themselves. Oak, maple, walnut, and magnolia trees grew alongside cycads, tree ferns, and grasses.
Towards the end of the Jurassic, a sauropod subgroup known as Titanosaurs grew to be very large. Titanosaur fossils have been found on every continent. Some examples include Amphicoelias, a diplodocid sauropod, 70-90 feet (20-25 m) long from Colorado, USA; Apatosaurus, a brachiosaurid sauropod, about 83 feet (25 m) long from Utah, USA; Dystrophaeus, a short-necked diplodocid sauropod, 60 feet (18 m) long from Wyoming, USA; and Barosaurus, a very long-necked sauropod, about 89 feet (26 m) long from the western USA and Tanzania Africa.
The Cretaceous Period, 145 million to 66 million years ago, was the last and greatest period of dinosaur dominance. It is also when modern humans first appeared on Earth. This period saw a proliferation of new dinosaur species as the planet’s climate changed, with forests spreading into polar regions and the emergence of dry, desert habitats. Some examples of this diversity include the Triceratops, Utahraptor, Iguanodon, and duck-billed hadrosaur dinosaurs. The first birds also made their appearance, including the pterodactyl and apterygod, which had no wings but used feathers for air-flapping flight. Some avian dinosaurs were as small as hummingbirds, while others could be as big as an elephant.
Rivers
In the Cretaceous period 65 million years ago, the Amazon River flowed toward the Pacific Ocean in the opposite direction it flows today. Scientists have discovered this by studying mineral grains buried in the sediment at the river’s mouth. They found that the westward tilt of the Amazon was caused by a highland that formed during the breakaway of South America and Africa, during the late Cretaceous. That highland was then replaced by the rise of the Andes Mountains.
During the Cretaceous Period, which was the third and final period of the Mesozoic Era, many rivers in South America were flowing eastward toward the Atlantic Ocean instead of westward towards the Pacific. This change was the result of tectonic forces and changes in climate.
Landforms
The Earth has many distinctive landforms, from the world’s largest river to the driest desert. Learn more about the natural and distinctive features of these landscapes by exploring these resources. These lessons will help middle school students discover the unique features of each continent and its landscapes.
Coastal plains form when river currents carry rocks, soil and other sediment into the ocean. Over time, this sediment builds up, creating a flat or gently sloping landscape. The Oxnard Plain in California, for example, is a coastal plain. It is rich in nutrients and is home to some of the juiciest strawberries in the world.
A gully is a landform that forms from erosion of the side of a slope or canyon. These gullies can be very deep and narrow. Some gullies have been used by humans as waterways. Others are filled with debris and other natural material.
The Cretaceous period was the last and longest period of the Mesozoic Era, extending from 145 million to 65 million years ago. The Cretaceous ended with the extinction of dinosaurs and the emergence of mammals.
In the Cretaceous, the Amazon River did not exist in its current form. Instead, it was part of a much larger ancient drainage system that drained into the Pacific Ocean. The tectonic processes that reshaped the continents during this time may have contributed to the Amazon’s change in direction.
Time period
The Cretaceous (krih-TAYS-sus) era, which lasted from about 145 million to 66 million years ago, was one of the most exciting times in Earth’s history. It is best known as the age of dinosaurs and other giant reptiles, but it also saw a spectacular diversification of life in general.
The end-Cretaceous mass extinction wiped out dinosaurs and almost all other land animals that weighed more than 25 kg. The survivors, including mammals, quickly filled up the vacant ecological niches.
For most of the Cretaceous, the supercontinent Pangea was rifting apart, creating new continents. This shifted the genetic divergence of life between the different parts of the world, and led to more dramatic weather patterns.
During the Cretaceous, the Amazon River flowed towards the Pacific Ocean in the opposite direction it flows today. This was because of a highland that sat where the river’s mouth now sits. Eventually, the rise of the Andes Mountains in the west forced the river to reverse course. As it did, sediments from the east were washed into the Amazon basin, resulting in a mix of young and old mineral grains in the river water.
