Mesozoic
Introduction
The Mesozoic is a geological era that spanned approximately 186 million years, from about 252 to 66 million years ago. This era is often referred to as the Age of Reptiles, due to the dominance of dinosaurs and other reptiles during this time. The Mesozoic is divided into three periods: the Triassic, the Jurassic, and the Cretaceous, each of which is further divided into several epochs and ages.
Geology
The Mesozoic era was a time of significant geological activity, with the formation of many of the world's mountain ranges and the breakup of the supercontinent Pangaea. The era began in the wake of the greatest mass extinction in Earth's history, the Permian–Triassic extinction, which wiped out about 95% of marine species and 70% of terrestrial species. The recovery from this event shaped the geology and ecology of the Mesozoic.
Triassic Period
The Triassic period, which lasted from about 252 to 201 million years ago, was a time of recovery and diversification following the Permian-Triassic extinction. The period saw the rise of the first dinosaurs, as well as the first mammals and crocodilians. The climate during the Triassic was generally dry, with large deserts covering much of Pangaea.
Jurassic Period
The Jurassic period, from about 201 to 145 million years ago, was a time of significant change in the Earth's climate and geography. The Jurassic was marked by the further breakup of Pangaea into the continents of Laurasia and Gondwana, and the opening of the Atlantic Ocean. The climate was warm and humid, with lush tropical forests covering much of the Earth.
Cretaceous Period
The Cretaceous period, from about 145 to 66 million years ago, was the last period of the Mesozoic era. The period saw the further breakup of the continents, the rise of flowering plants, and the continued evolution of dinosaurs. The Cretaceous ended with the Cretaceous–Paleogene extinction, in which about 75% of all species on Earth, including all non-avian dinosaurs, became extinct.
Paleontology
The Mesozoic era is perhaps best known for the dinosaurs, but it also saw the evolution of many other groups of organisms, including mammals, birds, and flowering plants. The fossil record of the Mesozoic is rich and diverse, providing a detailed picture of life during this time.
Dinosaurs
Dinosaurs first appeared during the Triassic period and quickly became the dominant terrestrial vertebrates. They were a diverse group, with species ranging from small, bird-like forms to the largest land animals that have ever lived. Dinosaurs are characterized by their upright stance, with legs positioned directly beneath the body, and many species evolved adaptations such as feathers, horns, and armor.
Mammals
The first mammals appeared during the Mesozoic era, evolving from a group of reptiles known as synapsids. Early mammals were small, nocturnal creatures, but they diversified into a wide range of ecological niches over the course of the era.
Birds
Birds evolved from theropod dinosaurs during the Jurassic period. The first birds, such as Archaeopteryx, had a mix of bird-like and dinosaur-like features, including feathers, a beak, and a long, bony tail.
Flowering Plants
Flowering plants, or angiosperms, first appeared during the Cretaceous period. They quickly diversified and became the dominant group of land plants, due in part to their co-evolution with pollinating insects.