Dinosaur Dominance

(230–65 million years ago)

Earth once teemed with creatures that roamed the lands, swam the seas, and soared through the skies. These creatures were much different than those of today.

In a grand chapter of Earth’s history, the era of dinosaurs unfolded between 230 and 65 million years ago, spanning a staggering 165 million years. These colossal creatures held dominion over our planet.

The Mesozoic Era, the Age of Reptiles, was subdivided into three periods: the Triassic, Jurassic, and Cretaceous. Each period bore witness to the rise and fall of various dinosaur species.

The Triassic period, which began 252 million years ago, marked the dawn of dinosaur life.

The first dinosaurs were modest in size, far removed from the colossal creatures that would later dominate the landscape. They were bipedal, a trait of many subsequent dinosaur species.

As the Triassic period gave way to the Jurassic 201 million years ago, the world underwent a transforming change. The climate became warmer and more humid. This led to a proliferation of lush vegetation that served as the primary food source for the herbivorous dinosaurs.

This period bore some of the most iconic dinosaur species, including the sauropods, such as the Brachiosaurus and the Apatosaurus, whose long necks enabled grazing on the leaves of towering trees.

The Jurassic period also saw the rise of fearsome predators, such as the Allosaurus and the Ceratosaurus, whose formidable jaws and razor-sharp teeth made them apex predators.

The Cretaceous period, 145 to 66 million years ago, marked the zenith of dinosaur diversity and dominance. This period was witnessed the emergence of new species, such as the Tyrannosaurus Rex, the Velociraptor, and the Triceratops. The Cretaceous period also witnessed the diversification of plant life, with the emergence of flowering plants, which served as a vital food source for the herbivorous dinosaurs.

The reign of dinosaurs was not without its challenges. The world was a harsh and unforgiving place. It was marked by catastrophic events that threatened the very existence of these prehistoric titans. Volcanic eruptions, meteor impacts, and climate change were just some of those perils.

The dinosaurs testified to the adaptability of life on Earth and also to the power of evolution. During their dominion, dinosaurs evolved into various shapes, sizes, and forms, each adapted to their specific ecological niche.

One striking example of dinosaur evolution is the development of flight. While the idea of a flying dinosaur seems unpractical, many dinosaur species evolved the ability to take to the skies. The pterosaurs, a group of flying reptiles that lived during the Mesozoic Era, were among the most successful of these aerial pioneers. These creatures ranged in size from small, insect-eating species, such as the Nemicolopterus, to giants, such as the Quetzalcoatlus, whose wingspans could exceed 30 feet.

The evolution of flight in the pterosaurs was driven by a combination of factors, including the development of lightweight, hollow bones, and the evolution of specialized muscles and tendons that enabled them to generate the lift and thrust necessary for powered flight. The pterosaurs were also endowed with a specialized membrane, known as the patagium, which stretched between their elongated fourth finger and their body, providing the surface area necessary for generating lift. This adaptation gave the pterosaurs access to previously inaccessible resources.

Another remarkable example of evolution is the development of complex social behaviors. Many dinosaur species exhibited sophisticated social behaviors, including cooperative hunting, parental care, and even the construction of communal nests.

The Maiasaura, a duck-billed dinosaur during the Late Cretaceous period, lived in large groups. Individuals worked together to build communal nests, incubate their eggs, and care for their young. Maiasaura nests were constructed in shallow depressions in the ground and lined with vegetation. The nests contained multiple eggs, with multiple females contributing to the same nest. This cooperative nesting provided increased protection from predators and improved incubation conditions.

The evolution of complex social behaviors was likely due to the need to protect their young from predators, the benefits of cooperative hunting, and the advantages of communal living in a harsh world. These social behaviors were facilitated by the development of sophisticated communication systems, including vocalizations, body language, and even visual displays, such as the brightly colored crests that adorned the heads of many dinosaur species.

66 million years ago, an asteroid 10 kilometers in diameter, struck the Earth with the force of billions of atomic bombs. This event triggered a cascade of catastrophic events leading to the extinction of the dinosaurs.

The impact generated massive tsunamis, released debris into the atmosphere, and triggered wildfires, leading to a dramatic drop in global temperatures. The world was plunged into darkness, as the dust blocked the sun, leading to a prolonged period of cold and darkness lasting several years.

This catastrophic event, known as the Cretaceous-Paleogene extinction event, led to the extinction of 75% of all species on Earth, including the dinosaurs.

Dinosaurs shaped the course of life on Earth. They paved the way for the rise of mammals, including our own species, Homo sapiens.