Middle Jurassic

A Time of Transition

The Middle Jurassic period, spanning from approximately 174 to 163 million years ago, was a pivotal time in the history of Earth, marked by significant geological, climatic, and biological changes. This period set the stage for the rise of many iconic dinosaurs and saw the continued breakup of the supercontinent Pangaea.

Geological and Climate Changes

During the Middle Jurassic, the supercontinent Pangaea continued to rift apart, leading to the formation of new oceans and the separation of landmasses. This tectonic activity created diverse environments, including coastal areas, inland seas, deserts, and lush forests. The climate during the Middle Jurassic was generally warm and humid, with higher sea levels and an absence of polar ice caps, creating widespread shallow marine environments.

Life on Land

The Middle Jurassic period saw the diversification of many dinosaur groups, which began to dominate terrestrial ecosystems. Some notable dinosaurs from this time include:

• Megalosaurus: One of the first dinosaurs to be scientifically described, Megalosaurus was a large theropod predator that roamed Europe, hunting other dinosaurs and large prey.
• Cetiosaurus: Known as the “whale lizard,” Cetiosaurus was one of the earliest large sauropods, with a long neck and tail, and a massive body adapted for a herbivorous diet.
• Eustreptospondylus: A medium-sized theropod found in Europe, it was an agile predator that likely hunted smaller dinosaurs and other animals.
• Callovosaurus: An early ornithopod, this small herbivorous dinosaur represents the early diversification of plant-eating dinosaurs that would later include well-known groups like hadrosaurs.

Marine Life

Marine environments flourished during the Middle Jurassic, with abundant life forms including marine reptiles, fish, and invertebrates:

• Plesiosaurs: These marine reptiles had long necks and broad, flat bodies with flippers, and they thrived in the shallow seas, preying on fish and other marine creatures.
• Ichthyosaurs: Resembling modern dolphins, these fast-swimming predators dominated the oceans, with species like Ophthalmosaurus known for their large eyes adapted for hunting in deep water.
• Ammonites: These shelled cephalopods were abundant and diverse, serving as important index fossils for dating marine sediments from this period.

Flying Reptiles

Pterosaurs, the flying reptiles, continued to evolve and diversify during the Middle Jurassic:

• Dimorphodon: Known for its two distinct types of teeth, Dimorphodon was an early pterosaur with a relatively short wingspan and a diet that likely included fish and small terrestrial animals.

Plant Life

The vegetation of the Middle Jurassic was dominated by conifers, cycads, and ferns. These plants formed the primary food source for the large herbivorous dinosaurs. The warm, humid climate supported dense forests and lush vegetation, creating diverse habitats for a variety of plant-eating dinosaurs.