DISCUSSION: Last month, the climate of the Triassic period was explored. If you missed it, be sure to check it out here! This is now the second of three pieces to look at the climate of the Mesozoic era, where this month’s focus will be on the Jurassic period.
The Jurassic period occurred between 199 and 145 million years ago. Dinosaurs had begun to evolve and thrive during the Triassic period, but the large increase in dinosaur diversity, as well as the presence of new plesiosaurs (marine reptiles) and pterosaurs (flying reptiles), began to manifest itself during the Jurassic period.
In the early Jurassic, animals were still similar throughout the world due to the connected nature of the continents – however, these continents slowly started to drift apart, allowing for a greater diversity of dinosaurs in the mid to late Jurassic. As continents drifted apart, more land masses and coastlines were created, allowing oceans to widen and sea levels to increase. Epicontinental seas (also known as inland seas) started to form due to these rising sea levels. These rising sea levels caused an increase in the humidity level, which marks a big difference between the Triassic and the Jurassic. While the Triassic climate was dry, the Jurassic climate was wetter and more humid, and almost resembled a rainforest in the tropical areas.
These rainforest-like conditions paved the way for lush vegetation to grow, slightly increasing the carbon dioxide levels, therefore creating a “greenhouse” climate and warming throughout the world. Vegetation in the Jurassic period included a more diverse set of plants, catering to all of the different types of specialized dinosaurs that had started to evolve during this time. Some examples of these specialized dinosaurs include tetanurans (both large and small carnivores), thyreophorans (armored herbivores, such as stegosaurus and ankylosaurs), and sauropods (large herbivores, such as Brachiosaurus and Diplodocus).
The many different types of plants that appeared in the Jurassic provided resources for all the different types of herbivores. The long-necked sauropods could spend their time devouring tall conifers, and the ground-level head of the stegosaurs and ankylosaurs could graze on the low-lying plants, such as ferns and horsetails.
One of the most diverse dinosaur fossil deposition on earth, the Morrison Formation, was created during this time. The Rocky Mountains began to uplift during the Jurassic period, and as they weathered, sands became deposited at the sides of the mountain into lakes, swamps, and streams. In the early twentieth century, this was the place to be to find fossils!
Stay tuned for next month, where the Cretaceous period is covered in the last of three pieces on the climate of the dinosaurs. If you want to read more storeis like this, and learn more about the geosciences, be sure to visit here!
© 2018 Weather Forecaster Joseph Fogarty