DISCUSSION: Studying dinosaurs was a highlight for many young elementary school students in science class. Triceratops, Stegosaurus, and the notorious Tyrannosaurus Rex are all fascinating creatures that nearly everyone remembers. However, the climate of the different periods of the Mesozoic era (Triassic, Jurassic, and Cretaceous) is not something everyone remembers. Yet it is important to study, as the climate of any particular period determined which types of animals thrived while others struggled for survival. This is the first of three pieces that intend to look at the climate and its relation to dinosaurs in the three periods of the Mesozoic Era.
The Triassic period, which occurred between 251 million and 199 million years ago, marked the first appearance of the dinosaurs. The Permian-Triassic extinction event, which happened 251 million years ago, is the largest known extinction event; a total of about 95% of all life went extinct. This event marked the boundary of the Permian and Triassic period, also known as the P-T boundary. Since almost all species became extinct, there was a very low biodiversity at the start of the Triassic.
A possible cause of the P-T extinction is the massive eruptive event of the Siberian lava traps, a large region of volcanic rock in Siberia, Russia. As these volcanoes erupted, the Earth underwent a global warming due to the massive CO2 emission. This warming created an uninhabitable atmosphere, which made the land mostly barren for the 5% of organisms that survived the extinction event. Another consequence of these eruptive events was oceans becoming an anoxic environment, i.e. they had little to no dissolved oxygen. This made marine life inhabitable as well at the end of the Permian period.
The geography of the Triassic period was a major factor in shaping the climate. The supercontinent Pangea started to take shape, with all continents together as one. The fact that all land was attached, combined with the low biodiversity of animals post-extinction, meant life was similar everywhere on Earth. The climate of Pangea was very hot and dry, especially in the interior. This may explain why reptiles and dinosaurs became dominant, and not mammals. Near coastal regions, a seasonal monsoon climate prevailed as well. The land was barren of plant life, but certain plants did survive the P-T extinction. These plants included ferns, woody plants, and gymnosperms (a plant with cones or pollen spores).
The surviving groups of animals that survived the P-T extinction were therapsids, who were mammal-like reptiles, and archosaurs, a more reptile-like organism. The archosaurs had evolved into dinosaurs by the mid-Triassic, and therapsids had almost gone extinct, meaning that the hot and dry climate was better suited to these reptilian-like animals. Many of these reptiles evolved into sprawlers, and some evolved into bipedal creatures (creatures who walked on two legs), such as Coelophysis (below). Towards the end of the Triassic, another group had evolved from the surviving archosaurs, called the pterosaurs (a term for winged reptiles).
Stay tuned for next month, where the climate and dinosaurs of the Jurassic period is covered. If you want to learn more about the geosciences, be sure to visit here!
© 2018 Weather Forecaster Joseph Fogarty