Gondwana: Gondwana was the great Southern landmass that formed about 250 million years ago when it broke apart from the super continent of Pangea.
Watch the video below to see how the Earth has changed over the past 600 million years. (credit: www.scotese.com)
Only 70 years ago most scientists thought the Earth's continents were fixed in position from the start of time. As geologists studied the Earth's rocks further and palaeontologists considered the locations of fossils a new theory gained popularity - that the Earth's land masses have been engaged in a magnificent waltz across the planet. This dance continues today as the oceans, mountains and valleys continue to change as a consequence of the moving of the Earth's tectonic plates.
Period: The supercontinent Pangea began fragmenting around 250 million years ago, producing the Northern landmass known as Laurasia and the Southern landmass Gondwana. Then, the massive landmass of Gondwana began to pull apart around 165 million years ago. This process took a long time. One of the last areas to separate was Tasmania (Australia) from Antarctica around 45 million years ago.
There were no humans living back then, so how do we know that the mighty continent of Gondwana ever existed?
These three specimens from the Permian (300 – 250 million years ago) have played a pivotal role in proving that the land mass of Gondwana once existed.
'Skeleton of the mesosaur Stereosternum tumidum from the Permian Irati Formation of Sao Paulo, Brazil. Thanks to G. Borgomanero with the assistance of H. Alvarengo. From Vickers-Rich, P. & Rich, T. 1999. Wildlife of Gondwana. Indiana University Press'
Mesosaurus: meaning "middle lizard" lived in the early Permian 299 to 271 million years ago. It was one of the first reptiles to return to the water living in freshwater lakes and ponds. Mesosaurus was only a metre long and had webbed feet and a streamlined body suited to swimming.
Fossils have been found in Southern Africa and Eastern South America. This small freshwater reptile could not have swum across the Atlantic Ocean and finding its remains confirmed that Africa and South America must have been connected long ago. Notice the location of Mesosaurus fossil remains in blue on the map below.
'Gondwana Triassic fauna' (1985) P. Trusler
Lystrosaurus: meaning: "shovel lizard" lived around 250 million years ago in the early Triassic. Remains have been found in what is now Antarctica, India, China and South Africa. It was a pig -sized herbivore. Lystrosaurus had two tusk like teeth and a squat posture with strong limbs. It was a mammal-like reptile that laid eggs. Lystrosaurus was common across the continents that formed Gondwana. Notice the location of fossil remains in brown on the map below.
Did you know that…. "The discovery of Lystrosaurus fossils at Coalsack Bluff in the Transantarctic Mountains by Edwin H. Colbert and his team in 1969–70 helped confirm the theory of plate tectonics and convince the last of the doubters, since Lystrosaurus had already been found in the early Triassic of southern Africa as well as in India." (Naomi Lubick, Investigating the Antarctic, Geotimes, 2005.)
Glossopteris: Meaning: "tongue" because of the shape of the leaf. The tall Glossopteris tree dominated the Gondwanan landscape from the beginning of the Permian (@ 300 mya) until their extinction about 50 million years later. Plants are an important part of the fossil record. The discovery of Glossopteris fossils across most of the Gondwanan land masses helped scientists to understand that the supercontinent Gondwana once existed.
Notice that fossil remains of Glossopteris, in green on the map below, have been found in most of the land masses that once formed Gondwana.
Links: (these links will open in a new window)
Present day countries and continents that made up Gondwana included:
- South America
Wildlife of Gondwana Exhibition
For more information, visit: http://www.geelongaustralia.com.au/nwm/