Problem 10 - Biology Today and Tomorrow with Physiology

Question

Did Pangaea or Gondwana form first?

Step-by-Step Solution

Answer

Gondwana formed before Pangaea.

Step 1: Understand the Definitions

Pangaea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. Gondwana, on the other hand, was also a large landmass, primarily consisting of what are now the continents of the Southern Hemisphere, and existed before Pangaea.

Step 2: Timeline Investigation

Pangaea began forming around 335 million years ago and started breaking apart about 175 million years ago. Conversely, Gondwana existed from about 600 million years ago and was fully formed by the late Precambrian era, surviving until it started fragmenting in the late Jurassic period.

Step 3: Sequence Conclusion

Given the timelines, Gondwana was already in existence before Pangaea formed. Gondwana was a component of Pangaea itself, implying it existed prior to the formation of Pangaea.

Key Concepts

Pangaea

Pangaea is one of the most famous supercontinents that existed during Earth's geological history. It formed about 335 million years ago.
Pangaea was a massive landmass that brought together most of the Earth's landforms. It wasn't a permanent fixture, though. Eventually, it began to break apart around 175 million years ago due to the processes of plate tectonics.
During its existence, Pangaea dramatically affected the global climate and environment.

• There were changes in ocean currents and atmospheric circulation.
• As a result, environments ranged from arid deserts to lush rainforests across different regions.

Its break-up led to the formation of the continents as we know today, influencing the evolution and distribution of life on Earth. The idea that continents were once joined and later drifted apart was initially proposed by Alfred Wegener, and it has since been supported by substantial geological and palaeontological evidence.

Gondwana

Gondwana is another key player in understanding Earth's ancient geography. It was one of the primary components that eventually became part of Pangaea. This vast landmass existed before Pangaea and highlighted the dynamic nature of Earth’s crust.
Gondwana started forming in the late Precambrian era. Over millions of years, it included large swathes of today's Southern Hemisphere continents, namely:

• South America
• Africa
• Antarctica
• Australia
• India

The breakup of Gondwana began in the Jurassic period, which then led to the independent tectonic drift of these regions. Its gradual disintegration played a crucial role in shaping the earth's current geological landscape.

supercontinent

The term "supercontinent" refers to a large landmass composed of many smaller continents. Supercontinents have formed and split several times during Earth's history.
These cycles are driven by plate tectonics, where Earth's crustal plates slowly move over the planet's surface. When the plates come together, they form supercontinents; when they separate, new oceans and continents appear.
Besides Pangaea and Gondwana;

• Rodinia and Columbia (Nuna) are other ancient supercontinents.
• Rodinia existed approximately 1.3 to 0.9 billion years ago.

Understanding the formation and breakup of supercontinents helps scientists explain plate tectonics, climatic shifts, and even mass extinction events. These dynamic cycles can influence every aspect of Earth's environment and biological diversity.

Precambrian era

The Precambrian era is a vast expanse of time, covering almost 90% of Earth's history. It spans from the formation of Earth about 4.6 billion years ago, up to around 541 million years ago.
This era is crucial for understanding the early development of our planet. It witnessed the formation of the first supercontinents, including Gondwana, during its later stages.
The Precambrian era is divided into several sub-eons, which include:

• Hadean
• Archean
• Proterozoic

During this time, Earth saw significant changes, including the earliest life forms and the build-up of oxygen in the atmosphere. Despite its length and importance, finding fossils from the Precambrian is rare due to the lack of hard-shelled organisms and the scarcity of well-preserved sedimentary rocks.