South African fossils of prehistoric tetrapods provided new insights into how life began on land. The discovery of the fossils revealed that four-legged vertebrates originated all over the world and not exclusively in tropical regions, as previously thought.
( Maggie Newman | AFP / University of Witwatersrand Johannesburg )
Scientists have found South African fossils of prehistoric Devonian amphibians, which are believed to be the earliest known four-legged vertebrates at Waterloo Farm in Grahamstown.
The two tetrapod fossils are called Tutusius and Umzantsia. The scientists described it as a cross between an alligator and a fish. Since they were classified as amphibians, the scientists concluded that they can eat small fish in water and tiny invertebrates on land.
However, the significance of the discovered fossils lies in the environment in which they were excavated.
Devonian tetrapods are touted as the ancestors of all vertebrates, as amphibious, aquatic tetrapods that first populated the country. First scientifically proven, their evolution takes place in warm tropical locations.
Now, with the South African fossils, it was finally known that they resided in colder environments. Specifically in the Antarctic Circle about 360 million years ago
Tutusius and Umzantsia
The paleontologists identified Tutusius from one piece of his shoulder girdle bone. The species was estimated at about 3 feet in length. The paleontologists decided to name the species after Desmond Tutu, the South African human rights activist.
Umzantsia, now about 2.3 feet long, has a slender lower jaw and small pointed teeth.
"Lively, they would resemble a cross between a crocodile and a fish, with a crocodile-like head, stocky legs, and a tail with a fishy fin," write the paleontologists at the South African Center of Excellence for Paleo-Sciences in a study published in The Journal Science
Rewrite the History of Early Life
Devonian tetrapod fossils are found virtually everywhere in the world. However, they were not found in the old supercontinent Gondwana, which today becomes Africa, South America, Australia, Antarctica, and India. The only fossil found in these amphibian tetrapods was a pine and footprint in eastern Australia.
Most, if not all, of their fossils were discovered in another ancient supercontinent called Laurussia, which today is North America, Greenland, and Europe.
Previous conclusions concluded that these amphibians migrated from the water through tropical areas to the land until they finally end in Laurussia. Consequently, subsequent studies on their evolution into land species have only considered the influence of tropical conditions.
However, it has been found that both Tutusius and Umzantsia fossils originate from the southernmost part of Gondwana
In the past, Devonian tetrapods were found from places that were in tropical regions during the Devonian period Specimens lived in the Antarctic Circle, "said Dr. Robert Gess, principal author of the study.
Together with Per Ahlberg, co-author of The entire team concluded that while tetrapods occurred in the late Devonian world, their evolution and migration to land but also elsewhere in the world could have taken place.
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