Researchers, including those from University of Cape Town in South Africa, have found several three-toed footprints measuring 57 centimetres long and 50 centimetres wide.
This means the dinosaur would have an estimated body length of around nine metres and be a little less than three metres tall at the hip, researchers said.
That is four times the size of a lion, which is currently the largest carnivore in southern Africa, they said.
The footprints belong to a new species, named Kayentapus ambrokholohali, which is part of the group of dinosaurs called "megatheropod".
The term "megatheropods" describes the giant two-legged carnivorous dinosaurs, such as the iconic Tyrannosaurus rex (T rex) which fossil evidence shows was around 12 metres long.
The study, published in the journal PLOS ONE, also reveals that these footprints make up the largest theropod tracks in Africa.
The tracks were found on an ancient land surface, known as a palaeosurface, in the Maseru District of Lesotho, a small country in southern Africa.
The surface is covered in 200 million year old 'currentripple marks' and 'desiccation cracks' which are signs of a prehistoric watering hole or river bank.
"That is because it is the first evidence of an extremely large meat-eating animal roaming a landscape otherwise dominated by a variety of herbivorous, omnivorous and much smaller carnivorous dinosaurs. It really would have been top of the food chain," said Knoll.
What makes the discovery even more important is that these footprints date back to the Early Jurassic epoch, when it was thought the size of most theropod dinosaurs was considerably smaller, researchers said.
On average they were previously thought to be around three to five metres in body length, with some records showing they may have reached seven metres at the very most, they said.
It is only much later in the Jurassic and during the Cretaceous, which starts 145 million years ago, that truly large forms of theropods, such as T rex, appear in body and trace fossil records.
"This discovery marks the first occurrence of very large carnivorous dinosaurs in the Early Jurassic of southern Gondwana - the prehistoric continent which would later break up and become Africa and other landmasses," said Lara Sciscio, postdoctoral Research Fellow at the University of Cape Town.
"This makes it a significant find. Globally, these large tracks are very rare. There is only one other known site similar in age and sized tracks, which is in Poland," said Sciscio.
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