Track marks from animals that lived during the Early Cretaceous period have been found in a large diamond mine in Africa.

The Catoca diamond mine in Angola, Southern Africa is the fourth largest diamond mine in the world but it offers more than just precious stones. The mine also holds tracks of animals that walked the Earth millions of years ago.

The track marks belonged to the Cretaceous gang of a long-necked dinosaur, a raccoon-sized mammal and a crocodile-like creature that marched toward a fresh water lake, most likely to satiate their thirst, and left behind their footprints on sedimentary soil 118 million years ago.

Vladimir Pervov, a Russian geologist from the Sociedade Mineira de Catoca, first spotted these ancient animal tracks in December 2010 and contacted scientists from the PaleoAngola Project, a program that investigates vertebrate paleontology in Angola. The scientists, in turn, asked the representatives of the mine to help preserve the ancient footprints.

Operators of the mine fortunately expressed support for the scientific investigations and decided to stop all of the activities in the particular area of the mine, renouncing potential income for the benefit of science.

Researchers have found almost 70 different types of tracks, including 18 sets that belonged to the large and long-necked sauropods, marking the first discovery of dinosaur tracks in Angola. The team also found the tracks of a crocodilomorph, an animal that belongs to a group of modern and extinct crocodiles and their relatives.

The discovery of 30 to 35 tracks of an unusually large mammal has been hailed as particularly noteworthy because most of the warm-blooded animals during the Cretaceous period were the size of a rat. The footprints of the mammal that were found in the Catoca mine suggest that it was about the size of a raccoon.

"Mammals evolved from very small-sized individuals," said Marco Marzola, who works with the PaleoAngola Project. "The first mammals were the size of a squirrel or even smaller, like a mouse. They evolved to become bigger in size, but only after the time of the dinosaurs."

The raccoon-sized animal's tracks give hints of what it might have looked like. The creature had five fingers and five toes, with the longest digit located in the middle; it likely walked like a bear or a human. Measuring about 1.1 by 1.3 inches, the creature's print indicates that it was extraordinarily large for a mammal at the time.

The discovery was presented at the annual meeting of the Society of Vertebrate Paleontology in Berlin on Nov. 5.

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