Researchers have discovered 56 million-year-old fish fossils in a desert area east of the Egyptian capital, Cairo, in a move that exposed the ability of these animals to adapt to seas that were boiling.

The British Daily Mail reported that the fish were able to navigate under water temperature of 35 degrees Celsius, with the current sea temperature ranging from 12- 25 degrees.

The researchers found fossils in dark oil rocks at a desert site called "Ras Gharib A," more than 300 kilometres east of Cairo.

The discovery involved more than 12 different groups of bony fish living in that era, called Paleocene and Eocene, in which the temperature of the seas was high.

However, fossils show that marine fish adapted to warm climates in at least some tropical areas during this period.

The study by a group of Egyptian and other scientists published in the last issue of the journal Geology shows that these fossils provide important information on how life responds in the tropics.

The Paleocene and Eocene period is seen as the best historical counterpart to the current state of the Earth, which is suffering from warming due to climate change.

Recent studies have said that the average temperature on the planet has increased by one degree since the mid-nineteenth century, due to the industrial revolution and associated pollution.

During the Paleocene and Eocene, groups of fish swimmed up to Denmark in the far north of the European continent to avoid warmer temperatures in the Mediterranean, showing how far these marine animals were going.

University of Michigan paleontologist and study participant Matt Friedman said: "The impact of the nature of the times on life at the time was of great importance."

He added that a big gap in our understanding was how life in the tropics responded, as many of the fossils were not well sampled. "

She pointed out that the fish site in Egypt gave us a quick look at the tropics, explaining that "they (fish) seem to be well beyond this era."

The Egyptian researcher participating in the study, Sanaa El Sayed, said that the newly discovered fossils give researchers the first clear picture of how fish survive and thrive during the Paleocene and Eocene, highlighting a number of fish ratios and environments.

The fossil evidence available "did not indicate a widespread crisis between marine fish at the time."