When giant hippos roamed Britain
LONDON, England (CNN) -- A rare fossil find in eastern England has revealed a prehistoric period when huge hippos roamed parts of Britain.
The hippos, six tonnes in weight and half as big again as their present-day relatives, roamed English swamplands with temperatures not unlike the African savannah, scientists say.
Their bones have been found alongside those of horses, hyenas, deer, primitive mammoths, rodents and plants giving what London's Natural History Museum says is an unprecedented insight into an unknown "warm" period 500,000-780,000 years ago.
"This is a rare and significant fossil find," says Simon Parfitt, paleontologist at the museum.
"To find two hippopotamuses together is very unusual, but to find evidence of the land surface around them is exceptional. The excavation site provides a unique opportunity to study an environment that we believe has never been recognized before and that, if we don't act quickly, could be lost forever."
The fossils were discovered on an inland site near Lowestoft by teams from the Natural History Museum and Queen Mary College, University of London.
"Initial research undertaken by scientists indicates that the site is incredibly fossil rich and could be internationally significant," says a spokeswoman for the museum.
"However, further research and urgent action is needed to carry out a rescue excavation and recover fossil specimens before the site is redeveloped in the next few months."
The English hippos were one-and-a-half times as big as today's animals.
The hippos lived in the Middle Pleistocene period when Norfolk was populated by exotic species as well as familiar plants and animals.
The scientific teams says that the presence of marine molluscs together with plant remains demonstrate the land had changed from a shallow marine environment to a warm freshwater landscape.
It is approximately 15 kilometers from Norfolk's present-day coast and insect fossils indicate the summer temperature at that time was 2-3 degrees Celsius warmer than today.
The team says that the ancient hippopotamus were larger than today's species and weighed about six-seven tonnes, compared to modern hippos that weigh up to four tonnes.
They had very prominent eyes which served as periscopes when submerged in the water. It is likely the hippos discovered died through natural causes and their bones show evidence of having being gnawed by hyenas.
The excavation site reveals layer upon layer of large and small mammals, fish, molluscs, insects and plant remains, the Natural History Museum says. It adds that the precise location of the site cannot be revealed due to health and safety reasons.
A selection of the fossils have gone on display at the museum's "Festival of Fossils" which began Thursday.