A new research says that cave bears went extinct because of their vegan diet 25,000 years ago.

According to Science Daily, cave bears or Ursus spelaeus lived for about 400,000 years ago during the last glacial period. Cave bears were larger than the modern-day bears; with a length of 3.5 meters and a height of 1.7 meters at the shoulder.

"The Cave Bear is a very different story," says Professor Dr. Hervé Bocherens of the Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) at the University of Tübingen.

Even though they're called cave bears, these ancient animals did not necessarily live inside caves. They actually just went to caves for hibernation. The cave bears' extinction might look like a normal occurrence of death, but researchers have found out a strangely large amount of bones and teeth of these bear in European caves.

This made scientists curious on why the cave bears have gone extinct.To find out, scientists took the bones found in "Goyet Cave" in Belgium and examined it. Dr. Bocherens and an international team took special interest in the Cave Bears' diet.

"We were particularly interested in what exactly the Cave Bears ate, and whether there is a connection between their diet and their extinction." explains the biogeologist from Tübingen.

The results show that cave bears mostly consumed plants. They are strictly vegan, making their diets unbalanced. They are even compared to Giant Pandas of today as "inflexible eaters".

"We assume that this unbalanced diet, in combination with the reduced supply of plants during the last ice age, ultimately led to the Cave Bear's extinction," Bocherens said in a statement via Fox News. There has been a lot of speculations about cave bears'mysterious extinction, ranging from indecisive temperatures, hunting and lack of food.