beaver is one of the largest living rodent species and the largest rodent native to Eurasia. Its head-to-body length is with a long tail length. It weighs around . In Norway, adult males average , while females average . Adults from the same country average . By the average weights known, it appears to be the world's second heaviest rodent after the capybara, and is slightly larger and heavier than the North American beaver. One exceptionally large recorded specimen weighed , but it is possible for the species to exceptionally exceed reportedly. Differences from North American beaver Although the Eurasian beaver appears superficially similar to the North American beaver, there are several important differences, chief among these being that the North American beaver has 40 chromosomes, while the Eurasian beaver has 48. The two species are not genetically compatible: After more than 27 attempts in Russia to hybridise the two species, the result was one stillborn kit that was bred from the pairing of a male North American beaver and a female Eurasian beaver. The difference in chromosome count makes interspecific breeding unlikely in areas where the two species' ranges overlap. Fur The guard hairs of the Eurasian beaver have longer hollow medullae at their tips. There is also a difference in the frequency of fur colours: 66% of Eurasian beavers overall have beige or pale brown fur, 20% have reddish brown, nearly 8% are brown, and only 4% have blackish coats; among North American beavers, 50% have pale brown fur, 25% are reddish brown, 20% are brown, and 6% are blackish. Head The Eurasian beaver has a larger, less rounded head; a longer, narrower muzzle. The Eurasian beaver also has longer nasal bones, with the widest point being at the end of the snout; in the case of the North American beaver, the widest point is at the middle of the snout. The Eurasian beaver has a triangular nasal opening, unlike those of the North American beavers, which are square. Furthermore, the foramen magnum is rounded in the Eurasian beaver, but triangular in the North American beaver. Body The Eurasian beaver has shorter shin bones than the North American species and a narrower, less oval-shaped tail, making it less capable of bipedal locomotion. The anal glands of the Eurasian beaver are larger, and thin-walled, with a large internal volume, relative to that of the North American beaver. Behaviour and