Dunsparce's 1.5m height is actually in reference to length, but Salamance is most likely measured in terms of standing. But for it's long length, it's hard to determine. For one, Dunsparce is relatively small for most snakes, some going up to 8.8m, which is more than Beartic's height. It's two closest real life counterparts would be folklore, being the Tsuchinoko (30 to 80 centimeters), which isn't that much shorter The other reason for this is it's other counterpart, the feathered serpent, a creature with no commonly accepted height. But looking at it's photos on Wikipedia, the feathered serpent is quite large, but my estimate is around 3.8m in length. Considering it's mix with a bumblebee, which can grow up to 4 centimeters, it's most likely a mix between the two, as the average between the last two is 1.9 meters.