The authors of Mediaeval bestiaries were not merely concerned with providing a description of creatures. No, for them, everything in Creation had a purpose - nothing had been made without an ulterior aim: the edification and instruction of sinful man. So, each creature described is not merely an animal but a living parable, imbued with moral or religious symbolism.
When the great ice-sheets covered the north, life retreated before them, but some species stayed and endured. Whilst man huddled around fires in his caves, mighty beasts roamed the tundra: the Woolly Mammoth, the Woolly Rhinoceros…and the Woolly Wyvern.
Small red flower, originally sprouted from the blood where St. Senren fell but now found widely over all Laurentia. Occasionally, a rare white flower will be found, with powerful magic properties. It is particularly prized by the religious order, the Senrenites.
Nearly every primitive culture has had rituals and celebrations to guarantee the proper passage of the seasons and to ensure the fertility of crops and animals. Oversight of these ceremonies was generally the provenance of local kings or priests.
Suppose that the adventurers dispatch one of these fellows. The local peasants may become hysterical, fearing famine and death will stalk the land. Alternatively, they may want one of the new heroes to become king. For a while, this can be a good thing, but the first time that the crops fail, the superstitious locals will want to sacrifice their new leader.