Thomas of Cantimpré [circa 1230-1245 CE] (Liber de natura rerum, Quadrupeds 4.16): The calopus, as Physiologus says, is the fiercest animal, so that no hunter is able to get close to it. The Calopus has long serrated horns and it is able to bring down tall trees by cutting. When thirsty, it drinks at the Euphrates river. However, there is there a bush that is bristly with delicate and abundant branches. When the Calopus approaches it, while playing with its horns, the Calopus binds its own horns in the branches and both fighting for a long time and not being able to free itself, it cries out horribly. With the calopus’s voice having been heard, a hunter runs towards it and kills the stuck creature. - [Translation from The Thomas Project]

Guillaume le Clerc [ca. 1210 CE] (Bestiaire, Chapter 2): Now I shall tell you of another beast, / Which has two horns on its head / As sharp as a blade. / This beast is so swift / That no hunter can overtake it / Unless it be too tired to run, / And I can well assure you / That with its horns it can cut through / A tree stout and full-grown. / This is proved and well-known. / Aptalos is the name of this beast; / It dwells in the region / Where the river Euphrates flows. / When it is thirsty it always runs / To that river and drinks of the water. / When it has drunk it goes straightway / Where there is a little bush / As thick as a bramble. / There the branches are so little, / So thick, so fine and so close, / Where the beast goes thrusting. / There it enjoys itself and plays so much / With its horns down and up, / That they are quite caught in. / When its horns are entangled / In the shoots, which are slender, / And it is taken in the bramble / Like a fish in a net, / Then it pulls and tugs as hard as it can. / When it cannot disengage its horns, / It struggles harder, but nothing avails; / Then it is angered and cries so loud, / That one can hear it from afar. / Then comes the hunter headlong, / And finds it there entrapped. / He strikes it with spear or sword / Or other weapon, and kills it. / For it cannot by any effort great or small / Escape from there or defend itself. / There it is fated to give up its life. - [Druce translation]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.15): Also another beast is lyke a wylde Bull, and is not so great, but hée hath full great hornes and sharp, with whom he throweth downe bushes and trées, & throweth strong Oakes downe to the ground, and at the last, to gather meate, he putteth his head among shrubs, and long roddes, small and tough, that compasse and wind about the hornes of the beast, and so the beast is tyed and held: and then he striveth and praunceth long therewith, and striveth against the winding and fastening of the roddes, and is faster and faster bound and holden, and when he hath long striven, yet he maye not delyver himselfe out of the bondes, but is alway faster & faster bound, then for indignation he loweth full loud, and the hunter heareth his great voyce, and knoweth that the beast is snarled, and fast helde: and then he commeth upon the beast boldly, that is most sharp and mighty, & slaieth him with his toole, and weapon, and durst not adventure upon him in great woodes nor in fieldes, but now he dare stay him when he is held among small rods. Phisiologus calleth this beast Aptaleon: If his words may be beléeved, it séemeth a wonder, why so strong & so fierce a beast draweth not his hornes out of shrubbes and roddes that are small: with the which hornes, hée so mightelye breaketh great trées & strong, and throweth them downe flatte to the ground. - [Batman]

Slavic Physiologus [15th - 16th century]: The aurochs is a great beast amongst beasts, and he has quite a dreadful beauty. His mane is wondrous; the forehead is fearful; he is the strangest and most notable of all animals. In a duel, he would press against [some] tree and, striking at the tree with his horns, he would lop off the tree branches. Not a single beast rules over him. He endures his craving for water. When standing beside water, he sniffs the earth. After he has drunk enough, he gets drunk and makes merry. Then he bows to the earth as an ox. When he finds sturdy clematis, he joyfully wraps his head and horns. But the hunter comes, finds him wrapped and thus catches him. - [Stoykova, English translation by Mladenova and Stoykov]