Horn size #2: aurochs with smaller horns

In the previous post, I presented a number of aurochs specimen with very large horns. This post is going to focus on the lower end of the horn size spectrum. Although the aurochs was a large-horned bovine in general, some individuals had surprisingly small horns – these small-horned aurochs are, however, not very numerous in the fossil and subfossil record, indicating that they were not common in the species either. 

 

-) The Prejlerup bull 

This skeleton is possibly the largest more or less complete aurochs skeleton that is on display, with a withers height of roughly 190 cm. Its horns, however, are not very large. They seem to be shorter than the length of the skull, what makes them “smaller” to me by aurochs standards. Surely the keratinous sheath would have added to the length, but the curvature shows that this would not have doubled the length of the horns, otherwise they would have crossed each other as the horns are not wide-ranging. 

 

-) The Önnarp skeleton 

This bull specimen has horns that are smaller than average for the aurochs. I know no measurements for the horn cores of that bull, unfortunately. Go here for the skeleton. 

 

-) The Himmelev bull 

Although the horns of the Himmelev bull are not tiny, they are quite a bit smaller than what is average for the aurochs. No measurments for the horn cores that I found. See here and here. 

 

-) The skull from Bauges 

In a cave in Bauges, France, a skull was found that has truly tiny horns by aurochs standards. No measurements for the horn cores of this skull are given, but there can be no question that they are significantly shorter than the craniocaudal length of the skull. Those are the shortest horn cores I have ever seen in an aurochs skull. The skull can be seen in this video. 

 

Still shot from the video linked above

-) The last Jaktorow bull 

We know exactly how long the horns of the last bull from the Jaktorow forest in Poland were because the sheath and not the core has been preserved. It turns out that it is merely 46 cm long, which is very small compared to horns of other, earlier specimen. Those were up to three times as long than this sheath, speaking of only the cores. The Jaktorow horn does not look like it is not yet fully developed, so it is probably from a grown bull. Overall, the horn is rather meagre, also compared to earlier sheaths which are thicker and more strongly curved. 

Those were the smallest-horned aurochs specimen preserved that I know of. They all have something in common: they are exclusively from the European subspecies, and they are all from the Holocene. And that might explain why aurochs with smaller horns existed: the presence of humans. I explain in the post linked in the post on large-horned aurochs why I think that anthropogenic influence is the reason for small-horned aurochs to appear. First of all, the aurochs suffered from a fragmented and confined habitat as civilization competed with the aurochs, there likely was hybridization with domestic cattle in the wild in Europe, and the aurochs was hunted for its horns. Trophy hunting is known to affect the morphology of animals. For example, large-tusked elephants have become rare in both Asia and Africa and tuskless elephants became more frequent. Also, the cape buffalo used to have much larger horns in the past than it does today, go here or here and compare with what is average for this species today. I think those factors are the most credible explanations for why smaller-horned aurochs appeared in Holocene Europe, at least I am unable to come up with any other explanation that is plausible for why the European aurochs decreased in horn and body size during the Holocene, as I write in the post linked at the beginning of this post.