All in all, the aurochs was a large-horned bovine. The horns were variable in size, also depending on if anthropogenic influence was present or not (I explain that in that post). With this and the upcoming post, I want to cover that variability. This post is going to cover some of the aurochs remains with the largest horns, to show the upper size limit, the upcoming post is going to show the lower size limit.
-) Various B. p. namadicus skulls
The Indian aurochs was smaller in overall body size than the European subspecies (in the lack of a complete skeleton no withers height data can be given), but had proportionally larger horns. Only a few crania have been published, and I have seen photos of only three with horns. One of them is at the Geological Survey of India, from the Narmada Valley:
The horn cores are rather wide-ranging and proportionally very large, although there are no size data given for namadicus horn cores that I know of. But I have seen a photo of that skull in frontal view, and assuming that the distance between the horns is 20 cm (which is typical for not so large European aurochs bull skulls), the horn span would have been 133 cm. Since I don’t have data for the length of the cores, I don’t know how long they are. But considering that there is no general rule for how much centimetres the horn sheath adds to the length in a bovine, the length of the horns in life can only be guessed anyway. I assume they easily surpassed one metre.
Another namadicus cranium shows fragmentary horn cores:
As you see, the part of the left horn core that is preserved is roughly the craniocaudal length of the skull, and it is nowhere near starting to curve inwards, meaning that quite a large part of the horn core is missing. This suggests that this specimen had even larger, very large, horns in life.
-) One suxianensis skull fragment
The skull fragment I am talking about was published in a Chinese paper (Xie Wanming: A skull of Bos primigenius suxianensis from Anhui. 1988). It is shown from several views:
What becomes apparent is that those horns are ridiculously long. I know no measurements for this skull fragment, so I can only estimate. If the distance between the horns was 20 cm (suxianensis was comparable in size to primigenius), the horn span would have been 137 cm. And this is only a conservative estimate as a 20 cm distance between the horns is actually from the smaller end of the size spectrum of aurochs skulls. Other Bos primigenius suxianensisspecimen show comparably large horns too, but this skull fragment stands out. It also deviates from the other suxianensis specimens in having a rather narrow angle between snout and horns, more comparable to the North African aurochs, while the other specimens had a larger angle between horns and snout.
An important question is how much the keratinous sheath would add to the length of the horns in life. The aurochs horn sheaths recovered vary greatly in the length they add to the bony core, from 5 cm to 33 cm. In any case, the horns of this East-Asian aurochs were very long.
-) The Wadi-Sarrat cranium
I have only seen two skulls of North African aurochs so far. One has very large horn cores and is the oldest aurochs skull found outside Asia so far, the Wadi-Sarrat cranium. Photos and measurements of this skull can be found in this paper. The left horn core has a length of 112 cm. With that length, the horn cores are actually longer than those of B. buiaensis, which has very wide-ranging horns and thus appears particularly long-horned. And this is only the bony core, with the sheath the horn would be larger in life. Calculating using the photo and the scale bar, the horn span must be 140 cm.
-) The Sassenberg bull
I used the Sassenberg bull for many full body reconstructions of the aurochs in the past, which I do not do anymore because I was told it is partly a composite specimen (life reconstructions based on this skeleton always looked a bit weird, now I know why). But the skull is authentic in any case, and it has rather large horns.
-) Skulls found near Rom
Frisch 2010 describes skulls found near Rome, which are notable because of their particularly large horns. One of them has horn cores of a length of 120 cm, which is the largest horn core length I found in the literature so far. Considering that the keratinous sheath can add up to 40% length to the core, it is easily possible that large-horned aurochs had horns of a length of 1,5 m. But without having the sheath we cannot be sure, it is also possible that it added only a few cm.
-) Two skulls found at Stonehenge
Stonehenge is not only notable for its stone monument, but also because it is an ancient hunting site where about 50 aurochs have been found. I have seen three well-preserved crania from that location, two of which have massive horns. Go here and here. It’s incredible how thick the horn cores of the first skull are, imagining the horn sheath they must have been very impressive in life.
-) The Viterbo skull
The skeleton displayed at Viterbo, Italy, is a postcranial skeleton with the skull from another specimen because the original skull was deformed during fossilization. The mounted skull of the Viterbo specimen has very thick and large horn cores.
-) The skull fragment from Groß-Rohrheim
Groß-Rohrheim in Germany is a Interglacial site in Germany where many of the typical Interglacial megafauna has been found, also including many aurochs remains. One skull fragment is notable for having massive – very large and very thick – horn cores. The horn span is, according to the publication listed down below, 142 cm and the diameter is 15 to 16 cm, the length is 103 and 105 cm. Considering the size of the fragment and the dimensions of the horn cores, this specimen must have been an absolutely impressive sight in life.
-) The Faborg skull
This cranium was found near Faborg in Denmark and is exhibited at the National Museum of Copenhagen, next to the Prejlerup bull skeleton. According to a picture description I found on google, the horn span of that specimen is 114 cm.
-) The possible siciliae skull
The skull from Sicily that might be of the dwarf subspecies B. p. siciliae shows very long and wide-ranging horns. Since the overall body size of the animal was small if it really was from the dwarf subspecies (which had a withers height of only 130 cm), it is questionable if the absolute size of the horn cores is as impressive as in the those from the mainland subspecies, but proportionally they are very large.
Looking at the largest-horned aurochs, it can be concluded that Bos primigenius was among the largest-horned bovines that would be around today if it had not been for anthropogenic influence. Only those of the wild Asiatic water buffalo are larger among extant bovines.
It has to be noted that these specimens I presented here are only the tip of an iceberg, and it is hard to say what was “average” for the aurochs, and if there were differences between the subspecies. The point of this and the upcoming post is to show the extreme ends of the horn size spectrum. The next post is going to focus on small-horned aurochs. As a little spoiler (or teaser): they all have something in common, something that might reveal why their horns were small compared to the huge horns of the specimens presented in this post.
Van Vuure, 2005: Retracing the aurochs – history, morphology and ecology of an extinct wild ox.
Frisch, 2010: Der Auerochs – das europäische Rind.
Von Koenigswald & Menger: Ein ungewöhnlich großer Schädel vom Auerochsen (Bos primigenius) aus dem letzten Interglazial von Groß-Rohrhiem bei Darmstadt. 2002.