How large were the largest aurochs?

The size of the European aurochs has been both over- and underestimated. The largest size estimate given in the literature I have seen so far was 230 cm at the withers (I don’t remember the source, unfortunately), the smallest for bulls was 145 cm. The latter is definitely inaccurate, as there is no evidence for European aurochs bulls with a withers height noticeably below 160 cm. But what was the upper size limit of aurochs bulls? 

 

The preserved skeletal material is the only reliable indicator for the size of the aurochs available as no living aurochs were measured. Complete skeletons are considerably rarer than finds consisting only of fragmentary material or single bone elements, but they are the better indicator for the size of the animal in life. But in order to give an accurate idea of the size of the living animal, it has to be mounted anatomically correct. Alas, most skeletal mounts of the aurochs have anatomical flaws. These flaws can make the withers height of the skeleton smaller or larger, depending on what is wrong. The Prejlerup bull skeleton, however, is mounted fairly correctly. I was unable to find a reliable source on the height of the skeleton. Using a photo of the skeleton in profile view with a person next to it whose height I know, I calculated the withers height of the skeleton and it turned out to be around 190cm. This is the largest size for a complete aurochs skeleton that I know of. However, it must be considered that the skeleton lacks the soft tissue surrounding the bones, so that the skeleton appears smaller than the individual was in life. For example, the intervertebral discs add quite a few centimetres to the length of the skeleton. The connective tissue between the leg bones adds to the height of the skeleton. The hooves alone might add 2 to 3 cm. And lastly, the skin and fat tissue adds one or two more centimetres. Therefore, it is not unlikely that the Prejlerup bull was 5 to 10 cm taller in life than its preserved skeleton. Thus, the bull might have been 195 to 200 cm tall at the withers in life. 

The Prejlerup bull is the largest complete skeleton from the European aurochs, but probably not the largest specimen found so far. Unfortunately, these specimens are not known from complete skeletons but from fragmentary, isolated remains. The perhaps largest European aurochs found is the London skull, exhibited at the British museum of London, which reportedly has a length of 91,2 cm [1]. This is very large, also compared to other aurochs specimens. The skull length in the other skulls observed by Nehring 1889 was between 64 and 72 cm [1]. Unfortunately, I do not have access to the original source by Nehring, so I don’t know if he specified what he means by “length” in his work – the length from the caudal end of the neurocranium to the cranial end of the nasal bone or to that of the premaxilla? I am cautious considering the huge size of the given length and assume it is from the end of the neurocranium to the premaxilla. This is still very large. 

How large was the animal that belonged to the London skull? In the lack of a complete skeleton, there is no other possibility to get an idea of the total body size than to extrapolate the size based on complete skeletons of other bulls. I used photos of four bull skeletons (Prejlerup, Vig, Sassenberg, Store-damme) in clear profile view and started to calculate. At first, I calculated the absolute skull length of the skulls of the skeletal mounts that I know the withers height of, the Sassenberg (165 cm), Prejlerup (possibly 190 cm) and Store-damme (175 cm) specimen in order to check if the calculation is plausible. The results were a skull length of 79 cm for the Prejlerup, 71,5 cm for the Sassenberg and 70,3 cm for the Store-damme skeleton. The latter two are in accordance with what was found by Nehring, the Prejlerup is slightly larger but the whole skeleton is larger than the other two. So the calculation results in plausible skull sizes for the given skeletons. The relation of the skull length to the withers height was 2,4 in the Prejlerup, 2,307 in the Sassenberg and 2,49 in the Store-damme and Vig specimen. Those are very similar values, the Sassenberg bull has the proportionally largest skull, but it has to be noted that it is partly a composite specimen. Under the assumption that the proportions of the London specimen were comparable to the other specimen, I calculated the possible withers height for the 91,2 cm long skull. The results were: 

If the proportions were identical to that of the Prejlerup bull: 218,4 cm

If the proportions were identical to that of the Sassenberg bull: 210 cm 

If the proportions were identical to that of the Store-damme and Vig bull: 226 cm 

If the proportions were intermediary between those of all four: 220,1 cm 

These are very large sizes. But we simply have that skull that was about 28% larger than what was found to be the average by Nehring 1889 – unless Nehring’s 91,2 cm for the London skull are inaccurate. However, I do not know Nehring’s sample size and if his sample was representative of aurochs from the northern half of Europe (which the other skeletons and most likely the London skulls were), and if all of the examined skulls were from males as females were smaller. There is at least one skull that might be comparable in size to the London skull, the Berlin skull. I saw this cranium two times, and I can firmly tell, it is huge. I don’t know if anyone measured that skull, however. But assuming the Berlin skull is of the same size or a similar size as the London skull, are the results of my calculation plausible? 

Well, there are several possible error sources. 

1. Nehring’s 91,2 cm for the London skull might be inaccurate 

2. The bull that belonged to the London cranium might have been oddly proportioned, i.e. with a head larger than usual for aurochs 

3. The photos I used might not reflect the natural proportions of the skeletons (I think they do) 

4. The measurements I took from the photos might be inaccurate or imprecise (in this case, the resulting absolute skull sizes for the skeletons would not be plausible, but they are) 

5. The four specimens do not reflect the variation in proportions within the European aurochs (since the values for the relative skull length are all very similar, except for the one specimen that is partly a composite, I do not think this is necessarily the case). 

The results of these calculations would certainly be more accurate if I had the possibility to take measurements from the actual bones, which I don’t have. But is a size between 210 and 226 cm for the largest aurochs plausible? Large wild yaks reach sizes up to 205 cm, gaur bulls 220 cm, and the extinct Bos (Bison) latifrons is said to have had a withers height of 230 cm. It must be considered, however, that these species have different proportions and longer spinal processes, resulting in a larger withers height. Thus, I am cautious. But I consider the 210 that result from calculating with the Sassenberg bull actually plausible for the largest aurochs. What would definitely be necessary is a) someone has to measure the London skull and Berlin skull to see if they really exceed 90 cm b) other suspiciously large aurochs bones, such as limb elements, pelves etc., should be checked – if they are by one fifth larger than the same elements from the complete skeletons, that is another hint that there were aurochs larger than 200 cm. However, extrapolating the size of an animal based on single skeletal elements is very risky in general. On the other hand, the London skull and the Berlin skull are noticeably larger than the skulls from complete skeletons which we know how tall they are. We need more complete material of very large aurochs to be sure how large they actually were.  

 

Literature 

 

[1] Frisch, W.: Der Auerochs – das europäische Rind. 2010.