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Monday, 6 April 2015

It's horn time!


Horns are probably the most wonderful body part of a bovine. Each species has characteristic horns, and so had the aurochs. An aurochs look-alike would not be complete if its horns would not resemble their wild ancestors. In order to breed cattle with authentic aurochs-like horns, one has to know what they looked like*. This is not problematic, since there are dozens of well-preserved aurochs skulls with complete or nearly complete horns. But beware that bony horn cores actually do not represent the actual size and shape of the horn because the keratinous sheath is missing. That’s why I did a lot of sketches done by tracking out the original skulls and adding the keratinous sheath. The sheath continues the spiral-like curve of the bony core and adds about 8% in diameter and 10-20% in length. Recently I did 22 reconstructions of aurochs horns based on photos of skull material that I am going to present here.



* For a detailed description of what the horns of this species were like, go here.

 


a) Location and age unknown to me. Rather wide-ranging and large – Pleistocene?

b) Italy, Pleistocene. Massive horn cores and skull, definitely male.

c) Britain, age unknown to me.

d) Germany, age unknown to me.

e) Germany, age unknown to me.

f) Location and age unknown to me. Likely male.

g) Germany, Pleistocene. Really wide-ranging horns.

h) Britain, Holocene. Likely a cow.

i) Italy, Pleistocene. Slightly asymmetric. Very likely a cow.

j) Denmark, early Holocene (Preljerup). Decent inwards-curve. Definitely a bull.

k) Italy, Pleistocene. Wide-ranging but well-pronounced curve. Likely a male.

l) Austria, Bronze Age. Wide-ranging. Likely a cow.

m) Germany, perhaps Holocene.

n) Britain, Pleistocene. Large specimen with impressive horns. Definitely a male.

o) Denmark, early Holocene. Wide-ranging, long-snouted à male.

p) Location unknown to me but perhaps Britain, age unknown to me. Wide-ranging, probably a cow.

q) Germany, age unknown to me. Well-pronounced curvature. Probably a bull.

r) Denmark, perhaps early Holocene. Rather upright and large horns, long skull. Likely a bull.

s) Denmark, early Holocene (Vig). Rather upright and weakly curved, long rostrum. Likely a bull.

t) Location and age unknown to me. Rather thick cores. Male.

u) Poland, age unknown to me. Long snout and small orbital openings à male.

v) Poland, age unknown to me.



It’s interesting to see the amount of variability regarding horn shapes regarding orientation relative to the skull, size and how far they curve outwards. According to Cis van Vuure, the orientation of the horn varies from 50° to 70° degrees, but using a photo I measured that the horns of the Vig bulls have an angle of about 80°, and that other bull from Denmark with the upright horns had probably an even higher angle. But the basic curvature itself is always the same (see the post linked above). In the sample presented in my drawings you won’t find a pair of horns that is even remotely lyre-shaped or facing straight outwards, or any other deviant shape.

I have been wondering why the horns of the aurochs were that variable. When you look at the horns of other wild bovines, they are rather stable. OK, the horn sample we have covers a large geological and geographical scale. But there is no clear gradient, neither in time or location, so the variability is found within the same population (one exception: I noticed that southern aurochs had a smaller angle between horns and snout than northern ones, with those Danish bulls on the one and the oldestAfrican aurochs skull at the other extreme. I assume that this is likely a result of genetic drift.)

One explanation could be that the selective pressure on one particular horn type was not that large as in other bovines, but that argument is not very strong because the horns of the aurochs were in more active, functional use than those of gaurs or banteng for example. Another explanation is that the population of the aurochs increased very rapidly as it spread over Europe and went through only through little genetic bottlenecks. But this idea does not satisfy me completely as well.



When you look at the horns as they are illustrated above, you might notice that some of them match very well with those of some modern day cattle. A lot of those horns resemble those of some Watussi and Heck cattle of the Wörth and Neanderthal lineage. Others also resemble those of a number of Highlands, Barrosa and also Texas longhorn. And of course, there are those with the “Iberian” type of horns as well.




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