The time is about 3000 B.C. and Neolithic humans arrive on a small Mediterranean island which will carry the name “Majorca” (or “Mallorca”) in the future.
The island is barren, animals that live here struggle to find a food source. For some time, the biggest mammals the humans that just arrived encounter are several types of shrew and mice. Until it appears, tiny, a bit clumsy but without fear: Myotragus balearicus, the Balearian mouse-goat.
By Xavier Vázquez 1
Today, we think that the arrival of humans was the death sentence for this special kind of goat. Totally isolated, it had been the victim of insular dwarfism caused by the lack of food. Missing any natural predators, it probably suffered a similar fate as the Dodo bird.
But what’s so special about this tiny goat?
For one, it looked slightly different from the goats we know today, mostly because of its teeth which gave the mouse-goat its name. The ever-growing incisor tooth is typical for rodents, not for goats and sheep. Additionally, it had front facing eyes like we do, which enabled 3D vision.
By Nachosan 2
But what is a lot more fascinating is the fact that the bones of this animal look a lot more like the ones of a reptile than of a mammal. Why?
Mammal bones show a constant growth, which comes with a constant need for food. Reptile bones, on the other hand, look similar to the cross section of a tree trunk, because they have a cyclic growth pattern. The mouse-goat shares this growth pattern.
By Biswarup Ganguly 3
This anomaly led several people to believe that the goats might have been cold-blooded. Were they? We can’t prove it but it's more likely that they just achieved a growth pattern similar to reptiles by adjusting their metabolism and growth to the hostile conditions.
Still, the thought that there might have a cold-blooded mammal 5000 years ago is pretty exciting. And who knows what evolution brings in the future?
Dwindling resources might force other mammals to evolve in a similar way, thousands or millions of years from now. It’s a shame we can’t stay and watch.
Sources:
Myotragus Balearicus, Extinction of Mouse-Goats
Mitochondrial DNA from Myotragus balearicus, an extinct bovid from the Balearic Islands
Goat Lived Like a Reptile -- A First
Picture Credit:
1 By Xavier Vázquez (Cosmo Caixa, Barcelona) [Public domain], via Wikimedia Commons
2 By Nachosan (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
3 By Biswarup Ganguly (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
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