Denizens of Madrid’s Miocene woods: the Chalicotheres
Chalicotheres were arguably the oddest of the herbivore mammals we could come across during a time-travel safari to the Miocene of Madrid. Many other animals would look vaguely familiar to us, from horse-like, rhino like and deer-like herbivores, to the elephant-like mastodons. But there is simply no living mammal to which we can compare the chalicotheres, members of the extinct family Chalicotheridae. They were perissodactyls, and thus related to living horses, rhinos and tapirs. But unlike them, chalicotheres had claws instead of hooves, and their body proportions were unique, with forelimbs disproportionately longer than the hind limbs.
Perhaps the strangest of all members of this strange family was Anisodon grande (previously known as Chalicotherium grande). Only a phalanx -fortunately an unmistakable bone- of this animal has been found in Madrid, but complete skeletons are known from fossil sites in France and Slovakia. Those skeletons reveal the striking adaptations of an animal that looked like no other.
In this species the difference in lenght between arms and legs was even more exaggerated than in other chalicotherids, and its detailed anatomy shows that the animal would walk on its knuckles, probably to save its large hand claws from wear. Those large claws would help this browser to reach relatively high branches while standing bipedaly on its hindlimbs.
But, as the hindlimb structure shows, once the animal reached its food, it would sit for long periods to eat it, much like living gorillas and giant pandas do. Not in vain some paleontologists call this unique animal the “horse-gorilla”!
This reconstruction of the skeleton and soft-tissue outline of Anisodon shows the usual posture it would use while munching leaves and twigs. The shape of the pelvis reveals the animal’s ability to spend long periods of time sitting down like this
With such strange body proportions, Anisodon would not be an especially fleet-footed creature, so one wonders, what would its anti-predator strategies be? Most likely it would stand its ground in the face of carnivores, rising tall on its hind legs and using its huge claws as defense. Towering over 2 meters tall, a pissed-off chalicothere would not be an enemy to tackle lightly!