History Files

Please help the History Files

Contributed: 84

Target: 400

Totals slider

The History Files still needs your help. As a non-profit site, it is only able to support such a vast and ever-growing collection of information with your help, and this year your help is needed more than ever. Please make a donation so that we can continue to provide highly detailed historical research on a fully secure site. Your help really is appreciated.



Cenozoic World

The Birds which Ate Horses

by Helen Briggs, 14 November 2001. Updated 14 January 2018


A spectacular new fossil of a tiny ancient horse helped to shed new light on the evolution of equines.

It was discovered that a developing foal inside the pregnant mare had been been preserved in remarkable detail. The fossil was found at the Messel open-pit mine in Germany, where more than seventy specimens of ancient horses had been unearthed by 2001.

Dr Stephan Schaal of the Senckenberg Research Institute, Germany, said that the find of the adult horse included the best preserved foetus ever discovered in Messel. Compared to other Messel horses, it had impressive preservation of the complete jaws with its teeth.

These forest-dwelling horses came from the Eocene Optimum, 49 million years ago, a period in which tropical forests stretched right to the poles, little or no ice was present on the planet, and temperatures at the poles varied less from the equatorial norm than they do today.

Killer birds

The largest of these early horse-like mammals were about the size of a pig, and giant stalking birds, Gastornis, took the role of top predators. Gastornis was a giant of its time, one of the largest animals of the Eocene at two metres tall. It is thought to have been a predator because its huge beak would have been far too powerful for simply crushing nuts and other vegetation, and it also had impressive talons on its toes.

Two species of the tiny forest-dwelling horses, Propalaeotherium, are known from fossil evidence at Eocene sites in Germany. These little forest animals had four small hooves on their front feet and three on the back. They walked on the pads of their feet, like cats and dogs.

The smallest of the samples found was the size of a fox terrier, and the largest about the size of a German shepherd dog. The stomach contents of most specimens show that they ate foliage, but one was full of fruit - a grape similar to that which is used to make wine.

Scientists believed the mammals browsed on whatever they could, including fallen fruit when it was available. This fossil also helped to shed light on how these ancient horses raised their young. All of the ten fossils of pregnant mares found at Messel were carrying one foal.

Running with the herd

This was evidence, according to palaeontologist Dr Jens Franzen, that even primitive horses had an evolutionary strategy of raising one or two offspring. That would point to some kind of special care of the offspring and would indicate that there was a herd involved in joint care.

The horses had just begun to diverge away from the group of odd-toed mammals, or perissodactyls, which were the common ancestors of living horses, rhinos, and tapirs. They had five toes which, over the course of evolution, fused into the one hoof found in modern-day horses.



Some images and original text copyright © BBC or affiliates. Reproduction is made on a 'fair dealing' basis for the purpose of disseminating relevant information to a specific audience. No breach of copyright is intended or inferred.