The skeletal remains of Hyracotherium, a dog-sized horse-like creature at the Smithsonian National Museum of Natural History in Washington, D.C.

“Did you know horses were once as small as dogs?” My nephew said when his brother noticed the amount of dog, cat and horse art scattered on my household walls.

“It’s true,” he insisted. “Millions of years ago.”

Ok, I said, a bit skeptical become sometimes he gets superhero stories and science a bit mixed up.

But dare I doubt the recall of the dinosaur obsessed.

Behold. There it was in front of me: the skeletal remains of Hyracotherium, a dog-sized horse-like creature at the Smithsonian National Museum of Natural History in Washington, D.C.

According to the Smithsonian, about 55 million years ago these house-pet sized early members of the equine family scampered through forests across North America. Apparently, horses remained small for more than half their evolutionary history. They slowly evolved into grassland dwellers as climate conditions changed about 20 million years ago, and got bigger….

But not steadily bigger. One type of early horse called Nannippus, was actually smaller than its predecessors.  Some (not all) equine-like species became the majestic hoofed grazing animals we love today. The Dinohippus is the closest to the modern horse.

Hooves, not size, seemed to have made the difference. According to the Smithsonian, a number of three-toed species that did not evolve a single hoof went extinct. And for a time, small and large horse species lived in forests side by side. (Picture miniatures among a full-sized herd.)

I spent time looking at this little Hyracotherium, thinking about how well he would have fared if he – or those like him – didn’t evolve into the useful beast of burden size they are today. Would they have been cute household pets or animals on the endangered list as their habitats are consumed by condo development? If they weren’t a useful size, would they have even been domesticated?

What I do know is if I had learned about these ‘dinosaurs’ as a horse-loving little girl – not the monster creatures many boys love to hear roar – I might have taken more interest in grade five-science class.

The Smithsonian National Museum of Natural History

Side note:

The Smithsonian National Museum of Natural History is awesome (along with all the other – free- Smithsonian museums in D.C.).  The Natural History Museum is home to 126 million artifacts including the African Bush Elephant greeting visitors since the 1950s, more dinosaur skeletons than you can shake a bone at, and the Hope Diamond. Yes, that Hope Diamond.

[Like Washington D.C? Let us know in the comments section. Then check out a related post about The Briscoe Western Art Museum.]