One of the rare disagreements between my parents came early in their marriage. My dad, George Mitchell, a biologist, had shot a magnificent buck pronghorn, had had its head taxidermied, and then wanted to give him pride of place in my mother’s elegant living room.

My mother, Constance Mitchell, a modern painter who carefully curated her surroundings, was horrified. Immune to Dad’s protestations that this pronghorn was, as he wrote in his journal, a “museum-quality specimen,” she banished the stuffed beast to the rec room in the basement where it promptly became a quizzical witness to our family life. It was so lifelike that it often seemed to me it was simply passing by and had thought to poke its head through the wall, keen to see what we were watching on television.

Dad was right about one thing. Pronghorns are majestic to begin with, but this fellow was something special: inky Y-shaped horns as thick as my wrist, square snout splotched with black, supersized dark eyes tipped with long lashes, a pair of white chevrons running down the buff of his throat. Even after decades on the wall, his ears were pricked so high I could almost feel him listening in on our conversations.

My dad, who died in June 2017 at 91, loved that pronghorn. But not just that one. He loved the whole species, Antilocapra americana. In his 1980 book, The Pronghorn Antelope in Alberta, my dad refers to his passion as an affair of the heart that never lost its fire. Maybe it was the lure of the unknown. The pronghorn was a scientific mystery when my dad was hired as the Alberta government’s first game biologist in 1952 and began to study it.

Even the basics were obscure. At what age did pronghorns begin breeding? How many young did they have? What did they eat? How did they survive the winters? How many were there in Alberta and Saskatchewan, the very northernmost tip of its continent-wide range? How many had there been? All unknown. But unless you knew this most elementary information, how could you predict whether they would stick around? He set about the messy, painstaking, life-consuming business of finding out.

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The pronghorn’s ancestor evolved in North America around 25 million years ago. Eventually, that ancestor, Merycodus, spawned a family of about a dozen species of hooved grazers from one the size of a jackrabbit to the lone, big survivor that became swift enough to race the hungry cheetahs and fearsome hyenas that then populated North America.

But while the cheetah, hyena and all the other pronghorn relatives died out in North America — the pronghorn’s closest genetic relative today is the giraffe — Antilocapra americana triumphed. And while it is the fastest land-runner in the Western Hemisphere, clocked in a sprint at 100 kilometres an hour, its unique gift is its ability to go the distance, literally and metaphorically. It has an uncanny ability to convert the oxygen in its muscles into velocity, to keep up a car-level pace for 10 minutes.

The pronghorn survived not only the climate stresses of the ice age, but also the arrival of humans, becoming the main grazer of the North American Great Plains. Its range exceeded even that of bison.

Theodore Roosevelt, 26th president of the United States, was fascinated with what he often called the prong-horn antelope, writing about its tremendous speed, sharp sight and sweet meat. But he confessed himself baffled by its behaviour.

“Antelope possess a most morbid curiosity,” he wrote in his 1885 book Hunting Trips of a Ranchman. “The appearance of any thing out of the way, or to which they are not accustomed, often seems to drive them nearly beside themselves with mingled fright and desire to know what it is, a combination of feelings that throws them into a perfect panic, during whose continuance they will at times seem utterly unable to take care of themselves.”

All hunters had to do to attract a pronghorn in those days was wave a red handkerchief at it, Roosevelt writes, and, fatally inquisitive, it would draw ever nearer, stamping and snorting, until it got within rifle range.

By the time my father was born in 1925, the pronghorn was near extinction. From a North American peak population of about 35 million a century earlier, the species was reduced to as few as 13,000, says John Byers, a zoologist at the University of Idaho who has studied the animals for 35 years. That’s a drop of 99.996 per cent.

The reasons? It was hunting, some of it to feed a trade exporting wild meat to Europe; it was the campaign to rid North America of wolves, grizzlies and cougars, because when they were gone, the coyote reigned to feast on pronghorn fawns; it was the miserable cold and deep snow that plagued the start of the 20th century.

And it was fences. Although pronghorns can jump — Byers has seen one jump over a human — they choose not to. They always think there’s another way around. But as the Prairies became more settled, fences began to abound. Pronghorns, many of which migrate hundreds of kilometres a year seeking food, could no longer get through.

When my dad started studying them, their numbers had crept up thanks to a continuous closure on pronghorn hunting, but they were still in considerable peril. I spent my childhood summers scanning the Prairies for them. My family would be driving along the Trans-Canada Highway from Regina, where my dad began teaching at the university in 1966, to the Pacific Ocean — “the coast,” we called it.

Pronghorns travel in herds, white bums flashing, legs seemingly too spindly to hold up their robust bodies, terribly alert. Every time I saw them then, I was overcome with wonder at their synchronized speed. I had no idea that they had once been so much more plentiful. And despite my dad’s chops as an ecologist, I had no idea then that pronghorns are remnants of what was once a far richer dance of life on the Great Plains, with the extinct pronghorn kin and cheetahs and hyenas, but also dire wolves, giant short-faced bears, lions, jaguars, mastodons, woolly mammoths and ground sloths, among many others.

“In the hurtling pronghorn, the vanished predators have left behind a heartrending spectacle,” writes the journalist William Stolzenburg in his 2008 book Where the Wild Things Were: Life, Death, and Ecological Wreckage in a Land of Vanishing Predators. “Through the smoking displays of wild abandon runs a desperate spirit, resigned to racing pickup trucks in its eternal longing for cheetahs.”

Watch Alanna Mitchell read an excerpt from this story: