A close, fast encounter with a pronghorn
July 29, 2022
I was in the Oklahoma panhandle in late June for fieldwork in the Morrison with Anne Weil and her crew at the Homestead Quarry. It’s always a fun trip, in part because we see a lot of wildlife out there. One of my favorite panhandle critters, and in fact one of my favorite animals, period, is the pronghorn, Antilocapra americana. Pronghorns are North America’s fastest land animals, and probably the fastest land animals in the world after cheetahs. That’s because they evolved to outrun American cheetahs, Miracinonyx, which went extinct about 12,000 years ago. Once you are familiar with pronghorns, you could never mistake one for a deer. Body profile alone is enough to tell, even at great distances: deer are graceful-looking animals with long, tapering legs, whereas pronghorns look like lozenges on stilts.
On June 21, we were heading back to Black Mesa after checking out some new-to-me Morrison outcrops north of Boise City, Oklahoma (see Richmond et al. 2020). I was driving my Kia Sorento, with a couple of students also in the truck. I came over a hill going about 65 mph (105 kph), and a female pronghorn that had been grazing in the ditch decided that would be the perfect time to bolt across the road. I thought I was about to have a fairly disastrous high-speed collision with a large-ish ungulate, but between my braking and her veering off a bit, we narrowly missed colliding. Instead, she ended up running down the road, parallel with my truck, seriously about 1 meter ahead and left of the driver’s side front tire. For a few seconds, I was driving 55 mph (89 kph) and she was keeping pace, and it didn’t look like she was really taxing herself. Then I realized that she was technically out ahead of the bumper and could still decide to run in front of the truck, so I accelerated and got past her, but the key point is that I had to speed up to about 60 mph (97 kph) to do it. Once I was past her, she trotted to a stop and stood in the middle of the road, watching me drive off (the road ahead was empty, and I was watching her in the rearview mirror).
I’ve read other anecdotal accounts of people driving alongside pronghorns that were really booking it — some memorable ones are recounted in the Guinness Book of Animal Facts and Feats (Wood 1982) — but I never imagined that I’d get to experience something like that. It was cool as heck, and one of the best wildlife encounters of my life. It all happened too quickly to get any photos, so I’m illustrating this post with pronghorn photos I got on a stargazing expedition to Black Mesa in September, 2020. I also have some half-decent pronghorn photos in this post from 2016.
References
- Richmond, D.R., Hunt, T.C. and Cifelli, R.L. 2020. Stratigraphy and sedimentology of the Morrison Formation in the western panhandle of Oklahoma with reference to the historical Stovall dinosaur quarries. The Journal of Geology 128(6): 477-515.
- Wood, G. L. 1982. The Guinness Book of Animals Facts & Feats (3rd edition). Guinness Superlatives Ltd., Enfield, Middlesex, 252 pp.
Sauropod Vertebra Picture of the Week 
July 29, 2022 at 3:02 pm
Fantastic experience!
Here is what I don’t get, though:
That works as a just-so story, but then why did all the American deer not also evolve cheetah-speed to avoid the same predator?
July 29, 2022 at 4:13 pm
What is the consensus on the fastest known ornithomimid ?!? Could a cheetah even catch it ?!?
July 29, 2022 at 5:02 pm
Mike, different habitats.
Cervids in North America (except caribou) are overwhelmingly woodlands creatures as opposed to plains.
July 29, 2022 at 5:12 pm
That works as a just-so story, but then why did all the American deer not also evolve cheetah-speed to avoid the same predator?
Because deer prefer more brushy and forested environments, whereas pronghorns are creatures of the plains. You might as well ask why not all antelope can run as fast as gazelles.
Also, all North American deer are significantly bigger than pronghorns on average, and could probably stand their ground against cheetahs. When African cheetahs charge a group of gazelles, sometimes the larger (usually male) gazelles will just stand their ground, and the cheetahs bypass them to go after the runners. There’s a hypothesis that cheetahs are really only good at tripping running prey, and would struggle to take down a large gazelle in a straight fight, so they don’t try. (I’m sure it’s happened, but it’s not common. This is probably part of the reason why most antelope can’t run as fast as gazelles — they don’t have to, because cheetahs don’t usually try for them.)
In any case, the coevolution of pronghorns with American cheetahs is the best idea anyone has come up with for why pronghorns are so much faster than wolves and cougars.
What is the consensus on the fastest known ornithomimid?
I have no idea, and I also have no idea how we’d even know with any certainty.
Personally, I don’t even trust “top” speeds for extant animals. The pronghorn I drove beside was doing 55 mph at least, which is what most sources report as the top speed for the whole species, but that was just one random female pacing an SUV for a bit. I’ll bet that the Usain-Bolt-equivalent pronghorn running for its life could go a fair bit faster. Same for cheetahs, ostriches, etc.
July 29, 2022 at 5:33 pm
(Don’t forget that your car’s tachometer is probably lying to you, so “55 mph” is more likely around 52 or 53. I mean, still no slouch.)
So there are no smaller plains browsers in the USA than pronghorns?
July 29, 2022 at 5:48 pm
There were dwarf pronghorns, Capromeryx, in North America in the late Miocene, but they seem to have gone extinct before the evolution of the American cheetah in the Pleistocene. I’m pretty sure that after pronghorns, the next-smaller cursor on the plains of North America is the jackrabbit, Lepus.
Good point about the tach.
July 29, 2022 at 5:49 pm
Immediate update: I am woefully ignorant of the variety of small ungulates that existed in North America in the Pliocene and Pleistocene, so it’s possible that I’m missing a lot of relevant critters that only went extinct very recently, which should be in the conversation if we’re talking about the evolution of plains-running animals.
July 29, 2022 at 7:43 pm
My son pointed out to me how much pronghorn skulls look like giraffes’.
In a race, the pronghorn would get across the finish line first, but the giraffe would win anyway, by a nose.
July 29, 2022 at 8:36 pm
I love pronghorn.
The two Pleistocene genera which come immediately to my mind are Stockoceros and Tetrameryx, which lived alongside the modern genus until about 12,000 years ago. As far as I know, they’re both about the same size as the living pronghorn (which are small animals – maybe 1.2m at the shoulder, from memory). Both would have appeared to have four horns at a distance, though technically they had two, but their horns were branched close to the base. The actual four-horned Pleistocene pronghorn was Hayoceros, which was slightly larger, but still not a particularly big animal. I’ve always wondered if these various extinct pronghorn could run as fast as the living pronghorn.
(Antilocaprid horns are curiously different from bovid horns in that they have a permanent bony core, and an annually discarded keratin sheath, and they can be branched, causing some to argue they’re not technically horns, but their own weird thing.)
I seem to recall that their amazing speed isn’t a perfect defense; I’ve read puma, wolves, bobcat, and golden eagles occasionally take pronghorn. And I’d wager jaguar will take pronghorn occasionally where their range overlaps in Mexico.
All the places I’ve actually seen pronghorn have somewhat irregular ground and lots of vegetation that is about as tall as a pronghorn, so I’d guess trying to get a good measurement of a wild pronghorn’s speed in a safe, ethical, and repeatable fashion would be really hard.
I think the blog synapsida.blogspot.com did an overview of Pleistocene herbivores in north america quite a few years back, I should go look for it.
Finally, although I’m not an expert, I seem to recall Capromeryx, at least Capromeryx minor was still around in the Pleistocene, and it was quite small – 60 cm at the shoulder is the estimate I seem to remember.
July 29, 2022 at 8:56 pm
ok I think the overview I was looking for is mostly in these two blog posts:
https://synapsida.blogspot.com/2013/08/pleistocene-pt-10-of-armadillos-and.html
https://synapsida.blogspot.com/2013/06/pleistocene-pt-9-before-bison.html
Unfortunately they’re mostly about animals larger than pronghorn, though I’d guess one of the pampathere and one of the armadillos is somewhere between the hares and the pronghorn in size, though in most cases it’s not specific about sizes.
Capromeryx minor is mentioned in part 9, which is about the Irvingtonian, the part of the Pleistocene just prior to the Rancholabrean
Also those blog posts are about 10 yrs old …
July 29, 2022 at 9:32 pm
So there are no smaller plains browsers in the USA than pronghorns?
Jackrabbits are definitely smaller with very similar diets. (Which is seasonal grazing or browsing, not only browsing.)
July 29, 2022 at 10:04 pm
arrgh – with respect to pronghorn height, I made a typo, I meant maybe 1m at the shoulder, not 1.2m. Plenty are less than a meter. Also, pronghorn are leggy animals – I doubt they are as heavy as one might guess from that height.
July 29, 2022 at 10:34 pm
I decided to look up pronghorn size, which is what I ought to have done in the first place. According to the entry on the animaldiversity website, pronghorn females stand 860 mm at the shoulder and males 875 mm at the shoulder. This is somewhat less than 1m – I think the 1m I was thinking of was the maximum from a range, probably from wikipedia, which gives a range of 81-104 cm at the shoulder for males.
refs:
https://animaldiversity.org/site/accounts/information/Antilocapra_americana.html
https://en.wikipedia.org/wiki/Pronghorn
The animaldiversity entry has a nice overview of their adaptations for running, including some of their skeletal adaptations, for example:
“Pronghorns have unguligrade foot posture, which lengthens the legs by allowing them to stand on the tips of their digits. The length of the radius bone is as long, or longer, than the femur. The ulna is reduced and partially fused to the radius. The clavicle in ungulates has been lost and the scapula has been reoriented to lie flat against the side of their chest where it is free to rotate roughly 20° to 25° in the same plane in which the leg swings. The ulna and radius have been reduced to eliminate the twisting and rotating of the elbow. The reduction of bone and associated muscles in the distal limbs decreases limb weight, giving them more speed. Pronghorns have modified their joints to act as hinges allowing only motion in the line of travel. This has been done by introducing interlocking spines and grooves in their joints.”
This last part seems different from what I recall of cheetah and Thompson’s gazelle, which I think are highly adapted for sharp turns.
July 30, 2022 at 4:02 am
That’s a lot of great information — many thanks!
July 30, 2022 at 4:23 am
Great experience! I had a similar encounter with an emu who ended up running in front of my car for a while – dense bush on each side if the road made it hard for it to get away from the road for a few hundred metres. But the speeds involved were much lower – about 40 km/h from memory.
Mike T: I don’t know about deer in N. America, but the ones here are very rarely seen away from dense scrub / woodland. From what I’ve heard of Pronghorns they don’t mind more open habitats, which maybe put them at greater risk of cheetahs. But I’m guessing, mainly.
July 30, 2022 at 7:56 am
There seems to be a sweet spot for super fast animals; jack rabbits are too small and horses are too big.
As well as pronghorns and cheetahs super fast animals seem to include saiga antelope; gazelles( Gazella, Eudorcas, Nanger and Procapra); blackbuck, and springbok.
Hartebeeste and the Tsessebe, Topi, Tiang group (Damaliscus) are a bit larger but are also very fast and have huge amounts of stamina.
Reportedly the Boer used to try to hunt them from horseback but even a wounded animal could keep running ahead of a horse as long as one tried to chase it.
I have seen on television a person driving a vehicle along a modern road in Saudi Arabia and some gazelles showed up alongside the road and had no trouble keeping pace with the vehicle for a minute or so before they veered off.
Ostrich reportedly also can reach extreme speed but I have seen on television a group of male cheetah hunting and catching an ostrich.
Also I read about a cheetah chasing a gazelle(I don’t know which species) and the gazelle tripped and was caught almost immediately; the cheetah was then unable to hold down the struggling gazelle which subsequently escaped.
Normally captured gazelle are winded by running at top speed so are easily choked by cheetah.
This suggests that large gazelle in the genus Nanger may be more difficult for single cheetah to catch although groups of males probably would succeed.
August 4, 2022 at 11:24 am
What a fabulous encounter! Possibly relevant:
Janis, C.M. and P.B. Wilhelm. 1993. Were there mammalian pursuit predators in the Tertiary? Dances with wolf avatars. J. Mammalian Evolution 1:103-125.
The authors posit that cursorial adaptations in ungulates evolved long before those of carnivorans, and their adaptive value lies mainly in allowing animals to reach sparse or patchily-distributed resources quickly and efficiently; the ability to outrun predators is a nifty side benefit, not the driver of these adaptations.
Whether this applies to the hypercursorial adaptations of pronghorns, I don’t know. Some of the South American proterotheriids were similarly shaped to pronghorns and single-toed, but AFAIK South America had no cheetah-like predators at that time.
August 4, 2022 at 4:13 pm
I accidentally surprised a herd of these creatures from about 100 yards away while hiking Black Mesa at sunrise in 2019. The alpha male coughed and snorted at me before bolting off with the herd following closely. A few minutes later I spotted them with binoculars up on a ridge line looking down toward where I was walking in the valley. I was definitely being watched!
August 4, 2022 at 6:33 pm
Super-interesting stuff, everyone, especially the idea that ungulates did not initially evolve cursorial adaptations to outrun carnivores. Although I wonder how much a carnivore actually has to look ‘cursorial’ to be an efficient ambush or burst-speed predator. Badgers and bears don’t look particularly cursorial, but they’re fast as hell when they want to be, and I’ve seen some horrifying videos of grizzlies running down caribou and other deer. Still, the mismatch between body plans is food for thought (then and now, I guess).
I remember out in the Cloverly Formation in 1998, the pronghorn would come to the edge of a bluff to watch Scott Madsen and me prospecting. They were definitely keeping an eye on us.
August 5, 2022 at 3:28 am
@nathanparker11
The prototheriids may have had to evade Phorusrhacid birds.
Some of those look like they would have made efficient cursorial predators.
August 5, 2022 at 10:52 am
@LeeB – Good call on the phorusrhacids, I was only thinking about mammalian predators.
@Matt Wedel – Even non-cheetah felids have fairly short limbs and super flexible trunks, sort of the opposite of cursorial adaptations. Non-cursorial animals are not necessarily slower sprinters than cursorial ones, they’re just not as good at marathons. Supposedly. I’m not sure how much the argument from morphology has been tested by analysis of the performance of actual animals.
August 7, 2022 at 6:23 pm
Nathan Parker’s comment remiminds of something that has always confused me: biologists (especially in popular communication) often write about cursoriality as if sprinting and distance-running are the same thing, and I don’t understand why people think that; to me they seem like different things that have a few overlapping requirements, but even more conflicting requirements.
It seems to me that if you want to sprint, you accelerate has hard as you can until you’re done, but if you want to run a long distance, you do NOT start with a sprint; you accelerate gradually until you reach a fixed speed you can maintain for the distance, and then you spend the rest of the run AVOIDING acceleration as much as feasible; you avoid speeding up, you avoid slowing down (which is also a form of accleration), you avoid turning (also a form of accleration), as much as the track you’ve chosen to run allows. (An exception would be the kind of running in which several runners run in a line, and every so often, the runner at the end of the line sprints to the front of the line – but that form is specifically designed that way *because* it is intended to super-arduous; it combines conflicting types of exercise in order to be extra difficult. )
You see a similar phenomenom in cars; most cars that are fuel efficient have mediocre 0-60 accleration, and most cars that have good accleration have mediocre fuel efficiency.
Further, accleration requires changes in gait, and changing gait is easier if you’re flexible, but if you’re trying to maintain a steady speed, that same flexiblity wastes energy.
So here’s my question: does “cursoriality” refer to sprinting, or to distance running?
August 8, 2022 at 12:00 am
From what I’ve read, mammalogists definitely consider “cursorial” animals to be those with adaptations for distance running. The classic hallmarks are limbs with long distal segments and short proximal ones with the muscle mass concentrated as much proximally as possible; joints that limit limb movement outside of the parasagittal plane; reduced digits; digitigrady or unguligrady; and often a stiffened torso. Wolves and horses are the paramount exemplars, as well as many of the artiodactyls.
I don’t know of a term for rhinos, felids, bears, and other animals that are great at charging but not so good at cruising.
It gets a little hazier when “cursorial” is applied to birds and other archosaurs. Ostriches tick off all the boxes, but do roadrunners or seriemas? I’ve seen both of these described as cursorial.
The term is often used in a relative sense, in that a cursorial animal is one that seems better adapted for sustained movement at a moderate pace than do its close relatives. Paleontologists speak of cursorial crocodylomorphs, for example, which I doubt would be considered cursorial by mammalian standards if applying either morphology-based or performance-based criteria.
August 8, 2022 at 5:36 am
There is complicated overlap in that animals like pronghorns or gazelles can sprint at really high speed when they put their mind to it but can also run at lesser speeds for long distances when they decide to disappear over the horizon.
Horses, Hartebeest, Wildebeest and Topi are other good examples of this.
August 10, 2022 at 9:45 am
This makes sense when you look at human running performance. Olympic sprinters are built like bears, and long-distance runners like gazelles. Very different optimisations.