The Rise and Fall of the Bone-Crushing Dogs

Thanks to WIX for supporting PBS Digital Studios In its day, it was quite literally top dog. By some estimates, it could grow as big as
a brown bear. And with its powerful jaws and stout teeth,
it was not only a skilled hunter — it could also crack open the bones of its prey. It’s known today as Epicyon, and it stalked
North America from sixteen million to seven million years ago, during the Miocene epoch. The largest of these creatures were the most
massive dogs that ever lived. But they weren’t like the dogs that we know
today. Epicyon hailed from a lineage known as the
Borophaginae, often known by their more common — and way more metal — nickname, the “bone-crushing
dogs.” A huge and diverse subfamily of dogs, the
bone-crushers patrolled North America for more than thirty million years, before they
disappeared in the not-too-distant past. So what happened to the biggest dogs that
ever lived? Part of what happened to them was … dogs
as we know them. Our dogs. And another thing that happened to them? Cats. The only important thing that Epicyon has
in common with your golden retriever or whatever is that they’re both canids. Dogs, wolves, foxes, and all their kin belong
to the family Canidae. Today there are 34 species of canids, from
the leggy maned wolf to the big-eared fennec fox. Now, some experts think the earliest canid
was a small, weasel-like creature called Prohesperocyon, which first appeared about 36 million years
ago in southern Texas. Not everyone’s convinced that Prohesperocyon
was a canid, though. It may have been part of a different group
of mammals, called the Miacidae, which shares a common ancestor with modern carnivores. Either way, every canid — from the giant
bone-crushers to the pup that’s probably watching this with you right now — all share
some key traits. They all eat meat, though there are some that
eat plants and invertebrates once in a while. And other distinguishing trait can be found
in their ears. Canids have hollow bony structures toward
the back of their skulls called auditory bullae that protect the delicate bones of the middle
ear. Lots of other mammals have them too. But in canids, they’re especially big, and
it’s thought that these extra large spaces help dogs and wolves hear low-frequency sounds. Now, tens of millions of years ago, some ancestral
canid, whether it was Prohesperocyon or someone else, was the predecessor to the first of
the three great subfamilies of canids. And only one of these subfamilies survives
today. The earliest group was the Hesperocyoninae. These were small, nimble carnivores that were
adapted to the warm, forested world of the Late Eocene. And the founding member of this group was
Hesperocyon, which appears in the fossil record around 37 million years ago in the great plains
of North America. Who’s the cutest little ancestral dog? Aren’t you? Yes you are! It probably ate smaller mammals, and some species may have climbed trees. Because, just like cats, they had fully retractable
claws, a trait that canids eventually lost. As the Eocene transitioned to the Oligocene, the
climate cooled. The woodlands of North America started to
gave way to grasslands. And large herbivores moved into this new environment,
evolving traits that helped them eat grass and run long distances. And as the prey species grew, some of the
hesperocyonines did as well. In short order, this splinter group left the
forests and began hunting the new prey on the new grasslands. For example, one of Hesperocyon’s descendants
was a little critter called Archaeocyon. It appears in the fossil record around 30
million years ago and may be the earliest member of the second great subfamily, the
Borophaginae, the bone-crushers. Unlike its ancestors, Archaeocyon had shorter
jaws and thicker premolars. But, it wasn’t quite ready to actually crush
bone. Instead, Archaeocyon and most of the early
borophagines were small, opportunistic omnivores, kinda like raccoons. It wasn’t until the mid-Miocene that new
species appeared that ate meat almost exclusively and were big enough to start competing with
the largest of that first wave of dogs, the The hesperocyonines. And that’s where mighty Epicyon comes in. One species in this genus—Epicyon haydeni—was
the biggest of the big, thought to be the largest canid of all time. According to one estimate, Epicyon could’ve
tipped the scales at 170 kilograms, making it more than twice as massive as the heaviest
grey wolf on record. But we talked to an expert in bone-crushers
— Dr. Xiaoming Wang at the Natural History Museum of Los Angeles County. And he said that 170 kilos was probably a
low estimate and that the biggest Epicyons might’ve been “substantially larger.” In any case, all the Epicyon species looked
very different from the dogs and wolves we know today. In addition to their distinctive domed foreheads,
they had wide palates and massive cheek teeth. These features allowed them to perform the
feat that would eventually give them their full-metal nickname: They could crunch through
solid bone. They did this to get to the nutritious, calorie-dense
marrow of the bone. And we know this because, in most of the big
bone-crushers, their cheek teeth show distinctive marks — the same marks that modern hyenas
get by gnawing on bones. And some samples of fossilized poop from Epicyon
have even been found to contain bits of bone. Now, for years, scientists thought that these
were signs that borophagines were scavengers. But the more recent thinking is that at least
some bone-crushers actively hunted prey that were as large — or even larger — than they
were. Maybe even in packs. After all, large modern predators like wolves
tend to do the same thing. So there’s no reason to think the borophagines
acted differently. And because they were powerful, but not built
for speed, many experts think that bone-crushers were probably what are known as pounce-pursuit
predators. Like coyotes, they probably chased their prey
for short distances, and then wrestled them to the ground. But, whatever they were doing back then, they
were doing something right. Because, at the peak of their success, six
to twelve million years ago, there were about fifteen different species of bone-crushing
dogs. In addition to the giant Epicyon, for instance,
there was Cynarctus, about the size of a coyote and just as much of an opportunist. Judging by its teeth, most of its diet consisted
of insects and plants. But, by contrast, there was also a lineage
within the genus Aelurodon that became increasingly carnivorous over time. As the Miocene epoch was drawing to a close,
bone-crushing dogs roamed North America from Maryland to California and from Montana to
Mexico. Then their fortunes took a downward turn. One of the culprits in their decline was the
third and final subfamily of canids: The Caninae, the only group of dogs that would be left
standing. Canines first appear a little over 30 million
years ago. And there’s a debate over whether they arose
from small Hesperocyonines or from small bone-crushers. It’s just another of the many fascinating
things that paleontologists are still fighting about. But we do know that one of the first canines
on record was Leptocyon. Which, again, isn’t it super cute? I just want to…boop! It made its debut in the early Oligocene
and was about the size of a fox. Like other early canines, it had a long snout
with thinner teeth. So it couldn’t bring down big game like
horses or camels, but it was adept at catching small, fast prey. But the most noteworthy thing about these
new, early canines was their legs. While Epicyon and other bone-crushers were
getting bigger and heavier, canines slowly developed into cross-country marathon runners. The trend started way back with Hesperocyon,
which had pretty long legs. But by the time Leptocyon showed up, they
were even longer, allowing it to make longer strides. And by the late Miocene, yet another streamlining
trait appeared: the reduction of the “big toe” on each foot. Through natural selection, this fifth toe
shrank away, becoming little more than a tiny nub in some species and disappearing altogether
in others. These shrinking toes helped make canines’
feet and legs lighter. And that, combined with their longer stride,
allowed them to adopt a totally different hunting strategy. Instead of pouncing on their prey like bone
crushers did, canines could run their victims down for hours, until they dropped from exhaustion. If you’ve ever seen a wolf hunt, you know
this is the method they still use today. And this strategy might also explain why canines
are the only dogs that still exist: Because they were best equipped to go up against the
newest and fiercest competitors in North America. You could say they’re dogs’ oldest foes:
cats. And I make this face when I say cats because i’m not 100% a cat person Cats first evolved in Eurasia some 33 million
years ago. But about 14 million years later, they migrated
across the Bering Land Bridge and quickly spread south. And some experts think it was competition
with cats that ultimately did in the bone-crushing dogs. Large new cat species, like Pseudaelurus,
were ambush predators that probably competed with the bone-crushers for the same prey. And simply put, the cats were just better
at it: More efficient, with retractable claws, they had a much easier time wrangling their
prey. So while the canines went on with their own
set of prey and long-distance hunting strategies, the bone-crushers, once the most dominant
of the canids, found themselves struggling for survival. The last of the bone-crushing dogs, a genus
known as Borophagus, vanished about 2 million years ago. And that first subfamily, the hesperocyonines,
had already died out about 13 million years earlier, unable to compete with both and bone-crushers
and the arrival of the cats. So two out of the three canid subfamilies
are dead and gone. And there’s no definitive proof that any
Hesperocyonines or bone-crushers ever left North America. But the canines spread well beyond the continent. They crossed Panama and entered South America,
which now has its own native canine species, like the maned wolf. Further west, canines made their way across
Eurasia and into Africa. And with a little help from seafaring humans,
the forerunners of the iconic “dingo” dog landed in Australia 4,000 years ago. So, if you’re inclined to, you can read
the story of the bone crushing dogs as something of a cautionary tale. It reminds us that being “top dog” isn’t
all it’s cracked up to be. We tend to think of big, powerful predators
as being the ones that rule their ecosystems. But their position is actually one of the
most precarious: When the local environment changes and competition appears, it’s the
large, specialized carnivores that often struggle to adapt. Or if you want, you can just blame everything
on the cats. Now, I want to thank for supporting
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100 Responses

  1. Hannah Hyde says:

    Prehistoric dogs: BONECRUSHERS

    Dogs now: Scared of thunder

  2. TheKeithvidz says:

    Hymn. less than cuddly.

  3. M Oz says:

    I will just blame the cats.

  4. Thomas Gullett says:

    This guy deserved his own TV show.

  5. Evili says:

    If that dog was here today? Get some howitzer cannons.

  6. splendor Inthegrass says:

    damn he is sexy…

  7. CamperKiller says:

    I want one

  8. Krystal Rossi says:

    This guy is a good narrator.

  9. VertigoCrime says:

    I wanna know what that deer looking thing is, it looks so strange yet so cool

  10. gunfighterdrummer says:

    So dogs have gone soft too huh.

  11. Paul W. says:

    I love the brilliant artwork by Jay Matternes.

  12. Billy Campbell says:

    Please give measurements in pounds, feet etc. Its easier to understand. and

  13. fck fracking says:

    Damn it’s like a supersized pit bull. Imagine that damn thing lunging at your throat lol

  14. Sjorben says:

    dogs suck cats are awesome

  15. King gay says:

    It's okay, you just need to find the right cat.

  16. raqFarha says:

    OK, but what was that deer-thing with the hairy Y shaped horn on its nose that the bone crusher was drawn attacking?

  17. Random Nerd Of Doom says:

    I think modern dogs are the smartest animals ever….they domesticated us to feed them and take care of them and they don’t have to do anything in return.

  18. Billion Dollar says:

    Raccoons are dogs wow

  19. Jacob Dennis says:

    Guy looks like he's on meth

  20. Black Mamba says:

    I blame the cats

  21. jake saenz says:

    i balame cats

  22. Larissa Rose Tracey Nuñez-Hill says:

    If u havent done a video on bear dogs can u?

  23. Nkosi Rooms says:

    If all animal's fade out so will humans one day maybe buy are own creation like transformers are something haha.

  24. David Stewart says:

    Great video and informative … BUT speak slower … you are not in a race

  25. AlphaAlfred says:

    Why is this episode about the dog and NOT THE HAUNTING CREATURE THE DOG WAS HUNTING THAT WAS THE COVER. Wtf was that 1/10 scary eyes, too many horns

  26. Kevin Kaythanrodrigolage says:

    Criticism to cats >:(

  27. Savage Facts says:

    A bunch of pictures and computer animated stuff here, lets shows a few pic and skulls from random animals and say it belonged to a dog.

  28. Dr S4T4N says:

    Bone crusher looks a bit like Pitie bull

  29. anj bantaya says:

    .i would love to learn history,but the way you speak it make me stupid

  30. Joy to the Marshmellows says:

    Ok but imagine an animal that was basically a mix between a dog, a ferret, and a cat. That would be the most adorable thing ever, wish they were still around today.

  31. hectorsoy says:

    Imagine the size of their poop!!! It was bad enough picking up the poop of my german shepherd!

  32. Alfredo Forte says:

    You showed a picture of a hyena while talking about dogs…my understanding is that hyenas are really cats..

  33. Bobby Babylon says:

    today kangal dogs are the biggest bone crushing dogs

  34. Bizzy Beast says:

    For some reason I think dogs where mans worst friend

  35. Mazin Bazon says:

    I don't see how the cats could kill those dogs they grow as big as a bear and a lion isn't that big

  36. Porter Helfer says:

    Does anyone know what th a animal it’s chasing in the thumbnail is?

  37. Macus Aurelius says:

    "Some experts think"??? Sounds like a lot of expert speculation.

  38. Will Janzen says:

    Are we sure that Hesperocyoninae didn’t evolve into cats? I think there are fossils out there just waiting to be found by archeologists that will turn the fossil record on its head.

  39. Dirk Frey says:

    Great video. Only one issue. You say the Epicyons look very different from modern canids. Yet you repeatedly show artwork of something that looks like a very doggy, large dog. No domed forehead nothing. Great art… but seems completely inaccurate by what you explain.

  40. pink unicorn says:

    Cats rule 👑🐈

  41. Michael O'Neill says:

    But dogs evolved from wolves??

  42. WWTormentor says:

    Can you do a video on the evolution of modern cats including the big cats such as lions. Thank you

  43. Paul Whitfield says:

    Ps : 50,000 years dingo
    We all ready had marsupial cat / dog /tiger..
    Still here..
    The story of my people .
    Thank you..
    We feel ..

  44. shrimpisdelicious says:

    So, dogs adapted to a strategy of running prey down long distances, did they?

    Sounds familiar…

  45. Ghostdog says:

    American Bullenbieser and American XL Bullies look like Bone Crushers in a way ..

  46. C Ul says:

    Great video – I just wish it started a little further back with the common ancestor of cats and dogs.

  47. Carol Peletier says:

    blame it on the cats.

  48. Loki Vanni says:

    They competed? Ohhh…No wonder cats and dogs are always portrayed as enemies in media 😮
    Every dog watching this video: (Growls) Damn cats 😡

  49. Patrick Dulfo says:

    Awwwww cute woffie crushin skullies

  50. Miguel Forster says:

    why do the illustrations try and resemble domestic dogs? They obviously fckn didnt have small floppy ears

  51. Jordi Vanderwaal says:

    Now make a video of those ancient cats pls. How they evolved and spread throughout the world, how many of their species went extinct and how many other animal species they managed to "eliminate". 😛

  52. Cris James says:

    I can’t help but wonder what kind of antelope is the prehistoric dog chasing in the drawn photo that keeps repeating.

  53. emery hurst says:

    The arrival of bears in north America probably didn't help the bone crushing dogs either.

  54. M Anime says:

    Dogs Million of years ago: BONE CRUSHING DOGS

    Dogs nowadays: cant even hunt for their own and wait for their owner to feed them

    Dogs Millions of years ago: Pathetic

  55. Guy H. says:

    Very educational! Love these videos.

  56. Jamorris Price says:

    Vaporion joltion flamtrion pokemon got to catch em all.

  57. shadetreader says:

    Team Cat!

  58. Chad Kras says:

    THOUSAND Years ago not millions! This world is deceived! arrrghhh

  59. dryzabones atom says:

    Dogs a few million years ago : were better than you

    Cats: deletes 2 species of dog

    Dogs : I regret

  60. anonymous one says:

    You should point out that the previous hypothesis is wrong, that current domesticated dogs didn't come from wolves. Both wolves and dogs derived from another ancestor. Dogs were never domesticated by humans, but already domesticated when humans and dogs started living together the way we do now.

  61. Positivity says:

    Why do they kinda look like bulldogs…. wait for they aren't extinct. lol

  62. Dessert Island says:

    Study for exam
    Me: no

    Watch bone crushing dog

  63. Kaldwin Poison says:

    Evolution of ferrets would be awesome

  64. Bom NYO says:

    Misleading and huge waste of time.

  65. Dale Longgone Basye says:

    But we have multiple reports of dogmen types what your view

  66. Christian Deininger says:

    I totally love your shows

  67. lil1will24 says:

    The bone crusher is the pit bull from HELL.

  68. Patrick Forget says:

    And they also shrunk up and they became hyenas on the African plains you look at him that's what they look like even the small dogs the very first ones look like cats

  69. D Flame says:

    Bone crushing dog: exist

    Hooman: ooohh come here big puppy come her.. Arrgghh not the neck aargghh! dies

  70. n1xio says:

    It's literally called epic

  71. Micah Lagerquist says:

    Thanks for fueling my dislike for cats. Cats ruin everything

  72. Emiliano Caprili says:

    So the "bone crusher" canidaes and the "long runner" hyaenidaes got extinct, while the "long runner" canidaes and the "bone crusher" hyenidaes survived until today. Maybe I'm wrong, but I think this could be related to the different evolution of African erbivores from the evolution of the ones of America and Eurasian more than the apparition of the felidaes.

  73. pandaplays 341 says:

    So what im hearing is big pitbull i love pitbull's i wish i could have the bone crusher

  74. GalaxyofGreatnesstv says:

    I wonder why my lab adores cow bones.

  75. Raji Fredrick says:

    A mix of horse and cat?

  76. E-BOY 11 says:

    I dont like cats but i do like big cats like lions or tigers plus cheetah

  77. Root Beer says:

    1200 dislikes from toxoplasmosis hosts…

  78. Qwerty 1234 says:

    I have always wondered why are there only big cats and no big dogs 😔

  79. Spirit悪の says:


  80. Kamikaze Killjoy says:

    So all i heard from this was… cats are so amazing they basically wiped out dogs… because had dogs been batter than the cats… 2 other species would have survived… huh… thanks pbs… i think I'll start sending this to my dog friends.

  81. RauserCraft525 says:

    Now : potat

  82. edgy tween says:

    From crushing bones to barking at doors. How the mighty have fallen.

  83. FarmvilleMonster says:

    K9 M8

  84. Logic Talks says:

    Epicyon Haydeni is my favorite

  85. Toguro 100% says:

    ‘ Evidence of bone was in there fossilized poop’
    I’m addicted to this channel, sorry.

  86. Nathan Evans says:

    Foxes have retractable claws. SAME LIKE CATS.

  87. Pennyyak Harper says:

    I love eons.

  88. Roberta Yoder says:

    Where can I buy one ?

  89. jorge 88 says:

    Was a bone crusher stronger than a lion?

  90. Dondragmer says:

    Makes a pit bull look like a bichon frise.

  91. Dondragmer says:

    They took over the econiche of hyenas in their time.

  92. Jay Wulf says:

    Cats suck

  93. warystatue33 says:

    So this is the predecessor of galiath the hound of the Philippines

  94. warystatue33 says:

    So this is the predecessor of galiath the hound of the Philippines

  95. Nate says:

    When they say that the ancestral dogs had fully-retractable claws like cats, I thought there may be more to the story. Something like them branching off from a common ancestor. Kind of like siblings who didn't like each other and divided the world between them until cats decided to take over the dog territories…

  96. Jason Matthew Oliver says:

    I am a cat and I find this video offensive.

  97. Cá Rô Chiên says:

    When the bandit came.
    Bone crushing dog: come here boy, I will crush your bone with my jaws and teeth.
    Today dogs: RUN BOSS, run now, we must run now, if you do not run, okay, I do not care about you, bye-bye.😃
    Big as a bear, wow, I very interesting with this size, if it hasn't extinction, then there will haven't more thief.👍

  98. Sum Arbor says:

    Buried the lead on the dog/human weapon/hunting platform and how op we are together.

  99. ligma nutz says:

    Bewn. Pewp. LOL

  100. MARCELOUS Neal says:

    My pit crushes bones when I feed him cow ribs sooo…

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