Paleo Profile: The Giant, Bone-Crushing Weasel

Three views of Megalictis: restoration, skull reconstruction, and original skull. Art by Adam Hartstone-Rose.
Three views of Megalictis: restoration, skull reconstruction, and original skull. Art by Adam Hartstone-Rose.

Some beasts catch you by surprise. I’m not talking about ambush predators – though such a statement would hold true – but rather prehistoric mammals whose very existence comes as something of a shock. The latest to make me go “What the hell?” is an enormous weasel that used to prowl western North America.

Paleontologist William Diller Matthew named carnivore Megalictis ferox way back in 1907. The mammal’s teeth and osteology clearly showed it to be a cousin of martens and stoats, yet their dimensions “indicate an animal which may best be described as a gigantic wolverene [sic], equaling a jaguar or a black bear in size.” And given that cats were meek little things at the time Megalictis lived, paleontologists thought that this weasel had evolved to take on a lion-like lifestyle during North America’s long Cat Gap.

But now paleontologist Alberto Valenciano and colleagues have discovered that Megalictis was no feline wannabe. Through a new analysis of previously-undescribed skull material, the researchers not only refine the evolutionary relationships of America’s giant weasels, but they also make the case that the teeth and jaws of Megalictis were more like those of hyenas and some deep-jawed dogs than to cats. In other words, this huge weasel was a bone-crusher.

Additional Megalictis skull material. From Valenciano et al., 2016.
Additional Megalictis skull material. From Valenciano et al., 2016.

Fossil Facts

Name: Megalictis ferox

Meaning: The entire name translates roughly to “fierce giant wolverine.”

Age: Between 22.7 and 18.5 million years ago.

Where in the world?: South Dakota, Nebraska, and Wyoming.

What sort of critter?: A mustelid, or a member of the group that includes weasels and their relatives.

Size: Estimated as being about the size of a jaguar.

How much of the creature’s body is known?: The new study focused on skull material from several individuals, including a nearly-complete cranium and almost-perfect lower jaws.

References:

Matthew, W. 1907. A lower Miocene fauna from South Dakota. Bulletin of the American Museum of Natural History. 23 (9): 169-219

Valenciano, A., Baskin, J., Abella, J., Pérez-Ramos, A., Álvarez-Sierra, M., Morales, J., Hartstone-Rose, A. 2016. Megalictis, the bone-crushing giant mustelid (Carnivora, Mustelidae, Oligobuninae) from the Early Miocene of North America. PLOS ONE. doi: 10.1371/journal.pone.0152430

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face
Alcide d’Orbigny’s Dawn Beast
The Shield Fortress
The Dragon Thief
The Purgatoire River’s Whale Fish
Russia’s Curved Blade
The Dawn Mole
The Oldest Chameleon
The Wandering Spirit
Teyú Yaguá
New Caledonia’s Giant Fowl
The Giant Tarasque Tortoise

Paleo Profile: The Wandering Spirit

The skull of Mupashi migrator. From Huttenlocker and Sidor, 2016.
The skull of Mupashi migrator. From Huttenlocker and Sidor, 2016.

There’s no foolproof way to avoid extinction. A disease, a global cold snap, an asteroid with a deadly trajectory – these are all things that every other species in the entire history of life hasn’t been able to foresee or plan for. One day the world changes, and only the lucky survive.

But there are a few ways that entire lineages of organisms have inadvertently made themselves resistant to extinction. One of the best, it seems, is to spread far and wide over the planet. At least then there’s a chance that some members of the family will persist in a refuge, able to stick it out through the worst of the extinction pulse.

This is just the sort of good fortune that was with the therocephalians. These were the “beast heads”, ancient protomammal relatives of ours that could be found all over the ancient Northern and Southern Hemispheres during the Permian period of Earth history. That distribution was helpful during the catastrophic mass extinction at the end of the Permian, around 252 million years ago, as some therocephalians managed to survive the disaster in pockets of prehistoric Africa, Europe, Asia, and Antarctica.

How and when did these ancient cousins of ours expand to inhabit so much of the Permian world? The fossil record has kept the answer a secret, but, paleontologists Adam Huttenlocker and Christian Sidor report, a new protomammal from Zambia helps flesh out the story.

They named the little creature Mupashi migrator. The protomammal wasn’t very big – you could have held it’s arrow-shaped skull in the palm of your hand – but it’s not the size that matters most. The closest known relatives of Mupashi, the paleontologists found, were species that lived in prehistoric Russia, far, far away from ancient Zambia. It’s a long-distance connection that hints at pathways, perhaps along the prehistoric coastlines, that let therocephalians disperse to different landmasses, and in time many of these animals split off into new forms. This was not preventative planning – the protomammals couldn’t have known what was coming – but they way they shuffled around the world gave them an edge when their world came crashing down.

The skull of Mupashi from above. From Huttenlocker and Sidor, 2016.
The skull of Mupashi from above. From Huttenlocker and Sidor, 2016.

Fossil Facts

Name: Mupashi migrator

Meaning: Mupashi is the Bemba word for spirit or ancestor, while migrator is a reference to the wide geographic range that the protomammal’s family occupied during the Permian.

Age: Between 259 and 254 million years ago.

Where in the world?: Northern Zambia.

What sort of critter?: A protomammal belonging to a group called karenitids.

Size: The skull is a little more than three inches long.

How much of the creature’s body is known?: A nearly-complete skull with several articulated neck vertebrae.

Reference:

Huttenlocker, A., Sidor, C. 2016. The first karenitid (Therapsida, Therocephalia) from the upper Permian of Gondwana and the biogeography of Permo-Triassic therocephalians. Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1111897

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face
Alcide d’Orbigny’s Dawn Beast
The Shield Fortress
The Dragon Thief
The Purgatoire River’s Whale Fish
Russia’s Curved Blade
The Dawn Mole
The Oldest Chameleon

Giant Flesh-Eating Koala of Legend Was Real

The skeleton of Thylacoleo in Naracoorte Caves National Park. Photo by Karora.
A skeleton of Thylacoleo in Naracoorte Caves National Park. Photo by Karora.

If you ever go on a camping trip to Australia, you might be told to beware the dreaded drop bear. There won’t be a chase. You’ll just be walking along, minding your own business, when a dark shape plummets onto you from above, pinning you down before your realize that you’re being eaten alive by an overgrown koala. The only way to protect yourself, the locals will advise, is to slather yourself in Vegemite and speak in an Australian accent. The efficacy of changing your name to Bruce is unknown.

This is all nonsense, of course. There are no carnivorous koalas with a taste for tourists hanging around the eucalyptus trees of Australia. Yet, despite the fact that the drop bear is a modern hoax, I’m still tickled by the fact that the mythical animal’s description closely matches a very real animal that prowled Australia during the last Ice Age. Paleontologists and fossil fans know this beast as Thylacoleo carnifex, the “marsupial lion.”

Despite the mammal’s name, Thylacoleo doesn’t hold much leonine resemblance. The carnivore’s skull is a modified version of a koala’s or wombat’s, just with cleaver-like shearing teeth at the cheek instead of grinders. That fits given that Thylacoleo belonged to the group of marsupial mammals called the diprotodonts, which includes kangaroos, wombats, koalas, and possums today. Thylacoleo was closer to being a carnivorous koala than a pouched cat.

The kinship of Thylacoleo is only half of the drop bear equation, though. The other has to do with its hunting habits. Back in 2010, paleontologist Roderick Wells and colleagues found that the paws of this marsupial predator would have been just as useful for climbing trees as grappling with the large prey of its era. Now Samuel Arman and Gavin Prideaux have forwarded even more evidence that Thylacoleo was a skilled climber: thousands of scratch marks in the lair of Australia’s real drop bear.

Southwestern Australia’s Tight Entrance Cave yielded the essential clues. In addition to a bonebed cradling the bones of both living and extinct marsupial species, the main chamber of the cavern is marked here and there by V-shaped scratch marks. Only one animal in the cave matches the size and anatomy required to make the largest scratches: Thylacoleo. And while Arman and Prideaux concede that some of the smaller scratches could have been made by other animals trying to find their way out of the cave, from possums to Tasmanian tigers, their preferred interpretation is that most of the smaller scratches were left by Thylacoleo joeys who were reared in the safety of the cave.

Scratches likely made by Thylacoleo in Tight Entrance Cave. From Arman and Prideaux, 2016.
Scratches likely made by Thylacoleo in Tight Entrance Cave. From Arman and Prideaux, 2016.

The nature of the bones in Tight Entrance Cave bolsters this vision of Thylacoleo hunkering down in the dark. Relatively few of the bones in the cave show bite marks. This means that the cave was not the habitat of bone-eaters, like Tasmanian devils, and might indicate that Thylacoleo was much like a cat in primarily dining on flesh and viscera, leaving bones mostly intact.

At different times, off and on between 140,000 and 51,000 years ago, Thylacoleo apparently used the cave as a refuge. And from where the claws marks are situated among the inclines and boulders, it seems that these predators had qualms about taking difficult routes through the dark. “Many claw marks within TEC are located on steep surfaces, despite more gradual inclines being available on other sides of the central rock pile and boulder,” Arman and Prideaux write, and the entrance to the cave itself appears to have been a steep deadfall for other creatures. This suggests that Thylacoleo was a skilled and confident climber, clambering in and out of a cave that trapped other species. And if Thylacoleo could haul itself around rocky caves, it could almost certainly scale trees.

Humans undoubtedly saw Thylacoleo. The mammal was still very much alive when people arrived on Australia around 50,000 years ago, and there may even be Pleistocene art of the mammal. The mythical drop bear, however, didn’t appear as a tall tale until the 20th century, so there’s no link between what people actually saw and stories used to make tourists shudder at the sound of a creaking branch in the night. It’s convergence, but it’s a wonderful sort of convergence. So much of prehistoric life was so strange that we could have never imagined those species if we hadn’t come across their remains. The drop bear is a rare case when our species, in jest, stumbled upon something real and just as scary as our  imaginations can muster.

Bonus: In response to a piece I wrote for Slate about real creatures that could inspire Hollywood monsters, artist Ted Rechlin made this wonderful poster for a Drop Bear movie starring Thylacoleo.

Reference:

Arman, S., Prideaux, G. 2016. Behaviour of the Pleistocene marsupial lion deduced from claw marks in a southwestern Australian cave. Scientific Reports. doi: 10.1038/srep21372

Paleo Profile: The Dawn Mole

The jaw of Eotalpa anglica. From Hooker, 2016.
The lower jaw of Eotalpa anglica. From Hooker, 2016.

The word “mole” is practically synonymous with an underground lifestyle. The little mammals that bear the name are supposed to be near-blind denizens of the world beneath our feet, tunneling through gardens for tasty worms and other morsels. And, fair enough, some moles live this way. But not all. The desman is a snouty mole that swims, some moles forage above the ground but beneath the cover of leaf litter, and the tiny shrew mole Uropsilus doesn’t seem to show any acumen for digging at all. Thanks to some tiny fossils recently found in England, however, it seems that this variety of moles sprung from ancestors that were skilled at scratching into the soil.

Paleontologist Bernard Sigé and colleagues named the critical mole in 1977 from the basis of molars found on the Isle of Wight. They called it Eotalpa anglica, and at 37 to 33 million years old it has stood as the oldest mole ever since. And now, thanks to tiny fossils sifted out of the Eocene rock, it appears that Eotalpa was already doing what moles are famous for.

Natural History Museum paleontologist Jerry Hooker has described the smattering of new bones. The feet of Eotalpa don’t show the swimming adaptations of the star-nosed moses and desmans, Hooker writes, meaning that moles did not start off as semiaquatic mammals as had once been suggested. And while the mole’s hands weren’t quite as extreme as some of its living relatives, their anatomy is more consistent with moles that are dedicated diggers. Even older moles, which Hooker expects might be found in Asia, may help flesh out how moles switched surfaces, but for now Eotalpa indicates that these beasts were underground before it was cool.

eotalpa-claws
The reconstructed finger of Eotalpa anglica in multiple views. From Hooker, 2016.

Fossil Facts

Name: Eotalpa anglica

Meaning: England’s dawn mole.

Age: Between 37 and 33 million years old.

Where in the world?: The Hampshire Basin, England.

What sort of critter?: A mole.

Size: Not estimated, but within the range of living moles.

How much of the creature’s body is known?: Isolated microfossils consisting of the upper and lower jaws, parts of the hand and arm, ankle, and lower leg.

Reference:

Hooker, J., 2016. Skeletal adaptations and phylogeny of the oldest mole Eotalpa (Talpidae, Lipotyphla, Mammalia) from the UK Eocene: the beginning of fossoriality in moles. Palaeontology. doi: 10.1111/pala.12221

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face
Alcide d’Orbigny’s Dawn Beast
The Shield Fortress
The Dragon Thief
The Purgatoire River’s Whale Fish
Russia’s Curved Blade

Prehistoric Animal Bit Like a Sabercat, Crunched Like a Bear

The skull of Kolponomos, with jaw muscles in red. From Tseng et al., 2016.
The virtual skull of Kolponomos, with jaw muscles in red. From Tseng et al., 2016.

Stroll through any museum hall well-stocked with fossil mammals and it’s tempting to look at the extinct beasts as variations on familiar themes. There’s a sloth, but bigger. There’s a camel, but smaller. I guess that weirdo in the corner looks something like a pig. We shove the remains of the extinct into expectations of the familiar even if the fit isn’t particularly good. And that’s a shame. Fossil mammals were stranger than we often give them credit for, and they often behaved in ways that no modern animal does. Just look at Kolponomos.

In the wide spread of the mammal family tree, Kolponomos was a carnivoran. That’s the group that includes cats, seals, bears, civets, and the dog snoring on the couch next to me as I write this. From there the phylogenetic haze sets in, however, with the 20 million-year-old Kolponomos fitting in somewhere around bears and their extinct relatives the bear-dogs, but not really belonging to either line. Regardless of which group can claim Kolponomos, however, what makes this beast so strange was the way it fed. This almost-bear bit like a sabertoothed cat, crunching mollusks in grizzly-like jaws studded with otterish teeth.

The idea that Kolponomos fed on shellfish has been around for a while. The mammal has been found in marine rocks from Oregon, Washington, and possibly Alaska, and the cheek teeth of these fossils show extreme wear from a diet of hard foods. In fact, Kolponomos so regularly dined on clams and mussels that the blocky crushing teeth are often “lakes” of softer dentine with the harder enamel fencing them in. Yet no one had tested this idea, nor how Kolponomos went about prying its food up from rocky shores. Now paleontologist  Jack Tseng and colleagues have finally looked Kolponomos in the mouth.

A restoration of Kolponomos by
A restoration of Kolponomos by Ken Kirkland.

From the anatomy of the shoreline mammal’s jaws, Tseng and coauthors expected that it shared a habit in common with saber-toothed cats. The front of the jaw in Kolponomos is deep and buttressed, giving it a prominent chin just like the famous sabercat Smilodon. In the cats this condition is thought to reflect an attack strategy of anchoring the head with the lower jaw and then using the leverage to drive the famous canines through their prey with a powerful contraction of neck muscles. Kolponomos was no sabertooth, but Tseng and coauthors thought that the mammal could have used the same strategy to detach mollusks from their beds.

To find out, Tseng and colleagues took a multi-pronged approach involving virtual models of Kolponomos, Smilodon, and five other carnivorans to examine bone stress during simulated bites and compare shape, adding examination of tooth wear patterns to see how the hypothesis held up. What they found was that Kolponomos fed like no mammal alive today.

Kolponomos bite sequence. Courtesy Jack Tseng.
Kolponomos bite sequence. Courtesy Jack Tseng.

Tseng and coauthors were on the mark with their Smilodon suspicion. Despite being distant relatives and feeding on entirely different prey, the lower jaws of both Kolponomos and Smilodon were extremely similar in their anatomy, shape, and response to anchor bite stress. The anchor bite was the key. More than that, the researchers found that even though the teeth of Kolponomos resemble those of sea otters the crushing portion of the extinct mammal’s jaw was actually much more like that of a bear in being stiffer but with less mechanical efficiency. Otters show the opposite condition, indicating that there’s more than one way for a carnivoran to be a shell-crusher as far as lower jaws are concerned. This makes the jaws of Kolponomos a multitool, the front strengthened for prying up shellfish and the back stiffened to crush through those defenses.

So if you were to visit coastal Washington about 20 million years ago, you might have seen something almost like a bear, but not quite like a bear, ambling along the rocky shorelines. Sniffing out a shellbed, the burly carnivore opens its jaws to jam its lower teeth into the colony of clams, biting and jerking its neck. The first shove doesn’t work, but the beast bites again and with another spasm the clam comes free with an audible pop and a little arc of spray as Kolponomos tosses its head back. There’s no hope for the bivalve now – with a swipe of its tongue the mammal shoves the snack to its cheek, and you can hear the shell give way beneath molars flattened through repetition. A quick swallow and the mammal’s snout is back in the shallows, ready to pry out another morsel as well as our preconceived notions about what fossil mammals were really like.

Reference:

Tseng, Z., Grohe´, Flynn, J. 2016. A unique feeding strategy of the extinct marine mammal Kolponomos: convergence on sabretooths and sea otters. Proceedings of the Royal Society B. doi: 10.1098/rspb.2016.0044

The Biggest Giraffe of All Time

The reconstructed skeleton of Sivatherium, courtesy John Hutchinson.
The reconstructed skeleton of Sivatherium, courtesy John Hutchinson.

“Palaeontology, in truth, is based on a narrow but solid foundation of fact, propped up by much that is uncertain or unstable, which future time must test, try—or reject.” So said anatomist James Murie to his peers at a meeting of the British Association, Edinburgh in 1871, and the inspiration for his big picture claim was a strange beast that had been dug up from India’s Siwalik Hills.

Named Sivatherium giganteum over three decades earlier, the hefty mammal seemed to be a mashup of deer, ox, giraffe, and other parts. Murie, for his part, believed the mammal was something distinct but related to America’s pronghorn, acting as a bridge to giraffes, but one can only hope he believed his own words. His hypothesis turned out to be wrong. As paleontologists eventually confirmed, Sivatherium was a burly giraffe.

All the same, I was struck by how Murie framed his argument about “Shiva’s beast” for another reason. Sivatherium is something of a forgotten celebrity. It was commonly included in books and lectures about “prehistoric monsters” in the 19th century, often touted as being a hoofed mammal as big as an elephant, but it eventually faded from view as dinosaurs soaked up almost all of our prehistoric affection. Sivatherium was pushed to the background, mostly known to fossil mammal aficionados, but now there’s something a revival in extinct giraffe studies.

Close on the hooves of a study that placed Sivatherium and its relatives in the context of giraffe neck evolution last year, a different team of anatomists consisting of Christopher Basu, Peter Falkingham, and John Hutchinson have gone back to revise just how large the impressively-ossiconed mammal really was.

What drew Basu to Sivatherium? “The real honest answer is that this animal just looks so cool,” Basu says. The “charisma” of the giraffe’s skull and bones sparked Basu’s imagination. But in fossiliferous terms, Basu says, Sivatherium was so widely different from what we envision when we think “giraffe” that studying the animal offered the opportunity to get a better handle on all the different ways it was possible to be a giraffe.

An outdated restoration of a moose-like Sivatherium. From Extinct Monsters.
An outdated restoration of a moose-like Sivatherium. From Extinct Monsters.

In order to piece the fossil mammal together, Basu and his coauthors turned to the Cautley Collection house at the Natural History Museum, London. This included the original Sivatherium bones used to describe the animal back in the 1830s as well as “key anatomy” for estimating body size such as neck vertebrae and limb bones. And for the parts that haven’t been found yet, Basu says, the modern giraffe and okapi provided a guidebook since some of their bones are very similar despite their disparate forms.

But how to put flesh on the bones of an animal that’s been extinction for thousands of years? There are two popular methods these days, Hutchinson says. Paleontologists can use an equation relating the bones of an extinct animal to a living species of known mass, or they can build a model – physical or virtual – of the whole animal to get a species-specific estimate of body mass, and often times both of these methods are used together as a check against each other. In this case, the two were in accord – Sivatherium had to be downsized.

Sivatherium came out “at least as heavy as a heavy large bull giraffe, or as heavy as a common hippo”, Hutchinson says, in excess of 3,000 pounds. There could have been larger ones, he notes, but even so they wouldn’t have been anywhere close to the 6,600 pounds of a typical elephant. This puts a lower cap on how large ruminant mammals got to be, even though Sivatherium is still among the largest of them all.

Not that such superlatives really matter. The animals themselves didn’t care. The more important point is that this conclusion came from the first rigorous reconstruction of what a Sivatherium skeleton looked like, assembled nearly two centuries after the animal was named.

Basu is right. Sivatherium is too strange to be left collecting dust, and, as I’ve been arguing lately, we really shouldn’t let dinosaurs have all the fun. How Sivatherium actually lived still teases my brain, and I’m glad that Basu, Falkingham, and Hutchinson have cleared some of the mythology surrounding the herbivore to give us a clearer view to the mammal, especially as new discoveries will continue to change this fantastic beast.

Reference:

Basu, C., Falkingham, P., Hutchinson, J. 2016. The extinct, giant giraffid Sivatherium giganteum: skeleton reconstruction and body mass estimation. Biology Letters. doi: 10.1098/rsbl.2015.0940

Carnivorous Fossil Beast Lived Like a Civet

The hyaenodont Tritemnodon, envisioned as a civet-like beast. From A History of Land Mammals in the Western Hemisphere by W.B. Scott.
The hyaenodont Tritemnodon envisioned as a civet-like beast. From A History of Land Mammals in the Western Hemisphere by W.B. Scott.

The entire Cenozoic history of the world is often laid out something like this: dinosaurs were in charge until 66 million years ago, when a wayward asteroid decided otherwise, and then mammals breathed a sigh of relief as they took over. About 60 million years after that the first humans swung down from the trees, and no one has been able to argue with absolute certainty whether this has been a good or bad thing.

Of course there’s far more to the story. The “Age of Mammals” doesn’t get the respect it deserves these days.

Even though the entirely of the Cenozoic is short compared to other eras – 66 million years can fit comfortably between dinosaur superstars Tyrannosaurus and Stegosaurus with over 20 million years to spare – it’s still a significant chunk of time where different groups of beasts have waxed and waned as evolution and extinction have shuffled them around the planet. It’s the making of the world as we know it, and even if we feel that fossil mammals of the Cenozoic are familiar the fact of the matter is that we barely know them at all. A slinky carnivore named Galecyon embodies this point.

Galecyon was a hyaenodont. These were some of the most abundant and diverse meat-eating mammals of the Eocene – the archaic equivalents to cats, dogs, civets, and hyenas that filled niches similar to those that would later be rediscovered by the carnivoran mammals – and paleontologists have uncovered a wealth of hyeaenodonts from the Eocene strata of the American west. In one five million year strip between 55 and 50 million years ago, called the Wasatchian, paleontologists have found about 20 different species of hyaenodont in eight different genera.

The humerus (top) and ulna (bottom) of Galecyon. From Zack and Rose, 2015.
The humerus (top) and ulna (bottom) of Galecyon. From Zack and Rose, 2015.

Given that mammals have such distinctive dentitions, and teeth fossilize more readily than bone, untangling hyaenodont relationships and lifestyle has primarily involved looking them in the mouth. These efforts have suggested that there were different morphs that occupied various niches – that there were various ways to be a hyaenodont. Getting postcranial proof of this notion has been difficult, though, partly because of a lack of study and partly because the scarcity of good skeletons. Now, drawing from a skeleton of Galecyon found in the Wasatchian age rock of Wyoming, paleontologists Shawn Zack and Kenneth Rose have tried to partially fill this gap in our understanding.

The skeleton, found by paleontologist Jonathan Bloch, includes parts of the jaws, vertebrae, pectoral girdle, arms, hips, and legs. Based on these parts, Zack and Rose write, Galecyon would have been between 11 and 17.5 pounds in weight, or about the size of a large skunk. More importantly, though, the various articulations and muscle attachment points on the bones suggest that Galecyon was a hunter that spent most of its time on the ground but could climb into trees when necessary. The mammal’s joints were primarily suited to the limbs moving in a forward-back motion, like a dog, but parts of the arm and ankle hint at a greater amount of flexibility and grasping power than other animals at the time that spent all their time terrestrially.

So Galecyon was an animal caught between two lifestyles. It wasn’t stuck on the ground, like the carnivorous “wolves with hooves” called mesonychids, but it wasn’t as adept in the trees as some of its relatives like Prolimnocyon. Instead, Zack and Rose write, Galecyon probably lived like a modern civet or weasel – content on the ground but able to run up a tree if needed. And this fills out just a little bit more of the Eocene world. This was an odd time in life’s history, when the great forests that spread across North America boasted life simultaneously familiar and strange. It’s not enough to simply plop each species in this leafy habitat within our mind’s eye. We want to envision how all the pieces fit together. Now we can start to do that for Galecyon, imagining the little carnivore padding along the forest floor before scampering up the nearest tree to glare back at us.

Reference:

Zack, S., Rose, K. 2015. The postcranial skeleton of Galecyon: evidence for morphological and locomotor diversity in early Hyaenodontidae (Mammalia, Hyaenodontida). Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2014.1001492

Rare Fossil Offers a View to a Beast’s Old Age

Adult and juvenile Desmostylus. Art by Justin Santos.
Adult and juvenile desmostylians. Art by Justin Santos.

Picture a prehistoric animal. Don’t worry, I won’t judge you if it’s Tyrannosaurus or another super-popular species. Any creature will do. Now, what age is the animal you imagined? I’d be willing to bet that it’s an adult, representing a healthy individual in the prime of life. (If not, and you pictured a hatching or an aged or injured animal, take your moment of pride in being ahead of the curve and hang on a second.)

In art and film and even within the science of paleontology itself, we often envision extinct species as healthy adults. There are plenty of intersecting reasons for this. We’re bound by a typology that needs to find a standard, a baseline of normalcy, that represents a species, not to mention that even in our own lives we remember the influential and famous as adults rather than as their childhood selves. Adulthood is when things get interesting. And with fossils, we often lack individuals from the very young and very old parts of their species’ lifespan. Babies are snacks for carnivores and most individuals in a population never make it to old age, meaning that we end up with a fossil collection of subadults and adults who evaded the jaws of predators but expired before they hit old age. We don’t envision creaky old Triceratops or saberkittens very often because we just don’t find them in the same numbers of the midrange individuals.

But every now and then someone’s fortunate enough to stumble across the ontogenetic bookends of a species’ life. One such stroke of luck befell construction workers in 1996 as they were working on southern California’s State Route 241. As it chewed through the 11 million year old rock of the Puente Formation that rings the Los Angeles Basin the excavation turned up the lower jaw of an extremely unusual marine mammal, and it turned out to be a real old timer biologically as well as geologically speaking.

The jaw of an old Desmostylus, showing a downturned canine but a lack of cheek teeth. From Santos et al., 2016.
The jaw of an old Desmostylus, showing a downturned canine but a lack of cheek teeth. From Santos et al., 2016.

That jaw, described by paleontologist and friend of the blog Gabriel-Philip Santos and colleagues, belonged to Desmostylus. Paleontologists are still working out what these fossil mammals were. For a long time they seemed to be cousins of elephants and manatees, although some recent research has suggested that they were early offshoots of the same line that spun off horses and rhinos. Regardless, though, they can immediately be recognized by their teeth. Their premolars and molars are “bonded pillars” – the literal translation of Desmostylus – and their bodies looked like some kind of mashup between hippo and sea lion.

Yet the jaw dug up from the tollway construction project lacked the characteristic molars. The sockets, Santos and coauthors report, are not so much empty as filled with remodeled bone. Throughout the animal’s life a limited set of chewing teeth erupted and moved forward to provide fresh chewing surfaces to cope with all the sand and grit attached to the seagrasses and other vegetation it ate, and apparently the mammal was so adept at this that it wore down its last set of teeth beyond the nubs. The beast even managed to feed itself as its tooth roots eroded away and bone reclaimed the open holes. And so the fossil has filled in just a little bit more about what paleontologists know about this species, but the relic is more than that. The gray, near-toothless Desmostylus reminds us that there was far more to prehistoric life than the vibrant days of ancient youth.

Reference:

Santos, G., Parham, J., Beatty, B. 2016. New data on the ontogeny and senescence of Desmostylus (Desmostylia, Mammalia). Journal of Vertebrate Paleontology. doi: 10.1080/02724634.2016.1078344

Paleo Profile: Alcide d’Orbigny’s Dawn Beast

From de Muizon et al., 2015.
The nearly-complete skeleton of Alcidedorbignya inopinata. From de Muizon et al., 2015.

Vertebrate paleontology has a sample size problem. Only a fraction of all the creatures that ever lived became preserved in the fossil record, and an even tinier sliver of that array has been discovered, cleaned, and studied. Even the most famous animals, like the fearsome Tyrannosaurus, are known from a (figurative) handful of individuals scattered through swaths of rock spanning a million years or more. Finding enough fossils to even start to pick at the biology of an extinct species is a tall order.

But every now and then paleontologists strike just the right spot. One such locality, near Tiupampa, Bolivia, is simply known as “The Quarry”, but don’t be fooled by the lackluster name. This is one of the best places in the world to find the skeletons of the mammals that thrived just a million years after a wayward asteroid closed the Age of Reptiles for good, and, as paleontologist Christian de Muizon and colleagues report in a massive monograph, this place has supplied an exquisite record of one of the earliest placental mammals to skitter around in the end-Cretaceous aftermath.

de Muizon and Larrry Marshall named the mammal Alcidedorbignya inopinata in 1992. Back then, it was mostly known from teeth and pieces of jaw. But in the years since the initial finds paleontologists have uncovered a nearly-complete skeleton, several partial skulls, and hundreds of other scattered elements. With all this new material, de Muizon and colleagues set about piecing together this dawn beast in greater detail than possible before.

There’s not an exact modern equivalent for what Alcidedorbignya was. It was a tiny member of a totally-extinct group of mammals called pantodonts that thrived in the earliest days of the Paleocene. And unlike its larger relatives, Alcidedorbignya was a nimble little beast that was probably adept at running through the trees as well as scampering around on the ground, able to stand up on its hind legs to have a look around or grab a morsel when necessary. The restoration of the mammal by Justine Jacquot-Haméon makes me think “cat squirrel” isn’t too far off, although the beast wasn’t closely related to either.

What’s still unclear is what led so many Alcidedorbignya to become buried in the same place. Especially strange is that The Quarry has yielded 33 jaws of juvenile animals and 35 jaws from adults, raising the prospect that these were gregarious mammals or that the youngsters hung around with their parents. Were these mammals social, or did the a local flooding event hit at just the wrong time of the year, taking out the next generation as well as their parents? The case remains open. With so many bones of Alcidedorbignya to compare and scrutinize, though, this little mammal offers one of the best chances we have to envision the world just after it was freed from the claws of the “terrible lizards.”

Caption
Alcidedorbignya in its Paleocene environment. Art by Justine Jacquot-Haméon.

Fossil Facts

Name: Alcidedorbignya inopinata

Meaning: The genus name honors French naturalist Alcide d’Orbigny.

Age: About 65 million years old.

Where in the world?: Tiupampa, Bolivia.

What sort of critter?: A pantodont, one of the mammals that proliferated after the demise of the non-avian dinosaurs.

Size: About the size of a large squirrel.

How much of the creature’s body is known?: Multiple fossils including a nearly-complete skeleton, at least three juvenile skulls, several hundred dental specimens, and more.

Reference:

de Muizon, C., Billet, G., Argot, C., Ladevèze, S., Goussard, F. 2015. Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny, and palaeobiology. Geodiversitas. doi: 10.5252/g2015n4a1

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback
Amidala’s Strange Horn
The Northern Mantis Shrimp
Spain’s High-Spined Herbviore
Wucaiwan’s Ornamented Horned Face

How Jaguars Survived the Ice Age

A jaguar at the St. Louis Zoo. Photo by Brian Switek.
A jaguar at the St. Louis Zoo. Photo by Brian Switek.

The mastodons, ground sloths, and sabercats are all gone. They all slipped into extinction around 10,000 or so years ago, along with an even wider variety of fantastic beasts and birds that fall under the category “megafauna.” But not all the Ice Age megamammals died out. We spend so much time mourning the losses that we often forget the survivors that carry whispers of the Pleistocene world. Among these resilient beasts is the jaguar.

Jaguars are old cats. They first evolved in Eurasia sometime around three million years ago before spreading both west and east, eventually inhabiting a range from southern England to Nebraska and down into South America. Today’s range of southern Arizona to Argentina—over 3.4 million square miles—is only a sliver of their Ice Age expansion. And it wasn’t just the jaguar’s range that shrunk. Today the spotted cats are about fifteen percent smaller than their Pleistocene predecessors.

Nevertheless, jaguars survived while the American lion, the sabercats, and other predators vanished. How? In order to investigate this question, biologist Matt Hayward and colleagues looked at the jaguar diet and how the cat’s prey preferences changed over time.

Drawing from 25 published studies documenting 3,214 jaguar kills, Hayward and coauthors found that jaguars are pretty finicky for apex predators. The big cat’s menu spans 111 species—ranging from cattle to rodents to monkeys to turtles—but, contrary to what has often been written about the cat, the jaguar is not really a generalist that hunts anything and everything.

The most common parts of the jaguar diet, Hayward and colleagues found, are capybara, wild pig, caiman, collared peccary, nine-banded armadillo, giant anteater, and white-nosed coati. These species account for 16-21% of the jaguar diet. The stats also showed that prey including peccaries, brocket deer, giant anteaters, and coatis which were hunted 85% of the time when they were present in the jaguar’s range. Crunching the numbers a bit further, the zoologists found that jaguars seemed to especially target capybara and giant anteater. On the other hand, jaguars never preyed upon tapirs and almost never touched primates.

Jaguars come out of all this as a paradox. They are burlier than leopards, yet they prefer to hunt a narrow range of prey that falls in the shallow end of what jaguars should be able to tackle. This might have something to do with why the cats have shrunk. Jaguars aren’t large enough to take on tapirs alone, yet human hunting on mid-range prey—such as deer—has made such herbivores too rare to rely upon. So despite their size, jaguars responded by picking out smaller prey which Hayward and coauthors dub “suboptimal” for what the cats initially evolved to do.

The jaguar’s not alone in this. Coyotes have gone through similar changes. The scrappy canids are Ice Age survivors, too, and they were significantly larger during the Ice Age. When all their competition disappeared, coyotes became smaller and ended up living on the fringes in a world heavily influenced by humans.

Flexibility made all the difference for these carnivores. Even though jaguars no longer prowl as much of the world as they once did, and are currently listed as “near threatened” on the IUCN Red List, they were able to persist where so many other carnivores perished by shifting their diets. “It may be that jaguars survived this mass extinction event by preferentially preying on relatively small species,” Hayward and coauthors write. The fossil record of cougars tells a similar story: By eating parts of carcasses other cats didn’t want, mountain lions were able to survive the tough times. And even though the cause of the loss of many Ice Age celebrities remains debated, the survivors are truly the animals we should be looking at in greater detail. How they succeeded may hold the secrets to why so many other species failed.

Reference:

Hayward, M., Kamler, J., Montgomery, R., Newlove, A., Rostro-García, S., Sales, L., Van Valkenburgh, B. 2016. Prey preferences of the jaguar Panthera onca reflect the Post-Pleistocene demise of large prey. Frontiers in Ecology and Evolution. doi: 10.3389/fevo.2015.00148

A Crushing Bite Gives Sea Otters Their Cute Mugs

A southern sea otter off Piedras Blancas, California. Photo by Brian Switek.
A southern sea otter off Piedras Blancas, California. Photo by Brian Switek.

All otters are adorable. That’s as much of a fact as the existence of gravity. But among the 13 or so living otter species, none generate as many “Aww”s as Enhydra lutris, the sea otter. These fuzzballs are so cute, in fact, that we often overlook their bad behavior. But what is it that sets them apart? There’s the dense coat of fur and their fastidious dining habits, of course, but they also look a bit different from most other otters. Sea otters have short, round faces compared to their relatives, and that’s all because of their specialist diet. To put it bluntly, I think a crushing bite has given sea otters an edge over their cute competition.

This epiphany came after reading a new paper by Texas A&M zoologists Lori Timm-Davis, Thomas DeWitt, and Christopher Marshall on the two major ways that otters feed. Some otters, like giant and North American river otters, primarily catch fish and other squirmy prey with their jaws, while otters such as Asian small-clawed otters and sea otters often nab mollusks, echinoderms, and other hardened prey with their dexterous hands before crushing through those exterior defenses with expanded cheek teeth. And given that there are trade offs between speed and power in any bite, Timm-Davis and colleagues expected that the differences between these two feeding styles would be visible in the shape of the otters’ skulls. With that in mind, they measured and estimated the bite mechanics for 150 otter skulls representing four different species, as well as parsing out three different populations of sea otters.

The skull of a southern sea otter at Año Nuevo State Park, California. Photo by Brian Switek.
The skull of a southern sea otter at Año Nuevo State Park, California. Photo by Brian Switek.

The otters generally met the researchers’ expectations. Giant and North American river otters, which subsist primarily on fish, have longer, narrower skulls capable of fast bites. Just the sort of setup for snapping at slippery and fast-moving prey. The Asian small-clawed and sea otters, which more often rely on plucking up slow-moving invertebrate morsels, have wider, shorter skulls and jaws, delivering a slower but more more powerful bite. Sea otters take this to the extreme, with wide, rounded cheek teeth best suited to pulverizing hard foods.

Not that all sea otters behave the same way, though. When Timm-Davis and coauthors looked at the differences between isolated Russian, northern, and southern sea otters they found that the skulls of each population clustered together in slightly different shapes. This appears to be because of diet. Northern and Russian sea otters diversify their diet a bit by eating more fish than their southern cousins, and this difference shows up in the anatomy of their jaws. Among other variations, the southern sea otters had about 19.1% more crushing surface on their cheek teeth – the better to mash up sea urchins with. These relatively recent changes reflect how quickly differences in diet can start to affect the shape of otter evolution.

For the most part, though, even sea otters with more cosmopolitan tastes still share the deep, short, and wide skull shape that distinguishes them from their lithe relatives. Sure, all that fur, the little nose, and oildrop eyes complete the package, but the mammal’s lutrine looks go down to the bone. Their cuteness comes from their ability to crush.

Reference:

Timm-Davis, L., DeWitt, T., Marshall, C. 2015. Divergent skull morphology supports two trophic specializations in otters (Lutrinae). PLOS ONE. doi: 10.1371/journal.pone.0143236

Paleo Profile: Amidala’s Strange Horn

A restoration of Xenomeryx by Israel
A restoration of Xenomeryx by Israel Sánchez.

Fossil mammals don’t get the attention they deserve. If you’ve ever been to the sprawling fossil halls of one of the great eastern museums – the American Museum of Natural History, the Field, the Carnegie, the Peabody – you know what I mean. The skeletons of ancient camels, horses, cats, sloths, and their beastly kin are often treated as osteological distractions by visitors who are swiftly moving in the direction of the dinosaurs. And this imbalance holds for news, too. A new horned dinosaur with an unusual arrangement of ornaments is catnip for click-hungry websites, but a fossil mammal with headgear that’s just as strange? You’ll barely hear a peep. And while this post won’t solve this gross imbalance in our attention, it’ll at least highlight a truly strange herbivore just as worthy of headlines as any dinosaur.

The herbivorous mammal, named Xenokeryx amidalae by Israel Sánchez and coauthors, roamed Spain around 16 million years ago. It didn’t look quite like anything alive today. The beast had elongated canine teeth – giving it a sabertoothed look like musk deer and muntjacs – but it also had fur-covered ossicones jutting from over each eye and from the back of its skull.

Xenokeryx wasn’t the only mammal to sport such a strange set of headgear. It belonged to a group called palaeomerycids that all had their own ornamental arrangements jutting from their skulls. For a long time paleontologists were divided on whether these creatures were more closely related to giraffes or to deer, but the new skull material from Xenokeryx, as well as a revision of other species, has allowed Sánchez and coauthors to settle the debate. The palaeomerycids were apparently the closest cousins to giraffes, the two lineages splitting from each other about 30 million years ago.

There aren’t any palaeomerycids left. The last of them went extinct about 4.9 million years ago. That’s undoubtedly part of what makes them so strange. If some of them had survived, they might not seem any more exotic than their living giraffe cousins. But we need to remember these oddities from the more recent stretches of the fossil record. They fill in the more recent chapters of the story that’s still unfolding all around us, showing just what evolution can do when released from the claws of the ruling reptiles.

Skull elements of Xenokeryx. From Sánchez et al., 2015.
Skull elements of Xenokeryx. From Sánchez et al., 2015.

Fossil Facts

Name: Xenokeryx amidalae

Meaning: Xenokeryx means “strange horn”, while amidalae is a reference to Padme Amidala from the Star Wars prequels for the resemblance between her hairstyles and the mammal’s ossicones.

Age: Around 16 million years old.

Where in the world?: Le Retama, Spain.

What sort of critter?: One of the palaeomerycids, extinct relatives of giraffes.

Size: About the size of a deer.

How much of the creature’s body is known?: Elements of the skull, jaws, limbs, and teeth.

Reference:

Sánchez, I., Cantalapiedra, J., Ríos, M., Quiralte, V., Morales, J. 2015. Systematics and evolution of the Miocene three-horned palaeomerycid ruminants (Mammalia, Cetartiodactyla). doi: 10.1371/journal.pone.0143034

[I also wrote about this beast for Nerdist.com]

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle
Mexico’s “Bird Mimic”
The Greatest Auk
Catalonia’s Little Ape
Pakistan’s Butterfly-Faced Beast
The Head of the Devil
Spain’s Megatoothed Croc
The Smoke Hill Bird
The Vereda Hilarco Beast
The North’s Sailback

Did Sabercats Have Spotted and Striped Coats?

A Smilodon angles to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.
A Smilodon tries to get a better bite on a sloth at the La Brea Tar Pits and Museum. Photo by Brian Switek.

As far as fossil cats are concerned, there is no greater artist than Mauricio Antón. He has a knack for capturing the essence of fossil felids – be it a Homotherium pinning its prey or Dinofelis taking a cat nap – and I love that so many of Antón‘s illustrations feature spots and stripes. The sabercats I saw in books and stop-motion documentaries were never so colorful. They always seemed to wrapped in a relatively plain, dun-colored coat, making Smilodon look like a lion with abnormally-long canines.

Unfortunately, short of finding a frozen sabercat comparable to the steppe lion kittens announced earlier this year, we’ll  probably never know the precise span of sabercat shades. But maybe we can narrow the field a little. Today’s cats, both big and small, might be able to help us predict the presence of spots and stripes in their toothy, extinct relatives.

Today’s cats wear a beautiful array of coat patterns, from plain to dense constellations of spots and stripes. These different color options are largely dictated by two genes – Taqpep and Edn3 – the first of which lays down the general pattern of spots and stripes while the second controls local color differences, like hair banding. But these patterns don’t follow family lines. Just have a look at Panthera, the genus that includes most of the classic big cat species. There are lions (spots giving way to “plain” coloration), jaguars (large, filled-in spots), leopards (large open spots), snow leopards (large open spots), and tigers (vertical stripes) all within the same genus. Something else is more important than felid family ties in determining coat colors, and, in a 2010 study, ethologist William Allen and colleagues suggested that the answer is “ecology.”

After pulling images of 35 wild cat species from the web – because what else is the Internet good for other than cat pictures? – Allen and coauthors analyzed how coat patterns related to different species’ habitat preferences and activity patterns. Cat coats, they realized, “function as a background matching camouflage.” Cats in open, well-lit environments are more likely to have relatively plain coats while those living in forested habitats or active at primarily at night typically have complex patterns of spots and horizontal stripes.

Cats in open environments are more likely to have "plain" coats. Photo by K. Fink.
Cats in open environments, like mountain lions, are more likely to have “plain” coats. Photo by K. Fink.

There are some exceptions to this rule. Cheetahs, servals, and black-footed cats have spotted coats despite living in the same type grasslands as lions, while the elusive bay cat has a mostly-uniform coat despite prowling forests. Maybe these discrepancies have something to do with “microhabitats” or some sort of behavior not parsed out in the study, Allen and colleagues wrote, but for the most part a cat’s coat is more influenced by its ecology than who its related to.

The same probably held true for the sabercats. So while the forest-dwelling Dinofelis would be more likely to bear spots and stripes, Homotherium and other open-country cats may have lost their spots to be less conspicuous out in the grasslands.

So what about Smilodon? The cat is the ambassador for its long-fanged relatives as well as the Ice Age in general. While we may never know for sure, places like La Brea – where the sabercat is found in abundance – suggest that the iconic sabercat frequented shrubby chaparral. If the ecological connection held, therefore, Smilodon may have worn more subdued hues like the modern mountain lions that live in southern California today, or perhaps it was decked in solid spots much like the cheetah, serval, black-footed cat trio in Africa.

Despite its common nickname “saber-toothed tiger”, though, we can be pretty sure Smilodon didn’t have vertical stripes. Not only are sabercats and tigers distant relatives, but, as Allen and colleagues found, tigers are the only cats to have vertical stripes on their flanks. Perhaps the best we can hope for is that some Pleistocene artisan somewhere was inspired enough by the fossil cats to record their pelage palette for us to envision as Ice Age world that we just missed.

References:

Allen, W., Cuthill, I., Scott-Samuel, N., Baddeley, R. 2011. Why the leopard got its spots: relating pattern development to ecology in felids. Proceedings of the Royal Society B. doi: 10.1098/rspb.2010.1734

Kaelin, C., Xu, X., Hong, L., David, V., McGowan, K., Schmidt-Küntzel, Roelke, M., Pino, J., Pontius, J., Cooper, G., Manuel, H., Swanson, W., Marker, L., Harper, C., van dyk, A., Yue, B., Mullikin, J., Warren, W., Eizirik, E., Kos, L., O’Brien, S., Barsh, G., Menotti-Raymon, M. 2012. Specifying and sustaining pigmentation patterns in domestic and wild cats. Science. doi: 10.1126/science.1220893

Ortolani, A. 1999. Spots, stripes, tail tips and dark eyes: Predicting the function of carnivore colour patterns using the comparative method. Biological Journal of the Linnean Society. 67: 433-476

What Hyena Giggles Really Say

A spotted hyena in Kenya. Photo by Liaka ac, CC BY-SA 2.0.
A spotted hyena in Kenya. Photo by Liaka ac, CC BY-SA 2.0.

Spotted hyenas may be the chattiest carnivores on the planet. They whoop, rumble, low, and laugh, announcing their presence wherever they go. But what do all these calls mean?

Zoologist Kay Holekamp laid out the spotted hyena repertoire in a 2011 New York Times field journal. So far as we humans are able to understand, each category of call carries a general meaning that can be modulated by the sender to varying effect. Spotted hyenas low when they want to team up, “alarm rumble” to raise a red flag to approaching danger, and groan to greet cubs at a den, who then “squitter” to demand milk from mom. And their trademark giggle? That’s nervous laughter. Spotted hyenas usually titter when they’re being attacked, harassed by another member of their clan, or frustrated.

But there are more details embedded in hyena calls than we usually pick up on. In a 2007 study, Holekamp, Kevin Theis, and colleagues reported that spotted hyena whoops – their haunting, long-distance calls – reflect details about the age, and sometimes sex, of the hyena sending the signal. By looking at the acoustic details of 117 whoop bouts from 60 different hyenas, the researchers were able to discern that whoops become deeper with age and that the calls of non-juvenile males and females could be distinguished from each other (perhaps because the larger females have bigger chests that give them a deeper pitch). If you were a hyena, your whoop would carry essential information about who you are.

Mother hyenas grunt to draw their cubs out, and those cubs "squitter" to beg for milk. Photo by Budgiekiller, CC BY-SA 2.5.
Mother hyenas grunt to draw their cubs out, and those cubs “squitter” to beg for milk. Photo by Budgiekiller, CC BY-SA 2.5.

A hyena’s giggle is even more distinctive. A 2010 study by Nicolas Mathevon and colleagues on 695 giggles made by the University of California, Berkeley’s captive hyena clan (shuttered last year, sadly) found that the carnivore’s characteristic laugh carried cues about the sender’s age, status in the clan, and perhaps individual identity. This is all critical information for a social predator. If you’re going to work as a group, you need to know who’s talking as well as what’s being said.

And while some of these details might be lost on other species, hyena chatter can carry critical information for their carnivorous neighbors. Cheetahs, zoologist Sarah Durant discovered through playback experiments, will leave an area if they hear the sounds of lions or hyenas. In fact, Durant observed, the sleek cats were even less likely to go on the hunt after hearing the calls from their competitors. What was the point of bringing down dinner if a hyena might swoop in and steal it?

Lions are another matter. Despite their regal reputation, these burly felids often play the part of kleptoparasites. Lions have no qualms about bullying weaker carnivores off their kills, and, as argued by Hugh Webster and colleagues after playback experiments, lions will eavesdrop on the calls of other species to zero-in on an easy meal. Wild dog calls always generated interest, the researchers found, but male lions or mixed groups of male and female lions would also approach spotted hyena vocalizations in the hope of some grub on the go. At least hyenas can mitigate the risk of losing their lunch. One population in Zimbabwe started traveling in mid-size groups, rather than forming large foraging parties, in response to an influx of lions.

Short of a Babel fish, we’ll never be able to translate hyena giggles down to the level of “Hey! That’s my wildebeest leg!” or “Get lost, you mangy lion!” But hyenas don’t need the broadened vocabulary we have to keep their clans together. Their set of a dozen or so calls seems to suit them fine, with each hyena adding their own unique voice to the chorus.

References:

Durant, S. 2000. Living with the enemy: avoidance of hyenas and lions by cheetahs in the Serengeti. Behavioral Ecology. doi: 10.1093/beheco/11.6.624

Mathevon, N., Koralek, A., Weldele, M., Glickman, S., Theunissen, F. 2010. What the hyena’s laugh tells: sex, age, dominance and individual signature in the giggling call of Crocuta crocuta. BMC Ecology. doi: 10.1186/1472-6785-10-9

Theis, K., Greene, K., Benson-Amram, S., Holekamp, K. 2007. Sources of variation in the long-distance vocalizations of spotted hyenas. Behaviour. doi: 10.1163/156853907780713046

Webster, H., McNutt, J., McComb, K. 2010. Eavesdropping and risk assessment between lions, spotted hyenas, and African wild dogs. Ethology. doi: 10.1111/j.1439-0310.2009.01729.x

Talara, Peru’s Great Ice Age Tar Trap

Bones of Smilodon from Talara, Peru in the Royal Ontario Museum collection. Photo by Brian Switek.
Bones of Smilodon from Talara, Peru in the Royal Ontario Museum collection. Photo by Brian Switek.

Earlier this year, as I ran around the Royal Ontario Museum fossil halls trying to take in as much as I could in the short time I had before a talk, an Ice Age fossil stopped me in my tracks. It was a fossil horse jaw, but unlike any I had seen before. The fossil seemed impossibly black, tooth and bone stained to gorgeous ebony shades.

The beautiful fossil had been excavated decades before from a tar seep in Talara, Peru. I had never heard of this place before. When I think “tar pit”, I think La Brea. (Perhaps because, aside from being the most important fossil site on the planet, La Brea translates directly to “the tar.”) But the exhibits and a quick primer from ROM curator Kevin Seymour introduced me to an entirely different death trap that has produced a wealth of fossils colored by a deeper shade than the “La Brea brown” of their Californian counterparts.

Much of what’s known about Talara comes from a collection of over 28,000 bones collected from the site from A.G. Edmund in 1958. The vast majority of these fossils – about 63.4 percent of identified bones – are from mammals, and of these more than 79 percent are the remains of carnivores. There are plenty of other creatures represented at Talara – songbirds, amphibians, horses, camels, ground sloths, mastodons, deer, and more – but this place was primarily a deadly draw for the meat-eaters.

The skull of a jaguar from Talara, Peru in the ROM collections. Photo by Brian Switek.
The skull of a jaguar from Talara, Peru in the ROM collections. Photo by Brian Switek.

Some of the Talara carnivores are still with us. The Sechuran desert fox, wrote Seymour in an overview of the site, is represented by pieces of over 100 individuals pulled from the site and still lives in the area. And when I giddily started pulling open cabinets in the ROM collections on my second day at the museum, Seymour was kind enough to point out a stunning fossil jaguar skull that had previously been mistaken for an American lion. But the biggest of the Talara carnivores are long gone. The site has given up the bones of at least 51 dire wolves and 20 Smilodon.

Many of these animals were juveniles. While the sample isn’t nearly as extensive as that of La Brea, Seymour notes, the proportion of juvenile animals for the three most common carnivores ranged from 57 to 69 percent. That seems quite high compared to La Brea and Ice Age fossil sites in Florida, and could indicate that either there were more juveniles around at the time the Talara tar seeps were active or that the young animals were more naive and blundered into the trap more often.

All these figures are just the beginning of a new effort to understand the site. After early descriptions and fossil sorting by Charles Churcher and others in the 1960s, the fossils waited in the Royal Ontario Museum collections for a more recent surge of interest that is beginning to trickle out some new details about this sticky Pleistocene bonanza.

And Talara is not the only undersung tar pit around. In another new paper Seymour and Emily Lindsey surveyed several other sites in the Americas ranging from McKittrick in California to La Carolina, Tanque Loma, and Corralito in Ecuador.

Each site its own character and history. Tanque Loma, for example, is superabundant in sloths and has plenty of prehistoric elephants but totally lacks the big carnivores found elsewhere. La Corralito, on the other hand, has a somewhat more even mix of carnivores, sloths, horses, elephants. This is probably because these two sites didn’t kill the animals by suffocation in tar but were places where bones were laid down by rivers and then tar seeped up into them afterwards. There wasn’t the same deadly aroma of rotting flesh that pulled the wolves and sabercats to the tar in Talara and La Brea. For carnivores, those places were truly the pits.

References:

Lindsey, E., Lopez, E. 2014. Tanque Loma, a new late-Pleistocene megafaunal tar seep locality from southwest Ecuador. Journal of South American Earth Sciences. doi: 10.1016/j.jsames.2014.11.003

Lindsey, E., Seymour, K. 2015. “Tar Pits” of the Western Neotropics: Paleoecology, taphonomy, and mammalian biogeography. Natural History Museum of Los Angeles County Science Series, 42: 111-123

Seymour, K. 2015. Perusing Talara: Overview of the Late Pleistocene fossils from the tar seeps of Peru. Natural History Museum of Los Angeles County Science Series, 42: 97-109