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Bullockornis (with human-size silhouette for comparison)

Bullockornis (with human-size silhouette for comparison)

My sincere apologies for being such a truant blogger last week!  Not only did I fail to post any new articles since Tuesday, I unpardonably left you stuck with nothing but the flimsy Ms. Perry during that time. In order to apologize, allow me to take you on a trip to the island continent of Australia…15 million years ago during the Middle Miocene. During this time one of the largest birds ever lived across Australia: a giant fowl named Bullockornis.

Bullockornis

Bullockornis

Bullockornis was a 2.5 meter tall (8 foot 2 inch) gooselike bird.  The creature weighed in at approximately 500 kilograms (1100 pounds) and scientists believe it was actually related to the modern geese and ducks.   If you have ever met a modern goose, you will realize that a goose the size of a bear would be a formidable creature indeed.  Additionally Bullockornis possessed a razor sharp beak with immensely powerful jaw muscles.  It is hard not to imagine the giant bird nipping off a he-man’s arms like corn kernels or biting through bridge cables with this monstrous beak, but the truth is scientists don’t know what the bird used it for.  The monstrous goose could have been a hunting carnivore (like certain ducks are today) or an herbivore which grazed on heavy dense plants.  Perhaps, like contemporary geese, it was an omnivore which hunted, grazed, and opportunistically scavenged whatever it could get.

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Bullockornis was discovered in 1979 but it only became well known when some PR savvy writer christened it the “Demon Duck of Doom”  (which strike me as a silly 1930s Disney-style name, but I guess whatever gets people involved in paleontology is good).  The scientific name “Bullockornis”  means “bullock-bird” but, even though the bird was the size of an ox, it is actually named for Bullock Creek (a rich fossil location in the Northern Territory).  Bullockornis was not the only giant of the Miocene in Australia.  The Bullock Creek fossil beds also contained fossils of Giant horned tortoises, marsupial “lions” (i.e. thylacoleonids) and grazing Diprotodontids—giant wombats (although nothing so large as the mighty Diprotodon which evolved in the Pleistocene).

Fossil Bullockornis Skull

Fossil Bullockornis Skull

An artist's conception of Poebrotherium (an early camel)

An artist’s conception of Poebrotherium (an early camel)

Camelids are believed to have originated in North America.  From there they spread down into South America (after a land bridge connected the continents) where they are represented by llamas, alpacas, vicuñas, and guanacos.  Ancient camels also left North America via land bridge to Asia. The dromedary and Bactrian camels are descended from the creatures which wandered into Beringia and then into the great arid plains of Asia.  Yet in their native North America, the camelids have all died out.  This strikes me as a great pity because North America’s camels were amazing and diverse!

An illustration of the size of Gigantocamelus

An illustration of the size of Gigantocamelus

At least seven genera of camels are known to have flourished across the continent in the era between Eocene and the early Holocene (a  40 million year history).  The abstract of Jessica Harrison’s excitingly titled “Giant Camels from the Cenozoic of North America” gives a rough overview of these huge extinct beasts:

Aepycamelus was the first camel to achieve giant size and is the only one not in the subfamily Camelinae.  Blancocamelus and Camelops are in the tribe Lamini, and the remaining giant camels Megatylopus, Titanotylopus, Megacamelus, Gigantocamelus, and Camelus are in the tribe Camelini.

That’s a lot of camels–and some of them were pretty crazy (and it only counts the large ones—many smaller genera proliferated across different habitats).  Gigantocamelus (as one might imagine) was a behemoth weighing as much as 2,485.6 kg (5,500 lb).  Aepycamelus had an elongated neck like that of a giraffe and the top of its head was 3 metres (9.8 ft) from the ground.  Earlier, in the Eocene, tiny delicate camels the size of rabbits lived alongside the graceful little dawn horses.  This bestiary of exotic camels received a new addition this week when paleontologists working on Ellesmere Island (in Canada’s northernmost territory, Nunavut) discovered the remains of a giant arctic camel that lived 3.5 million years ago. Based on the mummified femurs which were unearthed at the dig, the polar camel was about 30 percent larger than today’s camels.   The arctic region of 3.5 million years ago was a different habitat from the icy lichen-strewn wasteland of today.  The newly discovered camels probably lived in boreal forests (rather in the manner of contemporary moose) where they were surrounded by ancient horses, deer, bears and even arctic frogs!  Testing of collagen in the remains has revealed that the camels are closely related to the Arabian camels of today, so these arctic camels (or camels like them) were among the invaders who left the Americas for Asia.

Aepycamelus (painting by Heinrich Harder)

Aepycamelus (painting by Heinrich Harder)

The bones are a reminder of how different the fauna used to be in North America.  When you look out over the empty, empty great plains, remember they are not as they should be.  All sorts of camels should be running around.  Unfortunately the ones that did not leave for Asia and South America were all killed by the grinding ice ages, the fell hand of man, or by unknown factors.

An artistic reconstruction of the newly discovered Arctic camels

An artistic reconstruction of the newly discovered Arctic camels

A Smilodon fends off the vulture-like Teratornis at what would later be called the Rancho La Brea tar pits, situated in Los Angeles, California (Painting by Charles R. Knight)

Lately this blog has been fixated on magnificent saber-toothed mammals.  We have featured the extinct saber-toothed whale, a saber-toothed marsupial predator, the little saber-toothed deer, and even the familiar walrus (in reality, a giant saber-toothed seal), but we realize that everyone has really been looking forward to the most famous saber-toothed animal of them all, Smilodon, the saber toothed cat.  Smilodon was actually a genus of several large cats, the biggest of which, Smilodon populator, weighed 360 to 470 kg (790 to 1,000 lb) and was larger than modern tigers or lions. In fact Smilodon species are sometimes known as “saber toothed tigers” or “saber toothed lions,” however taxonomists tell us such names are off the mark since the Smilodons belonged to the extinct Machairodontinae genus of felines rather than the familiar Panthera genus of big cats so familiar today.

About two and a half million years ago, Smilodon evolved in North America from an earlier genus of saber toothed cat Megantereon (there were a lot of other earlier genera of saber-toothed cats, not to mention even more genera of saber toothed carnivores which were not exactly felines—the whole story is complicated).  During the Great American Interchange with South America the big predators invaded South America at the same time armadillos were making their way up into North America.  Yikes, that’s a pretty lopsided exchange.

In addition to long razor sharp teeth, Smilodons possessed immense neck and forelimb muscles. Using the muscles of their front torso they would pull down and pin the great grazing metafauna of the American plains.  Prey animals almost certainly included bison, tapirs, deer, American camels, and ground sloths. Additionally Smilodons might have opportunistically killed juvenile mastodons and mammoths. To dispatch such large prey Smilodons employed their fearsome canine teeth with which they bit through the prone creatures’ necks.

Smilodon fatalis (reconstruction/specimen at the Page Museum)

Paleontologists have collected a great deal of fossil evidence concerning Smilodons, which suggest that the big cats were sophisticates social predators like today’s lions or wolves.  The number and nature of saber-toothed cat fossils recovered from tar pits suggests that Smilodon prides would converge together on prey animals caught in the petrochemical ooze–only to become trapped themselves.  Also some fossilized smilodons have shown evidence of badly broken bones healing—a rarity in carnivores which is generally only possible for pack/pride animals which can (sometimes) rely on a support network.

Thanks to their size, ferocious appearance, and highly characteristic teeth, Smilodons have a special place in human culture to the extent that few other extinct animals do.  The Flintstones had a pet smilodon named “Baby Puss” which evicted Fred from his house in the title sequence and the moral struggles of Diego the saber tooth constituted the moral hook of “Ice Age” a cartoon movie. Ironically for all of our apparent fondness for the great cats, it seems that human migration into the Americas may have been the downfall of the great cats (which vanished 10,000 years ago) but whether their extinction was the result of humans overhunting their prey, shifting climate, or some other factor remains an open question.

Smilodon by Knight

Diprotodon

The largest marsupial known to science is the now extinct diprotodon. Also known as the giant wombat or the rhinoceros wombat, this mighty marsupial grazer stood  nearly 2 meters (6 feet) tall and stretched 3 metres (9.8 feet) from nose to tail.  The animals flourished throughout much of the Pleistocene. From 1.6 million years ago until about 40,000 years ago, herds of Diprotodonts roamed across all of Australia.  These giant wombats were indeed closely related to today’s wombats and koalas: jointly such creatures make up the Vombatiforme suborder   Considering how formidable the bulldozer-like living wombat is, diprotodons must have indeed been like rhinoceroses and they probably occupied a similar top spot in the Australian web of life.

Unfortunately, like a substantial portion of Australia’s mega-fauna, the giant wombats disappeared shortly after humankind reached the island continent. The creatures apparently were destroyed by some combination of climate change, human hunting, and slash-and-burn land management. Aboriginal dreamtime lore makes extensive mention of a mighty furred beast called the bunyip–which has led anthropologists and paleontologists to speculate that the diprotodon has lived on in oral tradition for tens of thousands of years.

Fossil Remains of Diprotodon australis

Ah summer…the perfect time for a delicious guacamole quesadilla or a tasty avocado salad.  But have you ever looked inside an avocado?  Beneath the delicious green flesh is an immense hard seed as big as a golf ball.  Trees compete by spreading seeds efficiently.  The Norway maple in my back yard produces thousands of helicopter seeds which fly off in every direction on their own rotors. The black cherry entices countless birds to eat its fruit, pit and all, and thereby spread its seeds afar on feathered wings.  What purpose does the avocado’s giant seed serve?

Gomphotheres--can you imagine these guys running around Texas?

Well, avocado trees as a species are ancient.  They evolved together with giant mammals like glyptodons, gomphotheres, and giant sloths.  These immense herbivores could eat avocados whole and not even notice the seeds. The animals would forage away from the original tree and, in the course of time, leave the seed in a totally different location along with a pile of fertilizer.  Osage oranges are similarly symbiotic with the giant extinct grazers.  In the absence of these creatures, wild avocados and Osage oranges are slowly losing ground to other trees–even if human kind has planted the avocado for food and the Osage orange for its springy wood (which is perfect for archery).

Giant Sloth

So what happened to all these wonderful beasties?  Why is a nature documentary shot on the grasslands of Africa today so much more satisfying then one from the great Texas Llano?  Alas, they went extinct 12000 to 14000 years ago—just about the same time humankind showed up. It turns out the first humans to get to the New World loved killing charismatic megafauna even more than Buffalo Bill did.

Early Americans stalk a glyptodon.

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