The Land of Camels

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

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)

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

Serpents in Ireland!

Saint Patrick Expelling the Snakes

Just kidding—aside from zoos and the pet trade, Ireland actually famously has no snakes.  It is one the few snake-free large islands on Earth joined only by New Zealand, Iceland, Greenland, and Antarctica (well—everywhere far enough north or south is snake-free: the reptiles don’t really thrive in places where there is permafrost or truly cold winters).  Legend has it that it was Saint Patrick who drove the snakes out of Ireland.  Standing on a great hill he lifted up his crosier and focused divine energy upon the unlucky reptiles which then writhed en masse into the sea and never returned to the emerald island.

"Ssseriously, why are you doing thisss?"

It has always been a bit unclear to me why Saint Patrick would do such a thing. Ecoystems which undergo such catastrophic changes tend to go haywire with great alacrity!  Fortunately the story is entirely a myth.  If snakes ever lived in Ireland (and it doesn’t seem like they did), they were long gone by the time the first Christians showed up.  The real reason is even more interesting than the dramatic Moses-like power of Saint Patrick, but as with most actual answers it is also more complex.

Evidence suggests that snakes evolved 130 million years ago during the Cretaceous.  At the time Ireland was, um, underwater at the bottom of a warm chalky sea.  Early snakes slithered their way across landbridges, rafted to islands on washed away logs, and swam (like the sea snakes) from island to island but, during the Mesozoic, there was no Ireland for them to go to.

Europe in the Ice Age (the pale white area was under a huge sheet of ice)

When the Mesozoic era ended in the great ball of fire, the continents again shifted.  Snakes went through a substantial evolutionary period during the Miocene and the original python-like snakes evolved into many different forms.  These new varieties of snakes slithered into grasslands, deserts, forests, and oceans around the world, but they still could not get to Ireland (now above the waves) because a cold ocean was in their way.  Then the end of the Miocene brought an ice age.  To quote the National Zoo’s essay on “Why Ireland Has No Snakes”:

The most recent ice age began about three million years ago and continues into the present. Between warm periods like the current climate, glaciers have advanced and retreated more than 20 times, often completely blanketing Ireland with ice. Snakes, being cold-blooded animals, simply aren’t able to survive in areas where the ground is frozen year round. Ireland thawed out for the last time only 15,000 years ago.

So Ireland remains snake-free because of the world’s temperamental geology. The island was underwater or covered by ice during certain eras when the snakes might have arrived–geography has conspired against serpents coming to Eire and setting up shop.  The age of humans however has been marked by numerous introduced species cropping up everywhere.  I wonder how long Ireland will be snake free when a pet shop accident or crazy hobbyist could unleash a plague of serpents on the green island.  The fact that such a thing has yet to happen seems almost as miraculous as the original myth.

Although many people construe the whole story to be an allegory of Saint Patrick driving paganism and the old gods from Ireland (as seen here).

The Age of Cephalopods

A diorama portraying the seas of the Ordovician Period (from the Exhibit Museum, University of Michigan)

The Ordovician Period, the second period of the Paleozoic Era, took place from 488 to 444 million years ago.  During those 44 million years, the landmasses of earth were devoid of life except for hardy lichens, tiny algae, and a few lowly non-vascular plants. The oceans, however, teemed with diverse marine invertebrates and primitive vertebrates.  The ecosystems of these great shallow seas seem familiar–with colorful intermeshed filter feeders, grazing herbivores, and swift deadly predators. And yet the creatures are so alien as to make Ordovician reconstructions almost resemble another planet.  All of the creatures of a modern coral reef are replaced by strange analogs:  the dominant filter feeder were not corals but weird sponge-like animals—the archaeocyathids.  The grazers were conodonts and trilobites.  The predators were primitive sharks, huge scorpion-like eurypterids, and above all, the nautiloids–for the Ordovician was a time when cephalopods ruled the earth.

Clever mollusks with multiple tentacles, eyes, and a method of jet propulsion, cephalopods had evolved in the Late Cambrian from a snail-like ancestor.  Their taxonomy exploded in complexity during the Ordovician period.  They also left the shallow continental shelves to range across the pelagic ocean and to descend into the benthic depths.  The cephalopods of the Ordovician period were the nautiloids, animals which manipulated a bubble of air within a chambered shell to move up and down the water column.  They could grab prey with their many tentacles or retreat into their calcium-based shell. The family quickly exploded in complexity. To quote palaeos.com:

At least ten different orders flourished at this time, all but one appearing for the first time during the early or middle part of the Ordovician.  This astonishing diversity included straight, curved, loosely coiled, and tightly coiled shelled types, and even one group (the Ascocerids) that in order to become lighter and more streamlined lost the a large part of their shell altogether.  These intelligent carnivorous molluscs replaced the Cambrian Anomalocarids as the dominant life form and top predator of the world’s ocean.  The biggest, such as the endocerids, attained huge size; with shells of up to 10 meters in length they were the largest animal that, up until that time, had ever lived.

Some paleontologists have expressed doubts about this magnificent ten meter endocerid shell.  But, even so, it is worth remembering that this measurement did not include the tentacles and the head of the creature.  These giant orthocones must have been formidable predators, living on nautiloids, eurypterids, and jawless fish.  The great monsters are believed to have had weak eyes (and could probably be avoided by staying shell-side of the behemoths).  However an even bigger problem faced the tentacled masters of that world.

A giant orthocone

During Ordovician times, the land masses that are now South America, Africa, Madagascar, Antarctica, India, South Asia, and Australia were all joined together as a supercontinent, Gondwanaland.  Over tens of millions of years Gondwanaland gradually drifted into the Southern Polar regions of the globe.  This resulted in heavy glaciation, which in turn caused rapid deep freezes and sudden interglacial warm periods—in other words, an ice age.  This great ice age caused the depth of the ocean to fluctuate wildly which brought a crashing end to the Ordovician and its dominant cephalopods.   The mass extinction which ended the Ordovician period was the second worst in the history of the planet (eclipsed only by the mass extinction at the end of the Permian period).   More than 60% of marine invertebrates went extinct (including whole families of mollusks).   This was but one set back for cephalopods.  The family has burgeoned and then crashed many times, but it marked the end of their time as apex predator.

Various Ordovician cephalopods, including the infamous Cameroceras trentonese, shown feeding on a hapless Aphetoceras americanum, while a quartet of Cyclostomiceras cassinense swim by (illustration by Stanton F. Fink).