The Ancestral Australian Aborigines As a Possible Cause for the Extinction of Australia's Pleistocene Marsupial Megafauna

A few weeks ago, in my Anthropology class, we had to do a cultural profile of one culture group of humans.  I chose the Australian Aborigines and, having just finished Tim Flannery's excellent book "Chasing Kangaroos," this whole concept of the Ancestral Aborigines being the possible cause of the extinction of Australia's Pleistocene megafauna was still quite fresh in my mind, so I included it in the paper.  I thought it was pretty interesting, and so I have decided to share it with ya'll, too, with a few brief modifications to make it more Blog friendly!  Hope you enjoy, and if you want a more comprehensive look at the topic, I highly recommend "Chasing Kangaroos!"

Interestingly, paleontologists today are using the Australian Aborigines to help them figure out when Australia's Pleistocene megafauna went extinct.  While today, there are no native animals larger than the red kangaroo, Pleistocene Australia was a very different place, as was the rest of the world.  The Pleistocene Epoch was the time of the Ice Age megafauna.  With the exception of Africa and south-east Asia, in most places nowadays, the Pleistocene megafauna is extinct, but back then, the megafauna were a world-wide phenomenon.  In Eurasia, there were the giant mammoths and rhinoceroses, the cave lions and hyenas, the Irish elk, and the giant polar bear.  In North America, there were the mammoths and mastodons, the short-faced bear, the giant bison, the dire wolf, the giant beavers, and the saber-toothed cats.  In South America, there were the giant ground sloths, the armored glyptodonts, and many large relatives of elephants.  

Australia also had its fair share of Pleistocene megafauna, with marsupial lions, the giant short-faced kangaroos, the hippo-sized wombat Diprotodon, and echidnas that were the size of sheep.  There are two main hypothesis when it comes to what caused the extinction of all these animals: climate change, or hunting by early human arrivals on Australia, the first Aborigines.  No one could figure out whether it really was the Aborigines that had hunted the megafauna to extinction, though, because no one could figure out the date that the megafauna had gone extinct, nor could they figure out the date that humans first arrived on Australia.  Some people believed that the megafauna survived until around 6,000 years ago, while others believed that they went extinct a great many years prior.  The same difficulties confronted those scientists attempting to determine when humans first arrived.  The sediments of Australia are notoriously hard to date, and since the animals of Australia are so unique (especially following the extinction of the dinosaurs), scientists were unable to correlate their data with other places around the world.[1] 

As more scientific discoveries were made, a new method of dating rocks was discovered, called optically stimulated luminescence (or OSL for short).  Using OSL, paleontologists were successfully able to date many different specimens of the various marsupial Pleistocene megafauna, and found that, while many of them approached the 46,000 years ago mark, none of them passed it.  Many different specimens were used from all across Australia, but they all said the same thing: 46 was the answer. 

Meanwhile, with the new OSL tool in their bag, other scientists headed off to sites of known human habitation to attempt to date them as well, and these efforts proved to be successful.  One of the main places that they dated was a place known as Devil’s Lair, a known area of ancient Aboriginal inhabitance.  What was especially important about Devil’s Lair was that there was sediment present for the last 63,000 years, meaning that instead of just a snapshot of time, the scientists had an uninterrupted sequence of time to figure out when humans started living there.  As the scientists dated the sediments with the first signs of human inhabitance, they came up with the magic number: 46,000.  Other sites came up with the same number too, including Lake Mungo, the oldest human burial known from Australia.  At Lake Mungo, the dates were a bit less precise, ranging from between 45,000 and 47,000 years ago, but the data still seems to point in the same direction.  The ancestral Aborigines arrived on the continent at around the same time that Australia’s Pleistocene megafauna went extinct.  With this new dating technique, scientists were also able to determine that there was no significant climate change for many thousands of years on either side of the 46,000 mark, effectively ruling out that hypothesis.  So it seems that, for a time, the people who believe themselves as part of the land and the natural world around them actually destroyed a significant part of it.

[1] For example, paleontologists studying dinosaurs of the Late Jurassic Morrison Formation here in Colorado are able to look at closely related dinosaurs in other parts of the world like the UK and southern Africa (keep in mind that the continents were all together in one big landmass back then.)  That way, if the paleontologists are unable to determine the dates of, say, the Tendaguru Formation in Tanzania, they can look to the studies done on the rocks of the Morrison Formation for an accurate estimation.  This is a luxury that paleontologists, archaeologists and other scientists working in Australia simply do not have. 

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Animal Spotlight: Aurochs

This post is the birthday post of Govind Kamath!  Happy birthday, Mr. Kamath!  If you have a birthday coming up, just email me the date at cuyvaldar123946@gmail.com with the date and your favorite animal, and I will do my best to get a post in!

Over the years, you may have pondered, "Where does my burger come from?"  You probably just meant where was the cow that it came from.  But now here is something else for you to ponder.  Where the heck did the cow even come from?  Do you ever just see wild, black and white cows?  Well, I am here to tell you all about the evolution of the cow.

A Watusi/Longhorn pileup!  They actually crashed into each other, though!  Trust me, I was there, you can even see my sweatshirted elbow in the mirror thingy!

During the Pliocene Epoch, from around 5 to 2 MYA, the planet went through a cooler spell.  The frequent ice ages were a part of this cool spell, as was the most frequent Ice Age.  This colder weather caused many of the worlds forests to decrease in area, which in turn caused the world's grasslands to expand.  This led to the evolution of many large grazing animals, and helped contribute to the Pleistocene Megafauna, often called the Ice Age Megafauna.  One of these large animals that evolved was the Aurochs.

The Aurochs (Bos primigenius), first became domesticated during the Neolithic Age, or the "New Stone Age," probably around 12,000 years ago.  As a matter of fact, two waves of domestication occurred.  As you can see in the map below, there were three different subspecies of the Aurochs; one in northern Africa; one for Europe and Asia; and a third for the mysterious subcontinent of India, as Rajesh Ramayan Koothrappali says in "The Big Bang Theory."  The two different domestications happened with the Eurasian subspecies, Bos primigenius primigenius, and the Indian subspecies, B. p. namadicus. 

These two different domestications of these two different species of cattle led to two different domesticated cattle!  In India, we have the Zebu cattle, which has been given its own scientific subspecies name, Bos primigenius indicus.  The other, Eurasian kind has become the cow that we know today from driving down the street and the Chik-fil-A ads.  While other types of bovines (members of the family Bovidae, a group of ungulates that includes water and African buffalo, yaks, bison, and, of course, cattle) have been domesticated throughout the years, specifically the water buffalo, the south-east Asian Banteng, and the Indian Gaur, it is cattle that have remained the most widely used, for a wide variety of purposes, too.

The Aurochs is now extinct.  The very last recorded female passed away in 1627 in the Jaktorów Forest in Poland.

There are two particularly interesting breeds of domesticated cattle that I would like to now draw to your attention.  Back in December of 2011 on our trip down to Texas to visit my gramma, on the same trip where we visited the Heritage Museum of the Texas Hill Country and saw the Acrocanthosaurus footprints, we also visited the San Antonio Zoo, as well as the Natural Bridge Wildlife Ranch near San Antonio.  This is an awesome place for EVERYONE to visit!  You get to roll down your windows as you drive through a park chock-full of deer, antelope, zebra, and bovines, and you get to drop food for them!  There are also three members of the order Struthioniformes (aka the ratites), like the South American rhea, the Australian emu, and, most terrifying of all, the African ostrich.  The ostriches was absolutely terrifying, and I will talk about them in a later blog post!  But also at the ranch they had two pretty crazy types of cattle!

The first was the Ankole-Watusi, often called simply the Ankole cattle or the Watusi.  Originally bred in Africa, the Watusi was named after the Watusi tribesmen (now the Tutsi of Rwanda and Burundi).  This type of cattle has enormous horns that can span over six feet!  Both genders have these horns, and they can grow from between 1,500 - 1,800 pounds!  Below are some pictures that my family and I took of the cattle walking by our car!

A Watusi.  CHECK OUT THOSE HORNS!

Another Watusi.  CHECK OUT THOSE HORNS!

A baby Watusi!  HOW CUTE!

The second crazy type of cattle is the Texas Longhorn.  The Texas longhorn is, of course, native to the Lone Star State, and reports of the longhorn enduring thirst while still being able to fight off packs of wolves, as well as bears (presumably grizzly bears), from the pioneer times is not uncommon.  The longhorn, like the Watusi, also has six foot horns possessed by both sexes.  According to the Natural Bridge Wildlife Ranch Adventure Guide Book, the longhorn "helped form the basis of the ranching industry of the American West during the 19th century."

A Texas longhorn.  CHECK OUT THOSE HORNS.

Another Texas longhorn.  CHECK OUT THOSE HORNS.

The aftermath of the Watusi/Longhorn pileup seen above!

Whoever said cows weren't interesting!

What Is It? The Weekly Challenge #4 Answer

This weeks challenge was to figure out which, in the picture below, was a mammoth, and which was a mastodon. This weeks challenge was correctly guessed by two people, both Ilyssa A. and Masaki K., who both said mammoth on the left and mastodon on the right.  However, how can you differentiate between the two?  Obvious, we have two super-sleuth paleontologists on our hands who can differentiate, but I'm guessing that the vast majority of you might have trouble.  So here is a quick Mammoth Vs. Mastodon Guide, with just a few helpful ways to differentiate between the two.

A size comparison of a mammoth and a human, myself, at the excellent zoo called The Living Desert in California.  Photo Credit: Julie Neher

Check in a few hours for this weeks challenge!

The Function of Cheek Pouches

A possible ancestor of Diprotodon (the largest mammal known from anytime in Australia, as well as the largest known marsupial known from anywhere in the world, and a relative of the wombat), the skull of Euryzygoma dunense, another extinct, megafaunal, eight foot long, quadrupedal herbivorous marsupial, is quite interesting: it has two extended cheekbones.  This gives Euryzygoma the unusual mammalian property of its skull being wider than it is long.  Although to most this probably doesn’t actually seem all that exciting, the extended cheekbones have led to two interesting theories regarding their function in the living animal.  One we will look at in a few weeks (the week of August 3rd to be more precise), but the other one we will look at now.

The hypothesis came about when the skull of Euryzygoma was first described.  The scientists who first described Euryzygoma thought that the lateral extensions of the zygomatic arch resembled those seen in squirrels, gophers and various types of Old World Monkeys, like the macaque and the baboon. 

 In the living animals just described, these lateral extensions function as cheek pouches, which make it so that the animals that possess them can store food in them.  That is why you so often see a squirrel running around with its cheeks puffed out.   

Some scientists think that Euryzygoma might have used its cheek pouches to store water; thus, it would not need to spend so much time near waterholes that were most likely infested with large crocodiles.  This would also help Euryzygoma travel longer distances during a drought, enabling it to move greater distances to reach waterholes that other animals would simply unable to reach, having a much more limited range.