War of the Wombats

There are three different types of wombat.  There is the common wombat (Vombatus ursinus), the southern hairy-nosed (Lasiorhinus latifrons) and the northern hairy-nosed (L. krefftii).  They have been classified by the IUCN, respectively, as Least Concern, Least Concern, and Critically Endangered.  Unfortunately, all three wombats face threats that could easily result in their extermination from the wilds of the earth.  Fortunately, steps are being taken to prevent such a wombacide.

In Queensland, Australia  lies Epping Forest National Park.  In just two square miles of this park live the last ninety individuals of the northern hairy-nosed wombat.  Surrounding this puny area is a 20 kilometer long perimeter fence, erected after 10 wombats were killed by dingoes a few years ago, which, considering the severity of a ten percent population loss in such a small population, makes total sense.

Although these steps are being taken to protect the northern hairy-nosed, this species of wombat still faces several severe problems.  One such problem is the fact that 75% of these wombats are male, making a boom in their population more difficult to achieve.  Fortunately for the northerners, the southern hairy-nosed wombat has a very similar reproductive system as the northern hairy-nosed.  Scientists are therefore using female southerners as surrogate mothers for the northerners.  This method is referred to as "cross fostering," and has been used successfully when it comes to other marsupials.

The other major problem confronting the northern hairy-nosers is the fact that all of the animals are located in the same place.  In the event of a disease, wild-fire, or some other similar catastrophe, most or all of these creatures could be exterminated in the virtual blink of an eye.  Conservationists think it wise to create a second population of northerners, not too far away from the first, but far enough away to ensure that a disaster could not take out both populations with one fell swoop.  Scientists and conservationists have decided that it would be most beneficial to the northerners if they were to assist in their burrow construction.

These burrows, which can be over 100 feet long, would be time-consuming construction projects.  Not only that, but a single wombat will often use up to five different burrows, moving to a different one each day.  The first wombat doesn't just leave his or her old burrow unoccupied, however, as another wombat, probably the same one every five days or so (I would guess), temporarily moves in.  It's really less of a permanent residence, like a house, and more of a time-share condo.

But just how time and energy consuming would it be to dig such a burrow if you were a wombat?  Wombats have a problem with keeping cool.  If you ask my opinion, I suspect it has a lot to do with their body design.  As we discussed a few posts ago, animals that live in hot environments typically adapt in ways to increase their Surface Area to Volume ratio, or SA:V for short.  To learn more about why this is, click HERE.  However, fossorial, or burrowing, animals, like the wombat, aardvark, marsupial mole, and many, many others, try to keep their bodies streamlined.  Like dolphins and sharks, these animals want to be able to glide smoothly through their desired area (be it water or burrows).  Having random chunks of body, i.e. the ears of an elephant or a deer, would merely slow the animal down.  That is my theory, anyways.

To keep cool in the heat of the Australian day, wombats will take refuge in their burrows.  However, to be efficient enough when it comes to trapping moisture (as water can often be very difficult to come by in the habitat of the northerns), it has been estimated that the burrow would need to exceed fifteen feet in length.  It has also been calculated that the approximate amount of energy required for a wombat to dig a three foot long chunk of burrow is about the amount of energy that a wombat would expend running twelve miles.  That means for the comforting fifteen foot length of burrow, the wombat could instead run about sixty miles.  Clearly no small effort.

The way that the scientists actually figured all of this out was really quite interesting.  To see how long it takes for a wombat to dig a burrow, experimenters Glen Shimmin and David Taggart put one wombat into a box.  (Equipped with breathing holes, of course.  As pirates and I like to say, "A dead wombat digs no holes").  The human duo then dug a hole in the ground the same size as the box.  Placing the wombat-infested box into the ground, they then opened up one end of the container, allowing the wombat free access to the soil.  Instinctively, the wombat would begin to dig.  A half an hour later, Shimmin and Taggart ceased the wombat-excavation, and carefully measured how much dirt was displaced by the wombat, as all of the displaced dirt would conveniently be shoved (by the wombat) into the box!  Convenient, huh?  During the half hour digging session, the wombat moved more than 100 pounds of dirt!  Impressive, but the team concluded that, if conservationists were to release a group of northern hairy-nosed wombats into their new territory without pre-dug burrows, it was incredibly likely that the wombats would simply dig themselves to exhaustion, and subsequent death.  An undesirable outcome for all parties involved, it was decided to dig man-made burrows, resembling those of wombats, throughout the habitat, prior to the installation of the wombat center-piece.

What are some other problems facing wombats?  Well for starters, some of these problems, even when facing the wombats in the face, are virtually invisible to them.  Wombats, like Stegosaurus, rhinos, and myself (without my contacts), are virtually blind.  You don't need eyes if you are a fossorial (burrowing) creature; just ask the marsupial mole, the golden mole, or many other types of fossorial animals who no longer use, or even have, eyes!  However, when it comes to crossing roads, their terrible eyesight really takes its toll.  Hundreds, if not thousands, are hit by cars each year.

Other problems include starvation, drought, mange, and other people problems.  Starvation can be easily caused by the gradual squeezing out of the native grasses typically consumed by wombats by other, inedible grasses.  Drought should be self-explanatory; without water, the food dies.  Without water, there is no water.  Both are not good for wombats.  Mange, for wombats at least, is a fatal skin disease.  And as for the other people problems?  Let's just say that prairie dogs can relate.  (And now, even though I just said "Let's just say," I am going to go into more detail).  Like prairie dogs, wombats burrow.  And also like prairie dogs, the habitat of the wombat is perfect for ranchers.  So it goes like this.  Ranchers come along, and bring their cattle.  The cattle step in prairie dog/wombat holes, break their legs, and die.  The ranchers, enraged, take their rage out on the culprits: the prairie dogs or the wombats.  And as we have discussed before, wombat burrows can be quite extensive.  Furthermore, the entrance holes would have to be quite fat in order to accomodate such...robust occupants. 

As we have also previously discussed, much is being done in order to protect the wombat.  Another bit of good news is that a population boom of around 10% was recorded for the sole population of the northern hairy-nosed wombat!  Another wee bit of hope in a world that we willfully wish not to become wombatless.

WOMBAT FACTS:

1. Cooling Off:  Besides retreating into their burrows, wombats will also flick dirt onto their bodies to keep cool.
2. Olympic Runners:  Despite its dumpy appearance, the wombat can reach a top speed of around 25 mph.  This means that it can outrun an Olympic sprinter, like Usain Bolt!
3. Cooling Off V 2.0:  Besides retreating into their burrows and flicking dirt onto their bodies, wombats are also nocturnal, meaning that they avoid the heat of the day.
4. Life Span:  Wombats can live around twenty years.
5. Wombat Wesearch:  Prior to around fifteen or so years ago, not much research had been done on wombats.  Most of what we know has been discovered since that time.
6. Power House Excavators:  For their size, wombats may be the world's most powerful excavators.

Whitsunday Islands on Dwellable

Perfume-Loving Lions and Record-Breaking Cheetahs

Two interesting pieces of feline-news for you today!  The first actually takes place at the Denver Zoo!

13 year old male lion named Krueger seems to really like "Obsession," by Calvin Klein!  Apparently, if the perfume (or is it cologne?  Man-fume?) is sprayed inside of his enclosure, he goes to the same spot and "rubs his cheek on it."  When you actually think about it, it totally makes sense.  Perfumes and colognes are supposed to attract people due to pheromones inside of them.  Animals also use pheromones, mostly to communicate.

Has a cat ever done this to you?  Scent glands in the cheeks of cats (as well as in their paws) contain pheromones, used in communication.  Each cat has a unique scent, and it rubs off when they rub into things like this.  So when your cat greets you, it is partly due to affection, and also partly due to the fact that they are really marking you as their territory.  At least they aren't peeing on you!  So this explains why Krueger would rub his cheeks against the spots of Obsession sprayed around his enclosure.

Interestingly, the lions seem to enjoy Obsession more than other perfumes, and not all of the lions were attracted to it: only half of them were, in fact!  Emily Insalaco, an employee at the Denver Zoo, thinks that the lions like this particular cologne more than others due to the presence of cinnamon, which the lions have seemed partial to in the past.  If you want to see a video containing more information, click below.

http://www.9news.com/news/story.aspx?storyid=146948&catid=188


Next up is Sarah the cheetah, one speedy demon from the Cincinnati Zoo in Cincinnati, Ohio!  Multiple times has this amazing cat beaten the world record for the 100 meter dash, and once even twice in the same day!  The first link below is from Sarah's first world record break, where she broke the world record twice in one day in 2009.  The second clip below is from more recently, when Sarah yet again beat the record, in June of 2012. 


http://www.thetravelalmanac.com/lists/videos/animals-speed.htm

http://news.nationalgeographic.com/news/2012/08/120802-cheetah-sarah-cincinnati-zoo-fastest-record-science-usain-bolt-olympics/

Spring Valley on Dwellable

Top Ten: Extinct Sea Monsters (Part 4 of 5)

7.  Archelon - Archelon is the largest sea turtle that has been discovered to date, the closest living relative that Archelon has is the "Critically Endangered" leatherback sea turtle, the largest sea turtle alive today.  Living in the Late Cretaceous Western Interior Seaway between 75-65 MYA, Archelon has been discovered in the states of South Dakota, Wyoming and Kansas. 

8.  Leedsichthys - Often cited as the largest fish known to humankind, the largest Leedsichthys had an estimated length of 72 feet, but some researchers believe that it could have grown to sizes that would rival those seen in the blue whale, the largest known animal ever to live on planet Earth.   Although Leedsichthys swam the seas only during the Jurassic Period, the group that it belonged to survived until the end of the Cretaceous Period.  Remains of this filter feeder have been uncovered in England, France, Germany, and Chile.  


COMING UP NEXT WE HAVE:

9.  Tanystropheus
10. Tylosaurus

This post is part of the "Top Ten: Extinct Sea Monsters" series.  For the rest of the posts in this series, click HERE.  

Top Ten: Extinct Sea Monsters (Part 1 of 5)

Since ya'll kinda get gypped on Wednesdays with the "What Is It?" challenge, I decided that, when I do do the challenge, I will also include a "Top Ten" list.  I mean, come on now, who doesn't like lists?  I know some of my friends would be absolutely and completely lost without them!  So for today's "Top Ten," we are going to take a look at some of the world's most amazing, extinct sea monsters.  This is also up for debate, so if you disagree, just give me a holler!  Also, they are not in any particular order, I just kind of threw them all in there!  So without further ado, here we go, with our "Top Ten:  Extinct Sea Monsters!"

1.  Megalodon - This gigantic relative of the extant great white shark was thought to be simply massive: perhaps even sixty feet in length!  Living the world over, Megalodon stalked the seas during the Miocene and Pliocene Epochs, and only died out during the current Pleistocene Epoch, around two million years ago.  It is thought that Megalodon evolved to such gigantic proportions in order to be able to attack the massive whales that had started to evolve in the cooler seas of the Miocene and Pliocene.  Remember now: if it's a shark, then it's a fish!

A tooth fragment from Megalodon at this excellent restaurant called The Crab Shack on Tybee Island off of the coast of Savannah, Georgia. 

2.  Basilosaurus - A massive, predatory whale (and, therefore, a mammal) that cruised the seas in the Late Eocene Epoch, 40 to 34 MYA, fossil discoveries of this massive animal were reportedly so common in the southern United States during the early 19th century, that bones of Basilosaurus would be used as furniture!  It was first discovered in Louisiana, and is the state fossil of both Mississippi and Alabama.  Basilosaurus has also been found in Egypt and Pakistan.  At around sixty feet in length, the same estimated length of Megalodon, Basilosaurus is thought to have been the biggest creature alive at the time.

COMING UP:

3.  Liopleurodon
4.  Shonisaurus
5. Elasmosaurus
6.  Dunkleosteus
7.  Archelon
8.  Leedsichthys
9.  Tanystropheus
10. Tylosaurus

This post is part of the "Top Ten: Extinct Sea Monsters" series.  For the rest of the posts in this series, click HERE. 

Animals of South Dakota: Part 2

NOW.  What animals should you be watching for on your trip?  Well, I am so glad you asked!  There are going to be three main areas where you would be able to see wildlife; the Prairies (P), the Pine Forests (PF), and the Black Hills (BH).

1.  Bison - If you are lucky, you might get stuck for a few minutes as a herd of bison crosses the road in front of you!  Be careful when viewing these animals, and use common sense; don't be the stereotypical stupid tourist and get yourself trampled to death by the bison.  They are the largest living mammals in North America, and can be testy. - P, BH

2.  Mule Deer - Just like we have in Boulder.  - P, PF, BH

A pair of mule deer fawns, near my house

3.  Pronghorn - One of my favorite animals, the Pronghorn Antelope is the second fastest animal in the world, and the fastest in North America, capabable of running around 61 MPH.  Why it can do that, we will talk about next Wednesday. - P, BH

4.  Red and Gray Fox, Coyote - Just like we have in Boulder, except for the Gray Fox. - P

A picture of a gray fox, taken by me at Brookgreen Gardens in  South Carolina

5.  Turkey Vulture - Watch for these guys anywhere, but they should be especially easy to spot on the vast swathes of prairie separating you from South Dakota.  They are instantly recognizable by their "V-Shaped" wing profile, their relative lack of wing-flapping, as well as the fact that they are probably circling something in the air.  Usually groups of them will signifiy a dead animal, as they are carrion eaters. - P, PF, BH

6.  Bighorn Sheep - Just like we have in Colorado - PF, BH

7.  These are the main ones to watch for, but if you get really lucky, you might see one of the black-footed ferrets in the Badlands, or a badger in the prairies!

Animal Spotlight: The Capybara

Today, we are going to investigate the capybara (Hydrochoerus hydrochaeris).  Listed as "Least Concern" by the IUCN, both parts of its scientific name, hydrochoerus and hydrochaeris mean the same thing.  As you probably noticed, they both contain the Greek root "hydro," which, as you probably know, means "water."  The second half would be forgivable if you were unfamiliar with it: it means hog, or pig.  So, from its scientific name, we can assume that the capybara is a water pig.

Again, it would be understandable if you were to think that, as the capybara most definitely resembles a pig, at least superficially.  However, the capybara is not pig: instead, it is a rodent, related to creatures such as chinchillas.  As a matter of fact, the capybara is the world's largest extant rodent! 

Semi-aquatic, the capybara has evolved webbed feet, like many other semi-aquatic animals, like the POLAR BEAR.  An herbivore, the capybara must face attacks from many predatory animals, including the caiman (a relative of a crocodile), eagles, ocelot, puma/mountain lion, jaguar, and the anaconda, for who the capybara is its favorite meal.  The capybara generally travels in herds of around ten or twenty, but groups of up to one hundred have been seen before.

Capybara are fairly common zoo animals, and, when they escape into the wild, if they can find a semi-aquatic habitat that they like, they can often survive and thrive.  Sightings are common throughout Florida, and there have been sightings in California as well. 

When it isn't an escaped convict of the zoo, the capybara lives throughout most of mainland South America (thus excluding Trinidad and Tobago), except for the country of Chile.  These countries are Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname, French Guyana, Brazil, Uruguay, Argentina, Paraguay and Bolivia.

Not enough capybara for you?  Well just check out these two amusing video clips below!  The first one shows a capybara with a case of the hiccups at the Bristol Zoo in England (UK), while the one below shows squirrel monkeys riding capybaras at the Saitama Zoo in Saitama, Japan.

The Hiccuping Capybara

Squirrel Monkeys Riding Capybaras


Finally, here are a pair of pictures that I took of one of the capybaras at the San Antonio Zoo in Texas.  Enjoy!

One of the capybaras sleeping at the San Antonio Zoo in Texas.

One of the capybaras sleeping at the San Antonio Zoo in Texas.

Animal Spotlight: The Sloth

Today's "Animal Spotlight" is the arboreal South American three-toed sloth (Bradypus variegatus).  The three-toed sloth holds the record for the world's slowest mammal: in fact, it is so slow, that algae grows on its fur, giving it a greenish color.  The algae helps to camouflage the slow animal in the treetops of its rainforest home.  In the case that its camouflage fails it, then it will resort to taking a stab at its attacker with its incredibly large claws.  Definitely not something that you want to take a hit from.

After perusing a few sources, I have come up with a list of the top 10 sleepiest animals, as you can see below.  The numbers are all number of hours spent sleeping a day. 

1. Koala:            20-22
2. Sloth:             20
3. Armadillo:       19
4. Opossum:       19
5. Lemurs:          16
6. Owl Monkey:  17
7. Lion:              14-16
8. Hamster:        14
9. Squirrel:         13-14
10. House Cat:     11-12 

 HERE is a link to an earlier post about the koala, and why it is so sleepy.  The sloth apparently is so incredibly sleepy simply due to the fact that its leaves are so poor in nutrients, much like the predicament the koala finds itself in.

Two other sloth facts struck me as pretty interesting.  The first one is the fact that, due to a few extra neck vertebrae, the sloth can turn its head 270 degrees, as you can see in the picture below.

The second interesting fact is that, despite the poor ability of the sloth to walk on the ground due to weak hind legs, they are actually surprisingly adept swimmers, as you can see in both of the videos below.

A Sloth Walking

A Sloth Swimming


According to the website of National Geographic, the three-toed sloth is labeled as "Endangered" by the IUCN.  Sloths live in Central and South America, and the three-toed sloth specifically inhabits the countries of Venezuela, Guyana, Suriname, French Guyana, and Brazil.

Finally, to learn a little bit more about the sloth, click on the link below.  The video is a short clip narrated by David Attenborough, and is also quite amusing.  Enjoy!

Saying "Boo!" To A Sloth

Animal Spotlight: The Polar Bear

The polar bear (Ursus maritimus) is the world's largest extant, terrestrial carnivore, with males growing up to 1,500 pounds.  Like many animals that spend a good amount of time in the water, their feet are partially webbed to aid in swimming.  Although the fur of the polar bear is white, to help it blend into the ice and snow when it is hunting seals, its skin underneath is black, to aid in heat absorption.

In the picture above, it certainly looks like the polar bear is just enjoying itself, and having a good time.  While both of these may be true, the polar bear is actually cleaning its fur, presumably after a kill, given the blood-stained snow off in the left of the picture.  Below the picture is a link to a video clip from BBC's "Planet Earth," narrated by one of my personal heroes, David Attenborough.  In the video, make sure to watch for the fur cleaning.

This is the link to the Planet Earth link: https://www.youtube.com/watch?v=OwZH_aT0FGI

The polar bear, due to its immense size and lack of natural predators, fears nothing, humans included.  This, coupled with a natural, and insatiable, curiosity, often brings bears and humans into contact.  The video clip below is from another BBC show, called "Polar Bear: Spy on the Ice."  I first saw this show when we were in South Carolina this summer, and found it really interesting!  This clip is one of my favorite parts from it.

Polar Bears Attacking Spy Cameras:  http://www.youtube.com/watch?v=DvduCPXO_FE

Finally, we have another interesting YouTube video that I discovered today.  Watch and enjoy!

https://www.youtube.com/watch?v=JE-Nyt4Bmi8

The polar bear's range covers five different countries: Russia, Denmark owned Greenland, Norway owned Svalbard, Alaska, and Canada.

What Is It? The Weekly Challenge #3 Answer

Today's animal was easier for many of you, and we had a number of good guesses!  We had a few close guesses (like the American Kestrel, another North American bird of prey, but we had one totally right answer.  This weeks winner is Julie N., who guessed the Peregrine Falcon!

Peregrine Falcon

 The Peregrine Falcon is one of my favorite birds, mainly because of how it hunts.  It dives at medium-sized birds from up to 3,000 feet in the air, and often dives towards the birds with the sun at its back; that way, its prey has a difficult time of seeing them through the sun's glare.  In its dive, speeds of 175 - 200 mph have been recorded, placing it at the terminal velocity able to be achieved by the bird.  Some people have reported that the peregrine can exceed terminal velocity but, despite being taken in by this theory for a time, I believe that this not, in fact, true.  (I am not that into the math or physics, but I believe it might even be impossible, but I'm sure some of you know that better than me!)  Click on the link below to learn a little more, and to see the bird in action!

http://www.youtube.com/watch?v=cKqt05iR9WI&feature=player_embedded#!

Although their population numbers suffered tremendous, pesticide-induced blows during the 20th century, they have made quite a comeback throughout the United States.  However, it was a close call.  Use of pesticides like DDT (commonly known as DEET, used to be common in mosquito repellent before its negative impacts on the environment became fully known) caused the Peregrine Falcon's eggshells to become weak, and they were easily broken.  The result of this was very few baby falcons surviving to breed themselves.  In fact, at one point it got so bad that the Peregrine Falcon was listed as "Endangered" by the IUCN in the 1950's through the 1970's.  It became extirpated, or locally extinct, in both Belgium and the eastern United States.  However, now it is labeled as "Least Concern;" an amazing comeback, for an amazing bird.

This picture of the Peregrine Falcon was taken by me, last week at the Reptile Day at Dinosaur Ridge, near Golden.  My friend Masaki Kleinkopf and I went and were able to see a few pretty cool things, the Peregrine Falcon being just one of them.  I highly recommend going to check out the Ridge, as well as the museum they have there, it is really quire interesting!

Don't forget to check in later in the day for this week's 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.

The Komodo Dragon: Deadly Drooler or Poisonous Predator?

The Komodo dragon (labeled "Vulnerable" by the IUCN) has long had the title of "World's Deadliest Drooler."  Native only to the Komodo Islands in Indonesia, The story went that the Komodo would bite its prey and let it slowly die, eaten away from the inside out by all of the deadly bacteria that fermented in its mouth.  It ends up that this story, as that is all it is, a story, originated from just one or two accounts of the creature almost a century or so ago, and that they were based almost entirely upon observation.  After these accounts were made public, more and more researchers and scientists tagged on to this idea until, eventually, it was a scientifically accepted fact.

Further support for this hypothesis was observations of Komodos biting buffalo, a main food source, and simply hanging around for days, weeks, and (I believe) on at least one occasion, a month.  Scientists believed that the animals would slowly succumb to the copious amounts of bacteria that were at home in the mouth of the worlds largest extant lizard. 

While it is true that the mouth of the Komodo dragon was, in fact, home to a number of very virulent strains of bacteria, it seems that there are other players at work.  A group of scientists noticed that the Komodo dragon, and other closely related monitor lizards, all had interesting bulges in the sides of their mouths.  These bulges they thought resembled those seen in the Gila monster, one of just two lizards that were previously known to have venom, the other being Mexico's beaded lizard.  Komodo skulls are hard to get a hold of, however, and it wasn't until 2009 that the team of researchers were finally able to get ahold of a Komodo dragon skull to put through an MRI machine.  The MRI scan showed that the Komodo did indeed have venom glands.  Although the venom appeared not to be deadly, it was potent enough to act as a sedative.  This, the team concluded, was how the Komodo would kill its victims: sedate them with its mildly potent venom, and then finish them off when they were slow and torporous. 

This didn't explain why it sometimes took weeks for Komodos to finish off a buffalo.  Kurt Schwenk believes it is because the Komodos often don't want to risk life and limb.  So what they do is they bite their victims, and let a combination of shock and bloodloss do the trick.  As the prey slowly starves, being surrounded by Komodo dragons and unable to retreat anywhere, more and more Komodos congregate in preparation of the coming feast.  And given their slow metabolic rates, they can afford to wait, too: unlike a lion or a cheetah, they are in no hurry to finish off their prey, and see no reason to take unnecessary risks to finish off the prey.

While all of this research is highly disputed, and subject to many different points of interpretation, it does seem like the idea of the Komodo killing by its toxic drool is indeed false, although only future research will decide all of this for certain.

The Cichlids of the African Rift Lakes

Three of the largest lakes in the world reside in the 3,700 mile long Rift Valleys of Africa.  These lakes, Lakes Victoria (located in the countries of Kenya, Uganda and Tanzania), Tanganyika (split between Burundi, the Democratic Republic of the Congo [DRC], Tanzania, and Zambia), and Malawi (located between Malawi, Mozambique and Tanzania), rank among the top ten largest lakes in the world; third, seventh, and ninth, respectively.  (For some reason, these rankings differ upon where you look.  Lake Victoria as the third largest lake seems pretty universal, but the ranks of Tanganyika and Malawi differ for whatever reason.  You'd think that it would be pretty universal, but I suppose not.)  Besides being such large lakes, these lakes are important for other reasons, perhaps the most important reason (for biologists, at least) being their isolation.

You see, the three great lakes are islands, of a sort.  According to Websters, the definition of an island is "a land mass smaller than a continent and surrounded by water."  The Rift Valley lakes are essentially the opposite; "a body of water smaller than an ocean and surrounded by land."  For our purposes, an island is just something that has been isolated for a time, and allowed its flora and fauna to flourish in new and interesting ways.

And flourish it did in the Rift Valley lakes.  If you were to visit these lakes, snorkel or scuba in their waters, you would most likely notice a wide variety of fish.  You would not be wrong in this assessment; however, you might be surprised to find that most of these types of fish are belonging to a group called the cichlids (SICK-lids), and that all 1,650 plus species of these cichlids descended from a common ancestor.  While the dates of when the common ancestor of the various cichlids came to be trapped in their respective lakes, it has been estimated that the cichlids of Lake Malawi all evolved from a common ancestor trapped 700,000 years ago, and those of Lake Victoria around 12,000 years ago.  Trapped in these growing lakes while they were being formed, this small group of fish quickly came to dominate their new home, exploding in biodiversity to adapt to the wide variety of niches left open to them.

Tenuous can this biodiversity be, as recent logger-based erosion has shown.  Logging nearby to one of the lakes resulted in rapid erosion.  This erosion caused a great deal of silt to build up in one of the lakes.  This, of course, caused the water to become quite murky; think about your average beach, and how murky the water often is near the shore.  Many of the cichlids that lived in this area relied upon visual identification to recognize members of the same species for mating purposes.  With the cloudy, muddled water, this became quite difficult.  As a result, many fish from closely related species ended up mating with each other and, in the case of many of the couplings, resulted in viable offspring.  These viable offspring in turn bred with other species, lowering, at least temporarily, the biodiversity of the cichlids in this particular corner of the lake.

Blantyre on Dwellable

Cloning the Cheetah: Why Bother?

In an attempt to discover why the cheetah has such a low fertility rate, a team of scientists, including David Wildt and Stephen O'Brien, decided to take a look at blood samples from a number of cheetahs, labeled "Vulnerable" by the IUCN.  What they found was startling, and very worrying; the cheetahs appeared to be dangerously, perilously inbred; they were all practically clones of each other. 

Wildt and O'Brien decided to confirm this hypothesis by taking skin samples from a number of cheetahs, and attempting to graft them onto a number of other cheetahs.  In a healthy population of animals, the skin grafts would be immediately rejected.  This is because the body of the animal who received the skin graft would recognize the skin to be from another individual, a foreign body, and attack it, just as it would attack any foreign body (i.e., germs or bacteria.)  Even in humans, skin grafts are often rejected, even ones from close relatives.

Normally a very majestic looking animal, this particular cheetah seems to have been caught at a bad time.  Photo Credit: Ted and Gail Neher

So when every single one of the cheetah skin grafts were accepted by the other animals, this did not bode well for the cheetah.  This meant the genetic diversity of the cheetah was incredibly, shockingly low.  But why is genetic diversity so important?  Well, without genetic diversity, the DNA of the individuals comprising a given population are very similar.  These individuals essentially become clones of each other, with many similar attributes, most important among them their immune systems.  In a healthy population of, say, cheetahs, say that fifty percent of them are immune to a certain disease, most of them evolving from a common ancestor.  The other fifty percent of the population has absolutely no protection against said disease, and the illness ravages their population.  An unfortunate (and oversimplified) event, to be sure, but fifty percent of the individuals remain to rebuild the population to what it once was.  With the low genetic diversity seen in the cheetah, if a similar disease in the hypothetical above sweeps through Africa, it is quite likely that a much lower percent than fifty would survive.  It is also possible that this disease would so ravage the global population of cheetahs that they would simply be unable to recover from this catastrophic event.

A cheetah scratching a log at the Denver Zoo.  The cheetahs incredibly slender build can help distinguish it from other cats. 

So why is the cheetah so catastrophically inbred?  Most of the time, low genetic diversity is due to a given species having passed through a "bottleneck."  20,000 years ago, cheetahs spanned the entire globe; ranging all over Europe, Asia and Africa, two species of cheetah, or "proto-cheetahs" if you will, even roamed North America (Miracinonyx inexpectatus and M. trumani.)  When the most recent Ice Age drew to a close around 10,000 years ago, the dramatic climatic changes (and likely human influences, as well) resulted in the extinction of much of the world's mammalian megafauna. Researchers think that this mass-extinction managed to knock the cheetah's numbers down to a very small population, likely comprising a mere handful of individuals.  (In fact, I remember reading once that at one time, some people thought that a single pregnant female mother was able to survive, but I don't think that this idea is all that highly regarded anymore).  While the cheetahs were obviously able to build their population numbers and density by a significant amount than that seen 10,000 years ago, this bottleneck came with a price; genetic diversity was, and is, miniscule.

Works Cited:

The Biggest Carnivorous Dinosaur Part 3: Spinosaurus, The World's Largest Penguin

Spinosaurus quickly smashed its way to the top (literally!) following the success of Jurassic Park III.  At up to 56 feet (17 meters) in length, Spinosaurus (found in Egypt and Morocco) is unquestionably the longest carnivorous dinosaur that has ever been discovered, and by a significant margin, too.  But how could Spinosaurus be so successful when another carnivorous monstrosity, Carcharodontosaurus, lived in such close proximity?  The answer lies in what it ate; in fact, Spinosaurus appears not to have been as carnivorous as we once thought, and seems to in fact have been more piscivorous.  Essentially, it is thought that Spinosaurus might have survived on a diet consisting a great deal upon fish.

There is a great wealth of information that indicates the staple diet of Spinosaurus was fish.  Here we will take a more in-depth look at this evidence.

A picture of Spinosaurus drawn by the talented young artist Sam Lippincott.

1.  POSITION OF THE NOSTRILS:  Spinosaurus, unlike most other theropod (meat-eating) dinosaurs had nostrils situated very high up on its skull.  By contrast, most other theropods, like Tyrannosaurus, had nostrils very close to the front of the skull.  The nostril placement in Spinosaurus would have allowed it to stick its nose into the water quite deep, enabling it to hunt fish more effectively.

2.  SENSORY ORGANS ON THE TIP OF THE SNOUT:  Along with the high placement of the nostrils, Spinosaurus also had a number of small sensory organs at the front of the snout, revealed by CT scans.  These greatly resemble those of the crocodile, who uses them to sense where prey is by "seeing" tiny movements in the water.  Thus, a crocodile can attack its prey without ever seeing them with their eyes.  Spinosaurus appears to have been able to do much the same thing, making its hunting method of choice quite obviously effective, given its immense size.

3.  ISOTOPIC EVIDENCE:  A study of the isotopes in the skull of a Spinosaurus specimen revealed something quite interesting.  Spinosaurus shares a great deal of isotopic overlap with crocodiles, fairly aquatic animals.  By contrast, other carnivorous dinosaurs like Tyrannosaurus have very different isotopic readings, indicating a terrestrial lifestyle.  Given the great deal of overlap possessed by Spinosaurus and crocodiles, it appears that Spinosaurus spent much of its life like a crocodile; semi-submerged in rivers and streams.

4.  THE TEETH TELL THE TALE:  Spinosaurus, unlike most other carnivorous dinosaurs like Tyrannosaurus, Allosaurus, or the famous Velociraptor, possess conical, round teeth.  These other carnivores possess thin, blade-like teeth, made for slicing, crushing or tearing into other animals.  Spinosaurus has teeth much like a crocodile; round and conical.  These teeth are made for gripping and making sure that an animal does not escape. 

5.  THE TEETH TELL THE TALE....AGAIN:  Yet again, we come to the issue of teeth, and this is one of the most damning pieces of evidence of all.  During the time that Spinosaurus lived in North Africa, another inhabitant of these streams and rivers was a saw-toothed fish called Onchopristis.  Two fossils involving Onchopristis have been discovered in conjunction with the remains of Spinosaurus.  One was the skull of a Spinosaurus; imbedded in one of the tooth sockets was a vertebrae from an Onchopristis.  The other discovery was the barb of an Onchopristis embedded in the jaw of the Spinosaurus.

6.  PLUS:  We only ever seem to find Spinosaurus in shallow aquatic environments, where fishy prey would be abundant.

All in all, it seems like an inevitable conclusion to draw that Spinosaurus was, in fact, a piscivore, at least much of the time.  A fascinating example of the crazy turns evolution can take.

The Biggest Carnivorous Dinosaur Part 2: Carcharodontosaurus Vs. Spinosaurus

As I promised yesterday, today we are going to take a closer look at Carcharodontosaurus (kar-kar-o-DON-to-SAUR-us).  Carcharodontosaurus was a relative of Colorado's own Allosaurus.  However, Carcharodontosaurus was four times larger, and found in Egypt, Morocco, Algeria, Libya, and Niger.  At around 46 feet long, Carcharodontosaurus was similar in size to yesterday's Giganotosaurus (pronounced jig-a-NOTE-o-saur-us), and longer than Tyrannosaurus, though Tyrannosaurus was undoubtedly much bulkier.  Regardless, Carcharodontosaurus was a monster-sized killer, and almost certainly had a monster-sized appetite to match.  It is almost a certainty that such an animal would have a fairly large territory, and would have needed to eat a great deal to maintain its fast metabolism, similar to your average teenage dude.

Clearly, such a large predator had little competition from other carnivorous dinosaurs.  Or did it?  As a matter of fact, 95 MYA, North Africa was home to not one, but two monster-sized killers, Carcharodontosaurus, and the even longer, 50 foot (15 meter) Spinosaurus.  (Some not so conservative estimates even place the maximum size for Spinosaurus as 60 feet (18 meters) in length, but this does seem extreme.)

Now, in the modern day, predators can inhabit the same area.  Take the plains of Africa, for example; in many places, lions, leopards, cheetahs, wild dogs and hyenas all inhabit the same area.  There is a clear hierarchy amongst the animals, and each seems to get enough to eat.  However, this is partly because each animal exploits a slightly different set of resources, so contact amongst them is less frequent than if all five of the large carnivores all hunted the same animal, say, the Thomson's Gazelle.  This is a phenomenon known as resource partitioning, and it occurs all over the place in nature, arguably one of the most important factors involving ecology and evolution. Scientists believe that a similar sort of partitioning took place between the two mega-carnivores of Mid-Cretaceous North Africa, with Carcharodontosaurus being a terrestrial carnivore, while Spinosaurus took to the water.  We will conclude "The Biggest Carnivorous Dinosaur" trilogy tomorrow with a look at the environment Spinosaurus was able to so successfully exploit.

A fantastic visual representation of resource partitioning amongst large herbivorous mammals in Africa.  The giraffe, the zebra, and the wildebeest will all inhabit the same area and eat plants, but the types of plants can differ.  Photo Credit: Ted and Gail Neher

The Biggest Carnivorous Dinosaur Part 1: Move Over, T-Rex (Kind Of)

Tyrannosaurus rex, the "Tyrant Lizard King," has long been a dinosaurian favorite the world over.  He is quite the interesting animal, and simply massive; the publicity received by him and the giant-sized Velociraptor in Jurassic Park helped a bit, I'm sure!  However, T-rex is no longer thought to be the largest carnivorous dinosaur.  Well, yes he is.  But he isn't.

A picture of the Tyrannosaurus rex specimen Stan at the Morrison Natural History Museum.

Imagine someone who has never heard of the giraffe and elephant asks you which one is biggest.  You might say the elephant, because the elephant is much heavier and has more bulk.  But what if they mean which animal is taller?  Somewhat of a dilemma.  So using words like "biggest" (as I have done here) is not the best way to go.  So Tyrannosaurus still seems to be the heavyweight champion, there are other dinosaurs that, while more slender, were probably longer.  Kind of confusing, I know.

The fact that T-rex has some serious competition has put barely a dent into his popularity, and some of the other larger carnivores are receiving a lot of attention, too. The longest of these carnivores, which we will learn about on Wednesday, was possibly around 20% larger than Tyrannosaurus Rex!  Today, we are going to look at another enormous killer, of South American origin; the massive, the monstrous, Giganotosaurus.

A Giganotosaurus on display at Fernbank Museum, in Atlanta, Georgia

Giganotosaurus is an estimated 46 feet long, comparable in length to the average Tyrannosaurus!  We do have some specimens of Tyrannosaurus that are around the same size as Giganotosaurus, but either way: Giganotosaurus was a massive animal! Of course we don't actually know for sure what the maximum size for any dinosaur is as, unlike for most living animals, we generally have a relatively small sample set, but we can make close estimates based on the finds we have.  And these estimates indicate that Giganotosaurus grew to simply massive proportions.  One of the largest terrestrial animals that we know of is Argentinosaurus (who, like Giganotosaurus, was also found in Argentina), a sauropod dinosaur that lived at the same time as Giganotosaurus.  For Giganotosaurus to prey on even the juveniles of such a large herbivore, it would similarly need to grow to massive proportions.

Giganotosaurus vs. Argentinosaurus at Fernbank Museum, in Atlanta, Georgia

Giganotosaurus vs. Argentinosaurus at Fernbank Museum, in Atlanta, Georgia

This pattern repeats itself all over the world, the pattern of gigantism evolving in sauropods, along with the subsequent evolution of gigantism in the theropods (meat-eating dinosaurs), is a pattern repeated throughout the world, and throughout the Jurassic and Cretaceous Periods of the Mesozoic Era, the two periods in time when the rule of the dinosaurs was absolute.  Here are some more of the predator-prey, giant-sized carnivore/giant-sized herbivore relationships seen throughout the Mesozoic.  The first animal named will be the predator, and the second will be the sauropod.

Asia, 160 MYA: Sinraptor, Mamenchisaurus
Europe, 125 MYA: Neovenator, Ornithopsis
North America, 150 MYA: Allosaurus, Diplodocus
North Africa, 95 MYA: Carcharodontosaurus, Paralititan

In tomorrows post, we will look at the last relationship, and focus on another larger (or longer) than life carnivore, Carcharodontosaurus.