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.

Acrobatic Felines: The Caracal

(Almost) everybody loves cats!  Not only the domestic kitties, but wild cats too, like the speedy cheetah, the social lion, and the elusive snow leopard, among others.  But most people don't know that there are all sorts of different cats, and thirty-six generally accepted species of cats!  Many have numerous sub-species as well, the leopard having eight or nine all by itself.

Today, I am going to introduce you to one of my absolute favorite wild cats: the caracal, which is fortunately labeled "Least Concern" by the IUCN.  The caracal is found all over Africa, pretty much except in the rainforests and the deserts, as you can see in the map below.  The caracal is also found in various non-African countries, such as Israel, Iran, Arabia, Jordan, Pakistan, and India.

I am not going to do a lot of talking (which is not normal, believe me), as words can't really do justice to what this cat can do.  So just click the link below, and be amazed.  (I actually have never watched this video with the audio on, so I don't even know what he is saying, because I think that the audio would simply detract from the video.  Enjoy!)

http://www.youtube.com/watch?v=4dCXK6KhkTw

The Fauna of South Carolina: Reptiles and Amphibians

First off, don't forget to look below to see the answer to last weeks mystery animal, and to see a couple of pictures of this weeks!

Recently, my family visited some good friends of ours in South Carolina for a few weeks.  Not only did we have a lot of fun visiting them, we saw a lot of cool plants and animals there that we simply don't have up north!  For some of you, many of these animals and plants will be routine and boring, but hopefully there will be something in here that you will find interesting!  I think I am going to split this post up into at least a few different segments, with tomorrows post devoted entirely to the Black Skimmer, a very interesting bird that I had the good fortune to see hunt!  So today I am going to talk about some of the interesting reptiles and amphibians we saw down there, and over the next few weeks we can take a look at some of the birds, fossils and other things we saw down there!

Due to the increased heat and humidity, coupled with less of a swing between the seasons (i.e. it rarely snows and drops below freezing), the south is an excellent place to see all sorts of reptiles and amphibians.  We saw a number of turtles and a frog/toad or two when we were in the south, but what interested me more were the lizards.

A Carolina anole (Anolis carolinensis).  Despite its name, the Carolina anole is found in both South and North Carolina, as well as Florida, Georgia, Louisiana, Texas, Alabama and Mississippi.

A type of skink, but I have yet to ascertain its species, although I am almost certain its genus is that of Plestiodon

And then, of course, there's the gators.  The American Alligator lives in the same states as the Carolina anole, as well as Virginia, Arkansas and Oklahoma.  While we did see a few in the wild, all of these shots (except for that of the gator footprint) were taken at a place called Brookgreen Gardens, or at a restaurant called the Crab Shack.

This big gator we saw at Brookgreen Gardens

This is a picture of a gator footprint that I took.  You can see three of the toes very well, making it look a lot like a theropod dinosaur track, but you can see the other two toes as little holes in the ground.

This picture, and all the rest, were taken at an awesome (both food- and entertainment-wise) restaurant on Tybee Island in Georgia called The Crab Shack.

 

 

 

 

 

 This post is part of "The Fauna of South Carolina" series.  For the rest of the posts in this series, click HERE.

Sea Pines on Dwellable

What Is It? The Weekly Challenge #1 Answer

Well, it's that time of the week again!  We only had a few guesses this week, and no one got it exactly right, but there were some close guesses!  The two closest were Kristie C., who guessed an Adélie Penguin, and Masaki K. who guessed Cormorant.  Well, the correct answer to last weeks challenge is Waimanu.  Waimanu is the scientific name of the oldest known fossil penguin.  Two species are known, and both of them were found on the South Island of New Zealand.  One of the species, Waimanu manneringi, lived during the Paleocene, around 61.6 MYA; that means that the oldest known penguin was swimming the oceans only a few million years after the death of the dinosaurs!  Although Waimanu manneringi is the oldest KNOWN fossil penguin, it by no means is the oldest penguin.  In fact, it is quite likely that, were scientists to uncover a fossil that shows when penguins split off from the other orders of birds, we would not even recognize it as a penguin.  Waimanu had undoubtedly already adapted to a fully non-aerial lifestyle, and almost certainly behaved much like modern penguins do when it comes to breeding on land, near the ocean.


Works Cited:

Waimanu, the first penguin. (2010, January 30). Retrieved July 11, 2012, from https://fossilpenguins.wordpress.com/2010/01/30/waimanu-the-first-penguin/

Arthur the Aardvark

Almost everybody has heard of Arthur Read from the popular PBS show "Arthur."  What a lot of people don't realize is that Arthur is an aardvark.  And even more people don't usually even know what an aardvark is.

A fossorial (burrowing, like terrestrial or marine), nocturnal mammal from Africa, the aardvark is an insectivore, its favorite food being termites, and is labeled as "Least Concern" by the IUCN.  The aardvark, as you can see below, inhabits an incredibly large portion of Africa, including South Africa, Ethiopia, Kenya, Tanzania, Uganda, Mozambique, the Democratic Republic of the Congo (DRC), Burundi, Somalia, Angola, and many others.

The aardvark has several important adaptations for its burrowing, insectivorous life style.  Perhaps the most important are the large claws on its front limbs.  These claws enable the aardvark to not only dig out immense burrows for habitation use, but also to dig into termite mounds to extract a meal.  Interestingly, when the aardvark leaves its burrow to dig a new one, the old burrow is often taken up by the African wild dog, where the pups shelter until they are old enough to leave the protection of the burrow.

The aardvark also has thick skin, which keep the termites from biting it, allowing it to feast in relative peace.  A further adaptation to keep insects (as well as dust) out is in its nose: it can close its nose, preventing both bugs and dust from invading its breathing passages.  Finally, another very important insectivorous adaptation is the tongue of the aardvark.  The long, sticky tongue of the aardvark is usually about 12 inches long, equivalent to about one-sixth the length of the animal!  Long, sticky tongues are a fairly common adaptation for termite-eaters such as the numbat (Myrmecobius fasciatus), pangolins (Manis sp.), and the giant anteater (Myrmecophaga tridactyla) among them.

A southern tamandua (Tamandua tetradactyla) shows off its extraordinarily long tongue during an animal demonstration at one of Denver Zoo's teen career days.  Tamanduas are also insectivorous, and clearly also possess an amazing tongue.

Predators of Baby Leopards: You Might Be Surprised

One of my favorite TV shows is BBC's Big Cat Diary, which I believe I have already mentioned once or twice.  It has been called by critics as "The soap opera of the Serengeti," and has played for a number of seasons, under various other titles.  Essentially, the shows premise is a log of what two prides of lions (the Marsh and Ridge Prides) are doing, as well as my two favorites, the leopards and the cheetahs.

This is neither a leopard nor a cheetah, but a baboon skeleton.  It's probably poor planning on my part to not put a picture of what I've already talked about so far, but you're going to have to deal with it.  Or just pretend that's a cheetah, baboons and cheetahs are practically the same animal anyways.

In one episode I was recently watching, one of the co-hosts, Saba Douglas-Hamilton, said something that I thought was very interesting about leopard cubs.  She said that the top three animal threats to African leopards (besides humans, forcing the IUCN to label the African leopard as "Near Threatened,") are lions, hyenas....and baboons.  Check out the baboon skeleton (above) and mounted stuffed specimen from the American Museum of Natural History below!

I was actually completely kidding before, baboons and cheetahs are not really that closely related at all, and very few people have an excuse to confuse the two.

I knew baboons were an issue to leopards as one of the leopard stars of the earlier series, dubbed Half-Tail, was missing half her tail, hence her name.  The two hosts at the time, Jonathan Scott and Simon King, said that they thought the missing half of her tail was due to either a lion attack or, more likely, baboons.

Chilling like a villain: a leopard takes a break after staring out the window all day and stressing out about those stupid robins in that stupid birdbath.  Those robins better consider themselves lucky that there's glass between them, you mark my words.  Photo Credit: Ted and Gail Neher

I had never really thought about it before, but when I heard Saba mention it, I thought that was kind of strange.  Well, I looked up "baboon skulls" on Google Images, and I think I get it now; their canines can grow up to two inches long.  As a good comparison, the average lion typically possesses two inch long canines.  Now that is some serious dental hardware; I'm glad I'm not a baboon dentist!  (That, and I'm guessing that you don't get paid very much).

A baboon skull mounted at the American Museum of Natural History in New York City, New York.  Check out those nasty canines, they're frickin' huge!!

Baboons, like many primates (actually I believe all except for tarsiers), are omnivores, so theoretically they could use their canines to subdue and consume their prey.  However, it seems that male vs. male competition is the primary reason why baboons have such enormous canines.  Check out the "mandrill" webpage on the website for Bone Clones (for the lazy amongst you, HERE is a link), and you can see that the male has enormous teeth, while the female has a dentition that is much less impressive.  This seems to support the idea that baboons (at least the males) primarily use their teeth in interspecific intimidation, in order to frighten off other males and secure breeding rights to the females.

Works Cited:

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:

Smilodon Vs. Thylacosmilus: The Saber-Toothed Marsupial

Two million years ago, a saber-toothed predator stalked the landscape of South America.  Possessed with long, dagger-like teeth, Thylacosmilus was undoubtedly a terrifying predator of the plains of Patagonia.  This saber-toothed predator would have given even the saber-toothed cats pause, despite the fact that (to paraphrase Obi-Wan Kenobi), "He's more kangaroo now than cat."  Despite superficial similarities, Thylacosmilus was not a saber-toothed cat.  Instead, it was a six foot long, 500 pound saber-toothed marsupial.

A reconstruction of Thylacosmilus by the talented young artist Sam Lippincott.  Interestingly, the super-sized canines of Thylacosmilus grew continually throughout its life, unlike those of Smilodon or Xenosmilus (see below), two of the actual saber-toothed cats.  Photo Credit: Sam Lippincott

The immense canines possessed by Thylacosmilus had previously evolved in both the cat-like Nimravids and the various saber-toothed cats (amongst others), and is a classic example of convergent evolution, a topic, in my opinion, that is one of the most interesting happenstances in nature.  We will hopefully talk about convergent evolution sometime next week.

A mounted skeleton of Xenosmilus, a type of saber-toothed feline, at the Mace Brown Museum of Natural History at the College of Charleston in South Carolina.  I got to visit here in July of 2014, and it was a very nice little museum.  Compare the skull of Xenosmilus with that of Thylacosmilus (below).

Anyways, Thylacosmilus lived during the Miocene and the Pliocene Epochs, from 10-2 MYA.  Up until 2 MYA, South America had been its own, separate land mass, not connected to any other continents since some time during the Cretaceous.  2 MYA, however, something extraordinary happened: the Isthmus of Panama was formed, connecting the two continents.  With this connection, came something scientists have dubbed the "Great American Interchange."  Animals from both continents could move, and spread out into the other continents.  For some creatures, like the saber-toothed cats, this was a good thing; they moved down into South America from North America and dominated the landscape.  For other predators, like the terror-bird Titanis(again, a topic for another time), it was good, for a while; after moving into the southern part of North America, however, Titanis was outcompeted by other predators.  For Thylacosmilus, it was down-right disastrous.  Shortly after the Great American Interchange, fossil evidence of Thylacosmilus entirely disappears, similar to the competition between the dingo and the thylacine that drove the thylacine to extinction on mainland Australia.

The skull of Thylacosmilus on display at the American Museum of Natural History in New York.  Got to see this sucker in person in August 2014, when I visited with my good buddy Zach Evens! 

This is a partial post for the "Convergent Evolution" series.  That means that this post is partially included, but was not made specifically to be a part of that series.  HERE is a link to the Homebase for this series.  

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.

Fossil Hunting 6/30

Yesterday, my friend Masaki Kleinkopf and I went to check out a fossil site that I had found with another friend a couple of days ago. It looks to be Laramie Formation (towards the end of the death of the dinosaurs, in the Late Cretaceous), and a river seems to have been in this area. The most exciting fossilized things we found was a bunch of fossilized wood, as you can see below.

Fossilized wood

More fossilized wood

However, the most exciting that we saw of the day was definitely a wolf spider, probably three inches across. We saw the web first, and I was going to try and get the spider to come out with a long piece of grass (didn't want to get too close!) when I accidentally startled a grasshopper into the web. It couldn't get out, and suddenly the wolf spider appeared, and attacked it. It ran up probably ten or fifteen times, stabbing the grasshopper with its mandibles (I think that's what it was doing, anyways) and with its two front legs held up in the air. After awhile, the grasshopper was still alive, and the wolf spider retreated back down its hole. When we came back fifteen or so minutes later, the grasshopper was gone; probably dragged down by the wolf spider into its burrow to be devoured. I took a pic of the spider, but I think the  spider moved when it saw my phone, so all you can see is a blurry shot of the burrow.

Wolf spider burrow.  I think that the darker black in the burrow might be the  spider.

Besides wood, the Laramie Formation has yielded a number of dinosaur remains as well, among them being Edmontosaurus, Ornithomimus, Thescelosaurus, Triceratops, and Tyrannosaurus.  But first, here is a map of where the Laramie Formation is in Colorado.  Many of the dinosaurs that I mention below were found up in the north, near Fort Collins I believe.

We Interrupt Our Previously Scheduled Programming: RIP, Lonesome George

Well, we managed to get a whole day without me changing the programming!  I decided to let you all know about a saddening death that occurred a week ago today in the Ecuadorian-owned Galápagos Islands.

A picture of Lonesome George that my grandparents took several years ago on a visit to the Galápagos.  Apparently he was a little camera shy.  Photo Credit: Ted and Gail Neher

Lonesome George was the last survivng member of his supspecies. Ten of the fifteen known subspecies of the Galápagos Giant Tortoise survive in the wild. However, and eleventh subspecies survives in captivity, Chelonoidis nigra abingdoni. Consisting of a sole member, Lonesome George, it is easy to see where George got his name!

Researchers at the Charles Darwin Research Station, a biological research station in the Galápagos, have offered a $10,000 bounty on anyone who can find a suitable mate for Lonesome George. So far, all attempts at getting Lonesome George to breed with a member of another sub-species have been unsuccessful.

A herd of turtles (yes, Michael Scott, I'm looking at you).  These Galápagos turtles would belong to a different sub-species than Lonesome George.  Photo Credit: Ted and Gail Neher

Here is a brief snippet from a news cast regarding his death:

"Scientists had expected him to live another few decades at least.

Various mates had been provided for Lonesome George after he was found in 1972 in what proved unsuccessful attempts to keep his subspecies alive.

Attempts were initially made to mate Lonesome George with two female tortoises from Wolf Volcano. But the eggs they produced were infertile.

Two females from Spanish island's tortoise population, the species most closely related to Pinta tortoises, were placed with him last year."

The majestic hindquarters of Lonesome George.  Photo Credit: Ted and Gail Neher

Unfortunately, with his death, the world's most endangered animal has passed on the mantle to some other animal, unknown to me at this time, and perhaps even unknown to science.  Regardless, it is a sad day for people the world over with the loss of this titan; literally, as he was over 100 years in age, and was about 5 feet long and weighed 200 pounds!  He seemed to pass away from old age, though, so at least he went in a nice way.

And don't worry, we can get back to teeth and dental anatomy some time next week.  See you tomorrow.

Puerto Ayora on Dwellable

Another Living Fossil: The Coelacanth

400 millions years ago (MYA), during the Devonian Period, life had already gained a foothold on land.  However, in the seas, unless you were at the top of the food chain, there were a lot of predators to contend with.  If you were a fish in the middle of the food chain during the Devonian, you not only had to deal with ancestors of the modern day shark, but a now-extinct group of armor-plated fish, called the Placoderms.  Some of these Placoderms, like Dunkleosteus, grew to simply enormous proportions, around 30 feet in length!  One type of fish that lived during the Devonian and was most likely preyed upon by the sharks and the Placoderms was a fish known as the Coelacanth.

The Coelacanth (SEE-lah-canth) was a relatively unassuming fish, its closest living relative being the lobe-finned fish.  Fossils of the Coelacanth have been discovered ranging from 400 MYA to around 65 MYA, coinciding with the death of the dinosaurs.  In 1938, however, when one was hauled in on a fishing net off the coast of South Africa, the temporal range of this animal was extended by 65 million years!  Today, by studying the living Coelacanth, scientists have found that the fish gives birth to live young, unlike other fish.  Further discoveries both in Africa (off the coasts of Mozambique, Madagascar, Kenya and Tanzania) as well as Asia, around Sulawesi, Indonesia, of living Coelacanth specimens have further widened the current geographical range of the Coelacanth.

A specimen of the Cretaceous coelacanth Coccoderma nudum from Germany.  On display at the Mace Brown Museum of Natural History on the campus of the College of Charleston in South Carolina.

Unfortunately for this living fossil, it is labeled "Critically Endangered" by the IUCN, much like yesterday's living fossil, the mountain pygmy possum.  Just like the mountain pygmy possum, conservationist groups are working towards it's protection, trying to keep fisherman from fishing in the Coelacanth's habitat.  Hopefully, humans won't be the final nail in the coffin, so to speak, for this 400 million year old fish.