Bi Di Miss American Pie: Number Two Greek and Latin Roots!

A little while ago, I started a new series all about the Latin and Greek roots in the scientific names of different animals!  IN THE LAST POST, we examined animals with the Greek and Latin roots for "one," and today, we are going to kick it up a notch: exactly one notch, to be precise!  Today, we are going to examine the roots for the word "two!"  Let's begin with the cardinal (i.e. one, two three, etc.) form in Greek!  There are actually several roots that work here, but the one most commonly seen in binomial nomenclature is the root "di!"  Let's DIve right in!

• Our first "di" today is a small flying creature called Dimorphodon, a member of the extinct group of reptiles called pterosaurs.  The name "Dimorphodon" comes from three roots, "di," "morph," and "don."  "Di," of course, means "two."  In this context, the root word "morph" means "form."  In mythology and fantasty, a being that can take more than one form is often said to be able to morph their appearance.  Finally, the root word "don" is one of my favorites (and is used a whole lot in giving animals their scientific names): it means "tooth."  Altogether now: two-form tooth.  This name refers to the fact that Dimorphodon actually has two different types of teeth in its jaw.  For mammals, that's nothing special, but amongst reptiles, that is pretty rare!

• Dimetrodon-another animal with two kinds of teeth!  "Di" and "don" still mean the same thing as they did in Dimorphodon (above), but there is a new root in between: "metro."  For this root, think of the term "metric."  The name "Dimetrodon" actually means "two measures of teeth!"  Dimetrodon's two types of teeth would, in the groups that it is ancestral to, one day evolve to become the varied types of teeth that we see in the mouths of mammals!  Dimetrodon is more closely related to mammals than it is to any group of living reptile, and all of us mammals did evolve from a Dimetrodon-like ancestor!  So remember, if anyone ever tells you that Dimetrodon is a dinosaur, tell them that Dimetrodon actually lived around 40 million years before the first dinosaur ever walked the Earth!  That'll show them.

Dimetrodon (left) attacks the primitive amphibian Eryops.  Much like in the skull of Dimorphodon, you can clearly see the much larger teeth in the front of the skull and the smaller teeth in the back of the skull of Dimetrodon.

• Let's travel forward to the Late Cretaceous Period, time of Tyrannosaurus and Triceratops, to meet Didelphodon, a primitive mammal about the size of the living Virginia opossum!  As a matter of fact, it is from the opossum that Didelphodon gets its name: "Didelphodon" translates to "opossum tooth," as Didelphis is the genus name for the Virginia opossum and several related species of opossum!  In turn, "Didelphis" means "double womb," which presumably refers to the fact that the opossum, like all marsupials, has its internal reproductive tracts where the baby will develop for a bit, and its external pouch, where the baby will develop until full term.  

• A fourth animal with "two" and "tooth" in its name is Diprotodon!  The middle root, "pro," in this name means "forward," like the word "proceed."  So the name "Diprotodon" actually means "two forward teeth."  A quick examination of the skull of this massive mammal quickly reveals why!  Although it looks like it might be some sort of ungodly large rodent, Diprotodon is actually a hippopotamus-sized wombat, the largest marsupial known to have walked the Earth!

• Diceratops is a genus of ceratopsian dinosaur that is often considered to actually be a Triceratops.  The name, which means "two-horned face," was later discovered to already belong to a type of insect, and changed to the name Nedoceratops.  Some other paleontologists believe that Nedoceratops is really the same animal as Triceratops, but I don't really know enough about Nedoceratops to have an informed opinion on the matter.  However, paleontologist Jack Horner believes that Nedoceratops is an intermediate growth form between Triceratops and Torosaurus, and since I don't agree with his ideas of Triceratops ontogeny and that I think Triceratops and Torosaurus are definitely distinct dinosaurs, that leads me to suspect that Nedoceratops is more likely distinct, and certainly doesn't bridge the gap between Triceratops and Torosaurus.

• The name of Diplodocus, which means "double beam" originates from the two rows of chevron that are on the underside of the animal.  This was originally thought to be a feature unique to Diplodocus, a defining characteristic that would set it apart from other closely related sauropods.  Since Diplodocus was named by paleontologist Othniel Charles Marsh in the late 1800s, this feature has since been discovered on a number of other sauropods, including Barosaurus, also from the Morrison Formation, like Diplodocus.

• Dilophosaurus, one of the stars of the original Jurassic Park movie, gets its name from the two crests on its head.  Last time, we met Monolophosaurus, which means "single-crested lizard."  Therefore, Dilophosaurus means "two-crested lizard!"  

While it is the Greek cardinal root for "two" that is used most frequently in binomial nomenclature, it is the Latin root that is most often used for multiples (i.e. once, twice, thrice, etc.), the root "bi."  You can probably think of several words right off the top of your head that use this root!  In fact, the word "biped," used to describe creatures that walk on two feet (as opposed to, say, a quadruped), comes from the two roots "bi" and "ped," with "ped" meaning "foot" in Latin.  So literally, "biped" means "two feet!"  Let's look at a few more!

• Marshosaurus bicentesmus - A theropod dinosaur from the Morrison Formation (one who has received "Full-Post Status," as you can see by clicking HERE).  The exact relationships of Marshosaurus to other theropods isn't exactly clear, but some people think it might even be some sort of primitive coelurosaur, while others think it is more closely related to Megalosaurus and kin.  Regardless of its phylogenetic relationships, the name of Marshosaurus is quite exciting!  The genus name "Marshosaurus" honors the famous paleontologist Othniel Charles Marsh, who did a lot of work in the Morrison Formation.  The species name "bicentesmus" refers to the fact that the species was described in 1976, the bicentennial of the United States.  The bicentennial is, of course, a 200 year anniversary, and the "bi" in the name distinguishes a 200 year anniversary from a 100 year anniversary, or a centennial.

Here are two shots of a specimen of Marshosaurus that were on display in the lab at the Denver Museum of Nature and Science last year.  This first picture is the right maxilla, which would have made up part of the front section of the animals snout.

Here we have more of the same specimen, on display at the same time and the same place.  You can see several vertebrae and ribs in this shot.

• Baeolophus bicolor - This is the scientific name of the tufted titmouse, a small woodland bird native to much of the eastern half of the United States.  These little birds live in holes in trees that have been abandoned by woodpeckers, and are closely related to chickadees and, of course, the other titmice.  I couldn't figure out what the genus name "Baeolophus" means, but it is pretty apparent that the species name "bicolor" refers to the fact that this little bird is gray on its back, and white on its underside.  Some of the other species in the genus, such as the juniper titmouse (Baeolophus ridgwayi), are simply all gray.  

• Diceros bicornis - Here we have the scientific name of the black rhinoceros, a "Critically Endangered" species of African rhino.  According to some sources, the black rhino often prefers to eat Acacia leaves, presumably employing its prehensile upper lip to avoid the plants thorns.  The black rhino has pretty poor vision, with much better auditory and olfactory sensing capabilities.  Humans are easily the most dangerous threat to the black rhinoceros, with lions and the spotted hyena occasionally taking young black rhinos as prey, and even more rarely attacking adults.  The scientific name of the black rhinoceros literally means "two-horn two-horn."  As we have already established, both "di" and "bi" are roots that mean two.  Both "ceros" and "corn" are roots that refer to horns: think "Triceratops" for ceros (three-horned face), and "unicorn" for corn (one-horn).  

Works Cited:

Thorny Trees and 20 Inch Tongues: A Case of Coevolution

A few days ago, I saw a very spiky-looking tree on the Bird of Prey Route near my house.  A few weeks ago, I saw another tree, much larger than this one, along the banks of Boulder Creek that had some enormous thorns on its branches as well, some of them easily six inches long, and super sharp on the end!  I don't know for certain what kind of tree this, or the Boulder Creek tree, is, but a good candidate I think is the honey locust (Gleditsia triacanthos), or some other tree closely related to the honey locust.  Below is the picture of the tree that I took on the Bird of Prey Route.

And here is the picture that I took on my iPhone at Boulder Creek of this tree.  The thorns look pretty similar to those of the honey locust, and I think that the trunk of the tree looks pretty similar, too.

Now why do these trees have such huge thorns?  When it comes to nature, everything evolves with a purpose.  There is no reason why a living organism would evolve something without a purpose, especially something as involved as giant, six-inch long thorns.  The question is, what purpose do these thorns serve?  Well that's a darn good question, and I am very pleased you asked.  Much like the "thorns" that you can see on the tail of a Stegosaurus, they likely were to help keep the organism from being consumed.  We see similar thorns on the branches of some trees in the genus Acacia in Africa today.  There, the thorns help protect the tree from attacks from one of the largest plant predators alive today, the giraffe.  This tree....well, suffice it to say that you probably won't see many activists hugging this tree.

"Oh, maybe these thorns look deceptively big," you're thinking.  Wrong.  These thorns do not look deceptively big.  If anything, they look deceptively small.  These thorns are frickin' HUGE.

So the real question is, why the long thorns, Goldilocks?  Many paleontologists believe that, during the Pleistocene Epoch (which lasted from between around 2.5 MYA to about 12,000 years ago), many of North America's mega-herbivores, everything ranging from mammoths and mastodons, to giant ground sloths and the North American camel Camelops, could have been preying upon these trees.  Selective pressures slowly caused these trees to evolve protection against these mammalian mega-herbivores.  Mastodons especially had very robust teeth, which would almost certainly have made them excellent bark-munchers.

In Africa, the acacia tree, also known as the whistling thorn, the thorntree, or (my personal favorite) the wattle, has a very similar defense.  Unlike the honey locust of North America, however, the acacia tree still has to deal with intense predation today, and from a wide variety of herbivores, everything from gerenuk to giraffe, elephants to more giraffes.

You see, the giraffes love the acacia tree.  If giraffes had Facebook, then they all would like the "I <3 Acacia Trees" page.  I remember reading somewhere that they can eat up to 60 or 65 pounds of acacia leaves per day.  (To understand this, try imagining a large hunk of butter that weighs 60 or 65 pounds.  Now you have an idea of how many pounds that is.)  They love it so much that, if the acacia tree hadn't adapted to keep up with the continual browsing pressure, the giraffes might have loved the acacia trees to death!  In response, the acacia trees convergently evolved these sharp thorns, just like the honey locust tree in North America.  (We talk about convergent evolution quite a lot as it is one of my favorite topics, so click HERE to learn more about it!)  

The giraffes love the acacia, though.  They aren't going to give up on those lovely leaves, just like that!  So while these acacia trees evolved their thorns to protect their leaves, the giraffes evolved something spectacular: a prehensile tongue!  Don't believe me?  Well, one of my favorite things about the Cheyenne Mountain Zoo is that you can feed the giraffes there.  And guess what: their tongues are HUGE!  Below, I have a video of my good friend Masaki Kleinkopf also feeding the giraffes!  Check out my gangsta hoodie, yo.  

So, yeah.  Suffice it to say, giraffes have frickin' long tongues.  And they use these TWENTY INCH LONG TONGUES to help circumnavigate through the acacia tree's poky and spiny maze of thorns to reach the leaves!  The acacia tree wasn't going to just take this lying down, though: no giraffe is going to be feeding on my leaves, yo!  So the acacia tree adapted again.  This time, by employing the use of tannins.

Long story short, tannins are used by humans in a variety of ways, including tanning, food processing, and making cocoa and wine.  They also apparently taste terrible.  Don't ask me, I've never tried it, but then again I don't have a 20 inch prehensile tongue, so it's a whole different ballgame.*

Not only do tannins taste terrible, but they inhibit the digestion of the leaf matter in a number of nasty ways, none of which would be all that fun for the giraffe.  So when a giraffe starts munching on the leaves of the acacia tree, that tree will release tannins to make the leaves taste like....well, leather I suppose.  (Again, haven't tried either.)  This tannin releasing is a pretty cool adaptation all on its lonseome.  The giraffe begins to move off to another acacia tree nearby.  However, if it's within 50 yards or so (especially downwind) of the original, now tanniny acacia, then the giraffe is out of luck: the nearby acacias react in turn, releasing their own tannins, and rendering their leaves almost indigestible to the giraffes, as well!  I would imagine that, because of this, giraffes have in turn developed the behavior of moving upwind as they eat, and a cursory glance over the Internet indicates that this does seem to be a behavior observed in giraffes!  Coevolution at its finest!

Make sure to check back soon for our next episode in our coevolution series, all about a very fun little squirrel!  See you then!  In the meantime, you can read about what coevolution actually is, by clicking HERE.

*The second baseball metaphor that I believe has been used on this blog.  Refer to "23-Fact Tuesday: Prairie Falcon, Red-Tailed Hawk, and Great-Horned Owl at the Dino Hotel" and "Eye Black: What Works for Football Players Works for the Cheetah" to learn more about this sport.  

Works Cited:

Baby Prairie Dogs and Birdwatching on the Bird of Prey Route!

Today, with the summer weather and the lack of school, I decided to take my car over to what I like to call the "Bird of Prey Route," a little dirt road in between Superior and Boulder about ten minutes from my house here in Colorado.  You can usually see at least one or two different types of raptors there, and there are a number of other awesome animals that I have spotted there, as well!  Today, I saw a lot of really cool birds, as well as some baby prairie dogs, as you can see below!

This particular species of prairie dog is the black-tailed prairie dog (Cynomys ludovicianus).  Like the other species of prairie dog, the black-tail is a highly social little rodent.  Below you can see two pups "kissing" each other, a type of interaction that members of the same family group will employ.  I think this is just to help solidify familial bonds, but I'm not sure if anybody knows for certain.

Today, the bird of prey route did not disappoint!  Perched in the tree in the picture below is the red-tailed hawk (Buteo jamaicensis), definitely the raptor that I see most often when on the route.

I also saw a pair of American kestrels (Falco sparverius), the species of raptor that I see second most often.  I don't usually see the kestrels so close together, however, so perhaps this was a mated pair.  I did see one of them fly into a hollow in a tree, which might be where a nest is hidden away!

As I was watching the hollow in the tree where the American kestrel swooped off into, I noticed several European starlings (Sturnus vulgaris) flying into other hollows on the tree.  Then I realized that the angle of one of the hollows was just right, and that I could actually see the adult starling feed its young!  If you zoom in on the picture, you can see that the baby already looks pretty big, maybe even as big as the parent!

Black-billed magpies (Pica hudsonia) are especially abundant in the area, and I saw several of them as well.

This magpie looks like it is molting!

Now this particular tree presents a particularly provocative puzzle, as it is almost completely covered in some very sharp looking thorns.  A few weeks ago, I saw another tree, much larger than this one, along the banks of Boulder Creek that had some enormous thorns on its branches as well, some of them easily six inches long, and super sharp on the end!  I don't know for certain what kind of tree this, or the Boulder Creek tree, is, but a good candidate I think is the honey locust (Gleditsia triacanthos), or some other tree closely related to the honey locust.  Below is the picture of the tree that I took on the Bird of Prey Route.

Here is a picture of the thorns of the honey locust tree.

And here is the picture that I took on my iPhone at Boulder Creek of this tree.  The thorns look pretty similar to those of the honey locust, and I think that the trunk of the tree looks pretty similar, too.

Now why do these trees have such huge thorns?  That's a really good question.  I started answering (or at least trying to answer) the question here in this blog post, but everything rapidly started spiraling out of control and off focus as I started talking about giraffes, tiny squirrels, cheetahs, and extinct North American elephants.  For those of you who know me, it should come as no surprise that I spiraled so quickly off topic.  But regardless, what I had written ended up having enough material for at least three or more posts, so I have moved the answer to a different post, which I will hopefully be publishing soon.  Keep an eye out for that!  In the meantime, back to the future birds!  Here, we see a pair of barn swallows (Hirundo rustica) perched on a wire.

I'm not quite as sure about the identity of this particular bird.  Also a swallow, I am thinking that it might be a violet-green swallow (Tachycineta thalassina).

I believe this to be a vesper sparrow (Pooecetes gramineus).

A western kingbird (Tyrannus verticalis), another bird that I see all the time here, at least in the summer!

At last, we have one of the most exciting birds that I saw on the route today, the blue grosbeak (Passerina caerulea), a bird that I don't remember ever seeing before!

Remember to check back soon to learn all about those massively spiky trees!

Works Cited:

Robbins, C. S., Bruun, B., & Zim, H. S. (1983). Birds of North America. New York: Golden Press.

Stokes, D. W., & Stokes, L. Q. (2010). The Stokes field guide to the birds of North America. New York: Little, Brown.

Birdwatching at the Morrison Natural History Museum!

Last Monday, a snow storm hit Colorado....in the middle of May.  Although it snowed even as much as sixteen inches in some places, it melted pretty quickly afterwards, leaving an excellent opportunity for many birds that rely on insects for their meals.  After a rain, you can often see birds like the American robin or flicker foraging around (click HERE to read more), using the soft ground to their advantage to try and catch insects that were washed up out of the ground.  After the snow, it seems like a number of birds were attempting to do the same thing.  As I was closing up, I looked out behind the Morrison Natural History Museum, and noticed a bonanza of birds!  I ran downstairs and grabbed my camera, and tried to get some good shots.  Here, we have a male western bluebird (Sialia mexicana), perching on one of the blocks of sandstone from the historic Quarry 5 in Morrison.  This block contains dinosaur bone, making it ironic that the bluebird, a dinosaurian descendant itself, perched upon the block.

There were plenty of American robin (Turdus migratorius) running around, and got a few shots of them!

As we talked about in a PREVIOUS POST, winter causes many birds, including the American robin, to decrease their territoriality, and flock together.

There were several lark bunting (Calamospiza melanocorys) hopping around.  The lark bunting is actually the state bird of Colorado!

A European starling (Sturnus vulgaris) probes the ground.

There were several more male and female western bluebirds flitting around, and I got some pictures of them that I really like!  Below is a female perched on the fence next to the Jurassic Garden!

A male perched on a fence.  Notice the sexual dimorphism displayed here; the male displays much more vibrant plumage than does the female.

A female perched near my car!

Sometimes, I am really, really bad at identifying birds.  Below are two pictures of birds that I think I have identified correctly, but am not positive.  The first I think is a picture of a pair of chipping sparrows (Spizella passerina).

This one gave me a bit more trouble.  I think this bird is either a western wood-pewee (Contopus sordidulus) or a least flycatcher (Empidonax minimus).

Finally, a yellow-rumped warbler (Dendroica coronata)!

Works Cited:

Robbins, C. S., Bruun, B., & Zim, H. S. (1983). Birds of North America. New York: Golden Press.

Stokes, D. W., & Stokes, L. Q. (2010). The Stokes field guide to the birds of North America. New York: Little, Brown.

Top Five Extinct Crocodilians

As a reward for winning our Winter Trivia Contest, Carla has requested a "Top Five Extinct Crocodilians" post, and I was all too happy to oblige (but sorry it took so long)!  Let's face it: living crocodilians are pretty awesome, and their extinct cousins?  Even MORE so!  And although some of the creatures that we will look at in this Top Five list may not be crocodilians by the strictest sense of the term, those that don't entirely fit the bill are very closely related.  These "almost crocodilians," as well as the actual crocodilians, are all from a group of reptiles that we call the archosaurs.  Archosaurs include many fascinating animals, including the crocodilians, pterosaurs, dinosaurs, and birds, as well as their extinct ancestors.  Some of the members of this list are critters that look a whole lot like crocodilians, but just weren't quite there yet, as most sources state that modern crocodiles did not evolve until the Late Cretaceous.  Some people refer to this large group of crocodile-like creatures, as well as the crocodilians and their ancestors, as "pseudosuchians," which is what is used to describe the first few animals that we are looking at today!

1.  The phytosaurs are the first of these "pesudosuchian" groups.  Although at a glance they look pretty similar to the modern day Indian gharial, the phytosaurs lived in the Late Triassic, right around the time that dinosaurs were first evolving too, about 200-220 MYA.  We still have nearly 150 million years before the appearance of modern crocodiles!  As you can see below, the phytosaurs definitely resembled the later crocodilians in many ways, but they were different, too.  Just look at how far back on the skull those nostrils were!

2.  Our next pseudosuchian is one of my favorites, named Desmatosuchus.  A member of the extinct group called the aetosaurs, Desmatosuchus was actually an herbivore!  As you can see on the back of this animal, Desmatosuchus is yet another one of those fascinating creatures that has evolved dermal armor, similar to the armadillo and the ankylosaurs!  The giant shoulder spikes of Desmatosuchus definitely look a whole lot like those of the ankylosaurs, and served a similar defensive purpose.  If you traveled back to the Late Triassic period, you would have been able to find Desmatosuchus in the southern United States.

3.  While Poposaurus definitely looks a lot like a dinosaur, just like Desmatosuchus and the ankylosaurs, this is simply another fascinating example of convergent evolution!  Poposaurus, just like Desmatosuchus and the first dinosaurs, lived during the Late Triassic Period, about 225 million years ago.  For whatever reason, it was the poposaurs and not the dinosaurs that went extinct at the end of the Triassic Period.  Apparently, the Triassic town wasn't big enough for these two groups of bipedal reptiles.

4.  Postosuchus, a member of another group of pseudosuchians called the rauisuchians, looked a lot like Poposaurus, as this critter also is thought to have been able to walk on its hind legs.  Postosuchus and Poposaurus also both lived at the end of the Triassic, and both disappeared in the mass extinction event that jumpstarted the Jurassic.  Apparently, when it was first discovered, Postosuchus was thought to be a tyrannosaur ancestor, an understandable mistake once you look at the skull of this creature!

5.  This next crocodilian seems like a bizarre medley of different animals and, in some ways, it kind of is!  Meet Dakosaurus, a member of a group of extinct crocodilians called the metriorhynchids.  The metriorhynchids display numerous physiological adaptations that suggest they were quite comfortable in marine environments, such as paddle-like front limbs, hypertrophied nasal salt glands (presumably to help keep the body from getting an excess of salt), and a hypocercal tail.*  Unlike many other crocodilians, the metriorhynchids evolved sharp, serrated teeth, similar to those seen in terrestrial predatory dinosaurs.  These marine crocodilians also lost their dermal armor over the course of evolution, the tough, bony scales and scutes on the backs of modern day crocodiles that help defend them against attack from predators or other crocodilians.  Presumably, this lack of dermal armor would have helped make the metriorhynchids even more hydrodynamic.  Dakosaurus has been discovered in Europe, South America and Mexico, and lived during the Late Jurassic and Early Cretaceous.

*As you can probably tell from the complicated words used in these descriptions, the "hypertrophied nasal salt glands" and "hypocercal tail" are both direct quotes from the paper describing Dakosaurus (click HERE to check it out).  I had a tough time determining the exact meaning of the term "hypocercal," but as I understand it, it is a condition seen in many extinct fish and other marine creatures, in which the vertebral column bends downwards in the tail, (as you can see in the picture of Dakosaurus above), as opposed to where the vertebral column bends upwards, or simply doesn't protrude very far into the tail to begin with.  Amongst other creatures, the ichthyosaurs seem to have a very similar tail design, as you can see below.  I'm not certain what, if any, the distinction is between hypocercal and reversed heterocercal; either way, this sort of tail definitely seems like it would be a good adaptation for swimming!

Works Cited:

The Lord of the Fellowship of the Island Dwarves of the Lesser Sunda Islands

We've already talked about island dwarfism several times on the blog, with examples as varied as the Zanzibar leopard, the dwarf dinosaurs of Hațeg Island, and the Channel Island fox from Catalina Island.  But now is the time for something that is several times more epic.  Today, we are going to look at the wacky, crazy, and very odd sized animals that were native to the island of Flores in Indonesia as recently as 20,000 years ago!  And oddly enough, this paleoenvironment had many similarities with the fantasy world of Middle Earth in Lord of the Rings.  Don't believe me and want to learn more?  Well that, my friends, is known as a hook, a literary device used in the opening paragraph of a work of literature to grab the readers attention.  So if you're not hooked right now, then that's because you don't like fun.  The day may come when your courage to read my blog fails....but it is not this day.  At least I hope not.

A size comparison of the brave little Hobbit, the dwarf elephant Stegodon, the Komodo dragon, and the giant stork Leptoptilos robustus, drawn by the illustrious illustrator Zach Evens!

If you aren't already familiar with island dwarfism, here's a brief summary.  Oftentimes, populations of animals will become trapped on islands.  Over deep time, they can either evolve and adapt....or die.  On islands, what was beneficial on the mainland might not be quite as useful on a smaller, isolated chunk of land.  For example, if you are a larger animal, you are going to need more food than a smaller animal.  On the mainland, where food can be found in relative abundance, this usually isn't as much of an issue.  Furthermore, being large helps ward off predators, and can increase the likelihood of passing off your genes to subsequent generations.  So for some mainland animals, it pays to be bigger.

Now slow down and grab on to something solid.  Imagine a group of elephants becomes isolated from the mainland, and trapped on an island with limited food supply and other resources.  Now all of a sudden, its the larger elephants that are dying off, starving to death.  The biggest of the bunch are unable to find enough food for their regular breakfast (not to mention second breakfast or elevenses), and unable to pass on their genes.  Suddenly, being small is looking pretty good!  Furthermore, if the island that these elephants are trapped on has geographical features that ensure mainland predators shall not pass onto the island, then the smaller elephants aren't being removed from the gene pool by predators.  If you hit the gas pedal and speed up a few thousand years or so, you might get a population of cute little pint-sized elephants.  Which, as we have talked about before, does indeed happen, and has happened numerous times throughout history.

So there's island dwarfism in a cute little nutshell.  This tiny little idea pertains to the island of Flores in a big way, as it potentially miniaturized a member of the human family tree!  Meet Homo floresiensis, nicknamed "the Hobbit" by its discoverers!  At only three and a half feet tall, this little guy would almost certainly be wasted at cross-country!  Initially announced in 2004, the discovery of at least six individuals of this cute little member of the human family tree have shown that this proto-human was not simply a genetic anomaly of this properly proportioned Pleistocene populace, but instead a participant in this posse of pint-sized people.

One small brained individual contemplates another.  The smaller skull is a cast of the skull of Homo floresiensis.  Photo Credit: Zach Evens

The evolutionary relationships of Homo floresiensis are still poorly understood, as different bits of the skeletal anatomy indicate different possible ancestors.  For example, brain shape, thick cranial bones, a short flat face, and a sloping forehead are features echoed in another early human, Homo erectus.  H. erectus does seem like a logical candidate for the ancestor of H. floresiensis, as H. erectus is thought to have inhabited southeast Asia as recently as half a million years ago.

Other scientists believe that there is more to this hobbit than meets the eye.  Not everything matches terribly well with the "Insular Dwarfing of Homo erectus as an Explanation Regarding the Small Stature of Homo Floresiensis" hypothesis.  In proportion to the rest of the body, the brain does not typically dwarf nearly as much when it comes to island dwarfism.  However, the Hobbit's brain size did seem to decrease dramatically, a phenomenon not typically seen in island dwarfs, with the possible exceptions of the Myotragus cave goat and the Malagasy hippo Hippopotamus lemerlei.  Therefore, some scientists hypothesize that H. floresiensis is not actually a dwarf at all, but was instead a "living fossil," an informal term used to describe animals whose closest relatives are all extinct.*  In this other scenario, scientists suspect that H. floresiensis shouldn't even belong to the genus Homo, and instead is a descendant of Australopithecus, another genus of ancestral human, members of which are thought to have survived as recently as two million years ago.  If H. floresiensis was instead a living fossil, then an island might be the perfect place for this brave little halfling to find refuge.

Besides dwarfism, islands can also serve as evolutionary holdout areas for animals that might not have been able to compete with other species on the mainland.  An excellent example of this is a member of the reptilian sphenodonts, lizard-like animals who can trace their evolutionary origins past that of lizards and snakes, all the way back to the Late Triassic Period, when dinosaurs were first evolving.  Today, the only place where you can find a living sphenodont, known colloquially as the tuatara, is on a number of small islands off the coast of New Zealand.  For whatever reason, this fascinating primitive reptile was unable to keep up with the rapid pace of evolution on the mainland, and found island life to be more its speed.  Unfortunately, introduced animals such as rats carry the potential to exterminate the tuatara within our lifetime.  With nowhere to go when the going gets tough, islands can be very dangerous places indeed.

Several lines of evidence support the idea of H. floresiensis actually being a descendant of Australopithecus, including morphological characteristics of the teeth and mandible, as well as the small brain size mentioned before.  A third hypothesis has been created to explain away the small size of this early human, which pertains to pathological conditions such as microcephaly, Laron Syndrome, and myxoedematous endemic hypothyroidism.  To read more about the support for and against these pathological conditions in regards to H. floresiensis, you can click HERE: this post goes ever on and on, and we still have a lot more ground to cover.  Besides, is it not strange that we should suffer so much fear and doubt over so small a being?  Such a little being.

A quality pic that shows a modern human skull on the left, and the skull of the Hobbit on the right.

"Boy, it sure would be easier to cover all of this ground if we could ride on the back of some giant elephant thing," thought an innovative member of the Haradrim people one day in Middle Earth.  Fortunately for this dreamer, he wasn't the only one who shared this vision.  The oliphaunts, giant relatives of elephants, were in no short supply, and were eventually made to carry large platforms on their backs.  Boy, that sure would be convenient if one of those dwarf elephants found their way onto Flores and got themselves shrunk, wouldn't it?  Well, lo and behold, meet Stegodon!  Although its mainland relatives were some of the largest proboscideans to ever evolve, a petite little version of Stegodon was endemic to the island of Flores at the same time the Hobbit was!

You know what else would have been easier?  If Frodo had taken an eagle and flown over Mt. Doom, and dropped the Ring into the volcano.**  It would be a little TOO convenient for there to be a giant eagle that lived on the island of Flores and, unfortunately, this time you are correct.  There was, however, a gigantic relative of the modern day Marabou stork, Leptoptilos robustus, which measured in at an enormous 6 feet tall!  Since it was so large, some scientists suspect that this fool would not have been doing much flying.  Instead, this gigantic stork is thought to have stalked the Pleistocene landscape of Flores, living a primarily terrestrial lifestyle, most likely due to a lack of mammalian predators.  Kind of the opposite of island dwarfism: instead of big animals getting smaller, its small animals getting bigger!  Boy, that sure would suck if that gigantism happened to something gross like rats, wouldn't it?

So we've got hobbits.  We've got elephants.  We've even got giant birds.  Is there anything we're missing?  Sure there is: dragons.  Although there weren't any fire breathing dragons on Flores during the Pleistocene, there was a gigantic lizard that prowled the landscape!  Meet the Komodo dragon which, as luck would have it, is actually still alive today!  At ten feet long and weighing several hundred pounds, the Komodo dragon is the heaviest lizard alive today, and will take humans as prey if given the opportunity.  As a matter of fact, there has even been some speculation that the Komodo dragon evolved so large in order to hunt the dwarf Stegodon that also made their home on the island, but as far as I know this is simply speculation.

Obviously, there is still a great deal that we need to learn about this ancient ecosystem, as well as about the individual species that were a part of said ecosystem.  Preciouusssssss fossils can be very difficult to find: unlike other inanimate objects, fossils don't really care one way or another if they are found by anyone, and just kind of sit there.  With any luck, in the coming years, paleontologists might discover evidence of humongous Floresian spiders, giant wolves, or intelligent trees.  Or maybe even elves.  Whatever the future holds, you can rest assured that I will be there to report on the new findings.  You have my word.

And my bow.

And my axe.



*Here on the blog, we've talked about animals such as the coelacanth and the horseshoe crab, both of whom are often referred to as living fossils.  In this context, I'm using the term loosely, as H. floresiensis is no longer alive today.  Instead, I am referring to the fact that at the time H. floresiensis was alive, it might have been considered a living fossil.

**If that didn't ruin that movie for you, keep in mind that Indiana Jones is irrelevant to the outcome of Raiders of the Lost Ark, and that Luke and Leia are siblings and made out.


Works Cited:

Eye Black: What Works for Football Players Works for the Cheetah

I remember when I was younger I would always wonder why baseball and football players wore black paint under their eyes.  My dad told me that the "eye black" was to help to reduce the glare that their eyes received from the sun.  Although some people seem to disagree whether or not this is effective for human sports players, it seems that several animals have evolved a similar pattern on their face!  But before we dive in, a very special thanks to Anne Price for her help with this post!

I imagine that there are a number of stories told by native peoples of Africa that explain the tear marks of the cheetah, which you can see in the picture above.  The one that I have heard before (which you can read by clicking HERE) tells of the cheetah being told by lions that she was not a cat, and instead was a dog.  The cheetah then went to talk with the wild dogs.  But the wild dogs also kicked the cheetah out, saying that she was a cat and not a dog.  The cheetah, sad with the fact that she did not seem to belong to either group, cried so much that the tear marks were burned into her face.

Some scientists believe that these black marks, which they called "malar stripes" or "malar marks," actually evolved to help the cheetah see in sunny conditions, by reducing glare and keeping the sun out of its eyes.  This would have been the original "eye black," a phenomenon whose roots extend back much further than the origins of baseball or football.  I was surprised when I was researching this natural eye black, as I thought it was a commonly cited fact that cheetahs had this eye black to reduce glare.  However, many of the sources just mentioned the malar stripes, and didn't actually address their function.  

In the book "Big Cat Diary: Cheetah," Jonathan and Angela Scott propose an alternative hypothesis.  Though they do mention the anti-glare hypothesis, the Scotts suspect that a more likely alternative is that the tear-marks serve to "accentuate facial expressions," which they say would be an "important consideration in social interactions with other cheetahs."  The tear marks, "along with the growls and hisses that are an important part of a cheetah's defensive repertoire," might "deter competitors from approaching."  While this is well and good for the cheetah, and is likely at least part of the reason why the cheetah has the malar stripes, I have a difficult time believing that this is the only reason why some animals evolved the stripes.  We will get to my reasoning in a second.

What I find really interesting about these stripes is that they are unique to the cheetah in the cat world.  The cheetah, as is mentioned in the African story above, is a very unique cat, different in many ways from others felines.  One way in which the cheetah is different is that it hunts primarily during the day, and is much less a nocturnal animal than most cats.  If you look at the eye of your house cat, look for two things.  The first is the size of the eye.  Though the cat is quite small compared to you, Mr. Whiskers has eyes that are only a bit smaller than yours!  Second, look at the pupils.  Unlike the pupils of humans that stay circular regardless of the level of dilation or constriction, cat pupils constrict to tiny diamond slits, but dilate to large circles.  This is because most cats are active at night and during the day, and in order to protect their eyes in a variety of light conditions, they have evolved very mobile pupils.  

My cat Chimney.  Notice her slit pupils.  And the One Direction pillow in the background.  Photo Credit: Dani Neher

The cheetah does not have diamond pupils, and instead has round pupils.  This stems from the fact that cheetahs are primarily diurnal, and usually hunt during the day.  According to the Scotts, "just like birds of prey," cheetahs have a "patch of highly light-sensitive cells on the retina known as the fovea."  These cells provide the cheetah with the "most precise visual perception," and enables them to "spot prey from as far away as 5 km (3 miles)."  I find this comparison to birds of prey interesting, as both the cheetah and the prairie falcon, another animal with malar stripes, would have the need to be able to spot prey from a great distance, and in sunny conditions.  This large North American falcon has very similar streaks of brown feathers beneath its eye, which flow down the face.  According to "The Prairie Falcon" by Stanley Anderson and John Squires, the "black mustachial stripes near the eyes...may further reduce glare."

This idea is supported by other bird of prey experts, such as Anne Price, the Curator of Raptors at the Raptor Education Foundation in Colorado.  Eager to learn more about the similar stripes on the face of the prairie falcon, I emailed Anne, and here's what she had to say:

It’s meant to reduce glare by having the sun strike or be concentrated in the area beneath the eye, leaving the area above in proper contrast.  The black lines under the eyes of cheetahs, most falcons (gyrfalcons and merlins being notable exceptions) and even flickers have malar stripes, though in flickers they serve as signals for courtship, not for better visibility of prey species!

Other falcons that have the malar stripe include the American kestrel....

....and the peregrine falcon.

Not all falcons have the malar stripe, however.  As Anne mentioned above, gyrfalcons and merlins are notable falcons that don't have the malar stripe, but here is another one: the African pygmy falcon, the smallest of the African raptors!  This is a picture that I took of one at the Denver Zoo.

Furthermore, the black streak under the eye is also seen on the face of many species that the cheetah preys upon.  According to the cheetah section in "Wild Cats of the World" by Mel and Fiona Sunquist, 91% of cheetah kills in the Serengeti are Thomson's gazelle.  In Kruger National Park, 68% of kills were the impala, and in other areas such as Botswana, springbok are an important part of the diet as well.  73.9% of the kills made by cheetahs in Nairobi National Park were Thomson's gazelle, Grant's gazelle, and impala.  As you can see in the pictures below, all of these antelope have that black streak under their eyes, though it is less pronounced in the Grant's gazelle and impala than it is in the Thomson's gazelle.  One of the biggest reasons for markings on an animal that don't aid in camouflage or sexual selection (i.e. differences between male and female that are used to attract a mate) is to help with species differentiation, so that they don't waste valuable time and resources attempting to breed with each other.  But since all of these antelope have the black tear marks, as well as both genders of the species, that's probably not the role that the tear marks were playing.*

A Cuvier's gazelle at the San Diego Zoo, which also has very similar malar stripes.

A Speke's gazelle at the San Diego Zoo, yet another gazelle that has the same sort of malar stripes.

It is these antelope that make me wonder whether the cheetah evolved the malar stripe to "accentuate facial expressions," as proposed by the Scotts.  In my experience, antelope such as the Thomson's gazelle don't really go around making faces at each other, at least nowhere near as much as cats do.  The fact that both the predator and prey in this scenario possess the same adaptation makes me wonder whether coevolution has occurred.

Coevolution is a biological phenomenon in which the evolution of one animal influences the evolution of another.  A classic example would be flowers and the insects that pollinate them.  Flowers need their pollen to be carried to other flowers in order for reproduction to occur.  Oftentimes, these flowers employ the use of bees and other insects to do the job for them.  But to make it worth their while, the flowers supply the insects with a delicious meal of nectar.  When the insects land to suck up the nectar, they also pick up some pollen.  Then, when they fly off to another flower to indulge in some more nectar, they unknowingly deposit some of the pollen, and simultaneously pick up some more!

I find it possible that coevolution has occurred in regards to the cheetah and its prey.  Imagine if a certain lineage of cheetah evolved that had the black tear marks beneath their eyes, while the rest of their cheetah brethren did not have this black streak.  If the black streak did help them see their prey a little better by reducing glare, then perhaps these cheetahs were more successful hunters, and produced more offspring because of it.  Suddenly, the gazelles and impala are faced with a formidable foe that can suddenly see farther than they used to be able to.  In order to compensate, it's possible that the antelope who also had black streaks under their eyes were able to see farther as well, and spot the approach of a predator from a greater distance.  Strangely enough, I haven't been able to find anything anywhere suggesting that coevolution might have occurred here, so who knows!  I'm just throwing this out there, I'm not saying that's definitely what happened, but it's a prospect which I find intriguing and thought worth sharing with all of you.

*To read more about species differentiation and the role it plays in the success of biological organisms and species diversity, click HERE to learn more about the effects of logging on a type of fish called cichlids.

Works Cited:



An interview with Anne Price.

Anderson, Stanley H., and John R. Squires. The Prairie Falcon. University of Texas Press, 1997. (accessed December 16, 2013).

"General Information About the Cheetah." Cheetah Conservation Fund. http://www.cheetah.org/?nd=general_info (accessed December 16, 2013).

"How The Cheetah Got Its Tears." Cheetah Conservation Fund. http://www.cheetah.org/?nd=story_cheetah_tears (accessed December 16, 2013).

Stokes, Donald, and Lillian Stokes. The Stokes Field Guide to the Birds of North America. New York: Little, Brown and Company, 2010. (accessed January 23, 2014).