Moenkopi and Lykins: The Mid-Triassic in Western North America

In this post, we continue with out exploration of the Mid-Triassic, 240 MYA.  In this post, we look at the Moenkopi and Lykins Formations of North America, and see what they can tell us about this ancient time.  We also delve a bit into the evolution of fin-backs and sails as display structures, like you can see in the picture below.

In the Moenkopi Formation of North America, we can gain a more complete understanding of the terrestrial fauna of this time period.  We already discussed the rauisuchian Ticinosuchus and the protorosaur Macrocnemus from Monte San Giorgio, as well as the large temnospondyl amphibian Eocyclotosaurus from Grès à Voltzia, but there were lots of other very exciting animals alive back then as well.  Arizonasaurus, a poposaurid archosaur, was likely one of the top predators, and had a back adorned by a Spinosaurus-like sail, similar to the sail seen in the more primitive German archosaur Ctenosauriscus.

We talked about the poposaurs in a recent post which you can read by clicking HERE.  The poposaurs, as well as the rauisuchians, were both members of a large group that many scientists refer to as "pseudosuchians."  These animals were crocodilian in nature, and fairly closely related to them.  But some pseudosuchians, including some rauisuchians and poposaurs, actually evolved a body design similar to some types of dinosaurs, where they could walk on either two or four feet.

Let's jump back to the sails on the back of Arizonasaurus, Ctenosauriscus, and Spinosaurus.  The first two are fairly closely related to each other, but Spinosaurus is not closely related at all, separated by around 150 MY of geologic time.  The question is, why would these animals have convergently evolved these sails on their backs?  The orthodox answer is that the sails help the animal thermoregulate, that by turning the sail towards or away from the sun, it would help the animal warm up or cool off.  Similar ideas have been proposed for other animals that feature similar anatomical structures, such as Stegosaurus with its double row of plates down its back, or the primitive synapsids Dimetrodon and Edaphosaurus.

A model of a juvenile Stegosaurus from the Morrison Natural History Museum.  Other stegosaurs that are very closely related, such as Kentrosaurus and Wuerhosaurus, have very different shaped plates, and a different amount of plates, as well.

This idea has some major flaws, however, as argued by paleontologist Dr. Robert Bakker in his excellent and influential book "The Dinosaur Heresies."  In the book, Bakker points out that very close relatives of these sail-animals don't have these strange fins on their back.  If the thermoregulation theory is accepted, then that would suggest that these very closely related animals had very different thermoregulatory needs.  For example, Bakker points out that the primitive synapsids Dimetrodon and Sphenacodon are very closely related to each other, and most of their anatomy is very similar, other than the fact that Dimetrodon has that enormous sail on its back, and Sphenacodon has only a very slight elongation of its vertebrae.  If we accept the thermoregulatory hypothesis at face value, it would imply that, despite being very similar in anatomy and lifestyle, for whatever reason Dimetrodon and Sphenacodon had drastically different thermoregulatory needs.  Below, we have a chart showing a sail-back on the left with a closely related animal on the right, this one lacking a sail.

So what do we propose instead?  Most likely a means of attracting a mate.  In animals today, it is display structures and behavior pertaining to courtship that changes the most.  An excellent example of this is the birds of paradise from New Guinea, which we discussed in greater depth in a post with a similar focus, in regards to the plates of Stegosaurus, which you can read HERE.

Sharks, such as the very strange-looking Hybodus, have also been discovered in the Moenkopi Formation.

Where I live in Colorado, the Lykins Formation is approximately contemporaneous with the Moenkopi Formation.  The Lykins Formation isn't the most exciting of Colorado's geologic formations (at least not for people interested in fossils or excitement), but stromatolites can be found in some areas of the formation.  Stromatolites are layers of wavy and convoluted cyanobacteria that sometimes form in areas of shallow water.  Cyanobacteria by themselves aren't very big, as they are simply single-celled photosynthetic bacteria.  However, together, the gelatinous secretions they produce is enough to trap the sediment that settles out of the water, forming visible laminations that sometimes fossilize.

Stromatolites were much more common prior to the Cambrian Explosion approximately 500 MYA, as back then there wasn't really anything that could eat it.  Believe it or not, layers of cyanobacteria are notoriously bad at running away from herbivores, even something as slow as a snail or a slug.  Today, stromatolites are relatively rare, especially considering their past abundance, but you can still find them in isolated areas like Shark Bay, Australia, and Lake Salda in Turkey.  Most stromatolites form in areas that discourage herbivore grazing.  Shark Bay and Lake Salda are both hypersaline areas, places where most herbivores simply don't want to go (especially slugs and snails).  More recently, stromatolite-like growths were found living in an abandoned asbestos mine in Yukon, Canada.  This indicates to us that the parts of the Lykins Formation in which the stromatolites are found were likely not conducive to supporting herbivores, perhaps also due to hypersaline conditions.

Join us soon for our next post, in which we look at ancestors of both dinosaurs and mammals that were alive during this time!  We will also do a little investigating into different types of dentition, so stay tuned!

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Grès à Voltzia: Mid-Triassic French Lagerstätten

In our last post*, we got our first glimpse of some of the flora and fauna that inhabited the earth 240 MYA, in the Mid Triassic Period.  In that post, we mostly looked at the aquatic environments, fossils found at a fascinating place in Italy called Monte san Giorgio.  In good time, we will learn more about the terrestrial ecosystems and what lived on land.  But first, let us look between the aquatic and the terrestrial.  Let's look at the seashores of this ancient Earth.

To gain a better understanding of what lived on the margins of the oceans, we can look at Grès à Voltzia in France.  The importance of this site lies not just in the preservation of a large number of different organisms, but in the exceptional quality of said preservation.  Grès à Voltzia is considered a Lagerstätte, a German word referring to fossil sites that feature remarkable detail in the preservation of fossils, with famous examples including the Solnhofen Limestone in Germany and the Green River Formation in Wyoming.  The depositional environment that would one day become Grès à Voltzia featured deltas very close to the shore, and were home to many animals.  This prime habitat resulted in the burial of both terrestrial and marine animals, painting an even more complete picture of this ecosystem.

Here we have a picture lifted from my Instagram that shows three very different animals from the aforementioned Lagerstätten. What ties these three animals is their common ability to fly.  On the right, we have pictures of two fossil casts from the Solnhofen Limestone in Germany, deposited about 150 MYA.  Archaeopteryx, the primitive bird/dinosaur link, is on top, and Pterodactylus, a type of pterosaur, is on the bottom.  The picture on the right is of a bat from the Eocene of Wyoming, found in the Green River Formation, deposited approximately 50 MYA.  Despite its age, Icaronycteris was fairly similar to modern bats.  All three of these animals convergently evolved flight, and were not derived from a common ancestor.

Along the shores of these 240 MY old rivers, horsetails and and ferns grew in abundance, as well as several different types of gymnosperms.  Large amphibians such as Eocyclotosaurus made their home in these waterways, as they were tied to moist environments just like modern amphibians are today.

Horseshoe crabs like Limulitella, very similar to modern horseshoe crabs, are commonly found, as are many types of crustaceans, such as Antrimpos, a type of shrimp.

Insect larvae includes dipteran (true flies), odonatopteran (dragonflies and damselflies) and ephemeropteran (mayflies).  Annelids (segmented worms like the modern earthworm) have also been discovered here, as well as fish and a jellyfish.

The horsetails, such as Equisetites, grew along the edges of the water, while the gymnosperms grew further inland, probably reaching at least several meters in height.

A large number of insects, including the dipterans and ephemeropterans that we already mentioned, lived here.  Proto-cockroaches (blattopterans), beetles (coleopterans), and hemipteroids were all present, as well as myriapods (centipedes and millipedes), and spiders.  A strange mixture of modern and exotic looking animals to be certain!

Next time, we will be continuing our investigation regarding the flora and fauna of the Mid Triassic by learning about two North American geologic formations that might reveal a bit more about the terrestrial ecosystems.  Join us!

*As those of you who are familiar with myself and this blog, you are likely familiar with the fact that once I start talking, it takes a good deal to make me shut up.  The same is true for writing this blog.  When I originally came up with the idea to do a post about the flora and fauna that inhabited the Earth 240 MYA, flora and fauna that many people, myself included, are relatively unfamiliar with, it was supposed to be a relatively short post, maybe four or five paragraphs in length.  Instead, I ended up just writing and writing and writing.  I realized, as I often do, that A) so few people would be reading these posts to begin with, and B) those people who do wind up reading these posts would likely not have stuck around for an immense post that talks about everything from the ichthyosaurs of Italy, the stromatolites of Colorado, the insects of France, the communal latrines of Tasmanian devils, the lack of communal latrines of Maiasaura, the communal latrines of dicynodonts (yes, poop is cool), the heterodont condition of primitive whales, and everything in between, that it made more sense to split the post up.  This is the second installment of five (so far, at least) regarding the flora and fauna of the Mid Triassic Period, approximately 240 MYA.  It now occurs to me that I probably lost most of you in this long-winded exposition.  I don't want to just delete all this though, as future generations will find this fascinating glimpse into my thought processes an untapped reservoir of knowledge that is absolutely vital to an understanding of the ultimate being I shall become.  I think I will just make this whole thing an endnote.

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240 MYA: Messing Around in the Mid-Triassic

People tend to think of the dinosaurs filling the dominant terrestrial ecological niches during the entirety of the Mesozoic Era, from the Early Triassic all the way to the Late Cretaceous.  This is an oversimplification, however, as the dinosaurs didn't really evolve until the Mid or Late Triassic, and still up against competition from other groups of animals until the Early Jurassic.  Today, we are going to travel back in time 240 MY, back to the Middle Triassic Period.  This slice of time is approximately 10 MY after the mysterious Permian Extinction, and is about 10-15 MY before the first undisputed dinosaurs start showing up.  We are in a time when many of the animals that lived on the land and swam in the seas looked similar to life that is more familiar to us, but much of it was distinctly different.

All of the Earth's continents were united in the supercontinent Pangaea, surrounded by the super-ocean Panthalassa.  The Tethys Sea was nestled into what would one day become the somewhat smaller supercontinents Laurasia (North America, Europe, and Asia) and Gondwana (pretty much all the rest).  Warmer conditions prevailed, and the poles were ice free all year round.  Although the coasts seemed to be more hospitable to life, the center of Pangaea was not quite as welcoming, receiving little rain and remaining fairly arid.

There are several important sites around the world that preserve fossils from this time period.  Let's start in the ocean and work our way onto the land, starting with Monte San Giorgio.  This site along the border between Switzerland and Italy gives us insight into the ecosystem that flourished beneath the waves of the Tethys Sea.

Sauropterygian reptiles such as the ten-foot long Ceresiosaurus cruised around, likely hunting smaller sauropterygians such as Neusticosaurus.  These reptiles resembled the more famous Nothosaurus and the later plesiosaurs, with their four limbs greatly resembling paddles, all of approximately equal length.

The dolphin-like ichthyosaurs such as Mixosaurus and Besanosaurus would have zoomed around, feeding on faster prey such as squid and fish.  Mixosaurus was pretty much your stereotypical ichthyosaur, but Besanosaurus was a bit odd-looking, with all four fins/limbs being fairly close to equal in length, unlike the shortened hind flippers that is more commonly seen in ichthyosaurs.  Besanosaurus also seems to not have had a dorsal fin.

The giraffe-like protorosaur Tanystropheus also probably hunted fish and squid, using its extraordinarily long neck to ambush unwary prey items, sneaking up on them while the rest of the animal was still four or five feet away!

A drawing of the protorosaur Tanystropheus by the talented young artist Sam Lippincott!  Photo Credit: Sam Lippincott

The turtle-like placodonts like Paraplacodus and Cyamodus possessed large, flat teeth perfect for crushing the shells of molluscs and crustaceans.  The teeth of these placodonts are similar to the molars that you can see in the mouth of the walrus, a marine mammal that has a diet fairly close to the placodonts of 240 MYA.

Thalattosaurs like Askeptosaurus also probably fed on molluscs and crustaceans, and likely fish as well.  Askeptosaurus had a long snout, and superficially resembled animals like Ceresiosaurus and Nothosaurus.  In the picture below, the snout is tucked towards the animals left armpit, almost like it's trying to figure out whether Triassic animals can get B.O.

Several terrestrial reptiles have been discovered at Monte San Giorgio as well, such as the rauisuchian Ticinosuchus and another protorosaur like Tanystropehus (albeit one with a much shorter neck), Macrocnemus.  We'll talk more about the terrestrial ecosystems of the Mid-Triassic later, with more talk of animals like Rauisuchians!  Check back for our next post, featuring the French site Grès à Voltzia!

Lugano on Dwellable

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Animal Poop: More Fun, Tasty, and Aromatic Than You Thought!

If you're a fan of Bob's Burgers, you might remember the Season 4 episode entitled "Ambergris" (check out the full episode HERE), in which the Belcher children discover a strange, aromatic hunk of...something...on the beach.  This something turns out to be an interesting byproduct produced by the sperm whale: and even a small hunk of it can be worth thousands of dollars to the right buyer.  But what exactly is the stuff?

Much like the title of the episode, this hunk of surprisingly expensive junk is called "ambergris," and scientists believe its production is related to the sperm whale's diet.  Sperm whales (Physeter macrocephalus) love to eat giant squid who, despite their relatively squishy nature, possess a very tough beak, a feature seen in other cephalopods such as octopi and nautilus.  In my opinion, the cephalopods can be some of the most fascinating animals ever.  Period.  We can delve deeper into why these creatures are so fascinating some other time, but for now, I leave you with this video of the ultimate in animal spy-gadgetry that would make even James Bond sea-sick with envy.  (To see the full Ted-Talk that this video clip is taken from, click HERE.)

Another thing that I think is really cool about animals such as the octopus and the squid is that they have an extraordinarily tough beak.  Partially composed of keratin (the same thing your fingernails, hair, porcupine quills, whale baleen plates, claws of reptiles and mammals, horns,* etc.), this beak very closely resembles beaks seen in some types of birds, and is often referred to as a "horny, parrot-like beak."**  To truly understand the close resemblance, check out the pictures below!

Now, if you've ever tried to digest a bit of antelope horn or Komodo dragon claw, you might have noticed that it doesn't go down very easy, and comes out the other end with even less easy involved.***  For whales, most of the squid is pretty easily digestible, as they don't have to worry about scales or claws, feathers or hair.  That is, other than that tough, keratinous beak.  So what does the sperm whale do with this sharp section of squid structure?  The answer to that is kind of cool, albeit still poorly understood.

Here's what scientists think happens.  In order to keep the squid beak from harming the sperm whale from the inside, the whale somehow surrounds the tough bits of indigestible material (including the squid beak), to keep any sharp edges from being exposed.  That part seems to be fairly widely agreed upon, although it seems that the exact methods are still not terribly well understood.  Sources differ on how the ambergris leaves the whale's body, however.  One Scientific American article states that the whale passes the ambergris with its feces because "it smells more like the back end than the front" when it is first cast out of the body.  However, other sources explain that whale feces are liquidy, and hard matter could be difficult for the whale to process.  Instead, these sources state that ambergris builds up in the whale over the course of its lifetime, and are released when the animal dies.

So why is ambergris so poorly understood?  Well, researching whales, and sperm whales in particular, can be extraordinarily difficult.  You need the proper equipment, you need the money, and you need to be able to find the whales.  Sperm whales can also be more tough to study than other whales because of their natural behavior.  They will dive thousands of feet deep in search of their prey, and spend most of their time beneath the ocean's surface.  When they do protrude above the surface, it can still be difficult to find them, as they often don't protrude very far, and their spout of water released upon surfacing is much smaller than in many other whales.

Because of these and other factors, sperm whales remain poorly understood.  Ambergris is only known to form in the sperm whale and the related pygmy sperm whale (Kogia breviceps), both of which are very hard to study.  Furthermore, studies have found that ambergris is only found in 1-5% of these whales, making the substance even rarer still!****  Because it is so rare, no one has ever seen ambergris expelled from a sperm whale, and the association is only known because of dead sperm whale bodies with ambergris discovered inside.

In spite of this rarity, or perhaps because of it, ambergris is something of a hot commodity, and apparently has been for thousands of years.  The Scientific American article quoted above cites the use of ambergris in many different ancient cultures, including the ancient Egyptians, Middle Easterners, and the Chinese.  It seems to have been regarded as a "cure-all" in some cultures, including Britain during the Middle Ages.  More recently, it was commonly used in perfumes, to fix odors and make the smells hang around for a longer period of time.  Although synthesized replacements have taken the place of ambergris in many scenarios, there apparently still is quite a market for the stuff, and even a relatively small hunk of it can fetch a price of several thousand dollars from the right buyer!

As an interesting side-note, fossilized ambergris has been discovered in 1.75 million years old Pleistocene deposits in Italy.  Some of these fossils, which apparently number more than 25, are even about two feet high and four feet wide!  The abstract of the article (link HERE) describe these fossils as "the only known example of Pleistocene sperm whale coprolites," indicating that the authors of the article consider ambergris to be a poopy product of the sperm whale.  Within the fossilized ambergris, parts of squid beak and "altered organic matter" have been found.

So yes, ladies, long story short, it is possible (although unlikely) that you have sprayed yourself with squid beak byproduct that was somehow expelled from a sperm whale at some point in your life.  If you feel slightly foolish, just remember: you can be sure that you never drank any coffee that was created from the partially digested excretions that came from the hindquarters of the Asian palm civet (Paradoxurus hermaphroditus), or freshened up with the assistance of the male musk of the the aptly named musk deer (Moschus moschiferus), a scent which the females of the species find most alluring.

Oh wait, you might have done both of those.  Coffee made from animal poop....I have no doubt that Gene Belcher would love to have a cup.  Just remember on your next date, it's not coffee breath or a lack of perfume you have to worry about: its civet-butt breath and a lack of musk deer scent and whale byproduct.  You just better hope that there aren't any female musk deer around....

*Note that antlers are different from horns, and are not made out of keratin.  For a more in-depth discussion regarding the differences between antlers and horns, click HERE and HERE.
**Not that kind of horny.
***Based on speculation on the part of the author, and NOT personal experience.  Please do not try this at home without the supervision of a parent or guardian who has been trained in such matters.
****This statistic comes from the following source: http://www.environment.gov.au/node/18363.  It doesn't actually say how this statistic was determined, but I assume from analysis of whale carcasses.  I don't think many people have tried to look at the digestive systems of whales that are still alive.
*****Yes that kind of horny.

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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).  

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