Prehistoric Mammal Week: Mesonyx

Look under Andrewsarchus's tags for a bit. Wondering why I put 'artiodactyl' there? Y'know, under a carnivore?

Weeeelllllll...

This is not a wolf. Stay away from its kill, furries.

At one time, there was such a thing as a hoofed carnivore.  Although the favorite among most people seems to be Andrewsarchus, the genus Mesonyx shows a more typical hoofed carnivore, sporting four small hooves instead of claws on each toe. Mesonyx lived during the Eocene, a time when there were enough cool mammals to get their own week. Fossils of it have been found in Colorado, Utah and Wyoming.

Here's a small exercise in case you do not understand the true terror of a hoofed carnivore: Go to a farm (or Google) and pay a visit to a cow or pig. Now imagine said cow or pig using extremely powerful jaws to bite your neck, and you were too slow to run away because plantigrade feet really suck for that. Your feet are lame compared to those of a hoofed animal, which Mesonyx ate on a regular basis. Those not-wolf teeth would get you for that reason alone.

Hooved carnivorids went extinct simply by being Darwinized out. You can still see their modern relatives...

 

...at Sea World.

Whales and dolphins are the closest relatives we have to Mesonyx.  As time went on, Mesonyx's relatives became more and more water-worthy to pursue their fishy diets. Flipper's great great granddaddy could have torn you a new one easily.





Every whale from dolphins to orcas to the largest mammal alive at the current moment came from a wolf-like carnivore with hooves. Some whales and dolphins occasionally wind up with vestigial legs as a reminder. Evolution does some weird-ass things. This is one of them.

Prehistoric Mammal Week: Andrewsarchus.

When you're a paleontologist, squeamishness around skulls is not an option. Skulls tell you a lot. Was it a mammal based on the earbones and jaw? Did it eat plants, meat, or both? What were its strongest senses? How much space did it have for its brain? Hell, it's possible to theorize what an animal looked like based on the skull alone.



That's exactly what happened to Andrewsarchus mongoliensis. All we have from Andrewsarchus is one skull found in Mongolia, forever preserved in the American Museum of Natural History. It is three feet (approx. a meter) long from the tip of its snout to the base of its head. From that skull alone, we can tell that it was a mammalian carnivore.

A very big mammalian carnivore.

Andrewsarchus was the biggest mammalian carnivore that ever walked the earth. From the skull we have, we can guess that it was probably 6 feet high and 11 feet long from snout to pelvis. This is not counting how much it weighed. We would need a more complete skeleton to determine its build and weight.

The jaws of Andrewsarchus may have been the strongest of any mammal. Although not adapted for shearing, its jaws were capable of crushing bone, mollusc shells, and turtle shells. If we later find that it ate plants as well as meat, Andrewsarchus may have led a lifestyle similar to entelodonts - the 'terminator pigs' or 'hell pigs.' It lived around the same time as the brontotheres (Eocene), and probably ate them dead or alive.

Who's afraid of the Big Bad Not-Wolf?

Andrewsarchus probably had hoof-like paws as well. How do we know this? Wellll, stay tuned; tomorrow's beast will provide the answer to how we know a lot about Andrewsarchus, despite only having a skull...

...on a side note, this guy (under the name Andarch) was one of the authoress's favorite Vivosaurs to use in Fossil Fighters. Please help her get a 3DS by donating to the tip jar or clicking on the ads. This has been the first shameless plug on the blog aside from the tip jar itself, so it's not like we're nagging. 

Prehistoric Mammal Week: Neanderthals.

Did you really think that humans would go unscathed this week? You're a mammal, too. The porn on your PC proves it - only mammals can have fine-ass racks. By looking at that porn, you hereby acknowledge that the lineage of Homo sapiens sapiens is fair game for Prehistoric Mammal Week.

Or, well, one of the hominids that might be related to H. sapiens. We're really not sure about Neanderthals.

Hell, we can't even give you the proper scientific classification; it's either Homo neanderthalis or Homo sapiens neanderthalis, depending on whether you consider Neanderthals their own species or a subspecies. However you prefer to classify them, they were first found Belgium. The name comes from a specimen found in the Neander Valley near Dusseldorf, Germany. Although they were originally thought carnivorous brutes, plant matter has been found in their teeth, and the brain of an adult Neanderthal was as large as, if not slightly larger than, that of a modern human.

Homo sapiens and Homo neanderthalis derived from a common ancestor, Homo rhodesiensis, approximately 1 million years ago. Like humans, they lived in large social groups, made tools, and had a language. (One of the theories for the evolution of Basque, a language isolate, is that it is the last member of Neanderthal tongue.) The new view of Neanderthals gives them red hair and pale skin- both adaptations to a climate with less sunlight than Africa.

Uncanny Valley'd!

Neanderthals had several differences from modern humans. In general, they were stockier ("more robust") with barrel-like rib cages and proportionately shorter limbs. Their heads also had less neoteny, meaning that they look less baby-like than those of modern humans. They had almost no chin to speak of. We would not run screaming, just go, 'huh, that guy looks a little weird.'

The scary thing? Nobody knows what happened to them. These guys are one of our closest relatives, and nobody knows for sure how they died out. It's easy to see what could make something like tomorrow's animal die out, but a hominid? We don't like picturing ourselves, or even our cousins, going extinct.

There are constant debates raging about what, exactly, wiped out the Neanderthals. So far, there are three main theories concerning what killed them off.


One theory is that the H. sapiens from Africa violently eradicated the Neanderthals. Neanderthal skeletons have shorter limbs, proportionately, than those of hominids more readily recognized as the ancestors of modern humans. This meant that humans had a huge combative advantage over Neanderthals and could spend less energy hunting big game -not to mention each other. The not-Flintstones didn't stand a chance. Yep, Homo sapiens were always assholes.

The second theory states that Neanderthals were assimilated into H. sapiens. This is supported by European and Asian lineages having 1-4% of their genes in common with Neanderthals. There are a few subtle skull traits that also hint at hybridization. War and rape often go together; there is no reason that the first two theories could not gel.

Minus Dino and the tacky fashion sense, this might have happened.

The third theory cites climate change as the main reason for Neanderthals going extinct. Even though they were probably physically stronger than modern humans, they expended more energy per movement. Something as disruptive as a massive volcanic eruption would have put a largedent in their population. They were less adaptable in general. Humans won out because they dealt with the changing environment better.

The real reason could be one of the above theories. It could be two of them. Hell, it could even be a combination of all three of them. Whatever happened, it must have been pretty damn scary.

Prehistoric Mammal Week: Brontotherium.

Rhinos already look like something out of the past. They have tough skin. They're massive. They look just plain intimidating with those horns. They are built like tanks. Go figure there were a lot of rhinos and rhino-like creatures before mankind took over the world.

IT LIVES.

Brontotheres were not rhinos (Yes, the ancient rhinoceroses are pretty cool, too, but this isn't about them.) They were rhinoceros-like relatives of the horse that have a very well-preserved fossil record in North America. Like guinea pigs (O.o;?!) they had four toes on the front legs and three on the back.

The title beast, Brontotherium, was one such genus of rhino-ish creatures. They stood 2.5 meters (8.2 feet) tall at the shoulder and lived until the end of the Eocene. They preferred soft leaves and stems to tough vegetation. This restrictive diet and general inability to adapt to a changing climate ultimately led to their extinction.




Rhinos and not-rhinos had cooler headgear back in the Eocene. Many of the brontotheres and extinct rhinoceroses had horns that would look great on boss monsters. Brontotherium itself had a horny growth resembling a slingshot. The horns of brontotheres also had bone in there, whereas modern rhinoceroses only have keratin (fingernail material) in their horns. Since the horns of males are much larger than those of females, it is likely that they were used to attract mates or butt heads a la rams. 


Many Brontotherium fossils have been found in South Dakota and Nebraska - where, again, there is very little else. When storms washed up these fossils, the Sioux Indians thought that they belonged to massive horses that produced thunder by running over the clouds. The brontotheres found thus had actually been killed by the eruptions of the (volcanically active) Rocky Mountains. Damn humans, only coming around when all the cool stuff was done!

Speaking of...

Prehistoric Mammal Week: Hyracotherium.

 

The creature above is likely the ultimate Uncanny Valley beast. Its name is Hyracotherium, it lived in Asia, Europe, and North America, and it was about the size of a fox. It lived during the early Eocene (52 mya) - a time when, for reference, we had a relative named "Necrolemur." Hyracotherium looks like a creature that we all should know, but do not. We've seen this animal before, but where? Goddammit, it's on the tip of my tongue...



You have got to be kidding me.That little guy? A horse? He's got to be smaller than the smallest horse in Guinness.



Actually, Einstein is only slightly bigger. Nice going, evolution.

Technically, Hyracotherium is no longer a horse. It's a palaeothere- a type of ancient mammal that shows the starting traits of being a perissodactyl (odd-toed ungulate). There is still some debate over exactly where it belongs, but it did give rise to horses, regardless of whether it can legally be considered an equine or not. The old name for it was Eohippus - "dawn horse."

Hyracotherium is the oldest known ancestor of the modern equines, including horses, asses, and zebras. It started as a small creature with the five digits common to tetrapods. As time went on,  these little fellows became faster and faster, as well as bigger and bigger from eating new plants.The horse family lost toes until only the center digit remained and became encased in a sturdy hoof. They also evolved to love sugar cubes (irony!).



Some scientists also propose that Hyracotherium founded other perissodactyl lines, such as rhinoceroses and tapirs. Those are pretty neat, too; tomorrow will feature a look at brontotheres, creatures that look like rhinos but may have been more closely related to horses. If only Nintendo had some creativity left; Hyracotherium would be a great fossil Pokemon to make a three-way evo out of.

Prehistoric Mammal Week: Marsupial Lion.

Ah, Australia. Home of kangaroos, animal fanatics, that weird stuff called vegemite, boomerangs, and deadly spiders. Everything there, even the invasive rabbits, has evolved to tear humanity a new one. Kangaroos can drown dogs and cuddly wombats can smash one's head with their rear ends. HOW could this place get any more hardcore?



JESUS CHRIST IT'S A LION. GET IN THE CAR. GET IN THE FUCKING CAR RIGHT NOW.

Actually, that's not a lion. It's a Thylacoleo carnifex, a giant carnivorous marsupial that dominated the Australian food chain for a very long time. T. carnifex was about the same size as a small lion and could climb trees like a leopard. There is a high chance that it saved some of its kangaroo meat up there for later like a leopard, too. It lived during the Pleistocene, i.e. the era of huge mammals.

For those of you wondering how we know this was a marsupial and not a big cat, dentition is still the main way of determining mammalian evolution. Marsupials have a distinctive dental formation regardless of what they eat. The teeth on T. carnifex were not like those of a modern felid.

 

Thylacoleo definitely had a nice set of teeth. Hooooooo boy did it have teeth. The marsupial lion had the strongest known bite of any mammal. It weighed half the weight of an African lion but had just as powerful a bite, making those jaws the strongest of any mammal, living or extinct. It is considered the most specialized mammalian predator in existence, sporting more than just the cool teeth.



Like most modern cats, Thylacoleo also had retractable claws - a unique feature among marsupials. It also had semi-opposable thumbs to help it grasp and capture its food. Special bones in its cervix allowed it to 'tripod,' i.e. stand on its hind legs to slash and grab its prey better. That's not a cat - that's almost a furry.
 

Actually, yeah, kinda like that. 

What happened to these badass psuedo-cats? In a word, man. Men not only hunt giant beasts for fun and profit, but they deprive other giant beasts of their food sources in doing so. There will be a recurring theme of "when humans come around, the megafauna dies" this week. A shame this guy had to go; the way things were going, we could have had marsupial Na'vi. At least they were immortalized in Aboriginal cave drawings.

Derp.

Marsupials used to be more than just kangaroos and koalas. A lot of them were more like the Tasmanian Devil, the only extant carnivorous marsupial. Most of them were considerably larger than their modern counterparts. Even though the Marsupial Lion was not a real lion, get in the car. Or at least get a spear.

Prehistoric Mammal Week: Palaeocastor.

Rodents are very successful animals. After the dinosaurs died out 65 million years ago, they evolved to spawn like crazy and chew through anything that their giant incisors possibly could. They are currently the most diverse group of mammal if not the most populous. Overall, they are solid survivors.

They also evolved to scare the f*ck out of modern man. No, we are not talking about the mice that make 50's housewives jump up on chairs. We are talking about giant rats that grew as large as bears, making the current largest rodent, the capybara, look like a kitten. We are talking about gophers with horns that would make any exterminator scream in terror.

We are also talking about rodents that made structures like this:

 

That is called a "Devil's Corkscrew." These, umm, screwy formations can go up to three meters down into the soil. They appeared around areas that either currently had water or were known to be near lakes in the past. Such areas include Nebraska and North Dakota, places where there is nothing today.

For the longest time, nobody knew what the hell the Devil's Corkscrew was. Some suggested it was a type of freshwater sponge; others said it was ancient vegetation. It was not until a giant rodent's skeleton was found in one of the curls that people figured out what this silly straw of a geological formation was: A burrow.

Now, if I told you all to name a type of rodent found near water, what would you say?



If you said a beaver, congrats: the nutria have not invaded your area yet. The Devil's Corkscrews were indeed made by Palaeocastor (lit. 'ancient beaver'). There were several species of Palaeocastor with varying sizes. These beavers lived during the Oligocene Period in the North American Badlands (told you those places sucked). Castroides, a beaver the size of a bear, evolved later.


Leave it to beaver to terrify us all.

Devil's Corkscrews were made by Palaeocastor eating its way through the earth as opposed to digging. As with modern beavers, fossil evidence says that these ancient beavers had large families. Picture that for a minute: A family of rodents with teeth strong enough to chew through the earth. There is a modern rodent that does that, too:


You'll be seeing it in your nightmares. We think the ancient beavers at least had fur. 

What reduced the beaver family from several species to only two extant members? Probably competition. Although beavers were always around water, Palaeocastor were more terrestrial. There was less competition for marine rodents, so the result was the webbed-footed, paddle-tailed animal found all over Canada, the northern U.S., and Europe.


Oh, and Bibarel.

So the burrows and giant beavers are pretty strange, but how about something bigger? Check back tomorrow.

Prehistoric Mammal Week ho!

Okay. I'm still a zombie from twelve plus hours total on a plane, so I really, really hope this entry makes sense. It feels like I owe you all something after being gone for six weeks in Europe (and Turkey, a country that cannot decide whether it is Europe or not). The good news is that I was still clicking around Wikipedia and looking at whatever happened to be around me for inspiration for this blog. Expect more European fauna than before.

That said, let's talk about this week's theme: Prehistoric mammals.

It does not matter that these things are all mammals. You would still run screaming from them just like you would a dinosaur.

When most people think "prehistoric," they think "dinosaurs." That is a false perception. The Mesozoic era (Triassic-Cretaceous Periods) was sandwiched between the Permian and Cenozoic eras, both of which sported mammals or mammal-like creatures as the dominant vertebrates. Dinosaurs occupy a relatively small space of time compared to true reptiles, things that are between reptiles and mammals, and mammals. That chunk of fauna is small in the grand scheme of things. Interesting and popular, but small.

Prehistoric mammals are almost a niche interest. It's harder to find books on mammalian evolution than it is on reptilian evolution by a long shot. It feels like many people are willing to go 'dinosaurs died, now the world is ruled by mammals' while ignoring the necessary transitional steps between those two periods.

This is not to say that ancient mammals are completely untouched in popular culture. The Ice Age series has granted them some fine publicity, but pop culture misleads us about the mammals that once were. For example, in 'dino tubes' (tubes containing little tiny plastic animals), one will frequently see mammoths and saber-toothed tigers alongside Tyrannosaurus rex and Triceratops/Torosaurus. Giant dinosaurs and giant mammals never (or, for those of you supporting the 'dragons are dinosaurs that lived' theory, rarely) met. Emphasis on 'giant' - the dinosaurs did regularly interact with mammals, but they were very small.


Dear movie producers: The dinosaurs were BEFORE the Ice Age. Talk about misinformation.

So, if the dinosaurs didn't kill ancient megafauna and other extinct mammals, what did? Various things. Some were simply Darwinized out of the system by other mammals. Others were driven to extinction by Neanderthals or what other primitive humanoids have you (why do I say that? find out this week). Some would say that those two are the same thing. In short, Darwin did it, and those strange mammals are now nothing but bones.

This week will show you some of the amazing mammals lost to Darwin over that sandwich time between the dinosaurs and the present. What did they probably look like? How did they live? What killed them? Seven entries, seven mammals that should really get their own movies if they have not already. Look forward to it.