Wednesday, June 14, 2017

Smilodon: Beast of the Week

This week, thanks to multiple requests, we will be looking at a really popular prehistoric mammal.  Make way for Smilodon!

Smilodon was a prehistoric cat that lived in many parts of what is now North and South America during the Pleistocene epoch (more casually referred to as the "ice age"), from 2.5 million years ago to as recent as only ten thousand years ago.  There are currently three named species of Smilodon.  The most well-understood is Smilodon fatalis, which is known from literally hundreds of specimens found in California, which measured between five and six feet from snout to rump and a little over three feet tall at the shoulder as adults.  Smilodon populator was the largest, with canine teeth that could measure up to eleven inches long. Smilodon gracilis was from the oldest time, likely a direct ancestor of the other two, but only known from very partial remains so details of its anatomy is mostly unknown other than the fact that its teeth were more slender than those of its later relatives.  The genus name, Smilodon, translates to "Smiling Tooth" in reference to the fact that this cat had HUGE top canines that likely would have stuck out of the mouth at least partially even when the jaws were completely closed.  Assuming its diet was the same as modern cats, Smilodon would have been an obligate carnivore, eating only other animals.  (I hear you cat people out there.  "But, Chris!  My cat at home eats grass and other plants all the time!" Ah, yes.  But what does your kitty do after consuming the grass?  BARF!  In fact, because they cannot digest plant material, cats specifically eat grass to induce vomiting when they don't feel well.)

Smilodon fatalis with cub.  Reconstruction by Christopher DiPiazza.  Color scheme inspired by modern pumas.  Because of the vast span of places Smilodon remains have been found, it likely was adapted to living in a multitude of different habitats.  Pumas are known to exhibit the same success today, living in mountains, deserts, forests, and even tropical everglades.  That being said, Pumas aren't particularly closely related to Smilodon over any other modern cat.

Smilodon is a very popular and well-loved prehistoric mammal not just in the paleontology community, but also to the general public in general.  It is certainly up there with Woolly Mammoths, and even popular dinosaurs, like Tyrannosaurus and Triceratops.  However, it is only rarely referred to by its actual name in popular media, often called a "saber-toothed....tiger".   (I'm cringing just typing that.) Word to the wise; never EVER refer to Smilodon as a "saber-toothed tiger" in earshot of a paleontologist. If you do forget the proper genus name, it's always safe to refer to it as a "saber-toothed cat" instead.  This is because Smilodon was not a tiger.  In fact, Smilodon and its closest relatives appear to have diverged from modern cats, including tigers very early in cat evolutionary history, about 23 million years ago.  In other words, despite the fact that Smilodon was a cat, there is no species of living cat that we can say is any more closely related to Smilodon than any other.  The subfamily that Smilodon is part of, called machairodontinae, and the subfamily that includes everything from tigers to housecats, called felinae are as distant as they can be within the cat family.  That being said, could Smilodon have even roared?  Think about it.  Only modern cats in the specific genus, panthera, like lions, jaguars, and tigers, can roar.  Every other cat, including Cheetahs, Pumas (mountain lion), and house cats cannot.  It is very possible, since it was so distantly related, that saber cats, like Smilodon, couldn't roar either.  (Sorry if I killed your nostalgia/childhood there.  Just thinking out loud here.)

Smilodon skeleton on display at the American Museum of Natural History in New York.

Despite how popular Smilodon is, many people don't actually know that much about it, often assuming it was just another big cat that happened to have long front canines.  In reality, Smilodon had lots of really interesting features about it beyond the teeth. On the skull, aside from the front teeth, it had a particularly robust and almost blunt-looking face to accommodate the roots of those huge front canines.  So reconstructions of Smilodon that look like a just lion or tiger with long fangs are wrong.  Smilodon also had proportionally longer arms than those of other known cats, and a short, almost stubby tail.

Overall, Smilodon had a much stockier build than most cats.  This suggests that it relied on strength over speed to capture prey.  It is very possible that in life, Smilodon would have been an ambush predator, surprising animals that get too close to its hiding spot, then relying on its strong arms to overpower and contain struggling prey.  In fact, looking at the arm bones of Smilodon, it was determined that it would have had the strongest arms of any known cat!  Also remember that like all cats (except Cheetahs) Smilodon was armed with hooked, retractable claws on each limb, which were probably great at latching onto into, and immobilizing prey even further.  If you have ever played with a house cat before, you might be familiar with the behavior they do that involves holding on with their front claws, and rapidly kicking with their back feet.  As cute as this behavior is in house cats (my fiance and I endearingly refer to it as "gripp'n and kick'n"), it is actually a really effective disembowel tactic when dealing with actual prey.  Imagine how much damage a Smilodon could have done, digging its hooked front claws, backed up by those extremely powerful arms, and shredding its prey's insides with its hind claws at the same time!  Check out the video below of my cat, Petrie, who was happy to demonstrate this behavior on my foot for you all.  Thanks, Petrie.  (Don't worry.  My foot is still intact from the incident.)



But what about those amazing teeth?  Smilodon's teeth are actually the subject of much debate.  At first glance it seems like a no-brainer that they were simply an extreme stabbing/biting adaptation.  But it's not that simple.  You see, Smilodon's teeth were actually pretty delicate and prone to breaking if put under too much pressure.  So in life, if a Smilodon was just chomping as hard as it could into anything, it was bound to get hurt.  Remember, mammals don't constantly regenerate teeth like reptile do, either.  So where crocodiles and dinosaurs could afford to be less careful with what they bite, Smilodon can't.  With this in mind, a next logical guess would be that maybe Smilodon's long canines were for sexual display?  Plenty of other animals, living and extinct, have unusually shaped or large body parts, including teeth, for this reason.  The only problem with this hypothesis is the fact that we have literally hundreds of Smilodon specimens on the fossil record, and all of the adults have the same long teeth.  If they were really for sexual display, it is much more likely that they would differ between sexes, likely longer in males than in females.  Because this is not what the data shows us, we are probably safer going back to guessing that Smilodon was using those teeth for something other than looking cool, like dealing with prey, but it probably had to be much more meticulous about how it went about it.  Going back to those unusually powerful front limbs, a strong current hypothesis is that Smilodon used its arms to hold still struggling prey so it could use its canines to carefully stab the perfect spot, likely the jugular vein or the trachea(wind pipe).  The arms would have helped ensure that the teeth weren't damaged by the prey when it was still alive.

Smilodon skeleton on display at the Mesalands Dinosaur Museum in Tucumcari, New Mexico.

Smilodon's jaws can open wider than those of any other cat in order to make clearance for the saber teeth.  Despite this, at first glance, even with some clearance, those canines would get in the way if Smilodon tried to bite a piece of food off a carcass with the front of its mouth.  Looking at house cats eat bite-sized kibble can't help us here as a reference.  For a better clue we need to look at cats that have to bite off chunks of food from larger carcasses.  What you will notice is that when eating off large carcasses, cats actually don't use the front of their mouths that often to bite off smaller pieces.  They use the sides of their mouths, armed with large, sharp teeth, called carnassals, to cut meat like scissors.  This may have been how Smilodon got around its massive canines to feed itself, as well.  Check out the clips of exotic cats eating in this video below.  You will notice that most of the time, they are biting with the sides of their jaws to process food.  (at one point in the video they show a random Binturong, which is not a cat, but a civet.  Cute, but not as relevant.)




La Brea, California, is home to tar pits that are tens of thousands of years old, and is where the majority of Smilodon specimens on the fossil record have been found.  During the Pleistocene, animals would occasionally get trapped and die in these tar pits.  While these unfortunate animals were likely giving off distress calls, they would have attracted meat eating-animals to come and eat them, including Smilodon.  Those meat-eaters in turn would get stuck, themselves, and also die, attracting even more meat-eaters and...well you get the idea.  Hundreds of Smilodons have been unearthed out of these tar pits, as well of lots of other kinds of ice age animals, especially predators.  In fact, most of the remains that are found in these tar pits are of meat-eaters because of stuck animals acting as bait.  Even today, animals are still getting stuck and dying in the La Brea tar pits.

Thanks to all these wonderful specimens, paleontologists were able to learn a lot about Smilodon, including how it grew.  Like most mammals, Smilodon had a set of baby teeth, which would later fall out and be replaced by bigger, adult teeth.  The cool thing about Smilodon, however, is that the adult teeth didn't initially cause the baby teeth to fall out.  In fact, when it came to the famous saber canines, there was a period of about a year in a Smilodon's life where the adult canines were growing in next to the baby teeth.  The specimens that show this are extremely rare, even from La Brea, which suggests that juvenile Smilodons at that age probably weren't going out to hunt, and likely were still having food brought to them by parents.

Underside of juvenile Smilodon skulls.  The left one shows the baby canines alongside the growing adult canines.  These skulls were unearthed at the La Brea Tarpits, and are on display at the George C. Page Museum in California.

That is all for this week!  As always feel free to comment below or on the Prehistoric Beast of the Week facebook page!


References

Antón, M. (2013). Sabertooth (1st ed.). Bloomington: Indiana University Press.

Feranec, R. C. (2004). "Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of Smilodon fatalis from Rancho La Brea". Palaeogeography, Palaeoclimatology, Palaeoecology206 (3–4): 303–310. 

Kurtén, B.; Werdelin, L. (1990). "Relationships between North and South American Smilodon". Journal of Vertebrate Paleontology10 (2): 158–169. 

Meachen-Samuels, J. A.; Van Valkenburgh, B. (2010). "Radiographs reveal exceptional forelimb strength in the sabertooth cat, Smilodon fatalis"PLoS ONE5 (7): e11412. 


Mihlbachler, M. C.; Wysocki, M. A.; Feranec, R. S.; Tseng, Z. J.; Bjornsson, C. S. (2015-07-01). "Using a novel absolute ontogenetic age determination technique to calculate the timing of tooth eruption in the saber-toothed cat, Smilodon fatalis"PLoS ONE10 (7): e0129847. 

"Vegetarian Cat?" Vegetarian Cat? – Dr. Sophia Yin. N.p., n.d. Web. 14 June 2017.

Thursday, June 8, 2017

Safari Ltd Review: Coelophysis

It's always exciting when I get verification that Prehistoric Beast of the Week is getting noticed.  I love hearing from friends and family that they take the time to read what I post.  However, hearing it from strangers, especially in person, whether they come to see me at a museum, or other special event, has a certain surrealism to it.

I recently experienced a third kind of excitement when I was noticed by a major toy company that want's me to help spread the word about their dinosaur products.  Safari Ltd, known for making detailed, hand-painted, educational toys of dinosaurs since 1982, sent me an email, saying they would like to partner up with Prehistoric Beast of the Week, in hopes that I would review some of their models on here.  Of course, I said yes, and a few weeks later I got a big box in the mail from them, containing some of there awesome dinosaur figures.  So without further ado, let's get to know Safari Ltd's version of Coelophysis!

If you aren't already familiar with Coelophysis, it was a relatively small, meat-eating dinosaur that lived during the late Triassic period, about 200 million years ago, in what is now the Western United States, especially New Mexico, where it is the official state fossil.  Adults measure about ten feet long from snout to tail.  The genus name translates to "Hollow Form" in reference to the dinosaur's hollow bones, which was a trait common to lots of dinosaurs, actually.  For more detailed information on this dinosaur, be sure to check out my Beast of the Week post on it from 2015.

Full body shot of Safari Ltd's Coelophysis.  In my opinion, it's the best available toy of this dinosaur.

Safari Ltd's Coelophysis is part of their newest line of dinosaur toys for 2017.  When I first saw they were making Coelophysis for this year I excited for a few reasons.  First of all, Coelophysis is very rarely made into a toy, despite how well-known it is.  In fact, before this, I can think of only three or four other instances when Coelophysis was specifically made into a toy (and none this detailed)  The second reason I was pumped for this figure is because Coelophysis was a dinosaur who's bones I had the privilege of excavating  a few years ago with the Mesalands Dinosaur Museum in New Mexico, so it has a special little place in my heart in that respect.

The proportions are great on this model.  Most of Coelophysis' length is tail and neck, which this toy showcases.  The shape of the head matches almost perfectly with some of the real Coelophysis skulls that have been unearthed.  We know, thanks to many well-preserved, and complete individual specimens of this animal, that Coelophysis skulls likely became longer and more slender as they aged, or maybe even differed depending on sex.  Judging by the long snout and two bony ridges on the top of the face, this model is probably supposed to be of an adult.  The legs are not too skinny, which is great.  Yes, Coelophysis was a slender animal, but it still would have needed muscles to get around!

My cast of a Coelophysis skull.  The Safari Ltd model matches this wonderfully.

I am hard pressed to find anything really wrong with the proportions of this model, actually.  If I were to really nitpick, I'd say the lengths of the fingers are off.  In reality Coelophysis' first finger was shortest, middle finger was longest, and the third finger was in the middle.  This toy has the third finger longer than the first two.  On a good note, they did include the tiny, almost unnoticeable vestigial fourth finger.  In fact I only just noticed that fourth finger now as I'm reviewing it.

Note how the third digit is longer than the first and second.  But check out that vestigial fourth finger!

Another tiny note is the fact that Coelophysis would have held its tail out in the air behind it for balance in life, while this model has the tip of the tail resting on the ground.  HOWEVER I completely understand that in order for a model of a dinosaur made of plastic, and not of muscles and a sense of balance, would need the tail as a third point of contact to the ground in order to stand.  Safari Ltd has made other bipedal dinosaurs that balance just on their feet, but the feet had to be proportionally larger and wider, which would be much more noticeable if they tried to do it on a dinosaur as lightly built as Coelophysis.  I have also seen Safari Ltd and other toy companies put bipedal dinosaurs on a platform stand to get rid of the balance issue, but personally, I kind of hate the stands.  It sort of kills the play value of a toy.

I love the fact that the sculptor decided to add texture of feathers to this model.  This model goes all out with an even coat over most of the body except for the feet, hands, and face.  It even has feathers down the whole length of the tail!  We actually have no direct evidence of feathers on Coelophysis, but we have found feathers in a lot of other theropod fossils, as well as a few non-theropod dinosaurs.  Because of this, we have reason to think that basal theropods, like Coelophysis, may have had some kind of feathering on their bodies, too.  Using relatives that surround a kind of organism on a family tree to infer a feature, in this case feathers, is called phylogenetic bracketing.  Coelophyis may have used feathers in a variety of ways.  Feathers could have helped keep Coelophysis' body temperature regulated, keeping body heat in when then environment was cold, and shielding the animal's skin from the sun, when it was hot out.  Feathers could also help parents keep their eggs warm.  Maybe mom/dad sat with their eggs and kept them warm that way, or perhaps parents plucked their feathers out and used them as nest material?  Feathers also can slightly obscure an animal's profile, making it easier for it to hide in certain environments.  So the next time someone tells you a prehistoric dinosaur wouldn't have needed feathers, you can list at least three reasons why it would!

Texture on the face showcases small scales, which is totally plausible, and looks good.  This model has the teeth from the upper jaw sticking out despite the fact that the mouth is closed.  Whether or not certain dinosaurs had visible teeth when the mouth was closed is the subject of a lot of debate among paleontologists and paleoartists right now.  The look that this model chose to go with regarding this is still plausible as far as I know.


The feet show the same wide-rectangular scales that you see on the toes and tarsals of modern birds, which I think is a great touch.  In modern birds, these scales were found to be made of the same material as veined feathers, and is therefore used against artists who depict these scales on featherless dinosaurs, or dinosaurs with basal feathers.  The only problem with this assumption is the fact that crocodilians have similarly shaped scales on their fingers and toes so the structure is totally capable of popping up from different materials...OR crocodilians have ancestors with veined feathers.  Whichever idea you want to go with those kinds of scales are totally fine on any kind of dinosaur reconstruction, feathers or not, including this sculpt.

This toy showcases wide, rectangular scales on the toes and feet, which is totally plausible for this dinosaur.

The colors of this model are pretty, but still believable.  Most of the body is painted orange.  The ventral parts of most of the body are white.  There is a lateral black stripe that separates the orange and white parts on the neck, torso, and tail.  This part of the color scheme reminds me of a Thomson's Gazelle. There are also perpendicular black bands on the end part of the tail.  The hands and feet are greenish gray and the snout is painted pale blue.  The two ridges on the top of the snout are painted red, as are the thin rings around the eyes.  This splash of red could possibly be intended to show a sort of intraspecies display for Coelophysis.  Of course we have no idea what colors Coelophysis was in real life, but what Safari Ltd has going on here is definitely within the wide realm of possibility.

Overall I think this is currently the best toy form of Coelophysis on the market so far.  It's not very often that you can get an accurate toy of a Triassic creature, so this Coelophysis is a much welcomed addition to Safari Ltd's line.  It can be purchased anywhere Safari Ltd toys are currently sold, the Safari Ltd website, or the Safari Ltd Amazon site.

Special thanks to Safari Ltd for shipping this beautiful little model over to me to review.