STL Science Center

STL Science Center

24 November 2015

Why those Teeth?

What makes an animal develop the way it does is not as much of a mystery as it once seemed to be, but with an animal like Thylacosmilus there is still a healthy dose of skeptically looking at the teeth and thinking something like "Why would you possibly find that to be a beneficial morphology?" Plenty of researchers worldwide that are interested in either marsupials or carnivorans have asked many questions about the teeth of Thylacosmilus. The teeth of the morphologically similar saber-toothed cats are well studied and their extension beyond the mandible "makes sense" in comparison with that of Thylacosmilus. However, despite the clearly evident amazing morphology of these sabers, there are very few highly publicized papers on the dentition of these carnivores. That paper is actually an overview paper of many taxa, but it is still worth a read. Instead, research on the animal has focused on the brain, the ear (knowing how well a carnivore heard is integral to knowing aspects of their hunting ecology), and the postcranial skeleton. I admit that knowing the postcranial skeleton is very important for a variety of reasons (e.g. knowing that the animal was a marsupial, body shape), but there are a lot of different areas of this animal that continue to be very interesting. One of the best sources for today is, as most scientific books are, a relatively rare and harder to find text. The book is called Predators with Pouches and, while not a perfect source, covers Thylacosmilus quite well. Covering man extant animals, it also discusses extinct marsupial predators and does an acceptable job. Unfortunately, even the electronic book is over $140, which is normal for low volume scientific books. However, check out what can be seen online and try to enjoy it, even when a page you want to read is missing.

23 November 2015

Reconstruction of Skeletons

Videos on this popular felid-like marsupial are not often professionally created. That does not stop people from putting up videos of the animal, however. These videos are often quite badly done though, as a result, and are of the type that are often associated with terrible music choices where the volume has been left at the highest possible setting and the illustrations are not even always of the fossil animal in question. The best representation of Thylacosmilus that was available today was actually shown in a video of a skeletal display piece of the animal from Museo Municipal Punta Hermengo de Miramar. My knowledge of Argentinian town systems is awful, but it appears that this museum is in a town known as Miramar south of Buenos Aires in General Alvarado Partido (partido being a lower level administrative district of Buenos Aires). I like to learn about these kinds of things. Regardless, the museum put up this video of the display being prepared and set up and it is interesting to look at the entire skeletal display. The area in which the museum is located is an area in which fossils of Thylacosmilus have been found, making the display that much more poignant. The lateral view of the teeth and corresponding mandibular structures are not perfect in this display, but are rather interesting and beg the question of why such an arrangement would have come to exist.

22 November 2015

Facts About Thylacosmilus

(C) Angie Wilson
Amazingly Thylacosmilus is exceedingly popular on the internet, so much so that it has almost more pages dedicated to it than its more popular look-alike Smilodon. The pages dedicated to it range from encyclopedia type entries to much more open grouped facts compiled into short paragraph forms. The timeline for Thylacosmilus is presented in various forms, such as this one from Dinosaur Jungle (despite not being a dinosaur). The most interesting thing about Thylacosmilus is, of course, the teeth. The marsupial was smaller than Smilodon, but the teeth were similarly sized, but would have had to have been used in completely different ways. This will be discussed in much greater detail tomorrow and Tuesday, as there is a lot of different literature and movies showing those teeth. However, I encourage discussing this with kids over some interesting coloring pages, like these:

21 November 2015

Fur-bearing Finale

December will not start until after the next week begins. However, this is going to be the last No-shave November mammal week that we are going to have here this year. This week's animal is an interesting carnivore. In fact, it is one of the more popular carnivores that existed during the Cenozoic, though not the most famous of its family. We have previously discussed Smilodon, and this week we examine its cousin, the interestingly jawed Thylacosmilus. The name is not widely known, but the odd mandibles of Thylacosmilus atrox and its family (Thylacosmilidae) have been found for nearly a century and are well known. The Miocene to Pliocene cat-like animals inhabited South America and were, amazingly maybe, marsupials. Their resemblance to cats is actually quite a coincidence. Their gape is a rather interesting conundrum, considering their teeth, and their bite force is extremely weak for their size. This is going to be a week of examining the weak and discovering what makes a marsupial so very much like a cat. Look at that adorable little face:
Released into public domain by: ДиБгд

19 November 2015

Not So Popular Otters

Pretty much all of the evidence we saw this week pointed toward our lovely large otter Potamotherium being a rather large mustelid rather than a small basal pinniped. The fact that it is a mustelid may impact the popularity of the animal (seals and sea lions in particular are more popular than river otters) as may have the fact that it is a mammal. People tend to love mammals, but they seem to shy away from fossil mammals and turn to the reptiles of the past in terms of what they most often love and awe in paleontology. This is okay, but a bit strange. It also makes interesting furry animals like Potamotherium a lot less successful in the popular science domain than many other animals. The smaller size of Potamotherium makes it easier to disregard as well, though there is no evidence for this kind of trend existing. As a parting note for this week, here is an illustration that was shown earlier in the week with one of the animal's vertebrae. It is pretty spiffy.

18 November 2015

Skulls and Fur

Potamotherium valetoni saint gerand le puy Musee d'Histoire Naturelle, Paris
The idea of Potamotherium being covered in fur is directly related to the fact that it is defined as a mammal. The mammalian nature of the animal can be seen in its head, including the teeth, and otter-like body. The head is extremely otter-like. The fact that early pinnipeds had similarly shaped heads and bodies is the only reason that Potamotherium has been confused for a pinniped in the past. However, the skull of Potamotherium is equally, and I assume more appropriately, mustelid-like and has caused the animal to be categorized as a mustelid. In terms of looking like an otter we know that the skull is very similar to that of extant otter species. The resemblance would have been noticeable, though differences would have certainly been recognized as well. However, at 1.5m (5ft) long it was a very elongate version of the otter. Short nasal chambers have led to the inference that sense of smell in this animal must have been fairly weak. The eyes and ears, though, appear to be highly capable.

17 November 2015


As everyone not new here knows, I love a good old fashioned paper. The 1957 description of the anatomy of Potamotherium is not one of my all time favorites, but I do rather enjoy the thoroughness of a good anatomical description of an animal. Partially the allure is in the fact that Savage is painting a picture of animal that no one had seen at that time or had ever dreamed of seeing. This description and the fossil material would eventually enable other anatomists like Leonard Radinsky to study characteristics of the brains of these interesting mustelids (during Radinsky's time a pinniped influence in Potamotherium was not an issue). Potamotherium is a world traveler though. German scientists have discussed the animal as have the Italian journals and the Royal Society (one does not have to be European to publish in either of course).