Working Hard to Find Papers

Finding papers that are about, reference, or even vaguely mention Estemmenosuchus is actually a lot more difficult than I had initially thought it would be. The majority of the papers that make mention of the interestingly shaped therapsid are descriptions of faunal assemblages of Eastern Europe, Russia, or simply Permian fauna in general. These papers are exemplified online by Chudinov's (Tchudinov) 1965 paper Deinocephalians of the U.S.S.R. and Battail's 2000 paper A comparison of Late Permian Gondwanan and Laurasian amniote faunas. Chudinov actually described the two species of Estemmenosuchus in 1960 and 1968; these descriptions are not available online. Unfortunately, Chudinov's treatments of Estemmenosuchus are possibly the best and are certainly the best online at the moment.

Ugly Animals Get All the Love

Whenever a fossil animal is bizarre enough to be a little scary or to be called ugly outright it appears to gather an awful lot of attention in the media and within the general population. Estemmenosuchus is an animal that exemplifies this sort of massive interest across the lines of professional and amateur as well as including the typically disinterested portion of the population. Despite knowledge of the animal and its respected, if not well known, existence in the fossil record, it has not made am impact in the animation or documentary community that typically brings dinosaurs and other fossil animals to life. A Permian Monsters exhibit was once outfitted with an animatronic Estemmenosuchus and Gondwana Studios captured the statue in motion and displaying all the small conical teeth it was installed bearing. Seeing an interpretation in action is important to understanding how scientists envision this animal moving around its environment, regardless of the actual motions that this statue is engaged in (what I mean here is that it is roaring and moving its head around perfectly well, but there is no locomotion aspect to the animatronics). Maybe someone should have suggested this rather intriguing animal for a role in the Walking with Monsters series from 2005. It would have been contemporary with other Permian animals like Gorgonops, Dimetrodon, and  Edaphosaurus, to name a few. Perhaps this age will be revisited by television and film, but until then the movies for Estemmenosuchus are sadly lacking overall.

News Then Therapsids

In the somewhat recent past I  found myself thinking that perhaps we could use a name change here at Dinosaur of the Week. The fact of the matter is that we have covered a lot of dinosaurs and fossil animals in the past 7 years (give or take a week or two off a year for vacations and conferences we are talking about ~50 animals a year for 7 years) and the number of well known, well documented, and well represented dinosaurs have become rarer and rarer for us to cover. We could easily cover only dinosaurs, but there is a point, and we are very near it, where we will start to cover dinosaurs that are represented by singular fragments of singular bones and are highly hypothetical. In exploring other fossil animals we have extended the life of this blog beyond a few years and have been able to explore a much larger range of life on the history of this planet.

Why haven't we changed the name in all that time then? I have seriously considered it a number of times in the past year or two because I realize that we discuss much more than dinosaurs. There could be any number of good names: Fossil Animal of the Week, Extinct Animal of the Week, to name a few. So far I have decided that the fact that Dinosaur of the Week is acceptable as a name, though we could rebrand ourselves without losing an audience. The reason that I am reluctant to do so at the moment is that we have recently become more widely known. The site has been cited in scientific and educational presentations at conferences and it has been used in classrooms in public schools for an extended period of time. All of that said, should a name change occur, the change would be effected in the first week of the new year. This will give me time to make a final decision on a new name, how to rebrand the site, and to illustrate all of the necessary materials for the site. Now, on with the animal for this week:

©Roland Tanglao

Estemmenosuchus is a genus of Dinocephalian ("terrible headed") therapsid. Two species are known; E. uralensis Tchudinov, 1960 (type)and E. mirabilis Tchudinov, 1968. These two species are both known from the Perm region of Russia, an area near the Ural mountains in the center of the country. The name Estemmenosuchus means "Crowned crocodile" in Greek, but therapsids like these two species are actually mammals, and not at all related to crocodiles. A body measuring approximately 3 m (10 ft) that looked something like the body of sprawling hippopotamus was attached to this crowned reptilian looking head. Important questions remain: What are all of these growths made of? What were their purpose? What did this animal eat? What makes it a therapsid?

On the Nest

©Maurilio Oliveira

Guidraco venator is unique among pterosaurs in a variety of ways. The teeth are actually somewhat common in earlier pterosaurs like Dimorphodon, but the size of Guidraco is more rare for a pterosaur with those type of teeth. In terms of interpretations of Guidraco the animal is unique in that many of the illustrations of this pterosaur do not take place in the air. A number of interpretations do show Guidraco flying but we have not seen any of it diving toward food items, taking off or landing, or participating in any visibly powered flight (i.e. there are no interpretations or illustrations that appear to be showing down or upstrokes of the wings more definitively than they depict soaring. There is nothing wrong with any of these depictions, of course. However, as with any other fossil animal we discuss here, we do like to see a little variation in how animals are depicted because we know that animals engage in dynamic behaviors throughout their lifespans. There are a number of illustrations and interpretations of Guidraco walking on the ground. These are interesting, but not as interesting as the illustration we are looking at today. This illustration combines some odd perspective (like the directly facing Guidraco) and the aforementioned not seen before act of feeding (look in the background) with the pose of a sitting Guidraco and different wing positions which are showing hints of powered flight. It may look as though I set that up earlier in saying that we had not seen those things until now, but an image search with those keywords actually seems to have turned in the perfect storm of an illustration which we should look at in great detail. The behaviors that were, until I found this image, uninterpreted or at least had not been illustrated, represent a substantial portion of the life history of Guidraco and the ideas hypothesized in these representations of their lives can, potentially, tell us a lot about the pterosaur. This illustration also tells us a lot about how the researchers interpreted the life history of Guidraco based on sister taxa and the fossil that was known to them when they described it.

Mouth of the Dragon

Attributed to Feng Lan

Guidraco possessed approximately 82 teeth in its 38 cm (14.9 in) long skull. Both the mandible and upper jaw (consisting of maxillae, premaxillae, and nasals) were of equal length but the upper jaw contained 23 teeth on each side whereas the mandible contained 18 teeth per side. The first teeth in each row are held almost horizontal and, as the teeth are followed caudally in the mouth, they begin to curve more and point toward the open mouth; up in the mandible and down in the upper jaw. The mandible's rostral teeth are slightly larger than their counterparts in the upper jaw and for the most part the teeth are of similar sizes caudally. These forward most teeth come together, or occlude, in such a way that they form a basket of teeth and mouth which would have been very well suited to grasping fish and other "slippery" meals. The initial description makes mention of this dietary inference as well and leans heavily on the idea that this would have been the preferred diet of Guidraco.

Describing a Dragon

The description of Guidraco written by Wang, et al. in 2012 is available online with 15 different websites hosting the article or links to the article. The phylogenetic relationships of Guidraco and other pterosaurs are briefly described at the end of the paper, but the most important portion of the paper is the actual physical description of the pterosaur. This description includes a number of high detailed photographs of the fossil as well as detailed line drawings that point out individual bones of the skull. That, in turn, informs an accurate reconstruction of the skull which also accompanies the description of the fossil. The postcranial skeleton is also described in great detail in the paper, but is not illustrated in the reconstruction, but is labelled in the initial line drawing and shown in the details of the photographs.

It Flies, but it Doesn't Film

Guidraco is a very interesting animal with a scary set of teeth but it has garnered less attention than an animal this scary looking probably should be more involved in films, short and long. The only videos online that feature Guidraco are actually those that either describe toys based on the pterosaur or this WizScience video.

Chinese Dragons

By Ghedoghedo - Own work,
CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35328110

Possessing a name that is actually based on Chinese and Latin roots, Guidraco venator sounds as though it comes from a deposit in the African country of Guinea or the Asian country of Papua New Guinea (or simply the island of New Guinea, of which Papua New Guinea occupies half the landmass). However, as it was mentioned, Guidraco is a hybrid Chinese and Latin name. The Chinese portion (gui) roughly means "Malicious ghost" and the Latin portion (draco) means dragon. This malicious ghost dragon is actually an Early Cretaceous pterosaur from northeastern China's Liaoning Province (origin of many flattened birds and other Jehol biomass) and consists of a single articulated holotype consisting of the skull a portion of the post-cranial skeleton. Pterosaur preservation is notoriously "slabby" so it comes as no surprise that Guidraco is contained in a thick and flattened slab of rock. The most interesting feature of this slab and its fossil is, I think we can all agree, the very strange looking dental hardware in the pterosaur's mouth. This arrangement has been seen many times in pterosaurs, dinosaurs, and fish. Every time we have seen this the number one prey item that is hypothesized for teeth like this is slippery wet animals like fish; we can learn more about this throughout the week!

The Angry Squirrel Dinosaur

©Robinson Kunz

The vast majority of illustrations of Sciurumimus that we have looked at this week have portrayed this small coelurosaur as a very fuzzy and, honestly, a cuddly looking ball of adorable dinosaur. The truth is more than likely a lot less fuzzy and cute and a lot more predatory and periodically violent. The most realistic illustrations take into account the fact that Sciurumimus was a living, breathing, and hunting dinosaur that ate meat. This makes all of the feathery fuzziness on the caudal end of the animal a little more interesting, in my opinion. This feather covering would have kept Sciurumimus warm in cold times and, if the feathers were as short as they appear to be, would not be as well suited to being used for signalling as some other feathered dinosaurs' integumentary structures. The rostral portion of this particular Sciurumimus is all business and certainly predatory. The head is very much that of a predatory theropod and leaves very little question to the idea that this dinosaur was capable of hunting animals and making a meal of them.

The Furry Tails

© Román García Mora

Feathered dinosaurs are nothing new. In 2012 they were not really all that new, though the number of theropod, non-avian, dinosaurs that we knew had feathers was on the rise and the evidence from the fossil record was becoming not just more numerous but also clearer. Fossils like Sciurumimus represented the clearness of fossil integument in ways that previous discoveries simply had not been able to. In part this new picture of feathers was due to new methods; in Sciurumimus those new methods included filtered UV light enhancing the micro-details on the slab of the fossil. One of the benefits of this method has been that the UV light enhances the collagen and feather filaments in different ways. Because of this, collagen fibers of the skin can be differentiated from the feathers that covered the dorsal and caudal portions of Sciurumimus. Instead of simply stating that Sciurumimus was covered all over with feathers because some feathery structures were found, the actual amount of feathery covering, or at least a much better estimation, results from being able to differentiate the fibers as well. This has been well portrayed over and over again in the world of illustration.

The Description Alone

Sciurumimus was sensationalized prior to any description being published that detailed the anatomy or even what the fossil may have looked like. Nearly a year later the description of the fossil was sent for publication and the fossil was officially named and revealed to the world by Rauhut, et al. (2012). That paper is the only substantial paper that has been released concerning the animal to this point, but it is an interesting paper that details how the feathers were observed and described. Specifically, the fossil was observed to possess some interesting integumentary structures and these needed to be seen in greater detail in order to accurately describe them. Filtered ultraviolet light exposed the differences between collagen fibers and feather filaments along the tail of Sciurumimus. The differences, including high resolution images of the collagen fibers and feather filaments, are central to the paper's description of Sciurumimus both anatomically and phylogenetically.

A Short Tour in Squirrel Dinosaur Knowledge

©Emily Willoughby

There is actually no WizScience video for Sciurumimus; this is possibly the first time in years that we have been able to say that there is not a video available for a given dinosaur from WizScience. There is an equivalent, or near equal, video in German from another source (follow this link). The majority of facts this week instead come from websites that we are very familiar with. These include the ever useful Prehistoric Wildlife, which as always, includes a number of well known facts and some lesser known items such as a phonetic guide for saying the name correctly. Those interested in images of Sciurumimus may be most interested in The Dinosaur Database site which has compiled illustrations labeled as Sciurumimus. Some of these are adorable, I am not going to lie, it is a tiny fluffy dinosaur in some of the illustrations. This may or may not be entirely accurate, but they are okay either way as they are artist interpretations.

Squirrel Mocking

Photo by Ghedoghedo

2012 saw the official description of an informally announced coelurosaurian dinosaur with feathers preserved along its tail that were as bushy as the tail of squirrel. Adding further evidence to the feathering of the theropod dinosaurs, Sciurumimus albersdoerfi is one of the smallest and most primitive of the coelurosaurian dinosaurs. This proved a difficult distinction to make from the type fossil as it is a young juvenile animal; juvenile specimens always make definitive diagnosis difficult as their adult morphology may be exceedingly different from their fossilized state. This original type fossil is an exquisitely preserved relief fossil in a limestone slab from a formation in Bavaria that is chronologically similar to the Rögling Formation; this places it in the Upper Kimmeridgian immediately prior to the Solnhofen formation which contained Archaeopteryx.

Popular Tiny Dromaeosaurs

In 2007 Mahakala was popular for a brief time and heralded as a news story celebrating an interesting new building block of evolution. Mahakala was never popular as a dinosaur for being a dinosaur in the media, unlike animals like Tyrannosaurus and Triceratops. Measuring in at just over 2 ft of solid muscle and predatory fierceness, Mahakala was an interesting and tiny dinosaur that certainly warrants more attention than decade old news stories that amount to little more than two minutes of reading or air time. Its small size was, and still is, heralded as an evolutionary step in the direction of the miniaturization that preceded true birds within the paravian clade; another trait that warrants more popularity in the general knowledge of dinosaurs (and birds).

©Jaime Headden Creative Commons Attribution 3.0 Unported license

Of Flying Size

Dromaeosaurs are closely related to birds and research concerning dromaeosaurs and birds sometimes inform one another and other times are conducted in concert with one another. An interesting paper that crosses that boundary and discusses Mahakala and its implications on the evolutionary history of birds is Turner, et al. 2007. This paper describes and names the fossil remains of Mahakala omnogovae, previously known only as IGM 100/1033, and includes high resolution photographs of the known cranium and portions of the postcranial skeleton that contain important characters recognized as "paravian". The clade Paraves is defined by possessing characters typical of dinosaurs more closely related to birds than oviraptors, the theropod outgroup to Paraves. Possibly the most interesting aspect of this description paper is the portion of the paper following the description that discusses the diminutive size of Mahakala and the implications of the size and characters of the animal on the evolution of birds and avian dinosaurs before the evolution of powered flight.

A second paper worth reading today is the longer anatomical description of Mahakala published by Turner, et al. in 2011. This updated and more rigorous anatomical description does not single out novel characteristics of the animal like the first paper did; the shorter description is in part a victim of its appearance in the shorter format of a Science article. This longer version is 68 pages and uses every page to share high resolution images of single elements of the known skeleton one at a time as it describes each. More need not be said to describe the 2011 description of Mahakala because it delivers on exactly that; pure detailed description that vividly shows what this fossil looks like and its complete (as we know it) anatomy.

Mahakala Facts

First return on a search for Mahakala videos is the WizScience video that relays all of the facts that we know about the dinosaur. This video also contains a lot of different images of Mahakala. It is the perfect combination of facts and interpretations of this tiny dinosaur.

Newer Dromaeosaurs

©Nobu Tamura

It has long been hypothesized that the origin of dromaeosaurs was likely to be found in Asia where preservation is fairly good and basal characteristics of dromaeosaurs are found in a number of fossils. Mongolia and Northern China are prominent sites of these fossils, so it was not much of a surprise when Turner, et al. announced the description of what was called one of the most basal dromaeosaurs discovered to date in 2007, Mahakala omnogovae. Its name directly references the Tibetan Buddhist protector deity Mahakala and the southern province of Ömnögovi in Mongolia. The type specimen is a small adult, approximately the size of Archaeopteryx, consisting of portions of the cranium, limbs, vertebrae, pelvic, and shoulder girdles. Distinctively, Mahakala possessed a second toe on the hindlimb that was expanded and highly recurved. The small size of the dromaeosaur makes it a little less frightening than its larger descendants and cousins, but fear is relative when you are small enough to be the prey of this early diminutive dromaeosaur.

Looking Similar

Peteinosaurus illustrations are like many pterosaur illustrations in that they all look very similar and very often depict a flying reptile with wings spread and mouth open. The less popular version, which still turns up fairly often, depicts the pterosaur in question sitting on a branch or the ground ready to vault into the air. Somewhere in between there are hunting and swooping images. This image by Nobu Tamura captures the moment after swooping and chasing and the moments before our friendly Peteinosaurus would be ready to again launch (or fall) from the branch to take to the air once more.

Headless Pterosaurs

Despite well preserved slab fossils, not a single specimen of Peteinosaurus possessed an intact skull or any skull actually. The teeth of Peteinosaurus are known somehow, though. Three types of conical teeth are associated with the pterosaur and their shape indicated an insect based diet. The teeth and diet of Peteinosaurus are not the most unique characteristics of the fossils though. The fifth toe on each foot was elongated and had lost its claw. The toe possessed a joint that was different from the other toes of the foot. This joint allowed the fifth two to move in ways that enabled movements of the cruropatagium, the skin between the ankles, that acts as an airfoil. In a way, this structure acts like the retrices, tail feathers, of birds allowing for more precise control of flight movements. Some birds, bats, and pterosaurs like Peteinosaurus need precise control of their flights capabilities for aerial hunting in order to maintain pursuits. This cruropatagium most likely worked very much like a Barn Swallow's tail, as can be seen here:

Flying Literature

The literature history of pterosaurs is quite extensive. Peteinosaurus is not neglected in that rich history either. The paper naming and describing Peteinosaurus is difficult to find online, but luckily I know where to find it. One of the most prolific pterosaur researchers of our time keeps an updated bibliography of all pterosaur research and an archive of available PDF files of the studies he has collected over the years. Rupert Wild's 1978 opus "Die Flugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien" is only available in the original German, despite its publication in the Italian publication Bolletino della Societa Paleontologica Italiana. The study is a review of six fossil genera discovered in and around Bergamo, Italy and includes descriptive text alongside photographs of specimens and line drawings highlighting important structures from the fossils and their photographs. This is not the only review of Italian or Triassic pterosaurs featuring Peteinosaurus though. Fabio Dalla Vecchia's review of Italian pterosaurs is hosted in English and possesses a similar amount of detail, though not as much as Wild's review. However, if reading German is not something that one can do quickly or in their spare time in the near future, the descriptions of Dalla Vecchia are more than sufficient. Many of the other articles that are published which heavily feature Peteinosaurus are themselves reviews and new descriptions. Therefore, these two highly detailed descriptions of Peteinosaurus are more than enough to read today.