STL Science Center

STL Science Center

21 October 2017

An Old Ugly Dinosaur

©Nobu Tamura
One thing that creeps into horror movies and the Halloween season every year is the act of cannibalism. There are cannibalistic animals throughout the animal world but it is a taboo in most human societies and that makes many of us cringe when we hear about cannibalism in animal groups. Dinosaur cannibalism is rarely documented, but one theropod is particularly well known for its cannibalistic behaviors. Majungasaurus crenatissimus was an abelisaurid theropod and the apex, and possibly only large, predator of Madagascar during Late Cretaceous. At the time Madagascar was already an island separated from both the Indian subcontinent and African continent. As the largest predator on the island Majungasaurus had only other members of its species to truly challenge its supremacy as a predator on the island. Whether these clashes led to the evidence of cannibalism or it was a result of scavenging we do not know. However, Majungasaurus' cannibalistic behaviors and its abelisaurid body plan and often craggy frightening skull morphology make this theropod one of the ugly and frightening fossil animals that deservedly we are discussing during October and during the week leading into the Halloween week.

20 October 2017

Portrait of an Ugly Therapsid

One of the best things about very odd animals is that they tend to inspire a lot of interpretations and illustrations because they tend to spark the imagination. Estemmenosuchus certainly inspires fantastical illustrations; Dinocephalian fossils have a tendency to inspire fantastical illustrations because a number of them possess very intriguing and unique skulls. The reconstructed skeleton of Estemmenosuchus is equally intriguing; we will not look at illustrations only today however.

©Dmitry Bogdanov
It is important to note that the realistic nature of illustrations can be affected by the type of illustration we are looking at. Dmitry Bogdanov's style, like Nobu Tamura's, is very soft and often portrays the animal in sterile conditions on white backgrounds; this is not true for all of either artist's illustrations. However, this is not detrimental to the art and, in fact, the implied simplicity of the illustration of this Estemmenosuchus uralensis alows us to more thoroughly take in the entire animal and appreciate the posture, the size of the head, and the stout character of the overall animal. Estemmenosuchus, as we knew before seeing the animal as portrayed here, was a sprawling and squat animal with large canine teeth, which are very visible here. This illustration is labeled as a male animal. The largest canines are used as evidence to support hypotheses of sexual dimorphism in Estemmenosuchus in at least one paper.

©Vladimir Nikolov
More realistic appearances of Estemmenosuchus are as reliant on a stark and bold illustration style as the first is on a softer and cooler colored style. These are most realized in the line drawings that accompany the description papers, but can also be found in the styles of artists like Raul Martin, Dinoraul, and Walter Myers. The illustration included here as a representative of the more realistic appearing (because of its hard lines and high contrast as well as lack of soft tones) was drawn by Vladimir Nikolov. The description of this piece by the artist states that the scene depicts two male members of the genus are engaged in territorial combat. The fierce looking faces and skulls of the animals were apparently not enough to warn one another off from actual physical fighting, as we see in many extant species today.

18 October 2017

Sprawling Horned Faces

From Chudinov 1965
Estemmenosuchus has a crown of horns. The crown of horns has been hypothesized to have been used for intraspecific signalling and display short of combat; combat with the horns was probably used as an absolute last resort by these animals. The reason that it would have been used as a last resort is that the horns were massive bone structures. Unlike antlers, horns are composed of bone and insult or injury to these structures can be much more traumatic to the animals than damage to antlers (injuries to antlers are serious of course though). The horns of Estemmenosuchus were composed of extremely thick outgrowths of the frontals and cause the skull to appear even more massive than it is. Known skulls of Estemmenosuchus are approximately 65 cm (26 in) in length. That is not the only thing that is large and unique about Estemmenosuchus though. This large therapsid (approximately 3 m  or 10 ft long) also had a sprawling posture; this is somewhat typical in therapsids and Permian reptiles as well. Some have used this sprawling posture as evidence for an herbivorous diet, saying that the sprawling posture enabled the animal to hold a large fermenting gut with more support than if it had a posture like cattle or a similar mammal; this seems less than ideal given what we know about extant mammals. The canines of Estemmenosuchus are used as evidence to a different, more omnivorous but not quite carnivorous, dietary regimen.

17 October 2017

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.

16 October 2017

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.

14 October 2017

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?

13 October 2017

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.

11 October 2017

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.

10 October 2017

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.

09 October 2017

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.

07 October 2017

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!

06 October 2017

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.

04 October 2017

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.

03 October 2017

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.

01 October 2017

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.

30 September 2017

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.

28 September 2017

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

26 September 2017

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.

24 September 2017

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.

23 September 2017

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.

22 September 2017

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.

20 September 2017

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:

19 September 2017

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.

18 September 2017

Supporting Character on Wings

First and foremost, here is a link to the episode of Dinosaur Train that introduced "Petey the Peteinosaurus" (there are a number of versions of this but this is the only full episode that is not flipped horizontally). The first episode of the original "Walking with..." series was about dinosaurs specifically and mentioned supporting characters like Peteinosaurus (and mammals and amphibians) in passing. Peteinosaurus, however, benefited, in terms of the show, by existing during the Triassic dawn of the dinosaurs. The first episode of Walking with Dinosaurs focuses extensively on the environment that fostered the rise of the dinosaurs. This environment was populated by various protomammals and archosaurs, one of which was the "exotic hunter... Peteinosaurus" as Kenneth Branagh describes it. The short blurb about the flying reptile is not an enormous portion of the episode, but we know that Peteinosaurus is an important member of its environment. Its hypothesized role can be seen clearly in the show, as can its acrobatic capabilities.

17 September 2017

Two Movies

Peteinosaurus appears in a few television roles, but only one is relevant today. There is a second video that is relevant to today in that it relays facts and shows some relevant illustrations of the flying reptile. The cartoon that is relevant today is, as it usually is on a Sunday, a short clip from the PBS show Dinosaur Train. As usual, the alliterative name of the Peteinosaurus in this episode is Petey. The clip attached here, however, is just Dr. Scott talking about facts like height and weight of Peteinosaurus and not a portion from the actual episode with Petey in it.
The second video clip is from WizScience and is nothing but straight facts and a single view of one of the fossil slabs containing Peteinosaurus material.

16 September 2017

Flying Fun

Aerial acrobatics in the days of the dinosaurs were not conducted by birds or bats, not early on at least. During the Triassic there were a number of small reptiles capable of flight, the pterosaurs. One of the smallest, oldest, pterosaurs of the Triassic was Peteinosaurus zambelli. This small pterosaur had a wingspan of approximately 60 cm (24 in), one of the smallest known for pterosaurs, and weighed about the same as a Common Blackbird (or American Robin for North American readers). Known from fossils from northern Italy, Peteinosaurus has been well preserved mainly on three slabs of material that house very flat and fragile specimens. This is not abnormal for pterosaurs as they possessed very strong but light bones. Peteinosaurus is slightly abnormal for pterosaurs in that it is known to have possessed three different types of teeth (called tridontomorphy). These teeth were used for catching insects and hypothesized features of the manus and wing may have been highly suited to permit precision aerodynamic control of the pterosaur in flight, meaning that at least some of the insects Peteinosaurus hunted may have been flying meals.

14 September 2017

A Furry Star

Whenever any fossil is found in a level of completeness like that of Castorocauda it becomes a little bit more famous than other fossil animals. Sometimes this popular knowledge of a taxon remains and continues onward for centuries (T. rex, etc.) and sometimes it lasts mere moments (Morganucodon, perhaps, for the non-professional readers). Castorocauda appears to have retained some of its initial popularity, but has generally been mostly lost to the public over the past decade. In that time, however, Dinosaur Revolution and Dinosaur Train both capitalized on the discovery and description of this small swimming mammal. Arguably, Dinosaur Train did a much better job of describing and showing the features of Castorocauda, as we can see in the clip below. Dinosaur Revolution mentioned some of the characteristics of Castorocauda, but these were largely ignored in its animation. The tail and overall body shape can be seen clearly, but the show depicts Castorocauda running through a forest and into a hollow tree whereas the Dinosaur Train scene below takes place at the edge of a marshy lake possibly like the area from which the nearly complete Castorocauda fossil was recovered. Granted Dinosaur Train is much more educational and thoroughly proves it by comparing mammals against mammals and mammals against dinosaurs and pterosaurs as well as describing the characteristics of Castorocauda in great detail (for a kid's show).

13 September 2017

Fur Anatomy

The fur of Castorocauda has been described as consisting of two kinds of mammalian fur: guard hairs and underfur. These two kinds of fur seen in the fossil of Castorocauda provided some of the first very solid evidence of a furry mammal in the Jurassic; evidence of mammalian traits and some samples of fur and hair have been seen prior to this, but, as with feathers, this was one of the first truly wonderful collections of soft tissue that is generally lost to fossilization processes. It is also one of the earliest mammals recognized to have possessed the modern mammalian fur arrangement and follicle structure. The first kind of fur that was definitively recognize in the fossil is what is known as underfur or undercoat. This fur is short, flat, curly, and dense. It is this hair that keeps mammals dry in water and warm in winter. These rather different capabilities of this layer of fur are similarly achieved through the trapping of dry air against the skin which both repels water and maintains a buffer of warmth against the cold of the environment. Underfur serves as a thermoregulatory buffer for the skin and, overall, whole organisms like us and Castorocauda from the temperatures outside our bodies.

This is in contrast to the role of the second layer of fur recognized in Castorocauda: guard hairs. Also colloquially referred to as the coat, guard hairs are the main centers of pigmentation in fur. Display patterns, camouflage, and the shininess of a mammal's fur are reliant on the pigments collected in the guard hairs; these are of course regulated by other factors such as genetics and diet as well. Guard hairs are typically long straight hairs that come to a point and, in some mammals, can be fairly coarse. It is these hairs that we notice in threat displays, when frightened, and in other moments of agitation or excitement. Guard hairs also, as the name implies, guard the body. They do not trap warmth or repel water as well as underfur (though they are capable of doing so). However, guard hairs can significantly block harmful ultraviolet radiation from reaching the skin, something that the underfur does not do as much of (possibly because of the presence of guard hair of course).

What does all of this fur mean to Castorocauda? Thermoregulation, as a small mammal, and thermal insulation, as an aquatic mammal, created enormous metabolic requirements for Castorocauda. Out of the water, seasonal shifts in temperature would have caused the animal to need more or less of a coat of fur, but may not have been so demanding that Castorocauda possessed seasonally variable coats. We can remain open to this possibility as we do not know exactly how much of a temperature shift between seasons mammals were readily tolerant of during the Mesozoic, but it may be that the shifts did not cause radical changes in coat length or color (see #7 on this list specifically). In the water, coat length changes the dynamics of locomotion and, if we consider mammals that we know to be semiaquatic, we can make inferences on whether or not Castorocauda would have benefited from having a long coat; color changes based on season may not have affected the animal at all. Most semiaquatic mammals possess short, coarse guard hairs with a few exceptions, river otters and beaver, for example, possess long guard hairs. The unique mammalian hairs of Castorocauda, regardless of their seasonal changes, pigmentation, or general coarseness, were and remain an important feature of the mammalian body plan. The fur allowed Castorocauda to stay warm all year long and to dive into waters both warm and cold to chase fish and crustaceans (or other invertebrates). Weighing in at up to 800 g (about 2 lbs), Castorocauda would have gotten a great deal of help in maintaining its body temperature in colder waters from a thick coat of fur.

12 September 2017

The Literary Accomplishments of Small Mammals

Castorocauda is one of the better preserved mammalian specimens of the fossil record. Not simply of the Jurassic fossil record, but the entire mammalian fossil record. There are a number of younger finds that are wonderfully preserved for various reasons that include age, lagerstätten preservation (tar pits and tundra finds included), and occasionally luck. Regardless, the 2004 fossil find of Castorocauda has given mammalian paleontologists a lot to study and that has given us a lot that we are able to read. Ji, et al. 2006 introduces the approximately 425 mm mammal to the world and is openly published on Science's website, allowing everyone to read it without downloading a PDF or paying for the full article. Pictures of the fossil show that the mammal was preserved in a slab of rock with only small portions of the hindlimb, torso, and neck absent from the fossil. Science also hosts an article on mammalian brains (Rowe, et al. 2011) that mentions Castorocauda and discusses the animal's integument and subsequent meaning of these hairs in relation to brain development and sensory inputs. The majority of other papers that mention Castorocauda are likewise filled with very short single paragraph or less mentions of the animal to show one point or a snapshot in the development of a system. The major paper that we have for Castorocauda, however, is extensive and describes the animal and its functional morphology in high levels of detail.

11 September 2017

Supposed Jurassic Beaver

Dinosaur Revolution was a Discovery Channel documentary that aired in 2011and consisted of four episodes that explored topics from evolution to defensive and offensive tactics of different dinosaurs. The third episode specifically examined how dinosaurs and their contemporaries hunted one another or defended themselves from predation. That episode included what some refer to as a "Jurassic Beaver", though we know better that Castorocauda was not related to beavers at all. The episode is available (for the moment) online and you can get to it below:

10 September 2017

Information In Motion

Castorocauda has few informational websites. Instead of sending people to multiple sites to learn some quick facts about this Jurassic mammal today, here is the WizScience video that contains pretty much all the information that can be found on a myriad of sites.

09 September 2017

The Not-A-Beaver Family Tree

©Nobu Tamura
In the past, at least once, we have discussed the rodent family Castoridae which includes the two extant members of beaver (North American and Eurasian Beaver both). This week we will be discussing a beaver-like animal from the Jurassic that, despite appearing to look very much like an extant beaver, was highly specialized for a semi-aquatic lifestyle similar to that of a beaver. There is also a great deal of similarity between river otters and our animal this week, which earned this cynodont mammal its specific epithet. The only animal that this animal convergently shares traits with, but not a name reference, is the platypus. The animal in question, Castorocauda lutrasimilis, actually translates to "Beaver Tail, Otter-like" and therefore directly references both similar extant animals. This animal, as stated, is actually a cynodont, a group of therapsids that appeared during the Permian and includes modern mammals as well. The closest family members of Castorocauda, other docodonts, are also extinct, with the family completely disappearing from the fossil record in the late Mesozoic. Castorocauda itself is found in 164 MA Jurassic rocks from Inner Mongolian fossil lakebed sediments. A wonderfully preserved fossil of Castorocauda was recovered in 2004 that possessed hair, including an undercoat of fur. Another difficult to preserve portion of mammal anatomy that was wonderfully preserved in Castorocauda is the delicate and tiny middle ear including the ossicles.

08 September 2017

Lacking in Illustrations

The exquisite preservation of Heliobatis is often all anyone needs to imagine this animal punting along (that is correct verb to describe ray swimming) the bottom of the freshwater habitats they called home. Few illustrations, paintings, or other media have been carried out to depict Heliobatis in action within its habitat. Another, potential, reason that there is not a high demand for illustrations of the ray is that it appears to have been quite similar to extant rays, making illustrated representations of the ray appear less fantastic and awe inspiring than many other paleo art; this is not a reason to not create art of course. It is hard to pick a single image of Heliobatis to share as a wonderful depiction of the animal today because of all of the good photos of the well preserved fossils. Regardless, if I was forced to choose one single specimen to hang on my wall (Heliobatis fossils are for sale all over the internet, by the way), I would go with the image shown here. The detail is wonderful, as usual, but in a different way than the majority of other fossils. The slab is darker, and therefore the fossil details are also darker. The higher contrast makes thee anatomical details pop out a bit more and the contrasting elements of relieved and elevated portions of stone in the slab have a more natural look to them.

07 September 2017

Anatomy For All

©Brian Greenstone
Heliobatis fossils from the Green River Formation are very nearly the epitome of lagerstätten fossils. Because the preservation is so exceptional, there is a lot known about Heliobatis and its anatomy. The life history of these freshwater rays is well known because of this as well. We know that Heliobatis most likely ate small crustaceans, fish, and mollusks because we have found teeth in the fossils. Those teeth are small triangular biting teeth that are oriented very closely together.  These teeth could have been used defensively, however; like extant rays Heliobatis had a barbed stinger on their tails. Their stingers consisted of approximately three modified placoid scales (also called dermal denticles). The placoid scales were also found on the skin of these prehistoric rays and are very similar to the dermal denticles that are found attached to the skin of extant rays, skates, and sharks. One of the other very important characteristics of that we know of from the exquisite preservation of these animals is that they were sexually dimorphic. Male chondrichthyians, including Heliobatis, possessed clasping organs that are used to fertilize the female's eggs. More can be read about this topic in various places; the shortest version can be found here.

05 September 2017

Written Rays

Many of the papers that appear in preliminary searches concerning Heliobatis either use the ray for comparison or note a collection of fauna from a given locality. These are of great worth to us in that they both require descriptive text about Heliobatis and both types of writing tend to provide or ascribe behaviors or habitat information to the sun ray. These are, in turn, both useful for understanding the organism and its environment and generating more hypotheses about the animal and its life history. As mentioned previously, the teeth of this ray are typically well preserved and they have been studied frequently in conjunction with the teeth of other fossil rays to discuss phylogeny, differences in environment, and in the context of dental evolution. In some instances, all three of these topics are discussed, to a point of course; that is a lot of information to attempt to shoehorn into a single paper. There are papers that discuss locomotion of skates and rays as well, using Heliobatis and other rays pelvic girdles to predict what their swimming will look like.

04 September 2017

Zooming In

Heliobatis, despite being well known for a very long time, is not really a charismatic animal that has garnered a lot of demand in the documentary, cartoon, or feature movies of the world. As a somewhat stereotypical looking ray, it did not really possess any anatomy that would have stood out enough to garner special attention. There are very few videos in general that have anything to do with Heliobatis. We shared some of them yesterday. The only remaining video that definitely features Heliobatis is an eighteen second video zooming in and out of one of the fossils. That video can be seen here.

03 September 2017

Skate Video

For those that lie to read their videos, there is a really informative video posted by the user Gemini Bull. The video is really a compilation of information found on all kinds of different sites online. The video and information on the video show a lot of images of Heliobatis and actually make it such that many different links would not be required to learn from this week, for the sake of keeping the post free from redundancy. One of the better sources online, that is not a video, to learn from is the virtual fossil museum. Prehistoric Wildlife also has some information though it is almost entirely taken from Wikipedia. It does have the only size comparison with a person shown online; that makes it worth a view as well.

02 September 2017

Rays and Skates

© Didier Descouens
Rays and skates are members of the Chondrichthyes, a class of animals that first abundantly populated the oceans during the middle of the Devonian period and has persisted into the modern age. Other members of the class include sharks, chimaeras, and sawfish; sharks representing the best known members of the group. The rays that we are interested in this week are some of the most well known fossil chondrichthyians from the Eocene known as Heliobatis radians (Sun skate/ray). The ray Heliobatis was originally described in 1877 by O. C. Marsh (simply as Heliobatis) and has since had four genera synonymized under the name Heliobatis. Particularly well-known from the Green River Formation, Heliobatis is best known specifically from the Fossil Lake sediments of Wyoming; many of these are housed or on display in either Fossil Butte National Monument ("America's Stone Aquarium") or the Yale Peabody Museum. The known fossils housed and displayed in those two locations are highly detailed. The details are so well defined actually the sexually dimorphic characters, defensive characters, and the feeding apparatus have all been described. Teeth are observable in many of the specimens and based on the triangular shapes of the teeth, the diet that has been hypothesized for Heliobatis is largely based on small fish, crustaceans (there are numerous crayfish and prawn fossils associated with the same formations as Heliobatis), and mollusks.

31 August 2017

Frog Prince(ss) of Popularity

Living permanently in water, Palaeobatrachus was the kind of frog that people often think of when someone suggest that they imagine a frog going about its daily routine; this or a similar idea are common things in kindergartens worldwide, I promise. This, in coordination with its revival as a cartoon character on a popular children's series and numerous entries in scholarly papers as well as short texts on frogs (such as Tertiary Frogs from Central Europe). Scholarly articles and cartoons alike appear to be enough to make this fossil amphibian popular enough for it to continue to be well known and widely distributed in image, text, and even video online.

30 August 2017

The Lungs of Frogs

The typical lungs of your average frog are similar in general shape to the lungs of other terrestrial vertebrates in that they appear as lobes of soft tissue at the end of a trachea. They are also similar in function as they allow for blood and air to interact allowing for gas exchanges within the organ itself in specialized structures called alveoli; frogs have a much lower concentration of these structures in their lungs than other vertebrates. The lungs of Palaeobatrachus were not too different from those of their descendants in function, but their morphology was considerably different. Whereas extant frogs possess centrally located lungs housed in the thorax, the lungs of Palaeobatrachus were located within the dorsal sides of their thorax. Extant frogs, of course, do not only use their lungs to breathe. Gas exchange occurs within the mouth (minimally) and cutaneously while submerged; frogs make use of dissolved oxygen in the water to exchange gases through their skin. It could be hypothesized that the dorsal lungs of Palaeobatrachus laid the groundwork for these centralized lungs and also that they aided in enhancing the development of the system of cutaneous respiration we see in extant frogs. Cutaneous respiration may have, at the time, been the main method of filling the lungs of Palaeobatrachus as well, meaning that the lungs were an added adaptive characteristic of this frog; there exist today many small terrestrial amphibians completely lacking lungs. Perhaps these lungs enabled the frog to take in a large amount of air before diving and stay submerged longer in potentially oxygen poor aqueous environments. The evolutionary history of amphibian lungs is far more complex than we have time for today, unfortunately, but there are many resources available to delve into this history.

29 August 2017

Volumes of Frogs

The number of papers written about Palaeobatrachus is well more than enough for a book all on its own. There are papers from this year that mention Palaeobatrachus and compare it to other fossil frogs, but these are not the meat and bones of the literature that details the knowledge that we have on Palaeobatrachus. There have been many different descriptions, recently even, of new species of Palaeobatrachus. The most recent descriptions, from last year, are of species known as P. diluvianus and P. eurydices; these species do not appear in any mentions of Palaeobatrachus species lists. New descriptions of fossil frogs, however, are not the only studies that have been published about Palaeobatrachus that are interesting and have made significant impact on the study of these particular frogs and fossil frogs in general. A particular favorite of mine is Roček, et al. 2006 on tadpoles and gigantism in Palaeobatrachus juveniles. A second favorite that I would recommend reading is about the diet of Palaeobatrachus. Wuttke and Poschmann 2010 describes a lagerstätte fossil of an unspecified Palaeobatrachus species with fossilized stomach contents. Those contents were made of small fish that the frog clearly captured and ingested (i.e. fish that were eaten by the frog).

28 August 2017

Short Dinosaur Train Day

Today there is only a single documentary/feature that shows Palaeobatrachus and discusses it. Dinosaur Train has an entire episode about the family venturing out on a camping trip that also features this central European frog. The family meets Patricia Palaeobatrachus during the middle of the night when they hear a strange and scary noise.

27 August 2017

Ancient Frog Links

Palaeobatrachus appears in a number of links and on a number of websites that are helpful for children and other fossil enthusiasts of course. The links range from very easy and quick reads, such as the Dinosaur Train Field Guide (which actually reads the facts to you), to more difficult passages like those found on the Prehistoric Wildlife and Encyclopedia of Life pages. The Encyclopedia of Life pages are actually heavily stocked with information about the fossils, where they originated, and what we know about the life of the animal. Anyone wanting to skip a little reading, or having the facts read to them by the Dinosaur Train conductor, there are also videos dedicated to facts about Palaeobatrachus. The easiest to find, of course, is a short from Dinosaur Train featuring Dr. Scott Sampson, as seen below (the audio of the current version available has a little echo).

26 August 2017

Fur to Frogs

©Nobu Tamura; released as Palaeobatrachus gigas
Palaeobatrachus is a genus consisting of at least two named species, P. occidentalis and P. robustus (with others being mentioned that we will explore later), of amphibian that appears in the fossil record from approximately 130 MA to 11.6 MA; Fossilworks reports a range of 70 MA to 9.7 MA and these disparate ranges will be figured out later this week. An early frog, Palaeobatrachus is known from central Europe. Specifically, Palaeobatrachus is very common in the freshwater fossils of Germany. Early frogs, Palaeobatrachus, was extremely amphibious and spent very little time out of water. A lot is know about the entire life cycle of Palaeobatrachus with all stages of life, egg, tadpole, and adult, having been recovered from Bohemian rocks. Changing temperatures and changes in available suitable water sources caused Palaeobatrachus to suffer a reduced range of habitat. This, in the end, forced the frogs into extinction as continual climate change and shrinking suitable habitat forced the frog into what would be a losing battle with other taxa and the environment.

24 August 2017

Home Field

Megalibgwilia is known in parts of the world that are not Australia, but its popularity, in the form of common popular outlets such as books movies, websites, video games, and toys, appears to be entirely lacking outside of Australia. Websites, of course, reach well outside of Australia, but dedicated sites that we have not already shared and discussed are rare and do not add too much that we have not already shown concerning the giant echidnas. One of those few non-Australian based websites that share information about Megalibgwilia is Berkley's Museum of Paleontology website. This page more specifically discusses monotreme evolution, but Megalibgwilia represents an important step in the evolution of other echidnas. A lack of other sources aside, the popular entry this week is therefore ending abruptly and is shorter than usual.

23 August 2017

Megalibgwilia's Elbow

W. H. Wesley, Humerus of M. ramsayi
Owen's original description of Echidna ramsayi, later synonymized as Megalibgwilia ramsayi, consisted entirely of a detailed look at the broken left humerus of one of the "giant" animals. Eventually crania and postcranial remains were added to the descriptive list for this single species. All of the descriptions of M. ramsayi have amounted to a fairly complete picture of this first species of the genus. The second species, M. robusta, was described by William Sutherland Dun in 1896 and consisted of mostly complete remains. Megalibgwilia robusta is the oldest known echidna and, despite being known as a "giant echidna", is slightly smaller than the largest known monotreme of Western Australian; Zaglossus hacketti. Contemporaries of Zaglossus, the two species of Megalibgwilia were geographically separated from one another and their larger cousins in Western Australia. Megalibgwilia ramsayi appears to have been prominent across mainland Australia and extended to Tasmania whereas M. robusta has been restricted, so far, according to fossil remains, to New South Wales. The two species possessed snouts that are more well suited to probing and grabbing insects than grasping and probing for worms like the Zaglossus group of echidnas. As contemporary species, Megalibgwilia and Zaglossus may have possessed overlapping ranges, making diverse diets for the two groups of animals important in minimizing competition for food sources.

22 August 2017

Short on Papers

There are not many papers hosted online featuring Megalibgwilia. Considering that these echidna ancestors have been known and described for almost 150 years, the lack of modern articles is somewhat sad and almost depressing. There are plenty of articles that make passing mentions of Megalibgwilia or compare the "giant echidnas" to extant members of the genus. One of the original articles describing Megalibgwilia by Owen in 1883 originally named the animal Echidna ramsayi and consisted of less than a half page of text. That abstract of a lecture by Professor Owen can be viewed in the archives of the Proceedings of the Royal Society here. Unfortunately, Dun's 1896 description of the other species, Megalibgwilia robusta, has not been hosted anywhere online. Print copies may be nearly impossible to find as well given the age.

20 August 2017

Mega Facts

Megalibgwilia is an unusual animal for a variety of reasons. Some of these reasons are detailed in the facts that are know about the animal and shared on various websites and fact pages. There are a number of sites we have used before and many that many among us may have never heard of before that host files, short essays, and illustrations of the two species of this genus. The first of these familiar sites which appears in a search is the Dinopedia. Despite this animal clearly being a monotreme, a type of non-placental mammal now represented by only extant echidnas and the Platypus, the Dinopedia entry is fairly comprehensive and discusses Megalibgwilia almost identically as sources like Wikipedia. This makes it neither more nor less useful than Wikipedia of course. Wikispecies entries for the animals are taxonomically useful, but again, this information can be found in Wikipedia as well. A slightly more detailed history of taxonomy is available on the Fossilworks site which also provides some locality details for known fossils as well. One of the most interesting new sites is the Australian Broadcasting Corporation's site discussing the extinction of megafauna in Australia. While it does not specifically discuss Megalibgwilia exclusively, this site does discuss the environment it lived in and how it may have been subjected external and internal pressures leading to its extinction.

19 August 2017

Monotreme Party

In looking for  new animal this week we are going out of our normal range and into the time of the mammals. Becoming extinct approximately 50,000 years ago during the Pleistocene, the tachyglossid (a group that includes the extant genera of Echidnas) Megalibgwillia consists of two species, M. ramsayi (Owen, 1884) and M. robusta (Dun, 1896), and represents the oldest known echidna genus found. Both species are often referred to as the "giant echidna" but recent evidence shows that they are approximately the same size as the largest living echidnas rather than immense fossil animals, respective to extant echidna. Both species are represented by largely complete fossils and, because we know basically what the animals looked like, we can state that they were most likely as bizarrely intriguing as extant echidnas.

17 August 2017

Somewhat Well-Known

Conchoraptor has made a larger impact than many other dinosaurs. It is still not a widely known dinosaur, but it is known throughout the dinosaur community to a greater extent than many other dinosaurs. Conchoraptor is a dinosaur that is more well-known online than it is in most other media. It has appeared in books, illustrations, and has been featured in a few privately made tribute videos, but it does not appear in any games, movies, or documentaries. Having little to share in the vein of popular culture, there is at least a single private video that can, and is, shared here to show a variety of illustrations of Conchoraptor. As always, remember that these videos sometimes mislabel taxa unintentionally and that some of the images may not represent Conchoraptor as well as others. These images are open to interpretation as well.

16 August 2017

Feathers and Genders

At least one site mentions that Conchoraptor remains have been discovered with attached feathers. These feathers have been described sparingly, but have been described as sexually dimorphic characters of Conchoraptor. Sexually dimorphic characters are typically most reliable in adult animals. The assumption with the assertion that the feathers represent dimorphism is that they most likely came from adult specimens. One of the hypotheses of discerning adults from juveniles and sub-adults in Conchoraptor is less concerned with feathers and sexual dimorphism and more concerned with the crest on the cranium. Most oviraptorids possess a large crest along the midline of the skull that is larger rostrally than caudally. The original material lacks a crest entirely and remains recovered later also appear to lack crests or possess very minimal crests. The hypothesis that crests grew as the dinosaur aged are not abnormal or new, but without known fully adult specimens possessing full crests, we can neither, as yet, support nor refute that hypothesis. However, if evidence comes to light to fully support this and the hypothesis concerning dimorphism and feather morphology, then we will know a lot more about the life histories of these animals.

15 August 2017

The Brains and Skulls

Brains and other soft tissues are of great interest to scientists in extant and fossil specimens. There are a variety of ways to study organs in extant specimens and many of those methods can actually be applied to fossil specimens as well. Many of the methods used to investigate fossil soft tissue systems originate in studies of the soft tissues of extant organisms. These are systems that we can readily devise methods for and test out the methods on. Interpretation of the results can be compared with observations of behavior and organ use in extant animals as well. These model organisms and their organ systems allow for inquiries into similar systems in fossil animals. These steps result in studies such as Kundrat 2007 which looks at virtual brain models of Conchoraptor derived from CT scans of the skull. The scans are used to create virtual endocasts, or models of the negative space of the skull where the brain would have been in a living Conchoraptor. Endocasts show scientists potential lobes of the brain (assuming that the skull retained its original dimensions during the fossilization process). Kundrat 2007was able to identify characteristics of the brain that Conchoraptor appears to have shared, or at least approximated, with the brains of birds. Additional studies of the skull have been undertaken which look at other organ systems of Conchoraptor and use some similar methods. Kundrat and Janacek 2007 explored the hearing capabilities as well as the structure of the skull of Conchoraptor. They described pneumatization and sinuses of the cranium (another avian-like feature). This study also described and analyzed the bones surrounding the tympanum (eardrum). Recesses in the bone helped to describe the tympanum itself as well as the different portions of the ear. Specifically, Kundrat and Janacek were able to describe distinct proportions and geometry of the inner and middle ear of Conchoraptor and infer the hearing capabilties of the dinosaur.

13 August 2017

The Video File

There have been, as we have gotten more and more into the lesser known dinosaurs, fewer and fewer resources available at any given time. This has been related to the popularity of given dinosaurs, of course, and has not really made our job any easier when it comes to sharing interesting and new sources. However, we have a stable of consistent and helpful resources that we can typically fall back on that are reliable and accurate, which are far more important than new and interesting. For that reason, rather than posting a small number of websites all sharing the same basic information about Conchoraptor today, I would much rather share a single video, produced by WizScience, that summarizes all of those pages and does so over a series of illustrations and photographs.

12 August 2017

Shell Stealing Dinosaurs

Known from the Nemegt Formation of Maastrichtian soils of Mongolia, specifically the Red Beds of Hermiin Tsav, the conch stealing oviraptorid Conchoraptor gracilis. Barsbold 1986 described a partial skeleton and skull of an oviraptor which, like its cousins also discovered by Barsbold and the Polish-Mongolian expeditions of the 1970's, is a victim of the hypotheses of many scientists that the oviraptorid dinosaurs were stealing eggs rather than incubating eggs. The name Conchoraptor reflects Barsbold's hypothesis that the animal's lack of dentition was indicative of a diet that was rooted in mussels and other shellfish rather than eggs. This dietary hypothesis was unpopular at the time, though we now know that oviraptors, whether they fed on mussels and clams or not, were not feeding on the eggs that they were found with.The lack of crest, seen in this representation of the skull, is thought to have been a result of immaturity in the described holotype. This hypothesis will be explored during the week as we explore Conchoraptor.
©Jaime A. Headden
Creative Commons Attribution 3.0 Unported

10 August 2017

Fish Foods

©Florida Museum of Natural History
It has been determined, or rather hypothesized, that Enhydritherium had a mainly piscivorous, or fish-based, diet. This was based on the fact that Enhydritherium possessed bones in its front paws that are more similar to extant fish catching otters than to its ancestors which are thought to have lived on land and did not eat fish regularly. Modern fish catching otters use their mouths to catch their prey whereas the ancestors of Enhydritherium used their hands to catch and grab food items; this means that the hands of Enhydritherium and modern otters are not as adept at grasping and handling food items as their ancestors. Enhydritherium also possessed large attachments for neck biting muscles and, as a direct relation, probably had extremely large and powerful neck muscles. These would have been used to attack prey quickly and hold them as the otter then left the water to secure and feed on its fish prey. These neck and biting muscles were very important for Enhydritherium because it was not capable of chasing its food in the water. Poor swimming adaptations in the hindlimbs made Enhydritherium good at wading into water and escaping from the water, but unable to chase aquatic prey. The hindlimbs of the animal were much more adapted to terrestrial locomotion. As such, it was capable of long overland journeys like that which Tseng, et al. 2017 describes as a hypothesis of migration between the bicoastal populations of Enhydritherium.

08 August 2017

Otters and the Ocean

Due to being found near a coast and looking like their extant descendants, Berta and Morgan's initial description of Enhydritherium was heavily angled toward portraying the skeletal remains as those of a large ancestor of modern otters. Their description was not wrong, of course, and Enhydritherium is known to be one of the largest otters, fossil or extant, that has been recorded. As a large sea mammal Enhydritherium has garnered attention throughout the time that it has been known to science. This has led to a number of studies describing different aspects of the animal's life history. The most all encompassing study discusses, describes, and analyzes the osteology of the otter in order to describe its paleoecology; Lambert 1997. This is a fairly typical order of events in describing fossils and the world in which they lived that, in turn, allows for inferences concerning the interactions of this particular species both intra- and inter-specifically. What helps even more, of course, is the discovery of additional remains. Depending on how and where the remains are recovered, new answers can be found to old questions or new questions can be developed. In the case of the Mexican dental remains that we have seen earlier this week, old hypotheses have been refuted and new hypotheses generated concerning the movement of this otter. Tseng, et al. 2017 refutes old hypotheses of migration that include Arctic and Central American Seaway dispersal of Enhydritherium between what are now Florida and California. A lack of fossil evidence from either region is deemed troubling as supporting evidence of such migratory routes. However, the trans-Mexico route does possess fossil remains and, with a skeleton that appears to support terrestrial travel over long distances, also seems suitable for Enhydritherium.

07 August 2017

News and Finds

Furry extant otters are often described as adorable, mischievous, and sometimes simply with the word "awwww." The newest discovery of Enhydritherium fossils could possibly be described using those adjectives, but likely there is nothing that most people would find adorable about the teeth discovered in the Mexican wilderness. However, those teeth were the diagnostic element of the fossil that identified the animal for the crew. As Dr. Jack Tseng recounts, he recognized the teeth as carnivoran and another member of the field crew recognized the teeth further as belonging to an otter. Rather than summarize everything that he has told reporters, though, everyone should watch this video instead.

05 August 2017

Amazing Otters

Fossil mammal make appearances here from time to time. This week is one such time when mammals will be featured exclusively. Known from sites in California, Mexico, and Florida, and described initially in 1985 by Berta and Morgan from a Floridian specimen, Enhydritherium terraenovae was a North American otter dated from approximately 9.1 to 4.9 MA. The majority of sites where this otters fossils have been recovered are in Florida, but the newest discovery was made in the Juchipila Basin of Central Mexico. This find suggests that these otters not only successfully lived on both coasts, but that they may have migrated between the coasts as well. Unlike extant otters, Enhydritherium was not yet particularly aquatic, which enabled the animal to conduct movements across expanses of dry land in ways that extant otters would find both improbable and, most likely, impossible. Not many interpretations of this large otter, an estimated 16 kg (35 lbs), exist; however, its skeleton suggests that it already had a "weasel-like" body plan and was elongated, compact, and close to the ground. It may have appeared very much like Potamotherium but was likely more stocky and larger than this more recent member of the otter family.

04 August 2017

Interesting Interpretations

Figure 1: Old school Melanorosaurus herd with gracile forelimbs.
©Zdeněk Burian (1905 — 1981)
As an early sauropodomorph, Melanorosaurus has been treated in many illustrations as a proper sauropod. In a few illustrations it has been treated more as what was once properly called a prosauropod; meaning that it showed Melanorosaurus as a sauropod-like animal with more gracile forelimbs which look as though they may have been capable of reaching for food and potentially grasping items (Figure 1). Unfortunately, this is less likely than a more sauropod-like body plan. The Natural History Museum of London features an illustration that portrays Melanorosaurus as a stereotypical sauropod with a body shape similar to a diplodocid; . We would assume, with this interpretation, that the back possesses a hump of fat in the middle portion. That, of course, is not unrealistic, as it has occurred in extant and fossil animals numerous times. The kind of back shape that we expect from the skeletal reconstruction, without a hump of back fat, is well represented by Josep Zacarias' black and white illustration of Melanorosaurus. I have a number of favorite illustrations of Melanorosaurus that show varied amounts of the back fat hump; both the lean and fattened versions of the animal are acceptable and offer their own interesting versions of the potential life history of Melanorosaurus. However, the most interesting of those images, to me, is John Conway's image of a herd at a drinking hole. The animals possess neck wattles not shown in other interpretations and are portrayed in various postures across the image and in all plains of the image. A couple in the background are even rearing up on their hindlimbs. The scene has a lot of little activity in it in all corners.