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STL Science Center

17 November 2017

Finding a Unique Illustration

©Christopher DiPiazza
Almost every illustration that comes up in a search for Argentavis depicts a bird landing or taking off with the few exceptions that show the animal simply stretching its wings one way or another; the bird on a dead animal trying to scare off scavengers is a very common theme. The large wingspan and body of the bird are central to the identity of the fossil, so these themes make sense. One of the most charismatic images that I have found does incorporate the wide wingspan of Argentavis, but it also has a piece of its last meal in its beak. Although almost all of the illustrations of Argentavis already looked fairly fierce, this interpretation, possibly because it was drawn head on, looks more intimidating and angry. As we typically see in Christopher DiPiazza's work, the tones and colors are soft and very pastel-like. Despite this, the details are sharp and the pose is dynamic. Additionally, read the linked blog post by the artist. He has hit a lot of the same points we have hit this week, but his insights into his art shine through in his writing, and they are worth reading about while admiring the work.

15 November 2017

Massive Eggs and Wings

The egg of Argentavis is estimated to weigh approximately 1 kg and it has been hypothesized that they were laid once every two years. At 1 kg the egg is only a little smaller than that of the Common Ostrich, but Argentavis' egg laying cycles were similar to gulls and albatrosses rather than animals that reproduce annually. It has been hypothesized that the incubation cycle of these eggs was such that the birds were forced to incubate over winter. Chicks were thought to have lived with the parents for approximately 16 months before permanently leaving the nest. By contrast, the Wandering Albatross is the longest fledging extant bird, with the young bird remaining in the nest for 278 days. As with many extant gulls and other seabirds, Argentavis is thought to have then had a sexually dormant period, not achieving maturity until approximately 12 years old; Royal and Wandering Albatrosses reach maturity between 6 and 10 years. The fact that Argentavis was so large means that most predation and death probably occurred either in the nest or by from accidents and old age. How old Argentavis lived to be naturally is up for debate, but we know that a lot of extant birds, large and small, live extremely long lives today. The Kakapo of New Zealand is thought to live well over 100 years; with so few in the wild and their histories not being cataloged until recently, however, the oldest known member was approximately 80 at his death. Other parrots have been known to live into their 80's in captivity and individual Royal Albatrosses have been documented at 58 years old in the wild. The largest flying birds, Great Bustards, live to approximately 10 years, whereas the oldest eagles have been recorded at between 30 and 40 years old (depending on the species). All of these numbers make pinpointing the ages of large birds, especially those that can fly, difficult. Argentavis could have lived a lifespan like that of a large eagle, meaning that it could have lived up to 40 years. That means that an adult pair, laying one egg every two years, could have possibly reared 14 young during their lifespan. Not only a large bird, Argentavis may have had a rather sizeable population at one time or another because of their long lives, large size, and dedication to a single offspring.

14 November 2017

Flying A Great Bird

One of the questions that appears time and again with giant flying animals is "How do they get off the ground and how do they stay off the ground?" Because that is a popular theme with large flying animals, the first hit in a paper search for Argentavis is Chaterjee, et al. 2007: The aerodynamics of Argentavis, the world's largest flying bird from the Miocene of Argentina. The author's conclusions are centered around the hypothesized aspect ratio of the wing and estimated body weight. These parameters lead them to conclude that Argentavis was most likely similar to extant vultures and large condors in that it was probably not capable of sustained powered flight, instead choosing to use thermal soaring as its preferred method of staying airborne. Intermittent powered flapping would have been used as it is by these extant analogues as a secondary anti-stall measure but not as a power source for extended flight. This paper builds off of the new data and goes into more computer simulation than Vizcaino and and Farina1999, which initially tackled the problems of Argentavis flight without computer simulations, instead, it appears, relying on estimates of body size and inferred wing shape and comparing these with extant animals and known aerodynamic principals; the full text is not available anywhere online and what I have inferred comes from the abstract found here. The final article I will mention today addresses ecology (and reproduction). Palmqvist and Vizcaino 2003 details ranges, needed amounts of food, airspeeds, and clutch size to determine the ecological impacts and roles of Argentavis. Instead of spoiling this paper by writing in those facts, as I did above to a slight degree, I am going to simply encourage everyone to read and discover the paper's findings for themselves here. I find the paper to be interesting and find myself wondering if anyone would refute any of these findings; I have yet to find a paper that does so (I admit my search is short right now though).

13 November 2017

Quick Facts

Above are some quick facts about Argentavis presented in video form. This very quick video does not reveal much that we will not get into ourselves. There are some cryptozoology documentaries on the internet also; whereas these are strangely interesting, they are not necessarily historically accurate or important to watch in order to gain more knowledge about the bird. Aside from these kinds of videos and the short video shared here, most of the videos that show up with Argentavis as a keyword are related to video games.

11 November 2017

Birds and Thunder

©Nobu Tamura
In general, native peoples of both South and North America have a number of legends and mythologies describing giant flying animals. From the Thunder Bird (a generic term that encompasses a wide range of mythological figures from different tribes) to Tah-tah-kle'-ah (a race of cave dwelling "owl women" from Yakama lore) to Achiyalatopa (from Zuni folklore), native peoples have been influenced by the idea of giant birds flying across the sky. In some instances these are giant bird-men/women but regardless of the anthropomorphizing of giant birds, these legends could have been influenced by real living animals. One such giant flying bird has been discussed here before (See Pelagornis). Another giant bird, more often associated with the southern hemisphere but by no means entirely limited to that hemisphere, was Argentavis magnificens (Magnificent Argentinian/Silver Bird). Flying through the skies during the Late Miocene and known, at present at least, from only Argentina, Argentavis possessed a wingspan of approximately 6.07 m (19.9 ft) and 72 kg (159 lb) by the greatest estimates. This makes it the second largest flying bird ever known behind Pelagornis. In comparison to living birds, the largest wingspan is that of the Wandering Albatross at 3.65 m (12 ft) and the heaviest (sustained) flyer is the Kori Bustard at 11.4 kg (25.1 lb). At this size Argentavis must have flown much like Pelagornis; flapping powered flight may have gotten it airborne but thermal soaring would have been the most likely model for sustained flight.

10 November 2017

Iconic Images

Probably the best Bison latifrons image I have seen this past week (before looking tonight as I write this sentence) is that of Davide Bonadonna that I shared on the Facebook version of this page. Rather than paste it in here without contacting Davide, I will link his gallery where he hosts his illustrations. A large majority of bison illustrations are not as exciting as Bonadonna's or include modern bison being attacked by wolves (if not a hunting scene with Native Americans. In the "non-action but still fun" category one of the best images I have seen this week is Christopher DiPiazza's B. latifrons at the watering hole. I think I like this image more because it shows an interesting level of curiosity not often associated with the big brutish bison and also because it has softer tones that contrast with a lot of the images we have looked at over the course of the week. Please feel free to share more illustrations that you like in the comments.

09 November 2017

Documentaries Everywhere

I was considering what to do about the popular culture references today. There are a number of things that I could do, obviously, as we know that modern bison are something that the public is well aware of. I think, instead, that we should look at some documentaries which discuss the historical significance of bison as well as their current conservation status and situation. Though these documentaries do not specifically discuss the three species we have been discussing this week, the life history of extant bison is similar to that of their extinct family members and is therefore informative. The National Park Service covers a little history and their extant modern herds in the linked page. This second video, from the Kratt brothers (in their Wild Kratts series), may be a cartoon (mostly) but its appeal to the younger audience is not to be overlooked. The information that is given out in this video is useful, accurate, and does indeed go beyond it being a children's cartoon. There are also somewhat more traditional documentaries such as this "Fabulous Animals" show and Facing the Storm: the Story of the American Bison (which is movie length). I know that we are well away from extinct animals with these shows, but being able to see a modern descendant and how it lived on quite similar ground (ignoring the members of B. latifrons and B. antiquus found along the eastern seaboard) is important to trying to reconstruct the lives of the extinct animals.

07 November 2017

Buffalo (Bison) Papers

Many descriptive papers have been published for Bison latifrons and B. antiquus. Bison occidentalis, however, does not have as many description papers published concerning its remains. There could be any number of reasons for this, but after looking over papers and fossil locations as well as the Paleobiology Database (PbDb: the major reason for this might be that some sources, at least, consider B. occidentalis to be a subjective synonym for B. antiquus. This means that the type of the two species is not a shared fossil and that the debate on their synonymy is open. Unresolved taxonomy like this can lead to some sources like the PbDbnot acknowledging the species as unique while others at the same time do still consider it a unique species, such as Hawley, et al. 2013 which describes the occurrence of B. occidentalis fossils throughout the Wisconsin and Minnesota.

The range of these species has always been an interesting topic for research descriptions and has proved fruitful as well. Representative ranges can be hypothesized for each with articles detailing discovery sites and discussing their significance to the ranges. For instance, B. latifrons has been described in South Dakota (see above), Kansas, Nebraska, and even Georgia. Bison antiquus has been described from remains found in Florida, Alberta, Canada (with a mention of B. occidentalis as well), Washington, and Southern California. Bison occidentalis has been described from sites in Iowa, Alberta, Canada, Texas, and California.

A lot of papers go beyond simple description of these three taxa. A large number of papers published about these papers are from archaeological journals, which is highly logical. Bison, regardless of species, have been some of, and eventually the absolute largest, herbivorous North American mammals encountered by humans. Their use as food, clothing, crafting sources, weapons, and fuel for fires is well documented in North American historical sources and from archaeological digs (as a reference read Agogino and Frankforter 1960 and Wheat 1967). Associations of bison with archaeology is to be expected and some of the articles detail not only interesting aspects of the animal's life histories (refer to this article on butchering and taphonomy as an example) but also a great deal about their capability to endure hardships both human inflicted and natural. These include descriptions of diseases that have been studied in B. antiquus as well the effects of hunting in B. occidentalis.

There are a lot of articles here today, but I cannot apologize for the rich literary record of bison research; nor would I want to if I was asked to honestly.

05 November 2017

Three Sets of Information

My plan for this week is to, unlike other weeks, treat the three endemic species of North American bison as individual animals rather than discussing the genus as a single entity and pulling out interesting information regarding individual species. The reason we are approaching the information this way is because, other than overlap zones in the history of the genus, the three species are radically different morphologically and warrant their own attention as parts of the whole evolutionary history of the genus Bison. For a quick overview of fossil bison without reading the following paragraphs a short stop in the digital library of the San Diego Zoo may be all you need. To start, we will look at the three species in order of their history, meaning that B. latifrons is our first stop.

The artist Roman Uchytel is typically mentioned when we look at his illstrations and interpretations of paleofauna. Today, however, his art coincides includes a concise history of B. latifrons. His illustration, of course, is a nice addition to the information, but not the primary reason to follow this link to his website. Not to be outdone by the display shared yesterday from North Dakota, other states also have information on B. latifrons that were unearthed within their borders. Speaking to the range of the animal, there are also finds from San Diego and as far as Florida (B. antiquus is also mentioned on this site, attesting to its range as well) that are mentioned. This site shows and mentions the sale of fossils but such practices are not endorsed or encouraged here.

The intermediate species, B. occidentalis, also has space and information dedicated to it on Roman Uchytel's site. Again, his illustration is a positive bonus to the information provided. Most of the information is taken from Wikipedia, but that is not too important here. Bison occidentalis is not as well known as B. latifrons or B. antiquus, and most of the information online about this species is actually in the form of descriptive papers, which we will save for Tuesday.

As with the previous two species, B. antiquus has been illustrated by Roman Uchytel and he has paraphrased information from Wikipedia. Placing the three side by side is informative and interesting in its own right actually, so it might be worth the momentary effort. Bison antiquus has a few more resources online. This is partially due to its more recent history and of course to those resources being studied a little more in depth than the other fossil species. In addition to Florida and the western part of the North America, there are specimens of B. antiquus known from Ontario, Canada, Texas, and Florida.

04 November 2017

November in North America

It is possible that if you are from North America you are aware of the trend in the last 20 or so years to take back holidays celebrating European domination of the native populations of this continent. I remember personally seeing protests at Thanksgiving parades in Plymouth and more and more states appear to be dropping Columbus Day as an official holiday or at least renaming it. Given that the United States of America observes a Thanksgiving event in this month, the same holiday as the protests just mentioned for anyone not following U. S. holidays, I thought it might be interesting to look at the fossil history of some of the groups of animals that have been of special importance to the native cultures that once spread across this continent and that we have, to a significant degree, lost over the past 400 years. This is a look into how the animals that became important to the peoples of North America became the animals that they are now and what their fossil history, regardless of how recent those are, reveals about their evolution. I know these are not dinosaurs, but life on Earth is complex and filled with a lot more than dinosaurs, so hold on for the ride, or take a break and come back to us in December. The first animal that we will look at this month is the America Bison.

The American Bison (Bison bison) has a long history that, like a significant number of animals, starts on another continent; there is an extant European Bison (Bison bonasus) distantly related to and far more rare than the American Bison. The fossils we are going to discuss are the members of the family that arrived or thrived in North America prior to the appearance of what we would recognizably call the American Bison. Three extinct species of the genus Bison were endemic to North America prior to the appearance of Bison bison, the American Bison, in the fossil record. These species were, in order, B. latifrons, B. occidentalis, and B. antiquus. They range from approximately 240,000 years ago when B. latifrons is thought to have initially crossed the Bering Land Bridge into North America to approximately 5,000 years ago when B. antiquus appears to have gone extinct. The three species are not identical and B. latifrons is actually quite impressive, measuring in at 2.5 meters (8.2 ft) and estimated to have tipped the scales at 2,000 kilograms (4,400 lb); that is almost as tall as a modern Asian Elephant. The horns of B. latifrons measured approximately 213 centimeters (84 in) from one tip to the other. Bison bison measures in with horns approximately 66 centimeters (26 in) from tip to tip. Bison occidentalis is less well-known, but it is smaller than B. latifrons and its horns, also much smaller, pointed toward the rear of its skull, rather than the front. Bison antiquus was nearly as tall at 2.27 m (7.5 ft) but much lighter at 1,588 kg (3500 lb) and with horns noticeably smaller, though pointing forward, that measured approximately 1 m (3 ft) wide.
Photo from North Dakota Department of Mineral Resources. B. latifrons exhibit at the North Dakota Heritage Center

03 November 2017

All The Pictures

What is the absolute best illustration, scientific image, line drawing, or photograph of a fossil of Helicoprion? If you cannot think of an answer, you are not alone. Is it this image of the estimated size of Helicoprion? It might be this image of all of the hypothesized Helicoprion morphologies (I saved it for my own visual delight).  The Mary Parrish illustration shared on Wednesday is up on the list of good illustrations for most people. There are a number of poor illustrations; we will not share those here today. My personal favorite, as we always see here on Fridays (feel free to share your own of course, but I write it, I choose it typically). The thing this week is that I do not really have a favorite. Some of the best illustrations are outdated and terribly wrong, despite their wonderful appearance. Mary Parrish's interpretation is wonderful, and Nobu Tamura's is as well (see Saturday's image). The image for today, rather than being a favored illustration, is one of my favorite photographs of a Helicoprion fossil. This tooth whorl is immense in appearance and its rolling form is somewhat mesmerizing. I almost cannot stop looking at it honestly.

01 November 2017

Other Anatomy

The papers yesterday described the anatomy of Helicoprion's tooth whorl and as such, though we usually pick the most interesting anatomy and describe it on Wednesdays, we will have to discuss something slightly different this Wednesday. The topic for today still has to do with the tooth whorl; it is actually almost impossible not to discuss the only two materials that are known from Helicoprion  fossils (crushed cartilage and dental remains). Two hundred ninety million years ago Helicoprion was a successful predator in oceans globally, but what was it eating with its strange tooth whorl? The tooth whorl, according to the Smithsonian reconstruction, was not the first line of attack for this shark, and that is something important to talk about in terms of diet. When the tooth whorl is placed in the older positions (in the front of the mouth, the middle of the mouth, as an extension of the chin) the scenes we saw in the Animal Planet clip make a lot of sense; Helicoprion slicing fish and squid in half furiously as it swims about in the ocean. The interpretation of Mary Parrish (with help from Robert Purdy, Victor Springer, and Matt Carrano) places the tooth whorl in the gullet of Helicoprion. This positioning places the whorl in the same area as the gills (consisting of five gills rather than six/seven as is common in basal extant sharks for the shark enthusiasts) but without blocking their ability to extract oxygen from the water. The solution to the tooth whorl being in the throat was not having to swallow food before being able to chew it or bite at it. Instead, this reconstruction possesses a set of teeth similar to those of other sharks; a cartilaginous jaw housing rows of teeth that are used for catching, injuring, and otherwise stopping prey from getting away. The teeth in the throat, then, could have been used to snag prey as it entered the oral cavity, with the more traditional teeth pulling the prey into the mouth and the tooth whorl pulling the prey into the throat. Extant animals such as some snakes, fish, and other reptiles as well as extinct animals like mosasaurs possess teeth on the palatal bones that act in a similar way, helping to hold and move prey further into the throat and down the esophagus than mandibular and maxillary teeth are capable of doing. This version of the purpose of the tooth whorl is practical, if not as fantastic as some of the past iterations of the curious anatomical hypotheses.

31 October 2017

Papers for Halloween

Is there a better way to spend Halloween than reading papers about a fascinating and scary looking shark? There might be, but I am not going to tell you how to spend your evening. One could spend literally all night reading about Helicoprion; there is seriously that much literature out there on this very interesting shark. I will gladly pick out a few articles for everyone today though. First, I recommend reading both Chorn, et al. 1978 and Eastman 1900 for reviews of the early and more recent reviews of Helicoprion descriptions. Next, I would recommend reading Tapanila, et al. 2013. This study includes a CT image study of the tooth whorl and description of its anatomy and corrected placement in the mouth including a massive illustration of all of the hypothesized placements of the tooth whorl in recorded publications. Lastly, I suggest Ramsay, et al. 2015 which further explores Tapanila, et al.'s hypothesis, CT data, and compares Helicoprion with other genera of shark. This publication also discusses the overall morphology of the shark and how it went about using that tooth whorl in its daily life.

30 October 2017

Prehistoric Terrors

Helicoprion has appeared in a number of documentaries and has been mentioned in a number of shows that do not really concern the intriguing shark. This short clip from Animal Planet's River Monsters is the best clip available online from any of the documentary mentions of Helicoprion. It is also the only clip online other than the Discovery Canada clip shared yesterday. As a bonus, one can see a photo of a 3D printed tooth whorl on the River Monsters website for the episode Prehistoric Terror here.

29 October 2017

Scaring Children with Teeth

The teeth of Helicoprion can be somewhat frightening in a number of different ways. However, we should probably make sure that the kids in the audience are not frightened when they look at sites like Prehistoric Wildlife that showcase the teeth and the many different hypothesized alignments of those teeth over time. The number of alignments and positions of the teeth are actually somewhat amazing, all things considered; every idea that was put forth had those teeth in some interesting and new position in the body of the shark until their actual position was surmised in the last 50 years or so. In addition to the history of the teeth on Prehistoric Wildlife, there are a number of short informational videos and clips of longer documentaries from Discovery and Animal Planet that are worth checking out. This shorter clip from Discovery Canada goes well with the comprehensive fact page and leave us some other quality videos for tomorrow.

28 October 2017

Fearsome Sharks

©Nobu Tamura, 2016; most recent accepted iteration of whorl location
Few animals are as frightening to humans, as primates, as large oceanic predators. The diversity of sharks is such that we could discuss almost any member of the shark family and have a "scary" animal for the final full week of October. What most anyone would imagine is the obvious choice for a scary shark would is something in the Carcharodon genus; that being the group that contains C. megalodon (Megalodon) as well as C. carcharias (Great white shark). Instead, because it is one of the most interesting of the odd members of the shark family tree, this week we will discuss the genus Helicoprion. Contrary to most popular knowledge, Helicoprion is not a single species, but rather a genus consisting of 3 acknowledged and accepted species and 3 questionable species. These species are: H. bessonowi Karpinsky, 1899; H. davisii Teichert, 1940; H. ergasaminon Bendix-Almgreen, 1966; ?H. karpinskii Obruchev, 1953; ?H. mexicanus Mullerried, 1945; and ?H. svalis Siedlecki, 1970. Helicoprion is better known as the "tooth whorl" shark, owing to their unique spiral arrangement of teeth. The shark is known from global deposits spanning North America, Europe, Asia, and Australia, but the cartilaginous elements of the skull, spine, and body are unknown because of their relative inability to fossilize well. The whorl of teeth was, because of a lack of associated material, at one time or another, thought to have been the nasal process, a throat structure, and teeth, of course, placed in different portions of the jaw. Different specimens are named from different regions and for having disparate tooth whorls; the only possible evidence for individual species given the lack of other skeletal elements for most of the specimens.

27 October 2017

Iconic Representation

Deviant Paleoart via Creative Commons
As I have mentioned a few times this week, there are many illustrations of Majungasaurus out on the internet for people to view and be entertained by. There are many images of the dinosaur running, such as this one (though it is a bit skeletal). There are also interpretations of Majungasaurus roaring, which look quite frightening, to smaller dinosaurs, and is somewhat stereotypical, but nonetheless, classic subjects of illustration. This version of the mouth open posture is simply showing an interpreted gape and the rows of teeth Majungasaurus had in its mouth, which is nice to see and a nice inset to the main illustration. There is even am illustration on the National Science Foundation page detailing the hypothesized air sacs of Majungasaurus. These are all well done and worthy of note, but whenever I think of Majungasaurus there is one very specific illustration that always comes to mind. The image, shown here, is a specific view of the head of Majungasaurus in high detail. We could spend a day discussing, critiquing, and appreciating all of the illustrations here, but instead, as I am backdating this entry, we will move on shortly.

26 October 2017

Majungasaurus Everywhere

Majungasaurus has been seen in many different forms of media for the past 60 years. Originally described by the French paleontologist Rene Lavocat in 1955, Majungasaurus was named as the dinosaur of the province it came from, Mahajanga in northwestern Madagascar. Lavocat's described remains were not the first remains described, but the 1896 description of theropod remains from Mahajanga were published as new remains of Megalosaurus by another French paleontologist, Charles Deperet. Given this extremely long history of remains, the amount of popular knowledge and subsequent popular culture references of Majungasaurusought to be much more extensive than it currently is, despite the mistaken name. Following the 1979 description of remains under the name Majungatholus atopus (Sues and Taquet) the dinosaur garnered more attention, as a pachycephalosaur, until its theropod and cannibalistic nature became more well known and widespread after the 1998 discovery of Majungatholus-like set of remains. Those remains were described and reassigned to Majungasaurus, with the name Majungatholus then synonymized with the older name.

Aside from the two documentaries shared earlier this week Majungasaurus has not appeared in many places on television or in movies. However, Majungasaurus has been illustrated many different ways by many different artists and has been written about many different times by many different authors. Majungasaurus appears in dinosaur encyclopedias aimed at kids, kids picture books, general dinosaur knowledge books, and even college level texts. Perhaps speaking even more to the popularity of Majungasaurus is the copious number of toys and models produced in different poses and from different molds.

24 October 2017

Papers Everywhere

Being an ugly cannibal dinosaur has its perks. In the scientific community it has perks at least. The number of papers written about Majungasaurus (including its synonymous genus Majungatholus) is very respectable. The paper regarding cannibalism was shared the other day, though if you cannot find it through an institution of your own it is difficult to find online. I would share it if I had permission to do so, unfortunately it is not my paper. I can point out some other good topics that have been covered though.

The interesting anatomy of Majungasaurus is discussed in detail in a 184 page special memoir entirely dedicated to Majungasaurus crenatissimus published through the Journal of Vertebrate Paleontology in 2007. A number of different topics including the appendicular skeleton, phylogney, dentition, and observed pathologies are discussed in the memoir. Particularly interesting to myself is an article on the craniofacial anatomy. The craniofacial anatomy of Majungasaurus is a defining feature of the dinosaur and is covered in depth in the memoir as well. Majungasaurus is a dinosaur with a lot of bumps and nodules on its skull that cause it to look somewhat terrifying and rather interesting at the same time. These morphological oddities have been discussed in passing a number of times by a number of different authors but Sampson and Witmer tackled the topic head on in the memoir The paper discusses the anatomy of the skull in light of a then newly discovered cache of skull material. This entire publication can be found at this link on BioOne, though access to JVP articles is regulated and available to members only without paying for individual articles. I understand that this does not help anyone access the articles mentioned here if they are not members, but this is a one stop source for Majungasaurus information. Those without access can find a similarly populated list here, but please be aware that the list is 5 years old and some links may not work.

23 October 2017

Cannibalism Imagined

Due to the highly publicized knowledge of cannibalism in Majungasaurus there have been multiple iterations of animated and illustrated versions of Majungasaurus engaging in cannibalism. As stated earlier in the week, the act of cannibalism is intriguing to many different people and that is why there are so many different interpretations. There are two different documentaries that have animated this behavior. The two documentaries independently portray active predatory situations wherein one Majungasaurus attacks and eats a second individual. This, as we stated before, is hypothesized and, while making for good television, is certainly not a guaranteed certainty. In the BBC documentary Planet Dinosaur the predatory cannibalism occurs when there is a shortage of food and two young animals are still hungry, prompting their mother to secure some kind of food for the young. The second, History's Jurassic Fight Club, approaches the subject in a similar manner. Instead, a solitary Majungasaurus eating a smaller dinosaur it has killed is confronted by another Majungasaurus looking to steal a meal. Fighting ensues and one of the animals ends up with two meals. The downfall of both documentaries is not in presenting hypothetical situations or imagining dinosaur fights (most dinosaur documentaries love doing these scenes) but instead in the fact that Majungasaurus was an abelisaurid and possessed very unique forelimbs and hands. The BBC version of the dinosaur is closer to the reconstructed skeleton, but is still a little wrong because the arms are still facing forward and in a "want to hug you" sort of posture.

22 October 2017

Cannibalism on Display

How do we know an animal that is now a fossil was a cannibal? As with much evidence of cannibalism, even in extant animals, we must look at the teeth, the wounds, and how these two pieces of evidence are correlated. In the past, ichthyosaurs (specifically Shonisaurus and the ichnospecies Ichthyosaurolites) and Coelophysis were suggested to have been extremely cannibalistic in their behaviors. A little over 11 years ago, the cannibalistic tendencies of Coelophysis were analyzed and refuted; the supposedly cannibalized animasl turned out to be a basal crocodile and outside of the body of the second Coelophysis specimen accused. Ichthyosaurolites, on the other hand, is an ichnospecies based entirely on ichthyosaur coprolites that contain the skeletal remains of other ichthyosaurs; the name literally means "ichthyosaur coprolite (fossilized feces)".

From Rogers, et al. 2003. Caudal tail chevron of Majungasaurus. White arrows indicate drag marks and black arrows indicate impressions initial biting marks from Majungasaurus teeth.
In the skull of Majungasaurus, the teeth are characteristically shaped, spaced, and serrated. All of these identifiers have helped paleontologists to recognize the marks of Majungasaurus feeding on a number of other animals from Madagascar. Chief among the animals possessing numerous bite marks from Majungasaurus teeth are the sauropod Rapetosaurus and Majungasaurus itself. No other theropods are known from Madagascar during the 70 - 66 MYA time frame during which Majungasaurus is known to have lived. This was used as the first inference concerning the tooth marks on Majungasaurus bones. This in turn led Rogers, Krause, and Curry Rogers to look at the teeth of Majungasaurus and at the marks that they had left on Rapetosaurus bones in 2003; Curry Rogers had led the description of Rapetosaurus in 2001. The initial bite marks that we see (look at the black arrows) are spaced and shaped identically to the teeth known from the multiple Majungasaurus skulls that have been recovered. The drag marks (white arrows) indicae areas where the serrated denticles have been dragged across the bones.

The first argument that is made here, often, is that the results of interspecies combat might look something like this. However, there are two important aspects of these wounds that make the case for cannibalism more compelling. The first is that these wounds show no sign of healing; the bone would have likely attempted to heal itself, at least, a little, after a traumatic bite in which humerous teeth insulted and scratched the bone deeply enough to clearly score the skeletal material. The second is that these chevrons, and many other limb and vertebral elements that also contain bite marks like these, are inaccessible during combat as they are in areas that could only be (easily) bitten when other elements of the body were exposed either through decomposition or predation.

The remaining question, however, is whether this cannibalism occurred as a result of scavenging behaviors or if Majungasaurus actively hunted members of its own species. The two activities have been documented in various extant species including lions and chimpanzees, so neither would be exceptionally abnormal or unique to Majungasaurus. For more reading on the exact findings of the Rogers, et al. team, read the following paper:

Rogers, R.R.; Krause, D.W.; Rogers, K.C. (2003) “Cannibalism in the Madagascan dinosaur Majungatholus atopus.” Nature, Vol. 422, pp. 515-518

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,
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.