Living Under Your Feet

Hypsilophodontids are small, quick moving herbivorous creatures known worldwide from the Middle Jurassic to the Cretaceous. One species in particular, however, is of interest to us this week and is actually of interest to a great many other scientists as well. There is no extravagantly unique bone structure or defensive adaptation that sets this dinosaur apart from all other dinosaurs and makes it so worthy of extra attention. In fact, what sets Oryctodromeus cubicularis apart from other Hypsilophodontids is the living conditions in which it has been discovered. Unearthed originally in Montana, Oryctodromeus (which translates to "digging runner") has also been unearthed with its home intact and, in three instances, with the dinosaurs still at home. These "homes" were underground burrows, making Oryctodromeus the first dinosaur to be unearthed with evidence of burrowing behaviors. Three individuals in the burrow, identifiable as skeletons in advanced imaging, were found in a burrow that was lined with sand; thus the burrows are preserved as sandstone cores embedded in, typically, mud or clay based stone.Oryctodromeus skeletons were identified in the burrow by comparing their characters with the known characters of the species which are based off of many different excavations and a lot of identified and associated material of many different individuals. Small animals, about 6.8 feet (2.1m) long and approximately 70lbs (32kg), Oryctodromeus adults had basic digging tools for hands. Adaptations in the Montana specimens (named Blackleaf specimens for their location of discovery) have shown jaw, forelimb, and pelvic adaptations that would have aided in soil removal from the burrows. All of these, and more, will be discussed further in the coming week.

©Mark Hallet (via National Geographic, May 2008)

As Seen On TV

Saurophaganax, we have discovered, is different from Allosaurus in the way in which the vertebral column is constructed, not, as thought in the 1940's, in the way in which the tibia was constructed. We have also seen that there is a lot of knowledge out there about this dinosaur but that there is a lot left to study as well. As much as there is, and as much as there is left to study, it is not amazing that Saurophaganax has certainly left an impression on the popular culture of the world. Sunday we saw how Saurophaganax has made its mark on cartoons, children's books, and card games. Monday brought us Saurophaganax on the BBC, where available, and showed us the size differences of Saurophaganax and Allosaurus. We also saw the different representative sizes at other times during the week and yesterday we summed up those differences, and explained them, as they are found in the vertebrae of Saurophaganax. Today, on the day I typically pile in all the remaining popular culture references, I am fortunate in still having a generous amount of information to share, which is not always the case even with the most popular of dinosaurs. Saurophaganax has been created in Spore, like so many other dinosaurs.

I think this is probably the best in the bunch. It has also shown up as toys in a number of places based both off of the dinosaur itself and the cartoon representation which we saw on Sunday in Dinosaur King.

The second picture does not feel like loading on this computer, I will try again later; however, the image above is the Dinosaur King based Saurophaganax. The fact that Saurophaganax is missing so many bones may one day, provided more of its bones are found, allow it to remain separated from Allosaurus as a larger cousin rather than being relegated once again to being considered a species of Allosaurus. Should the second ever happen, I feel, as popular as Saurophaganax has become, that the public, and perhaps paleontologists as well, would react in much the same way that they did when Triceratops and Torosaurus were theorized to be the same animal. That debate is probably far from over though, so a comparative argument around Saurophaganax and Allosaurus would probably be just as lengthy considering how popular both dinosaurs are as separate genera.

Neural Arch-Nemesis

The tibia originally used to distinguish what was then Saurophagus from Allosaurus was not distinguishable from those found in Allosaurus. We have mentioned that a few times so far this week. The distinguishing characteristics of the vertebrae used by Chure (1995) to separate Saurophaganax and Allosaurus, however, were obviously different enough to warrant the widely accepted separation of the two genera though they reside in the same family. The question then becomes what is different between thevertebrae of Allosaurus and Saurophaganax and what exactly is a neural arch? A neural arch, for those wondering, is the posterior (rear) part of a vertebra. It is the arch that spans the hole through which the spinal cord is strung down the entire series of the vertebral column from brain to tail, to put it simply. As we can see from the diagram at right, the neural arch is composed of, and has coming from it, a number of processes of bone, not all of which are labeled here. Some of these labels sometimes change depending on both the animal and the source. For example, the dorsal spine is referred to as the spinous process in some diagrams. The number of these bones differs based on the animal and the number within each region of the body also differs depending on the animal. Humans have 24 vertebrae arranged in three sections; cervical, thoracic, lumbar with an additional 9 fused vertebrae in the sacral region (the last 9 are typically left out of the count of the vertebral column in human anatomy meaning we have 33 but only 24 are considered vertebrae) whereas cattle have between 49 and 51 vertebrae arranged over five regions; cervical, thoracic, lumbar, sacral, and caudal. Typically dinosaur vertebrae are looked at as being either cervical, dorsal, sacral (typically a fused set of vertebrae), or caudal. The guys at SVPOW, specifically Matt Wedel for this post, do a good job of going over dinosaur vertebral anatomy themselves.

Anyway, the neural arches of Saurophaganax show the following characteristics, as restated by Mickey Mortimer that distinguish them from that of Allosaurus:

- atlas lacks prezygapophysis for proatlas, does not roof over neural canal
- dorsal vertebrae with horizontal lamina along base of each side of neural
spine arising from spine base cranially, free caudally
- chevrons craniocaudally expanded distally

The atlas is the first vertebra in the vertebral column, meaning it is right behind the skull of the animal (below in our case). The pro-atlas is a dorsal (back of the animal) aspect of the atlas and the prezygapophysis is an aspect of the vertebra which projects forward (upward in humans) to help fit with the preceding vertebra in the column snugly (in this case it would extend to the base of the cranium had it existed). The second aspect, the lamina arising cranially and being free caudally means that the caudal (tail-ward) end of the vertebrae were not covered by that aspect of the bone as the cranial (skull-ward) end was. Chevrons being extended craniocaudally distally means that the chevrons of the spine, typically found on tail elements to protect nerves and blood vessels ventrally (from the underside, meaning these aspects of the bone are underneath the vertebrae) were expanded as they moved away from the center of the body, toward the tail.

Papers and Problems

©Chris Porter (Commissioned by OMNH)

Daniel Chure's original 1995 redscription and redesignation of Saurophaganax was published in a collection of papers and presented at a symposium on Mesozoic ecosystems. This paper was printed in the collection 5 years prior to Chure's dissertation thesis on another new species, this time and Allosaurus species. The significance of the paper redescribing and redesignating the holotype is that it came very early in Chure's career, which is somewhat rare, these days, for paleontology discoveries. Many discoveries are made by graduate students in cooperation with their advisors, but rarely do we see late undergraduates or early graduate students (not presenting a thesis yet) as making discoveries valid and important to paleontological research. Paul, in his newest book, presents the animal as "Allosaurus (or Saurophaganax) maximus" and notes that enough material and distinction within the material exists to create a new genus and species, but does not present it as a unique species, which is a little strange. Not many studies have been published that we can share online since the Chure paper of 1995;  however, there is a great deal of potential research that remains to be done on this animal, so hopefully we will see some quality research done in the next few years as new materials have been unearthed in New Mexico recently which may belong to Saurophaganax and certainly belongs to the Allosauridae.

Movie Apocalypse!

Saurophaganax, for a somewhat disputed dinosaur, has made a few waves in the world and certainly enough to be portrayed on film. Yesterday we saw a cartoon version of a meaty and robust theropod that could obviously hold its own in a fight (I know it was a made up cartoon fight, but who does not enjoy even a cartoon clash of dinosaurs?). Today we see how Saurophaganax is depicted by Dinosaur-Quest:

and then how BBC's Planet Dinosaur, if we are lucky enough to find a working clip (BBC shows do not always play in North America from their website; copyright laws or some such), depicts the differences in Allosaurus and Saurophaganax. The closest I come to finding a decent clip is a filmed off of a television clip with the sound edited (no idea why). Put it on mute and we can watch the differences without the sound edits. The BBC is very stingy about putting up clips that I want to use when I need them. If anyone has had the ability to watch Planet Dinosaur (I have not had cable, by choice, for nearly 6 years now) than it may have already come to your attention. If not, watch the link above and see how the BBC portrays the differences at least. Hopefully more visuals of the differences in Allosaurus and Saurophaganax will come into the limelight in the years to come.

The Children's Lizard Eater

Saurophaganax, for kids, is not really a foreign animal. It has appeared in a number of places, including in Dinosaur King in an episode called Dueling Dinos. I like that we can step away from the hard science one day a week to enjoy cartoons and being a kid in a way like this. Sunday is one of my favorite days in each dinosaur's week. I'm happy that I have found a lot of dinosaurs in cartoons lately as well. Saurophaganax does not stop with Dinosaur King though. It also has its own book, which I found through Target's website. It also has an information page through the Natural History Museum in London. There are not many coloring opportunities, but if you look online you can find a few black and white images.

Speaking of which. I am putting together some of my illustrations (I know they are not highly professional) as coloring books for some of my nieces. It ought to be fun.

To Allosaur or Not To Allosaur?

©Michelle (AKA Mitternacht90)

Saurophaganax, as we briefly discussed yesterday, poses a small problem. Looking at the skeleton, both from yesterday and today, it can be seen to possess many Allosaurid elements, especially in the claws and a vague resemblance in the top of the skull from the nasal back to the parietal; I think this may be an effect produced by the ridges and rugosities seen above the orbital fenestra as Allosaurus species were known to have such formations on their skulls as well. However, many theropods had a set of small nubs of horns or rugosities on the tops of their heads that bear resemblance to these, so we cannot use that as a piece of evidence that undeniably unites the two genera. Chure mentioned tibia characters that had been mentioned prior to his renaming of the genus, and subsequent separation from Allosaurus completely, but noted that these characters did not differentiate the two genera. Instead, he named characters of the neural arches of vertebrae in a sample labeled OMNH 01123 (Oklahoma Museum of Natural History) as a new holotype for Saurophaganax.

©Mineo Shiraishi

When it is fleshed out, however, Saurophaganax certainly resembles an Allosaurus in many ways. Part of the reason that we cannot easily tell the animals apart is due to the fact that the neural arches, which are used by Chure as a holotype and possess the characters used to separate the genera, cannot be seen in a fleshed out animal. What we are left with is a very Allosaurine dinosaur, which makes sense considering that Chure's classification of Saurophaganax still places the genus within the Allosauridae. Saurophaganax, then, would look somewhat like an Allosaurus in the same way that many hadrosaurs have similar characteristics within the same clade. The most notable, when fleshed out using the material available, is the similarity in the claws and those cranial rugosities and ridges. Considering Allosaurus' ability to use its own claws to take down prey it makes sense that a more "technologically advanced" member of the family would retain, and perhaps even fine tune, those weapons. The cranial protuberances were probably for species and individual identification as well as just plain looking beautiful along with that athletic Allosaur-like body.

©Nobu Tamura

This incarnation of Saurophaganax is a little more stylistic and gives us some more differences from Allosaurus. More than anything Tamura has highlighted increases in body size around the base of the skull, the base of the tail, and even given our typically agile looking Allosaurid frame a bit of girth. The size increase between Allosaurus and Saurophaganax, supposedly, was quite significant, and as such the agility of Allosaurus may have been lost to the later Saurophaganax which may have hunted using its sheer size to aid in taking down larger prey that were either slower moving, such as older sauropods, or it may have been more of an ambush predator whereas earlier Allosaurs were thought to have been able to run down some prey items and use their agility. Gigantism to wrestle prey items would not be a new idea in carnivore circles as many other theropod family possess, usually, either earlier or later members that seem to have been designed for that exact purpose (think of Utahraptor, Acrocanthosaurus, and Carnotaurus as examples of bulky wrestler-like theropods). Perhaps this is something that should be considered when thinking of the larger Saurophaganax.

Lizard Eating Master

©Chris Dodds (uploaded to Wikimedia Commons by FunkMonk)

The Lizard Eating Master, or Saurophaganax, is a Morrison Formation denizen of the late Kimmeridgian Age, Late Jurassic, of Oklahoma, USA. Saurophaganax lives in a somewhat precarious position. Some consider it a valid genus and species, Saurophaganax maximus, while other consider it to be a another representative skeleton of Allosaurus; namely Allosaurus maximus of course. That is not even the first name that has been debated about for Saurophaganax; the original name for the animal was Saurophagus, but this belongs to an already named fly-catcher (which is a bird). Regardless, the material on which Saurophaganax is based comes from four individuals in Oklahoma which are distinguishable from Allosaurus according to Daniel Chure. I think throughout this week we will try to get to the bottom of some of this mystery and perhaps even help in sorting out the mystery properly.

Achelousaurus' Spotlight

First and foremost, Achelousaurus appears in Spore as a created character. I think the job was done well, until the frill moves because it looks as though it was constructed of "hair":

Secondly, Dinosaur King, as mentioned before, is the only other popular culture reference we have to share today. There is one card, that I have found, are a small number of cards designed to be used in the game. These can be found on the dinosaur's page in the Dinosaur King Wiki. There really is not much else to say in popular culture news about Achelousaurus. That being the case, my American fans enjoy these Thanksgiving dinosaur images (everyone else, check out this neat dinosaur art!):

©Bob Diven

And this:

Following Trends

©Nobu Tamura

Kirkland and DeBlieux, as mentioned a couple of weeks ago now, described Diabloceratops. In doing so they made some generalizations about the evolutionary trends of the Centrosaurines based on their skulls. The Centrosaurine family tree was already organized in the way in which they described the evolutionary trends and as such they were not truly reinventing the family tree anywhere near as much as they were describing some observable traits in the skulls of the animals that they knew at the time to be members of the Centrosaurine clade. The general trend, it appears, starting at Diabloceratops (and now with Xenoceratops' discovery with that Centrosaurine dinosaur) the trend described is a continuous trend of parietal frill adornment while we see a reduction in supraorbital (think eyebrows!) horn reduction, the replacement of those horns with a solid nasal horncore, and the subsequent reduction of that horn structure. As each horncore site is reduced into nonexistence the bone at the site of origin becomes denser and rougher, eventually replacing the horn with a rough dense structure of bone, which would be highly suited to dispersal of forces consistent with headbutting another animal "safely". Achelousaurus is a long way down the Centrosaurine family tree, situated snugly between Einiosaurus and Pachyrhinosaurus, and as such exhibits traits in the skull reminiscent of both the previous and following animals (whether the three are a direct ancestry line or not is still open to debate, but the evidence is very strong for a direct lineage based on the skull evolution).

Einiosaurus has a dense boss where the supraorbital horns were in previous Centrosaurines and the nasal horn is exceedingly large but very forward curving and shows a large reduction in physical height from base to tip. Einiosaurus was preceded by Styracosaurus in the family, which had the largest nasal horns of the group, and the reduction of the horn in the way that it occurs seems quite random until we look at the skulls of Achelousaurus. Achelousaurus possesses a very stunted horncore that, in many interpretations, is argued to be simply the edge of the boss on the nasal region, but in the youngest skull discovered (age-wise, not geologically) appears to be a forward, straight off of the nasal and above the beak of the skull, jutting miniscule nasal; following the reduction trend and followed by the extremely dense nasal boss of the Pachyrhinosaurs. Seeing the trends in sequence (perhaps I will play with this sometime when I have more time) would be fantastic. The morphology of the Centrosaurine line is quite interesting and demands more study than has so far been afforded to it.

Achelousaurus: Paper Edition

Achelousaurus is not a really heavily written about Centrosaurine, though it cannot be said that nothing has been written about it in relation to other Centrosaurines or even in papers by itself. Finding such material is a little more difficult, but it is not entirely absent from the world. Some of the most interesting things anyone can read are about skull shape, when it comes to Ceratopsids in general, and Achelousaurus is no different in that respect. The Royal Tyrell's Ceratopsid symposium, from which the book that houses many of the papers cited in the last couple of Ceratopsians mentioned here, did an absolutely fantastic job of pulling together a lot of Ceratopsian research and publishing it is a single hardcover book was a very good idea on someone's part. I just need to get a copy of it some time.

Achelousaurs' Other Movies

Yesterday I shared Dinosaur King and how to draw videos of Achelousaurus. I almost wiped out all of the video resources for Movie Monday by doing so yesterday. There are no new documentaries or kiddy movies that show Achelousaurus, probably because it is hard enough to pronounce it anyhow and because there have not been many feature length films about dinosaurs in a few years. Documentaries have barely, as we know, hit the tip of the iceberg on dinosaur species, so we typically do not expect the dinosaur of the week to have featured heavily in any documentaries unless it is a big name dino that has been popular for quite some time. One Youtube poster has designed a very short animation that we can view and another, named Rob Mutch, has filmed the skull cast on display in the Museum of the Rockies. There is also a SPORE contribution, but I will save featuring that until Thursday.

Juvenile Achelousaurus for Juvenile Humans

There are a few good resources today. Science for Kids has a small fact page that is child friendly; we always like to see those on a Sunday morning. Additionally, though there is no Dinosaur Train episode which features Achelousaurus, there is a good deal of information and resources associated with Dinosaur King, which has not been true for the past few dinosaurs. Therefore, any young card player that is intrigued by the Dinosaur King slant on the dinosaurs we look at should be happy today. 4KidsTV hosts the episode of Dinosaur King in which Achelousaurus makes its debut as well. I rarely get to find the actual episodes that feature the dinosaurs we are speaking about during any given week when it comes to Dinosaur King (Dinosaur Train is a different story of course) so I am quite happy to be able to share the link to the episode with Achelousaurus. In terms of coloring pages, there are two ways to get pages to color this weekend. One is to draw it yourself, if you are any good at following drawing tutorials; I am terrible at trying to follow those drawing tutorial things. Either that or you can print and color this adaptation of Mariana Ruiz's image shared on Friday:

Images of Later Centrosaurines

©Rescast International

The skull of Achelousaurus possesses three dense bone groupings along the nasal, some of the frontal, and the supraorbital ridge. The nasal ridge is always depicted as a shield like protuberance or a straight up jutting protuberance of horn, but given the evolutionary trends of the Centrosaurine family, specifically the reduction of brow horns while a tall nasal horn was becoming prominent and then reduction of the height and an exaggeration of the forward sloping of the nasal horn, most prominent in Einiosaurus, this nasal boss could be then, in part, a horn core for a nasal horn that is in the last vestiges of the forward facing prominence found in Einiosaurus, especially because of the perceived close relationship of Einiosaurus and Achelousaurus. It is rarely shown as such, but I think that the end of the nasal bone structures may have supported at least a tiny horn which jutted straight forward off of the nasal bone, almost like a digging horn or the adornments found on male narwhals rather than just a dense patch of bone.

©Nobu Tamura

Most depictions of Achelousaurus show that nasal ridge as a boss of dense bone, which may indeed be correct and is obviously the most popular interpretation. The eye-brow ridge, or suprorbital ridge, bone is certainly dense and unless the alternate theory of Pachyrhinosaurus horns jutting from dense bone material is applied, then the dense ridges of bone are merely a shield like covering over the eyes much like we would find in the extremely thick domes of Pachycephalosaurs which leads to one solid theory for these ridges: Centrosaurines, once the evolutionary trend of horn reduction had been taken this far in later Centrosaurines that they possessed only thick areas of bone where horns once were, had changed from piercing defensive weapons/rival intimidators to headbutters like modern goats, though obviously much larger. We would then probably expect to see more of an ability in the hips to rear, like goats, or more power at the very least to sprint into a rival or predator, meaning that the cow-like structure of the body may need to be altered a bit.

©Mineo Shiraishi

One thing that certainly did not change, in terms of evolutionary trends (I put together a presentation for a posters and presentation class I am taking for my MS on Centrosaurine evolutionary trends, so I apologize for the heavy use of that phrase this week!) is that the parietosquamosal frill is still quite well adorned. The peak of Centrosaurine frill design, arguably, is the ostentatious frill which is exemplified by Styracosaurus with its lightweight protection and multiple spikes all along the ridge of the frill. Achelousaurus has a much simpler frill design, but it is still considered an adorned frill. The two spikes at the apex of the frill are standard for all Centrosaurines save a few (Centrosaurus, Coronosaurus, which used to be a Centrosaurus species until recently). Frills of the Centrosaurines are truly works of art. This is a little more minimalist in its approach than other Centrosaurines, but it is still a wonderful looking animal.

Achelous' Lizard

©Mariana Ruiz (edits by Michael B.H.)

Achelousaurus. Achelous' Lizard. Strangely named, considering that Achelous is a minor deity of the Greek pantheon and the remains of Achelousaurus were discovered in Montana in the Two Medicine Formation and described in 1995 by Scott Sampson. Achelousaurus was approximately 20 feet (6m) long and weighed an estimated 3 tonnes. Achelousaurus was a Centrosaurine dinosaur and as such was smaller than a Chasmosaurine, like Triceratops, but larger than Protoceratopsians, like Protoceratops. Being a Centrosaurine, Achelousaurus possessed an adorned parietal frill with two large spines forming from the parietal and dense bones over the eye where earlier Centrosaurines possessed supraorbital horncores and another area of dense bone over the nasal bone in place of the extremely large nasal horncores of other earlier Centrosaurines. Achelosaurus was one of the last of the Centrosaurines and marks the near pinnacle of the family's evolutionary tree. It is closely related, perhaps not directly, to Einiosaurus and Pachyrhinosaurus, older and younger Centrosaurines respectively. So far three skulls have been unearthed from the Two Medicine Formation, which makes study of Achelousaurus a little more comprehensive, as multiple samples of any skeleton will do, and means that our understanding of Achelousaurus is that much more in depth.

Microvenator: Popularly Forgotten

Microvenator is a popular little dinosaur, unfortunately it is not as popular in the mainstream culture as it is within paleontology. In paleontology it is an important little animal that tells a lot, despite its small size and missing bones, about the dinosaurs which are nested before and after it in evolutionary terms. Microvenator sits in a wonderful little spot in its family tree right at the end of the Caenagnathid  branch but right at the start of the Oviraptorid branch. This relationship between the two, though it is not illustrated as a "for sure" link between the two, allows for a lot of recognition of characters from each subfamily within Microvenator's bones, which, in a way, makes it a sort of missing link between the two groups. A subsequent find of a nearly complete, or more complete, skeleton of Microvenator would have an enormous impact on the study of the animal itself as well as both the Caenagnathidae and the Oviraptorosauria. Let us hope that someday someone will find a nearly complete, maybe even a complete (I do not think we should hope for more, like a mummified find, though it would be remarkable and quite a boon)

A Lot of Bones And A Small Dinosaur

Despite lacking almost half (47%) of its characters, Microvenator's type specimen is composed of a large number of bones from all over the body of the animal. Many of these bones are fragmentary or are small parts of larger skeletal apparatuses (such as metacarpals or single disarticulated vertebrae) and thus do not provide much of the greater picture or the defining characters of the animal. The jaw, as discussed, is such an incomplete sliver of the animal that it has been interpreted multiple ways; chiefly as either overtly Oviraptoran or completely Maniraptoran in appearance. To add confusion, initially, to the problematic shape of the lone skull fragment, Barnum Brown included what were later discovered to be Deinonychus teeth as examples of Microvenator teeth. We of course know that this is not true now that we know they belong to Deinonychus, but it leaves us with questions about whether Microvenator had teeth, as a transitional early Maniraptoran or a toothless beak as a primitive Oviraptoran dinosaur. The hands, as opposed to the jaw fragment, are reminiscent of later Oviraptorids as well as possessing characters from earlier Caenagnathids, lending more credence to the thought that this animal is a basal ancestor of the Oviraptorids. This may in turn lead to more definitive structuring of the jaw elements, though further concrete discoveries of Microvenator skulls would be infinitely preferable in terms of accurately describing the structure of Microvenator's skull. Hopefully sometime in the future an entire Microvenator will be discovered or at least weather out and be noticed somewhere along the Cloverly where the initial discovery was made by Brown in 1933, but until that time we will have to cope with an apparent lack of material to support the existence of this rather small, and primitive, Oviraptorid/advanced Caenagnathid.

Sues Again!

Hans-Dieter Sues is a prolific writer; no one can really argue with that. I think we feature some paper he has at least co-authored on a fairly regular basis each week here. This week, though, he has teamed up with Peter Makovicky to discuss anatomy and phylogenetic relationships of Microvenator. Granted this is a little older, 1998 when Makovicky was still a graduate student, it still does quite a bit for our understanding of how and where Microvenator fits into the family of Oviraptorids as well as geologically where it fits into the timeline of life compared to other dinosaurs. Makovicky and Sues provide an in depth look at the reexamined Microvenator and come to the conclusion that Microvenator has even more in common with the Oviraptorids than Ostrom thought. They do caution, however, that a whopping 47% of characters are unknown for Microvenator at the time of their study, and probably still close to that today, and as such there is a great deal of movement of the animal in phylogenetic groupings possible. Mark Wilkinson addressed, in 1995, three years earlier, the missing characters in a wider reaching article on how to rely on results even with large amounts of missing characters. A small number of characters for Microvenator were presented in a table within the article and the overall message of the article is obviously important for other dinosaurs as well that are missing larger proportions of their identifying taxonomic characters. Sadly, to this point, I have not taken any systematics classes and so some of these things are clearly, at the moment, lost on me, but I hope to remedy that soon.

Motionless Microvenator

Microvenator, for some reason or another, has not shown its face in any documentaries, kid's shows, cartoons, movies, short films, commercials, television shows, or flipbooks that have been posted online as videos. In fact, it does not even show up for more than a brief moment in a tribute video dedicated to Oviraptorids as a clade. This extreme lack of resources leads to a rather unique issue; we have absolutely nothing at all to share on this dinosaur on Movie Monday. I think this has happened to this extreme perhaps twice in my recorded knowledge, which is quite amazing really. In place of that I offer a look at the ilia of Microvenator compared to other described Oviraptorids and I have borrowed the caption from Jaime Headden, who I think deserves credit for the image in this form as well.

©Jaime A. Headden

 From Jaime's caption of the above image:

Preserved pelvis of several North American oviraptorosaurians. A, RTMP 79.20.1, referred to Chirostenotes pergracilis Gilmore, 1924 (after Currie & Russell, 1988); B, AMNH FR 3041, holotype of Microvenator celer Ostrom, 1970 (after Makovicky & Sues, 1998); C, GI 100/119, holotype of Nomingia gobiensis Barsbold et al., 2000; D, ROM 43250, holotype of Epichirostenotes curriei Sullivan et al., 2011 (after Sues, 2008); SMP VP-1458, holotype of Ojoraptorsaurus boerei Sullivan et al., 2011. Scale bar equals 10cm.

Kids and Fluffy Dinosaurs

Microvenator, as shown Friday, appeared to have been a fluffy dinosaur. The downy coat that appeared on Friday was only slightly different from the two feathered forms shown yesterday. I think it would make a good pet, the fluffy version, or at least a good pillow. Anyhow, there are not too many kid friendly links, regardless of the appearance of fluffiness and almost docility that are sometimes depicted in Microvenator. We do not have awful links, though I cannot say that we have fabulous links; we all now the quality that comes with Enchanted Learning dinosaur pictures. This dinosaur is more retro than it is awful though, I have to say. Retro is not bad, it is just... retro. As far as videos for kids go, we have nothing today. We do have ample coloring abilities though, using yesterday's images  actually. I would suggest using Rachel Clark's image though, as it has very good solid lines that lend themselves to coloring images very well.

A Choice of Skulls

Microvenator, as seen above, is based off of loosely related and, though it looks as though it is articulated, disarticulated fragments of bone. The skull has only been found in small chunks and the holotype used by Ostrom to describe the animal was only about half of a mandible, if that much. Therefore, any representation shown is an educated guess based on the description of Microvenator and subsequent taxonomic relationship derived thereof by Ostrom in his 1970 publication. Ostrom, of course, was not a slacker and his description is well thought out, thorough (for the time at which it was produced and published), and as exhaustive a description as it could be based on the fragmentary evidence available. Two basic models of the skull have been generated based on the description of Ostrom and the fragmentary evidence of the skull that is available including any newer materials that have been weathered out of the soil and collected since 1933 and 1970, the original discovery and description respectively.

©Rachel K. Clark: Depicting a robust carnivore.

One mode of depiction of that skull, best exemplified by this slightly older illustration, is that of a longer muzzled theropod. Based on the bit of mandible that was discovered in the original fossil grouping, the muzzle would extend a little but further forward than in other Oviraptorids, and this would not necessarily be incorrect. Remember that Microvenator is considered to be a rather primitive, or basal, Oviraptorid and may have thus retained a longer muzzle, even though it too may have been mostly beak like and toothless such as that found in later cousins and descendants of the species, as it was just recently divergently evolving from the other Maniraptors it is cousins with. Somewhere that face had to have changed over from the Maniraptor muzzle of a long toothy death machine to the more bird-like beak of the Oviraptorids and Microvenator, being as primitive as it is considered to be, sounds, and looks, like a fantastic place for that change to occur.

©Oyvind M. Padron: Depicting a more graceful omnivore.

The more recent version, however, shows Microvenator having already developed the bird-like beak of the other Oviraptorids. While not outstanding or ostentatiously strange, this sort of skull would assume that A) the fragmented mandible  was indicative of a bird-like jaw structure and B) that there is an even more primitive Oviraptorid or Maniraptoid form that is an intermediary between the Maniraptorid muzzle of sharp killing teeth and the toothless Oviraptorid bird beak. As with anything in paleontology, that is quite the possibility, but given the justification within the description and subsequent debates over the placement of Microvenator within the basal Oviraptorid slot it is difficult to think that Microvenator is not that intermediary between bird beak and toothed muzzle. However, the, so far, complete lack of sharp killing teeth associated with Microvenator does support the bird beak idea, which would allow for the diet of Microvenator being close to that of Chirostenotes and other Oviraptorids, namely consisting of small mammals, lizards, and vegetarian delights additionally, and make the idea of Microvenator as basal, but not the intermediary between true Maniraptorid and true Oviraptorid dinosaurs, hold a lot of water, figuratively of course, when depicted with the bird-like beak rather than the elongated muzzle.

More Bird Faced Killers

©Michael B.H.

Caenagnathids popped up on the North American Cretaceous land in, if it is accurate that Microvenator celer (small hunter) represents the primitive sister taxon of all other Oviraptorids, the Cloverly Formation (approximately 107MYA). The original specimen, the type (AMNH3041) consists of minimal material including a partial skull, numerous vertebrae, left hand, arm, foot and leg, a couple ribs, and its pelvis. The original collection, unearthed by Barnum Brown in 1933 (not published, though Mackovicky and Sues did publish his illustrations for the first time in 1998)  included several large carnivorous teeth that have been since attributed to Deinonychus. In 1970 John Ostrom, who had worked the previous year on publishing his description of Deinonychus, named and described Microvenator from the type specimen. Microvenator is, therefore, another example, like its later cousins Chirostenotes, an animal which was described using minimal material. It looks rather fluffy though, hardly like a killer, however, it was estimated at approximately 10 feet long as an adult; the type specimen is thought to be a 4 foot long juvenile.

Famous, Not Popular

Diabloceratops is a famous dinosaur for sure. In the past two years since the publication of the book which hosted the initial description paper Diabloceratops has gained a lot of notoriety. Granted this has not translated into a dearth of toys, children's books, games or plush toys, but Diabloceratops is well known. Diabloceratops was, and is, certainly well known enough in the paleontology community alone to be of great importance; typically we think of popular culture as museum displays and trinkets, but with a dinosaur like this "popular culture" for the moment at least is the paleo-community. It is quite popular in that community as a subject of study in terms of Ceratopsid evolution. No major papers have been published, to my knowledge, about the placement of Diabloceratops within the Centrosaurine or Ceratopsid family. I think I may have to look into it though, even though this week is just about over for Diabloceratops.

Horns and Family Evolution

Originally posted by Dave Hone. Courtesy James Kirkland

This image is loaded with information about half of the Marginocephalian clade. The Protoceratopsidae are clearly separated out until it branches over to Zuniceratops and moves into the true Ceratopsidae; I think the paleontology community as a whole would have very little argument in agreeing with the majority of that much of the image. Chasmosaurines are not stressed here and are thus relegated to an outlier branch with little to no description while Zuniceratops' other descendants are laid out in a manner which trends in two ways from oldest to youngest as well as from the general trend of number of horns; decreasing as the line progressed over time. It is interesting to note that the general trend is described as "losing horns" but it seems as though not all of the animals represented are truly losing horns. In fact, Styracosaurus, right in the middle, seems to have far more horns, on the frill, than any other Centrosaurine; though it does in fact only possess a nasal horn on the remainder of the skull. Diabloceratops had four horns that are clearly seen, a nasal horn is sometimes depicted on the dinosaur, while the furthest cousin down the line, Pachyrhinosaurus, is thought by many to have no horns at all; this is sometimes countered by the idea that the bony boss on the nasal bone is actually the base of a keratin based horn like in rhinoceroses which has yet to be found preserved in the fossil record. Looking at the skulls it almost feels like Centrosaurus and Einiosaurus should be more closely related also, given the shapes of their horns. Switching the placement of Styracosaurus and Centrosaurus would also, visually, follow the trend of lose of horns more accurately it appears.

Kirkland mentions that the antorbital fenestrations in Ceratopsidae overall appear, disappear, and reappear in later species on a fairly baffling basis. Diabloceratops had such a fenestration "at the contact of the nasal, premaxilla, and maxilla forward of the antorbital fenestra that we call the accessory antorbital fenestra (AAF)." Some of the Protoceratopsidae possess this opening, such as Magnirostris, as did some of the Chasmosaurine dinosaurs like Chasmosaurus itself. The reason that the opening is apparent in some Ceratopsids and not others has not, to my knowledge, been explained as yet, but it seems to be quite an interesting phenomena to study alongside the reduction in horns within the Centrosaurine dinosaurs.

Writing Of The Devil

Kirkland and DeBlieux's paper did not actually show up as a paper. Sure you can download it now as a pdf, thus making it a paper, this was linked in the Smithsonian blog Dinosaur Tracking by Brian Switek, so it should be free to use, plus it is hosted on Academia.edu, but the paper was originally published as a section of a then new book edited by Ryan, Chinnery-Allgeier, and Eberth titled New Perspectives on Horned Dinosaurs: The Royal Tyrrell Museum Ceratopsian Symposium (Life of the Past) and available on Amazon or in chunks of readable text on Google. To ask James Kirkland what he thought about the paper and discovery personally, we only have to look in the archives of another blog, Archosaur Musings written mainly by Dave Hone, where Kirkland authored a guest post. This, as opposed to many other recently named dinosaurs, is that availability of information one expects to see in the modern age, though we have to actually be aware of the fact this is actually an extremely rare exception to the rule even in this day of free flowing information. Publishers and authors and media sources in general still charge for this sort of information, which they have to to survive, and is thus understandable, but lamentable as well. While reading that paper, enjoy this wonderful artwork depicting two Diabloceratops by Paulo Marcio from Brazil (note the nasal horn the artist has added into his interpretation):

©Paulo Marcio

Not Quite A Movie Star

Diabloceratops, as a new dinosaur, is under the radar in terms of appearances on film. We have visited this issue before in discussing how newer dinosaurs are less likely to appear in documentaries, movies, or television shows for a number of years and then, even after a century or more, how some still do not get chosen to be represented in any way shape or form of motion entertainment. In some instances it is very odd that certain dinosaurs are not shown in movies etc. but with a dinosaur like Diabloceratops, only recently described and revealed to the public, that sort of thing is both very understandable and makes a lot of sense. There is a fairly well done tribute video, though I put it on mute after about ten seconds (we have discussed my dislike of musical choices for tribute videos many times over I think by this point), but it highlights some great illustrations and shows many interpretations of Diabloceratops by some very good artists, and we really cannot complain about that.

New Dinosaurs and Children

New dinosaurs always seem to be lacking in the "child friendly" areas of the internet, which really just means that we, as a paleontologically (I think I just made up a word) minded community need to put in the effort to build a better network for the children of the world to learn about all dinosaurs. I think I dive into this topic at least once a month. Had I the resources and know-how I would do it. Perhaps I will use some free time to learn how to make a killer website and put it together...

However, for the nonce, to sound sophisticated this morning, we shall have to make due with what we have to teach children about Diabloceratops. One would imagine that such an ornate and crazy looking dinosaur would have already accumulated some websites devoted to it or some of our favorite children's websites would have dredged out space for such a wondrous creature. I know that the newly, in the last year, opened Natural History Museum in Utah there is a Diabloceratops skull mounted on the wall (look in the lower center of the picture of the wall mounted ceratopsians) and, at the time that this entry was written about the museum, there was one in what was called the Paleolab that could be shown to eager youngsters. If you live in Salt Lake, or near enough to take a day trip some time, it looks as though it would be a wonderful museum to take a family to. I wish it had been there, in this capacity at least, the last time I was in Salt Lake, but in 2003 it was probably a vague thought in someone's mind. Toys and cartoons do not exist for Diabloceratops, neither do dedicated coloring pages (though you can always ask Andrey Atuchin nicely if you can use his line art to color, he's a nice guy, or Elijah Shandseight, though I do not know him at all), which is both unfortunate and sad.

Facing Diablo

©Taylor Made Fossils, Replica Cast

Diabloceratops, as mentioned yesterday, has a wicked looking set of horns on its face. Those horns were discovered in the original skull, which I think is the only skull discovered so far, and were almost entirely intact, which is an unusual feat in the arena of paleontology. The skull was found compressed, not crushed, with one side of the skull missing many key elements; the uncompressed side of the skull represented all of these elements well enough that a reconstruction was possible to create a full scale replica of the skull as it would have appeared in life, that is, non-compressed and in the correct living dimensions. The brow horns of Diabloceratops are unique amongst the majority of the centrosaurines not only because they exist, the vast majority of centrosaurine dinosaurs do not have actual horns above the brow ridges, but also because of the sheer size of those horns. Albertaceratops, another centrosaur, had brow horns as well (Greg Paul  2011 places Diabloceratops within the genus Albertosaurus), but the horns of Albertaceratops are slightly shorter than those of Diabloceratops. The frill horns of Diabloceratops are not abnormal, though, for the centrosaur family. Styracosaurus, for example, has a frill full of horns and is a contemporary of Diabloceratops, though is assumed to be slightly larger.

©Walter Myers at Arcadia Street

Walter Myers has been kind enough to show us the relative size of Diabloceratops compared to a living animal; the rhinoceros. Styracosaurus is a centrosaur that is a great deal larger, however, the frill of Diabloceratops almost makes the animal look just as big as its bigger cousin. This week, however, we are far more interested in Diabloceratops, so let us back away from Styracosaurus and Albertaceratops both and get back to Diabloceratops. The average white rhinoceros, that pictured, tops out at about 15 feet (4.6m) long and 6.6 feet (2m) tall weighing it at around 7,000lbs (3,500kg). As we can see with Mr. Myers illustration. To add in even more perspective, the horn of a white rhinoceros, perhaps this rhinoceros as well, averages approximately 35 inches (90cm) and can top out at 59 inches (150cm). This rhinoceros, assuming its average, shows by proxy that the horns of Diabloceratops' brow horns are approximately the same size as the nasal horn of the white rhinoceros and the frill horns are easily nearly double that size. Everyone can also easily observe, from both the illustration and the photographs of the replica skull, that there is no nasal horn present, that we know of, of course, present on the skull of Diabloceratops. Most centrosaurs present with nasal horns, with the exception of Diabloceratops (obviously), Alberaceratops, and Pachyrhinosaurus.

Wicked Curves

©Nobu Tamura

Discovered by Donald DeBlieux in 2002 (which rhymes just a little), Diabloceratops eatoni was named and described in a paper published in 2010 by DeBlieux and James Kirkland; Kirkland had the lead authorship on the paper. The specific name is in honor of Jeffrey Eaton, a paleontologist, and the genus name was taken from the "devil horns" of the skull. As a Centrosaurine Ceratopsian, Diabloceratops is a slightly smaller dinosaur than animals like the later Triceratops, a Chasmosaurine.What DeBlieux uncovered in the Utah "badlands" of Grand Staircase National Monument was a partial skull with the wickedly curving horns and a part of the lower jaw; the typical amount of skeleton that is usually associated with Ceratopsian digs (larger amounts of partial skeletons have been found, do not take that to mean all we ever find of Ceratopsians is their head). Kirkland noted that Diabloceratops is an extremely early Ceratopsid with many Protoceratopsid anatomical markers in the skull; perhaps even more Protoceratopsid markers than true Ceratopsian markers including fenestrations which would later close or disappear in geologically younger genera and species.

Popular Enough For Amateurs

Shapeways model by Adam Doyle

I do not know the whole story with this model, but I think I understand it to have been digitally sculpted and then 3D printed by an amateur dinosaur toy enthusiast; the fact that dinosaur toy enthusiasts can now sculpt and print their own scaled models of dinosaurs says a lot for how expensive quality models are and for how wonderful technology has become. Models like the one to the left are probably still somewhat expensive, in terms of toy models of dinosaurs, but these 3D printings are usually as cheap as the material that is chosen to be sculpted, and could thus be, overall, a lot cheaper for a single toy than a single model at Toy'R'Us where the model is marked up three to four times by the time it gets to the shelf! Regardless, Chirostenotes being popular enough for amateur toy sculptors and enthusiasts to go to the length of creating, ordering, and printing off 3D models is notable. The other major outlets in which we find Chirostenotes have been briefly examined over the week, such as in Dinosaur Train episodes, and has also appeared in some books, though I did mention that those books are typically the much higher reading level books on Sunday when I discussed children's books and how I could not find many, if any, for this animal. Tribute videos exist, as they do for most animals, so that is nothing at all new to our popularity days.