Discovering Staurikosaurus

Staurikosaurus was named in 1970 and discovered a while before that; 1936 to be exact. Edwin Colbert, the American that named the dinosaur, had the fortune of having the specimen loaned to him for study. His description and comparison with other materials lead to the discovery that this "archosaurian reptile" was one of the earlier dinosaurs of the Triassic. He named his new discovery after the Southern Cross, a constellation, and after the man responsible for the collection of this and many other discoveries in the Brazilian Triassic soils. His initial description of the material is very in depth and contains some nice plates; there is a combination of illustrations and photographs in the paper. Another paper which may warrant attention is a slightly newer paper by D.B. Brinkman and Hans-Dieter Sues. Their paper identifies and describes a Staurikosaurus sp. from Argentina's Ischigualasto formation. They also describe the relationships between Herrarasaurus and Staurikosaurus as sister taxa as well as confirm the placement of Staurikosaurus within the dinosaurs. There are a few other papers out there, but I think these two are good for one day as they are both a bit heavily detailed.

Fun with Art Snippets

Staurikosaurus, the Triassic dinosaur, is, as we noted, somewhat popular. That has led to a couple "tribute" videos as well as some video game references. As usual, not every single image in the tribute videos that pop up from time to time on the internet are carefully reviewed and are therefore not certainly the dinosaur in question. However, given that a good amount of skeletal material is missing from the discovered remains the illustrated versions of this dinosaur are, as we have seen, highly open to interpretation by the artist in terms of the exact reconstruction of those missing elements of the skeleton. That, then, leads us to these tribute videos that are widely open in their own interpretation of the dinosaur they are showing. There is an amount of fault of the people that create the videos in not finding images of the animal correctly or, worse, accepting every labeled animal they see as an authentic representation of that dinosaur. Some of that incorrectness is always found in these videos, but generally we can look beyond it. Though I know that I have had to edit posts from time to time, it concerns me a little more when these videos are massively incorrect in what they represent because sites like YouTube have such heavy traffic; though we can probably assume that a third of the traffic on the site is directed at a minority of the videos on there. Regardless, it is nice that the video has been posted and has views because it means that someone is interested in Staurikosaurus.

Staurikosaurus for Kids

Staurikosaurus has links for kids, which is pretty neat for a little understood early dinosaur. Thankfully, the Dinosaurs for Kids site has a nice quality page that is easy for kids to garner information from. Coloring pages are a little bit lacking, but that may have more to do with the fact that Staurikosaurus is still a little known dinosaur. The Dino Directory from the Natural History Museum of London also has a page set up for some facts that are easy for kids to read. Their size chart looks a little bit off, though; the Staurikosaurus is a bit larger than it probably should be.

The Completed Incomplete Skeleton

Oscar Alcober, Ricardo Martinez; retrieved from Wikipedia

The amount of skeletal material associated with Staurikosaurus actually fluctuates depending on the source, which is quite odd. Usually some sort of consensus of what skeletal element belongs to what animal gets hashed out eventually amongst scientists. Staurikosaurus, however, is, to my knowledge, composed of only the skeletal elements presented in the anatomical drawing shown above. Paul's latest illustration (via the Princeton Field Guide) shows a substantial amount of skeletal material in addition to this material. I saw no mention by Paul or other sources that cite where this material came from, though I have not done a comprehensive literature search for the week as yet so it may be that in a paper I have yet to review this week that the additional material comes to light. Until then, this is the material that was briefly presented yesterday. As can be seen, it is not extensive, though it is a fair proportion of the skeleton and the basal nature of the remains discovered do allow for some assumptions to be made as to the missing elements and their appearance.

©Dmitry Bogdanov

The exact structure of this early dinosaur is a bit "up for grabs" despite the assumptions that can be thrust upon the animal given its basal nature. In a similar image Nobu Tamura illustrates a similar but radically different anatomy for Staurikosaurus. Neither image can be attested to as perfectly correct but they both draw upon the knowledge of the primitive nature of this dinosaur. Dinosaurs of this size were just getting their start in the Triassic and as such were not the apex predators we see in later fossils, but were still quite capable of taking down prey. The manner in which they did so was a little less "dinosaur-like" than when we think of Tyrannosaurs and that sort of large apex predator. Hypothesized to brandish a five fingered hand and foot, these early dinosaurs had small heads and may have had claws that were used more for holding down prey than as killing implements. The Komodo dragon, or maybe even the Green Iguana, may have similar styles of feeding to what Staurikosaurus may have exhibited.

©Nobu Tamura

Both the Komodo dragon and Green Iguana both use their forelegs to hold down food items while pulling with their mouths. Staurikosaurus was bipedal as far as we know though, so does this necessarily make sense? The purported five fingers of Staurikosaurus, a body plan shared with the dragons and iguanas, would have enabled the dinosaur to maximize the flesh it held down as its jaws, which would have had to have been fairly strong, tore pieces of flesh from its victims; there is no knowledge as to whether or not Staurikosaurus was primarily a predator or a scavenger and an herbivorous diet is considered unlikely given the theropod body plan (please keep in mind that Therizinosaurs, though theropods, are considered herbivorous).

Journeys in the Triassic

We have not been to the Triassic in a good long while, but today we shall venture back there. Herrerasaurids are some of the earliest theropods and, arguably, some of the least understood still. Often this is due to incomplete fossil finds, such as the animal that will be discussed this week. However, a good portion of the post-cranial skeleton of this dinosaur has been recovered in Brazil, of all the places in South America. Typically when we here "dinosaur" and "South America" in the same sentence we typically think of Argentina and Jose Bonaparte. However, Staurikosaurus pricei was named by Edwin Colbert, born in Iowa, and more renowned for having a hand in the discoveries of Ghost Ranch, New Mexico, a lot of systematics work, and his work in Antarctica, just to name a sliver of the things he accomplished during his 96 years of life. Colbert's name for this 225 million year old agile bipedal predator translates to "Southern Cross Lizard" with the specific epithet being in honor of Brazilian paleontologist Llewellyn Ivor Price, who had actually collected the fossil. The fossil, as stated, is made up of quite a good portion of the post-cranial skeleton as well as the mandible. Hindlimbs, the pelvic girdle, and the vertebral column are nearly complete; however, the feet and forelimbs, ribs and cranial elements other than the mandible are lacking. All told, animals have been named on far less and the bones present indicate a predator that, at about 66lbs (30kg), 31in (80cm) tall, and 7.4ft (2.3m) long, was about the weight of the average Labrador Retriever but just a tad taller (and obviously longer). The remains that have been discovered and the primitive age of this dinosaur, however, have led to some educated guesses pertaining to the make up of the missing skeletal elements. Chief amongst these are depictions of the hands and feet of Staurikosaurus as five fingered and toed basal appendages. The running speed of Staurikosaurus, despite the primitive foot and pelvic girdle, is considered to be fairly quick given the structure of the legs. The long tail consisting of approximately 40 caudal vertebrae would have aided the quick little dinosaur in maintaining its balance at its higher speeds.

Panoplosaurus the Loved

Japan loves dinosaurs!

Panoplosaurus, as we have seen this week, is quite a loved animal. There are cartoons and mentions in books and many other places. Why, then, is it not as readily distinguishable from other dinosaurs like its cousin Ankylosaurus? I shared the crochet patterns and many different information sources and I made note that Panoplosaurus is discussed in many different books. With all of these different resources surely we should have a more automatic reaction to a picture of Panoplosaurus or a more ready identification at least of the animal. Panoplosaurus is popular enough in the dinosaur continuum that it has appeared in Dinosaur King and was even given away by Nabisco in the past; though it was mentioned to be a species that does not exist. Panoplosaurus has also been popular in museums as it has been displayed all over the country (I do not know about internationally). Not many people really seem to dislike Panoplosaurus though, so it does not come as much of a surprise that it would be on display in so many museums.

Lambe's Next Discovery

As has been discussed multiple times here, Lawrence Lambe was a prolific discoverer and describer of dinosaurs. Fortunately for him any rivalries he was a part of were not nearly as high profile as Marsh and Cope, which allowed him to focus a bit more on accuracy than volume; I think of the Marsh and Cope volumes of descriptions as having "machinegun accuracy" as opposed to the idea of one shot, one kill. Lambe was not, however, more often correct than Marsh or Cope, as the science has tweaked even his discoveries and ideas over the past century. Regardless, the point of bringing up Lambe is that we have his initial descriptions of this animal and can therefore look at the material secondhand rather than via many other sources. Over 200 scutes of armor, a good portion of a fore and a hind limb, a good portion of the cervical vertebrae articulated with the skull, pelvic and shoulder girdles and thoracic vertebrae were discovered together and delivered to Lambe. Lambe, however, did make an interesting mistake by placing Panoplosaurus, now known to be a Nodosaur, in the Stegosaur family (Stegosauroidea); he also assigned Euoplocephalus, another ankylosaur, to the stegosauria. Contained in the in depth descriptions of the skull we find that Lambe measured individual teeth in the skull and compared them to Stegosaurus, leading, in part, to his justification of this nodosaur as a stegosaur.

Lambe was not completely off, though, as the current convention holds that Stegosauria and Ankylosauria make up the clade Thyreophora as the Eurypoda (Scelidosauridae is also included outside Eurypoda but within Thyreophora). Lambe's attention to the detail of the armored scutes probably provided some of the best evidence, in later years, for the partitioning of the Eurypoda into Stegosauria and Ankylosauria, interestingly. I wish I had an exact paper to point to in reference to this change. Alfred Romer's 1956 Osteology of the Reptiles is widely considered, however, to be the definitive text for establishing Ankylosauria as a suborder within Thyreophora (Coombs and Maryanska. He divided the over 200 scutes into 7 major divisions; 1) Large plates; 2) Medium sized variable dimensions; 3) Moderately small keeled; 4) Small rectangular; 5) Small polygonal; 6) Small keelless; and 7) Irregularly shaped ossicles. He also included plates of the scutes, but my favorite plate is of the skull looking from front to back. Check it out:

References for today:

Coombs, W.P. and Maryanska, T. (1990). Ankylosauria. In Weishampel, D. B., Dodson, P., & Osmólska, H. (Eds.). . The Dinosauria. (456-483) Univ of California Press.

 

Lambe, L. M. (1919). Description of a new genus and species (Panoplosaurus mirus) of armored dinosaur from the Belly River Beds of Alberta. Transactions of the Royal Society of Canada series, 3(13), 39-50.

Systematics and Panoplosaurus

Kenneth Carpenter wrote, a few years ago (1992 was the original publishing year), an article in a text collectively called Dinosaur Systematics: Approaches and Perspectives. The text as Carpenter writes it, though you cannot read it all online, uses Edmontonia and Panoplosaurus as examples for Ankylosaur systematic arguments. Carpenter has published many other writings concerning Ankylosaur systematics as well and discussed Panoplosaurus in many of the articles. Most of his published articles, unfortunately, appear in edited anthologies and are therefore unavailable online. Coombs and Maryanska also discuss Panoplosaurus' anatomy in the original edition of The Dinosauria; the newest edition Ankylosauria section is penned by Vickaryous, Maryanska, and Weishampel and, of course, still mentions Panoplosaurus. Paul's Princeton Field Guide to Dinosaurs also mentions Panoplosaurus and that it enjoyed forested floodplains, swamps, and marshes. While the cartoon yesterday noted that Tyrannosaurs were the main threat to Panoplosaurus, Paul makes note that the main threats to Panoplosaurus were most likely Daspletosaurus and Albertosaurus. Not many scholarly papers are uniquely geared toward Panoplosaurus, which is okay, but still gives us little to read if we do not own one of these books.

Earth Day Post!

Happy Earth Day friends! Today I have two videos I want to share with you. One is a short informational cartoon starring our friend Panoplosaurus, and the other is a short computer model of the cranium and brain of our friend previously mentioned. The cartoon sort of speaks for itself and delivers some information in a manner which will be good for kids to digest it. The second video really does not say anything, but it is a nice visual and it is a good example of what rolls out of Dr. Witmer's labs from time to time at Ohio University. I am pretty sure at this point that everyone knows what to expect when they know the scans and models come out of his work and his student's work, but it is still fun to look at, so enjoy!

The Children's Nodosaur

Panoplosaurus is a child-friendly dinosaur. Not only does it look as though it would make a great pet; in the human world this is the sort of dinosaur that would undoubtedly be selectively bred as a lap-dog. Perhaps that is the reason they are so well represented in the child-friendly web pages around the internet. Our favorite child-friendly fact page at Kids Dinos has page set aside with quick facts. Additionally, the coloring page needs of children, and adults, can be taken care of over at Enchanted Learning. As usual, the site allows for online coloring as well as printing the picture and coloring offline; I hate the waste of paper, but I love the feeling of colored pencils, so I am typically torn equally when presented with the option. There is not much in the form of toys/models available for sale, but for our friends that know how to crochet, and I wish I did right now, you can make your own toy Panoplosaurus with these crochet patterns available for purchase. Grandmas usually love knitting and crocheting, not that younger people do not, and they would probably love to make one for you, and with you even, if they know how to do those things!

A Long Day Ended

©Brian Franczak

This is a late entry because I just got back in in the last few hours from doing some work on a National Wildlife Refuge. They were counting species of everything on the refuge. I helped with birds mostly. Anyhow, due to the lateness of it, and the fact that I am just plain tired today, I am not going to put up a lot of art today. Strangely enough, this was the perfect dinosaur for such an event to cause a lack of illustrations to be posted for. Panoplosaurus was a pretty basic nodosaur. Not only did it have a basic body plan, but it did not have many ostentatious ornamentations on its body. These things all coming together give us a fairly typical nodosaurian dinosaur, which is pretty much what we expect when we think of ankylosaurs and nodosaurs. That does not make this a bad thing at all, but it does make it a somewhat bland dinosaur in some aspects. I still think you look pretty nifty Panoplosaurus, even if you are kind of bland.

A Panoply of Armor

Uncredited (I am on the lookout for it)

Back in January I discussed an infant dinosaur discovered in Maryland that came to be called Propanoplosaurus, meaning "before Panoplosaurus". Perhaps I should have followed that closely by the dinosaur that the name somewhat came from, but I obviously did not, because I am discussing it this week. As with many other large herbivores of the Canadian and Western US' Cretaceous era soils, this is a wide, heavy, armored animal. Panoplosaurus was big in most every way. Its head was heavy and covered, dorsally, in thick bone. The thick cranium of the animal is not much when compared to the scutes discovered along its back and even along the caudal vertebrae of the tail. A Nodosaur, Panoplosaurus mirus ("totally armored lizard"), weighs in at approximately 6000lbs (2721.6kg or about 3 tons) and reaches lengths of 23ft (7m) for a middle sized individual.

A Good Giant Raptor Week

Looks a little naked though

I shared the image I posted with my wife last night. She freaked out. Apparently birds bigger than people are not very appealing to her; admittedly Great-tailed Grackles kind of freak her out with their size, let alone being a bird. For all of her freaking out around birds she does do a great job driving me around to photograph them, but I digress! Giant bird, giant Eumaniraptoran, or smallish dinosaur; whatever way you choose to describe Achillobator, it has been an impressive dinosaur to research and discuss. In terms of popularity out in the world, we have mentioned a small number of popular references already this week. What we have not seen as yet, however, is the video game contributions. Creators in Spore have gone to work making their own Achillobator models; I think this one is the most robust and interesting one to the left here. Additionally, and I find this kind of funny, there is apparently an island in World of Warcraft that has at least one giant dinosaur living on it that will occasionally produce an item called the Achillobator Ring when defeated. That is a different thing to share in terms of pop culture references generally shared on this site! Unfortunately, the popularity of the animal kind of stops there. In 2003 there was a short jolt on the dinosaur mailing list. That has pretty much disappeared from the record though (I found it on page 4 of the Google hits for Achillobator). Tomorrow I think we may start a week that is a little bit more popular, but I can never tell until we get really rolling. Hopefully this week will help Achillobator get some more attention; it is an interesting enough animal to deserve it!

Close Cousins?

Utahraptor on top, Achillobator below. Used with permission as noted on the image.
Taken from A Field Guide to Mesozoic Birds and Other Winged Dinosaurs

Utahraptor and Achillobator were related, somehow. They were the largest raptors in their homelands. They were also strangely "backwards" in terms of the evolutionary lines of their family; some of their character traits seem rather basal for somewhat advanced dinosaurs. These animals were both large terrestrial theropods built with squat bodies (compared to other raptors) that housed large muscle masses more likely to wrestle opponents and overwhelm them with sheer strength than lightning quick attacks. That is not to say that neither of these animals may have been able to execute quick attacks at opponents with jaws or claws; both of which would be devastating weapons. Two hypotheses have been circulated as to the use of giant toe claws of raptors but I think that I would be correct in saying that the more popular hypothesis still is that the claw was used to stab and slice through the arc of motion of the leg. The claws that both of these predators possessed, though through extrapolation of bone shards alone for Achillobator at this point, would have cause massive damage with such behavior. The less popular hypothesis is that the toe claw was used as an anchor for grasping onto prey while teeth and hands shredded the vital arteries and soft paunches of large herbivores. There is a bit of evidence behind that sort of behavior but there is also support for the other behavior hypothesis. However, with animals such as Utahraptor and Achillobator the second hypothesis, that of a grappling animal rather than a quick striking animal, has quite a bit of merit.

Achillobator was an Asian animal, in modern context, and had a different landscape for a home. The Mongolia of 90 Mya was a semiarid desert, kind of like some of it is today. The Utah of Utahraptor, which is considerably older at 125 Mya, was a marshy mud flat with open tracts of land. The squatness of both animals was most likely an adaptation that favored the reduction in length of hindlimb to produce the ability to hide closer to the ground in the low scrub environments in which they lived. Utahraptor lived in a time devoid of large predators; allosaurids, ceratosaurids, and megalosaurids had all disappeared from the landscape during the existence of Utahraptor. Large carnosaur reintroduction into the landscape likely led to a loss of niche and subsequent dwindling of population and eventual extinction of Utahraptor. Achillobator lived alongside many other carnivores, though. Until we have a better range of existence data for Achillobator we cannot really surmise the events leading to its disappearance from the fossil record.

Reference of the day:

Martyniuk, M. P. (2012). A Field Guide to Mesozoic Birds and Other Winged Dinosaurs. Pan Aves.

Books, Birds, and Elusive Papers

Scientific writing. I am still trying to wrap my brain around it. Over my lifetime I have developed a style, and it can be seen here quite well, but lately I have been tasked with writing scientific papers and they have not been pretty. One would think the more I read the better I would get at writing in that style, but not quite so yet. That makes the days I discuss papers that much more important in my own personal development. Today I, unfortunately, do not have many papers to share. I still have not found a way to get the original naming paper, not by the end of this week at least, but there are other essays and papers that refer to Achillobator in them. There are two papers that discuss evolution in Gondwana of dromaeosaurs and a paper on evolution of the dromaeosaur tail. The paper on Gondwana also describes a new Patagonian theropod (as of 2009). That theropod was named Austroraptor cabazai in the paper. The paper on dromaeosaur tail evolution also discusses and names a new dromaeosaur from Utah. Two specimens were not named but the third specimen was name Yurgovuchia doellingi. Achillobator comes into play in these papers in that the discussion of evolutionary lines in both papers mention Achillobator. Both Greg Paul's Princeton Field Guide to Dinosaurs and Matt Martyniuk's recently released Field Guide to Mesozoic Birds and other Winged Dinosaurs contain entries on Achillobator. Martyniuk's entry is longer and speculates a little on behavior inferred from the skeleton. Additionally, Martyniuk has illustrated a squat little Achillobator to accompany the entry (Martyniuk's "field guide" is much more like a modern fauna field guide in respect to illustrated specimens with entries).

Not A Video Day

©Jaime A. Headden (cropped for today)

Movie Monday has a sad showing for Achillobator, which, given its low skeletal remains content, is not surprising but is unfortunate; this is a pretty fantastic animal as we have seen so far. There is one of those "tribute" videos with music that I am perpetually saying I do not like. The largest problem with that, however, is that a lot of the images used are of nondescript "megaraptors" and other animals that are not Achillobator. Therefore, rather than have a very short post about nothing, let us look specifically at the legs of our mythical warrior.

The legs of Achillobator, despite the overall size of the animal, are quite small. Tibia and tarsus both are extremely short compared to the femur, though, admittedly, the heads of the tibia and tarsus both appear to be either missing or broken and chipped (though I have to admit I am going off of 2nd hand illustrations still). Shorter legs generally require higher energy consumption than longer legs to cover equal distances. The Achilles' tendon of Achillobator, obviously lending itself to the name, was reported as having to have been rather large, however, even on the shorter leg. The large tendon and the short leg most likely packed a rather large punch, causing great damage through the arc of the swinging motion of the leg. Not possessing as much speed but, rather, being more like the muscle laden Utahraptor, Achillobator was probably much more likely to wrestle and bring down prey with power than tiring it out in pursuit. This, then, would also make it much more likely to be an ambush predator like a lion rather than a pursuit predator like a cheetah. Of course, this is not necessarily the view put forth by the paper, but I cannot state the author's viewpoint as I still do not have a copy of the paper.

A Nice Day for Coloring

After a very windy night I am quite happy to say I have quite a few good things to share today. I do not want to go into anatomy today; I know I said a few days this week I may not do the "normal" themed topics of the day. Today is not one of those days. I have quite a few good links and pictures for today. First, let me say that there are quite a few bad links too. The Natural History Museum of London, for instance, has a pretty good set of information, until you get to the specific epithet, which is wrong. It could just be a spelling error, so let us not dwell on it! Another almost awesome fact site is found at AgeofDinosaurs.com. The only issue with their facts is that they do not tell the whole story of the discovery, instead using the year of publication as the year of discovery. Putting the two sites together and ignoring the two little mistakes makes for a good collection of facts. Combine those with these two coloring pictures and you have a good day to explore a new dinosaur with your loved ones:

Artist's Page

Looking at Skeletons

©Jaime A. Headden

The skeleton of Achillobator, as we have noted, is not complete. The fact that it was, and still is sometimes, thought to be a chimera is because the associated elements seem to come from all over the maniraptoran family. Were this a whole skeleton it would, because it possesses so many different elements, be a rather interesting living (well, dead) case study in skeletal transitions. Arguably the most recognizable element of the dromaeosaur family that is thought to be present, a second hypothesis places this bone on the hand, is the large "killing" claw of the "raptors". The size and length are inferred based on the heel of the phalanx that is said to represent the claw. Other elements of the skeleton also refer the animal to the maniraptoran family including the maxilla that was recovered.

The maxilla appears to be the end of the snout, thus encompassing the pre-maxilla as well, in some renditions though we can see clearly in the previous illustration that the maxilla only is interpreted as being represented by this piece of the puzzle. The ridges shown in what we would expect to be a widely opened fenestra are notably rare for all theropods, but it is seen in at least one other theropod. This rarity adds to the mystery and further confounds the findings with the teeth. The teeth are consistent with the sizes and ratios of length, width, curvature, etc. found in other dromaeosaurus and even troodontids. Visual comparison of the overall shape of the teeth supports that assertion, though we know just looking at something can be considered weaker evidence than the measurements of the teeth; thankfully we have both.

©Jaime A. Headden
Key to pelvises: A, Deinonychus antirrhopus; B, Adasaurus mongoliensis; C, Unenlagia comahuensis; D, Achillobator giganticus; E, Microraptor zhaoianus; F, Velociraptor mongoliensis; G, Sinornithosaurus millenii; H, Rahonavis ostromi; I, Bambiraptor feinbergorum; J, Archaeopteryx lithographica; K, Sinovenator changii.

One of the other issues that has been raised with the remains attributed to Achillobator is the odd morphology of the pelvic girdle. Looking at the pelvis, D in Mr. Headden's illustration, we can compare many of the elements to the other pelvises of maniraptorans that are also illustrated up next to it. Of particular note are the pubic boot, the "lowest" part of the pelvis in layman's terms. The shape is clearly different from all of the others in that it is almost completely ventrally flexed and it projects both anteriorly and posteriorly at the same time. This is a carnosaur related trait more often than it is a maniraptoran trait, as we can see above. Compare it to this carnosaur's pelvis.

References

Headden, J. A. (2002). Achillobator: Theropod Puzzle. Retrieved April 13, 2013, from Qilong: http://qilong.8m.com/Achillobator.html

Tackling Another Tough Opponent

Long time readers know that I enjoy, perhaps even love, taking on difficult cases from time to time around here. This is actually becoming slightly more normal as we get lower in the popularity barrel of dinosaurs. When we first started out the Triceratops and T. rex icons still stood before us and there were vast fields of papers, opinions, models, and other research to draw upon. Then we found our first few "iffy" animals; dinosaurs that were in doubt or, like Monoclonius, had actually been relegated (reassigned) to other genera and referred to other species. This week we shall continue looking at a problem child, in some eyes still despite some positive arguments for the validity of the subject, of the dinosaur world. At approximately 16 feet (4.9m) long and possessing bones that seem to make it drift up and down the family tree of the maniraptorans, this week's dinosaur was called Achillobator giganticus. The animal was named based on the fact that the Achilles' tendon would have been enormous in this animal and the word "bator" in Mongolian means hero. The specific epithet giganticus kind of speaks for itself, I think, in relation to what we will see of it and how it related to other maniraptorans. The trouble that has surrounded this large animal is that the bones, those bones that cause its relationship to winnow up and shimmy down the family tree, are characteristically in many different positions of expected development and this has led to the cry of "CHIMERA!" by some in the paleontology community over the years. During this week we will look over these bones and hopefully by the end of the week (I may need to tweak some of the days' themes to cover everything unique about this animal), we will all be able to form our own thoughts on the validity and perhaps even a generalized relationship of Achillobator with other maniraptorans.

©Matt Martyniuk

The Charismatic Stego

From How to Draw Incredible Dinosaurs to its inclusion in Dinosaur King, Gigantspinosaurus has been made quite welcome in the popular culture of the world. Considering that it is little understood and the exact physical orientation of its namesake spikes are still debated in many circles, it is interesting that it is popular already. In part it owes its face to the public to the fact that it has been around as long as it has even with its "dubious" name being out there for the first half of its existence (in our knowledge that is of course). Strangely, however, I cannot seem to find toys and models of Gigantspinosaurus, and we can all admit that that would make a fantastic toy/model. There are a myriad of Dinosaur King cards that depict Gigantspinosaurus, but that is a little bit different; a card game is not the same as a 3-D model. There was this promotional piece from Dinosaurs Unearthed, but that does not really qualify as a mass market toy. Spore, though I could not find videos this week, does have some creators that have engineered little Gigantspinosaurs, like the one found in this image.

Gigantic Spikes and Not Fully Grown

©Vladimir Nikolov

The skeleton of Gigantspinosaurus with those wonderfully large spikes is not even thought to be an adult skeleton. Imagine if these spikes were still growing when this individual died. Hopefully they did not grow too much larger, due to the stresses of carrying even larger spikes, and, if they were to stop growing in this sub-adult then they would appear somewhat smaller in comparison to the adult skeleton. If that turns out to be the case, as it could with future discoveries, then the name may almost be a misnomer because the shoulder spikes will not be as enormous or gigantic. Other issues arise with the idea that this is a sub-adult skeleton rather than a full grown adult skeleton. Some of these issues could be, of course, different bone sizes, muscle attachments and sizes, differences in dorsal plates, and even the "thagomizer" could be radically different; though I doubt that the "thagomizer" would be different. The skull is also mostly absent from this skeleton, meaning that the head is based on the basic stegosaur model rather than skeletal material. It is thought, though, that head was rather enormous as well; the lower jaw remains that were found seated about 30 teeth in each side.

Paper Day!

Everyone loves paper day. Today we have scholarly papers on Late Jurassic stegosaurs as well as mentions in evidence of early stegosaurs in China. A lot of the stegosaur papers that mention Gigantspinosaurus are fauna surveys of China or the overall Jurassic landscape. The history of the stegosaurs is actually quite well documented with body assemblages having been reviewed many times over the history of knowledge of the stegosaur family. Stegosaurs are a very popular family of dinosaurs, even more than most people seem to notice. The sheer number of papers on stegosaurs is astounding, however, not many of those hit specific specimens from China in great amounts of depth. Regardless, a pretty good overall picture of China in the Jurassic as well as the life of Gigantspinosaurus can be obtained by reading portions of the papers that deal with the overall behavior and the land of China during the Jurassic. The most unfortunate thing about trying to find stegosaur papers about Gigantspinosaurus is that the original paper, a 1986 paper by Gao and Huang, is in Chinese and not published online anywhere. So, in lieu of that, read the four papers, if you are feeling up to it, to get a good picture of Gigantspinosaurus and their world and have a great day!

Animatronics

I love finding videos that people shoot at little amusement parks or zoos, like the Memphis Zoo, that have seasonal dinosaur exhibits. Actually, the one at the Memphis Zoo is particularly well done and even outdoes the museum in Memphis. It is a recurring exhibit in the early summer or late spring, depending on the exact week it opens. If anyone is interested check out some of the photos I posted from last spring's exhibit over on this page. However, I am sad to admit that there was not a Gigantspinosaurus there. There is, however, one at King's Island in Ohio. I have not been to King's Island in a long time, but it looks as though their Dinosaur's Alive section of the park is fairly popular and they have a Gigantspinosaurus, which is pretty amazing. It is not the most accurate version ever, but it looks pretty good for a theme park dinosaur. It is also captured on video, the only Gigantspinosaurus video I have seen in my search today:

Some Kids Links

It is really nice outside today, a little windy, but nice. However, until now, I have been locked inside studying (boo studying, yay good test scores!) . I plan on going on a walk soon, but before I do, for those of you stuck inside because it is not nice, or it is nighttime wherever you live, here are some things to do. One is reading a child friendly fact page. It is not so much child friendly in that it is quick facts like I usually find, but the language is a bit easier for a younger audience I think. The name of the site is Dinosaur Jungle. Not a bad name really. You could do a puzzle if this 3-d puzzle was in stock, too bad it does not seem to be. So you can make due reading or perhaps coloring your own (or Zachary Miller's) Gigantspinosaurus drawing. It actually would not be too hard to take this rather simple how to draw stegosaurus tutorial and add some shoulder spikes!

Flying Stegosaurs

Prior to the readjustment of Gigantspinosaurus (I meant to admit yesterday that I find it very hard to not write "Gigant-o-spinosaurus" like its written in the figure caption) it appeared as though this rather large dinosaur was poised to take flight at any moment. In my head I can even see a cartoon in which the animal can move those shoulder spikes between those two positions, though that would be uncalled for, energetically taxing, and require a very odd set of muscles along the shoulder and back. Regardless, I am pleased to note that the spikes have been allowed to assume a more relaxed position officially. Either way, the weight of the spike at the shoulder like that would create a considerable stress on the animal whether it was a solid core of bone or mostly a hallow keratinous sheath, so there are definite implications to be considered in regards to those spikes and the impact they would have on feeding, mating, locomotion, display, defense... and we could go on.

Updated 20:33: Just to update the above without tearing it apart and rewriting the whole thing, I wrote the description of that backwards. It should state that the updated version from this diagram has the spikes facing dorsally rather than swinging ventrally. That alone may cause some confusion, and I apologize for that. I think my brain was in backwards this morning!

©Phil Wilson

Unfortunately, prior to the shift in hypotheses, some paleontologists and illustrators did get around to releasing images of the giant spikes of Gigantspinosaurus as protruding downwards from the shoulder. As we have seen, of course, the times change and the illustrations sometimes either follow very closely behind, get left behind, or become classics. The scene portrayed here, though not very old, is a classic representation of the newly hypothesized posture of Gigantspinosaurus' shoulder spikes and is done with very good scientific accuracy. Because that thinking has changed does not necessarily make any illustration outdated and certainly does not make it terrible; everyone has their viewpoints in paleontology and sometimes we simply just do not agree with one another (take a class in paleo with a diverse background of students if you do not believe me!).

©Chuang Zhao

Defensively speaking the spikes were probably much more a deterrent than a weapon; their rear facing angle, either pointed up off the shoulder or down off the shoulder, was not well adapted for thrusting or stabbing at encroaching rivals or predators. Being a stegosaur, even a basal stegosaur or huayangosaur as the case may prove, Gigantspinosaurus possessed a formidable weapon in the form of the tail spikes that were discovered with the skeleton. These were more than likely used in the same manner that is thought that other stegosaurs used their tail spikes to ward off predators. As with other stegosaurs, the dorsal plates were more than likely for display or some other purpose rather than defensive in nature.

Back to Land!

"Oh, hello!"

Basal stegosaur or Huayangosaurine, it does not really matter to Gigantspinosaurus sichuanensis. In fact, this thyreophoran probably was not too worried about much of what was going on around it because it was so well protected. The "thagomizer," I always have to take a moment to thank Gary Larson for inventing that term, on the end of the tail, basal stegosaur or not, is well developed and the shoulder spikes more than make up for the tiny array of dorsal plates along the vertebral column. The approximate size of the gigantic spiked dinosaur was about 14ft (4.2meters) long and about 1500lbs (700Kg) in weight. The first fossils were discovered in 1985 and reported as belonging to Tuojiangosaurus in 1986. It was not until 1992 that Gigantspinosaurus was used but was not accepted until 2006 when the 1992 description was authenticated and determined to be an efficient description. In 2008 skin impressions of Gigantspinosaurus were described and the history of the animal has become more laid out and elaborated upon many times since 1985.

Saying Farewell to Mosasaurs

©Nobu Tamura

Clidastes, so long! Clidastes deserves a lot more than that though. The last of the marine reptiles in this two month odyssey and a fantastic, spectacular animal and one of the best swimmers in its family; it deserves quite a bit more than a casual and quick farewell. While Clidastes is not a favorite of documentaries, books, other videos, toys, or any of the other popular cultural iconography and media that is typically displayed on Thursdays here, it is a favorite of the museums of the world. Partly this is due to the smaller size of Clidastes, making it a fairly easy animal to cast and mount in the limited spaces of museums. Another part of why it is popular in museums is that it can be used to show the history of mosasaurs, the fantastic adaptations of a marine reptile, and, of course, it is mounted in museums for its shear appeal as a sea monster. Who could honestly be unimpressed and unhappy with that devious smile in this illustration? This should be a far more popular animal regardless, and I am sad that it does not have a ton of pop culture references to share!

Locked Vertebrae

Found on a Wikimedia Commons Page

Aside from being the smallest mosasaur, Clidastes has an interesting name. I do not believe I mentioned before that the word mosasaur itself means "Meuse River Lizard," why I did not mention that before I do not know, but Clidastes' equally interesting name means "Locked Vertebrae." Typically when I hear the word locked I assume that there is an element of rigidity to whatever is locked; however, we know from the papers and previous discussion this week that Clidastes was anything but a rigid and immovable animal. In fact, we know that Clidastes was an agile swimmer and quite capable of graceful, perhaps not dolphin-like grace, movement through the water. The locking of the vertebrae actually serves to strengthen that body while allowing for these movements; that essentially means the vertebrae are locked together for stability and strength but still have a range of motion in the horizontal plane that is sufficient enough to allow for the high quality of swimming we expect from the animal. The strengthening of the tail, and entire backbone, also allows for the more intense attachment of muscles to power the swimming mechanism of this fantastic animal.

Clidastes In Europe?

Plate from Lindgren and Siverson (caption on pg 4 (222))

We think of marine species, for the most part, as being pretty much globally distributed. This is because most of us are not marine biologists and we see on television that dolphins, clownfish, seals, sharks, etc (the most photogenic and recognizable animals) seem to live in every ocean that has had a camera crew in it. That assumption, often, is extended back in time as well. That is, though, not the truth. Not until 2004 was a paper published on the first recorded Clidastes find in Europe; in Sweden to be precise. Over 15 years, from 1989 to 2004, bits and pieces of Clidastes skeletons and teeth were collected in Sweden and this paper, by Johan Lindgren and Mikael Siverson set out to describe the collected material and then went on to analyze the geographical implications of a Clidastes specimen being discovered so far away from the typical grounds of Clidastes populations, i.e. North America. The description itself is highly detailed and includes many comparisons to the type species (Clidastes propython), but off greatest interest to me were the sections on paleobiogeography and paleoecology. These are shorter sections but still contain good descriptions and reasoning to support their claims. In the pursuit of not delivering the entire message (and thus forcing readers to read the paper) I do not wish to go into more depth on these two sections here, but I encourage you to read at least those two sections near the end of the paper. Just to support the "sudden find" of a Clidastes in Europe, another paper by Caldwell and Diedrich (2005), announced the "unexpected mosasaur" Clidastes was discovered in northwestern Germany as well and thus backed up assertions put forward in Lindgren and Siverson pertaining to the global, "transoceanic" is the term they use, distribution of Clidastes while stating that they, Caldwell and Diedrich, could more confidently assign a time period to the remains of Clidastes in Europe. A very good day of reading in these two papers alone awaits!

Smallest Mosasaur Video Collection

Surprise! There are no videos. No April Fools' joke here, there just are not any Clidastes related videos. Not even a tribute video dedicated entirely to Clidastes. There is a video dedicated to "sea monsters" that has an image or two of Clidastes, but that is not very useful or detailed in terms of what we have come to expect from Movie Monday. There is also a video that has a computer voice over, which sounds awful and is a very short informative clip. I suppose it is better than nothing, but I hate the days that I cannot deliver as promised on any front, but such is the danger of covering any and all forms of prehistoric life during special months (and the occasional dinosaur that has never been mentioned in any videos as well). A short entry with a small selection is better than having nothing at all to share to educate ourselves though! It may inspire someone out there with some video editing skills to make a short video as well, we never know!