I Have My Own Special

Allosaurus shows up in a ridiculous amount of different documentaries; we all know that Allosaurus is a famous dinosaur with many popular outlets. Walking with Dinosaurs used Allosaurus twice; once in a documentary in the main series and once in a special episode detailing an imagined life of a specimen known to the world as Big Al. Dinosaur Revolution, Planet Dinosaur, and a good number of "forgotten" documentaries from the 1970's through the middle 1990's used Allosaurus as main characters or, at least major characters. The antagonist of Fantasia's Rite of Spring segment could easily have been an Allosaurus, and it may be that it was intended to represent Allosaurus, but it is not entirely well defined as being Allosaurus. One of the more imaginative of those mainline documentary clips would have to be the one linked here from Dinosaur Revolution. One can piece together why I say this after watching it.

Allosaurus Is A Family Dinosaur

The number of Allosaurus links that are geared toward children and lower level readers is admirable compared to other dinosaurs that are popular. New Zealand's Science Kids and KidsDinos have pages, as they do for most any popular dinosaur that one can think of. KidsDigDinos also gets into the Allosaurus craze but some of their facts are a little altered or slightly off base. Enchanted Learning does a good job of loading up all the facts that we normally see in a nice concise manner. As for coloring sheets to do while spending quality family time together discussing dinosaurs today; well, there is a lot to choose from, just check out this set of search results.

Skulls and Horns

Photo by Bob Ainsworth (Oklahoma Museum of Natural History)

The horns I mentioned yesterday consist of dorsal extensions of the lacrimals which make up the posterior boundary of the antorbital fenestra and the anterior boundary of the orbits. Much of the rest of the skull is typical of theropods, though there are characteristics of the skull that are unique to Allosaurus. The fleshed out Allosaurus appears slightly less ostentatious than the skull does as far as horns are concerned; however, the horns are not all that crazy and extended to begin with, so ostentatious appears a bit extreme in describing them. As with other theropods with cranial ornamentation, these could have been species and individual specific anatomical characters that influenced sexual selection and intimidation of rivals. There is no evidence that suggests these horns had any indicative features related to sexual dimorphism. In fact, the only noted sexually dimorphic characters are found in the pelvic region of the skeleton.

©Charles R. Knight

The Allosaurs of Charles R. Knight did not have horns on their lacrimals. That seems rather strange given that the lacrimals of Allosaurus were always there and known after the first skulls were completely recovered. Some small ridge detail is evident in this image, as in other Knight depictions of Allosaurus, but it was a normal system of illustrating Allosaurus at the time (see Rudolph Zallinger's version also). The ridge details visible in the Allosaurus of Knight are indeed small, but are there. The body has issues as well, but we are only worrying about the skull here, and there really are not that many problems with the old illustrations of the skull. The massive ear membrane may or may not be ccurate, but we will not worry about that until we have a mummified Allosaurus to compare it to.

A Big Show

In wrapping up the old set of original posts prior to the "modern" inception of Dinosaur of the Week we have the happy instance to work on one of the largest, most popular, and obviously coolest carnivores of the Jurassic. It is not Ceratosaurus (one of my favorites for coolest headgear) but Allosaurus that we are going to discuss this week; Allosaurus does have some neat little horns above and in front of its eyes though. This list of known, questioned, synonymized, and thrown out names associated with Allosaurus is fairly impressive. The usual suspects that we hear the most about are Allosaurus fragilis and Allosaurus saurophaganax (sometimes labeled as A. maximus). Allosaurus europaeus is the newest name used to describe remains attributed to Allosaurus; the remains for this purported species were recovered from Portugal's Lourinha Formation. The "Other Lizard" is one massively known dinosaur that captures as many, if not more, imaginations these days than Tyrannosaurus rex did in the last three decades or so. One cannot really blame people for falling in love with this massive but agile carnivore; paleontologists love hanging out with Allosaurus whenever possible after all and there is not much more endorsement needed than that.

©Encyclopedia Britannica

Armored Gameplay

Sauropelta is a recurring character in books about armored dinosaurs as well as dinosaur encyclopedias. These include books like this one with a rather odd looking dinosaur on the cover. The most widespread influences of Sauropelta outside of the Utah source materials are Dinosaur King:

and also those modified models and characters created in Spore:

Under Sauropelta's Armor

©Ely Kish

The Ankylosaurs routinely have their armor discussed and very rarely have massive amounts of other information related to the public about them. The feet, girdles (pelvic and pectoral), and limbs are the real heroes of the Sauropelta anatomy. These structures were built to support approximately 3,300lbs (1,500kg) of weight and to move that weight around on the Early Cretaceous landscape. At a standstill that is over 800lbs resting on each foot while at a trot, well we can see that each impact would be more weight and a lot of pressure on a foot, limb, and the appropriate girdle. The forelimbs were shorter than the hindlimbs meaning that the dinosaur, generally, would have been sloped forward and down from the hips. The center of mass would have been moved somewhat forward into the lower or posterior chest area.

Back to the Right Dinosaur

Sauropelta shows up in a few bits of literature that are available online; that is always very nice. One of these is dependent on one's ability to get Canadian Journal of Earth Science articles. However, if one does, it explains a nice skeletal and life reconstruction of Sauropelta that are both pretty well done and interesting. Additionally, there is another article that proves useful in reconstructing the world of Ankylosaurs in Utah. Three species are discussed in this review of the Cedar Mountain Formation. While an image of Sauropelta does not appear in this article, its description here puts to rest some of those more fantastical appearances we have seen (but I will leave it to the readers to discover this for themselves).

Scissors of Doom

Granted the clip I promised on Saturday has nothing to do with Sauropelta itself as a dinosaur, it does exhibit that potential scissor action of the dermal spikes of the tail. The action of the tail may be a little more derived than Sauropelta may have been capable of; however, it is hypothesis that may have some anatomical and physiological support behind it. To see the exact action in play fast forward that clip to 2:20, but remember, the dinosaur depicted had larger scutes and spikes on the tail, so Sauropelta would not have had as much leverage or reach with the scissor action. Sauropelta itself has not been tackled in any major documentaries that have been released or are available online. That, as always, is unfortunate. Early nodosaurs do not garner as much attention as their larger descendants and cousins, and are often left out of documentaries as a result. If anyone knows of a good clip that I did not know of and share, please share it with us!

Minimal Child Influence

Sauropelta is not a huge mainstream dinosaur and therefore does not impact the world of children's facts anywhere near as much as some dinosaurs have been known to do. It has managed to make it into a few child-friendly and lower level reading friendly webpages however. The easiest among these remains KidsDinos but London's NHM is always a reliable source of easy reading for dinosaurs as well. Pages about Sauropelta do also cater to higher reading abilities as well without too much information or technical jargon, which is always good as well. Pages that manage this the best are, typically, Enchanted Learning (which is a little closer to lower level reading this week) and the compiled data found on About. Videos and coloring pages dedicated to Sauropelta are lacking a bit this week, but that happens and we can be okay with that.

Sprawl and Spike

Sprawling dinosaurs have widely gone out of fashion, so why does it appear that this dinosaurs is sprawled out? Honestly, we can blame it on the angle and the position of the dinosaur. Sauropelta, as a nodosaur, lacked many of he offensive capabilities of other Thyreophorans such as Stegosaurus and Ankylosaurus. The lack of a tail armament would leave two options for a dinosaur like this; use your shoulder spikes or squat down and use your armor; tail scutes have been argued to have been used as scissors as well (see this coming Monday). In this image we have a top down view of a Sauropelta positioning its spikes and balancing its forelimbs in an awkward manner. This could be either to use those spikes as defense or to use them in the only offensive way something like this could be used; in other words this dinosaur is preparing to check an opponent like a hockey player. Which is correct is up for interpretation.

The second option, checking an opponent, would paint a much livelier image of Sauropelta. We would see a more agile dinosaur than we expect for larger armored animals because it would need some agility to be able to lunge at its attackers with anything resembling accuracy. To portray such litheness in a quadrupedal dinosaur requires a little thought on how "bouncy", for lack of a better word, the dinosaur should look. This lean but powerful fore-body portrayed here can help us to look at Sauropelta as a dinosaur ready for action on the front end in a similar manner to how Stegosaurus' pelvic region and tail is all business and looks as though it can pivot and swing with power. This is not a typical thought concerning nodosaurs and their bigger brethren.

Armor and Spikes

The Thyreophorans, Stegosaurs and Ankylosaurs, are noted to be heavily armored dinosaurs built equally for defensive and offensive capabilities with some specializing in one or the other end of that spectrum of abilities. One of those beautiful animals that has offensive and defensive capabilities and is alarmingly awe inspiring to look at is Sauropelta edwardsorum Ostrom 1970. Sauropelta was a fantastically imaginary dinosaur backed up by the fact of fossils. I say that only because its anatomical morphology almost makes Sauropelta appear to be an imaginary beast thought up by someone with a great imagination. The tail of this nodosaur was equal to approximately half the body length; a tail not used to counterbalance a long neck has other anatomical implications of course such as use as a weapon. The tail, being that of a nodosaur, was not particularly weaponized though. It, and the rest of the body, was covered in dermal scutes that are individual bony skin plates that have been recovered from a number of specimens. I mentioned that Sauropelta was not only defensively built and the shoulder and neck attest to this by possessing rather enormous (depending on the illustration/interpretation of fossils) shoulder and pro-pectoral spikes along the neck. There will be more discussion about these interpretations over the next week of course.

©John Conway

Coelophysis Everywhere

Spore is always a good outlet for dinosaur lovers to create models of their favorite dinosaurs. There are a handful of versions out there; this one is much more flamboyant and crazy than many other models. I like how out there the feathering portrayed on this model of Coelophysis is. The imagination and creativity of video game modelers is always pretty interesting and exciting to witness the first time you get to see it. Popularly, in other areas, Coelophysis has appeared in many places. It is featured in many different ways in the state of New Mexico including stamps, coins, and other aspects of being named the State Fossil.  Coelophysis has shown up as toys thanks to Jurassic Park, in part, and was a small enough model that the package actually contained two toys. There are a lot of books around as well including a few dedicated specifically to Coelophysis such as Dinosaur Ghosts: The Mystery of Coelophysis.

Sex in the Coelophysis

Just so everyone knows, thinking up fun titles is half the enjoyment I get out of writing these everyday; the other half is knowing that someone somewhere is learning or at least questioning what they know and critically thinking thanks to things I publish. Regardless, today I really wanted to mention that Coelophysis remains have exhibited evidence that suggests that these animals were sexually dimorphic. Discovering evidence of sexually dimorphic characters in fossil animals is always an intriguing and important part of being able to interpret potential interactions within populations. Certain sexually dimorphic characters can even lend themselves to interpretations of mating rituals; these are typically based on modern examples of similar characters in extant taxa. The difference in Coelophysis is not based on any interesting crests or additions to the skeletal frame. Instead, the dimorphism is suggested by differences in overall size of specimens; the forms are noted as being "gracile" and "robust". The two specimens initially used to describe these conditions are housed at the American Museum of Natural History and are AMNH 7223 (gracile) and AMNH 7224 (robust). As with many other sexually dimorphic species, the gracile form is thought to be female while the robust form is thought to represent male specimens. These forms are present in all ages of Coelophysis, meaning that the size difference is not only attributable to a difference in species and that sexually dimorphic characters begin to appear early in the life cycle. Gracile forms had longer skulls and necks, short forelimbs, and fused sacral vertebrae whereas robust forms had opposite characters in these areas. Some parental care has been noted in these animals and they have been considered gregarious due to the mass death assemblages at Ghost Ranch in New Mexico; though these may represent coincidental incidents in which food or water was limited and drew in large numbers of animals. Regardless, the sharing of food between adult and juvenile depicted in this image, is very neat and, though it does not show sexual dimorphism explicitly, we can assume that this is the female form with a baby and that they are gregarious animals here at least.

Denver Museum of Nature and Science

Ghost Ranch Writers

Many people have discussed, researched, and written about Coelophysis. Sometimes those writings appear in books, like this chapter on variation within Coelophysis bauri by Edwin Colbert that can be found in 1990's Dinosaur Systematics edited by Carpenter and Currie. That variation and the study of it leads to comparisons between taxa ultimately. The very similar Syntarsus rhodesiensis, recently renamed Megapnosaurus rhodesiensis due to a conflict of the name with a beetle, is a genus of coelophysid dinosaur recovered from North America and Africa that is extremely similar to Coelophysis morphologically. Because of the variation of Coelophysis, an in depth comparison of the two genera is necessary to point out the traits that separate them. Less direct comparisons have also been undertaken that look at the cranial mechanics of Coelophysis and later theropods that highlight the traits that began in Coelophysis and evolved over time in the derived specimens that were compared. Last but not least, it is important, in understanding the specimens that have been researched since the first Coelophysis skeletons were described, understanding the location and preservation of the largest deposits of skeletons. Ghost Ranch has been studied and the remains of many Coelophysis and other animals have been documented and researched within the area. Though from 1994, Schwartz and Gillette, discuss the geology and the taphonomy of Ghost Ranch, which provides important contextual information to Coelophysis since so many of the described specimens have originated at Ghost Ranch.

Coelophysis the Model

The models used for Walking with Dinosaurs with the Coelophysis segments were a bit older, given that Walking with Dinosaurs was produced prior to the rest of the "Walking with" series and were far more puppet-like than many dinosaur documentary models. Many of the dinosaur models in those sorts of documentaries are wireframe models done on computers. The Coelophysis compilation of models, both computer and puppet, still turn out quite well together over time. There should not be much surprise in how well it turns out, but if you have not seen it you really should check it out here. Coelophysis was built for speed, as is attested to by this clip from Discovery.

Coelophysis was built for running and jumping, clearly, and the skeleton is the key to those clues that lead to the knowledge of the manner of life that Coelophysis lead. Thanks to those computer models we can see Coelophysis come to life from those bones. Hurray for modern technology!

Gracefully Entering the Room

Kids love a slinking low profile dinosaur as much as they do a giant bone crusher. The slinking ones are sometimes not as scary, but they are good for darting in and making quick strikes at prey; kids love dinosaurs attacking their prey and everyone likes fast action. Regardless, there are a few good fact pages for this fast little dinosaur to dart in from and steal the show. There is KidsDinos and KidsDigDinos. The higher level readers can turn to Animal Planet and get more in depth information that challenges their reading level a bit more. The BBC has put together a page that has a little bit of written information in addition to a few featured clips from Walking With Dinosaurs, to give those avid little readers a bit of a break. The final relaxing point of today for our little scientist buddies is the ample number of coloring pages available. This is one of my favorites:

Just a Typical Dinosaur

©Nobu Tamura

Triassic dinosaurs like Coelophysis sometimes seem to be very stereotypically illustrated. The reason for that, of course, is because a lot of the generic traits of dinosaurs have their origin in the earliest Triassic dinosaurs like Coelophysis. That said, they are fascinating little creatures, Coelophysis, because they are the basic model for so many more derived theropod dinosaurs that evolved later in the history of dinosaurs. The elongate skull of Coelophysis and the overall gracile form are distinctive traits of Coelophysis that we can easily see in most illustrations of the animal. In some illustrations, in fact, Coelophysis appears very snake-like. Thankfully, we also have other illustrations like this one that are more robust in form.

©John Conway

Not too long ago, within the past decade  or so, dinosaur feathering has become much more universal than it once was. There is not necessarily a problem with this trend, but like all trends in art, they come and go and, with scientific illustration, are usually based on the majority consensus. That consensus right now has a lot more feathering visible on most known dinosaur genera. Illustrations like this one, lacking the feathering on the majority of the head, with some quill-like structures on the neck, are quickly becoming less and less normal and are even becoming unfavorable in many circles. The gaunt appearance of the head of this Coelophysis, however, follows the skull closely and accentuates the bumps and ridges of the bones exceptionally well. Despite this style of interpretation losing some favor in the scientific community it is still a valid interpretation and takes into account the anatomy of the skull particularly well.

Hollow in Form, But Not Substance

©Jeff Martz via National Park Service

Just to note, before we really begin, how interesting the name is, Coelophysis refers to the bones of the animal while the specific epithet (bauri) honors an anatomist who was at the time working with Marsh; this is interesting because the animal was named by Cope (Ceolophysis in 1889 from the original Coelurus Cope 1887) who described Baur as "the distinguished comparative anatomist of New Haven" while stating that he could not agree with Marsh on the genus being placed in any known order. Backhanded dismissals of other scientists aside, Coelophysis bauri has proven to be a difficult animal to pin down. As an early dinosaur of the Triassic, Coelophysis has many primitive characters as well as some traits that are early building blocks of all theropod dinosaurs. These include, in part, bone composition as well as primitive traits in the forelimbs and hindlimbs, and a long narrow head filled with serrated teeth. Primitively, the mouth is filled slightly more than halfway with teeth; the number of teeth and extension of their length along the jaw would be reduced as theropods evolved further. The lacrimal was devoid of ornamentation as well but some was discovered on the nasal; a primitive trait in comparison to more derived theropods. Coelophysis was also relatively small for a dinosaur as it was the size of a large dog at approximately 9.8 feet (3 meters) and around 3 feet (1 meter) tall at the shoulder. Peculiarly, Coelophysis is known to have fused clavicles, or a furcula, a trait usually seen in birds and bird-like dinosaurs. The inclusion of the furcula this early in dinosaur history is quite interesting and important in the development of theropods and birds.

Apatosaur Breathing

©Dmitry Bogdanov

Apatosaurus has been one of those dinosaurs that every post has included some sort of popular culture reference. Brontosaurus and Apatosaurus were both popular dinosaurs on their own but the synonymization of Brontosaurus with Apatosaurus actually had very little effect on the popularity of either name. Stephen Jay Gould and the United States Post Office defended using the name Brontosaurus in favor of Apatosaurus due to the popularity of Brontosaurus. The one highly noticed venue of popular culture that has seemingly escaped Apatosaurus is Jurassic Park, but anyone that has read the book should remember that there were 17 Apatosaurs roaming Jurassic Park along with all of those Brachiosaurs that "moved in herds". They do appear in modifications and base models of games like Zoo Tycoon and Spore.

There was also the question of breathing that needed to be settled; a neck that long produces some rather difficult engineering problems. The trachea of an Apatosaurus is a long anatomical structure. The pressure in the lungs and that outside of the body needs to be great enough that the volume of oxygen required for breathing can be taken into the lungs and carbon dioxide expelled or the animal, our Apatosaurus, will effectively suffocate. How does a 20 to 22 ton animal create the pressure required for breathing? How much pressure might that be exactly? Studies have shown that an estimated 30 ton Apatosaurus may have had up to 184 liters of dead-space volume in the thoracic cavity. Dead-space volume is air between breaths in oral cavity, trachea, and lungs. The assumption is that Apatosaurus possessed a crocodilian like breathing apparatus that lacks a diaphragm. Some estimates of the ability to replace this air have been done comparing Apatosaurus and ideal conditions of taxa specific respiratory systems. Reptilian systems are vastly inadequate to replace this volume and would have suffocated Apatosaurus; mammalian and avian systems are better equipped to replace the volumes of air proposed in Apatosaurus systems. Mammalian systems are adequate, but under powered as well, meaning that avian systems remain as the best equipped systems for allowing Apatosaurus to breathe efficiently; another possibility put forth is an unknown and undescribed system that has been lost in the modern world.

It is assumed that a four chambered 500 liter heart and 900 liter lungs filled a 1700 liter thoracic cavity (300 liters of tissue) in Apatosaurus. These assumptions in conjunction with reptilian resting metabolic rates and avian respiration, it has been hypothesized that an Apatosaurus required 69 gallons of water a day to live in addition to massive amounts of vegetation that it must have consumed.

Apatosaurus Growth

Wednesday's I sometimes have a lot of information to wed through and present. Apatosaurus is one of those dinosaurs that has been studied enough and is well enough known that we could easily fill a book with the information that is known about it. Specifically, for today, however, the point that we are addressing is the growth of Apatosaurus as has been evidenced in the fossil record. The paper on histology from yesterday addressed that issue quite well actually. The study, and other research has approximated adult age to have been reached in Apatosaurus at around 10 years of age; considering the layering of bone during growth it has been stated that this growth was rather quick. Sexual maturity has been approximated to be achieved around the 19th to 21st year of life and lifespans have been determined to top out between 28 and 31 years of age. These approximations were determined by a recent study of two individual specimens. Tomorrow, if there is time, I will contemplate tackling breathing in addition to the popular appeal of Apatosaurus.