30 August 2014

Alectrosaurus is Short

In looking at illustrations and discussions the past 24 hours or so I have noticed that there has been a lot of debate around where in the family tree Alectrosaurus belongs. Some say it is an albertosaur, some say it is not. Some say it is not even a tyrannosaur. Most of that is either because of the low number of remains attributed to Alectrosaurus or because the remains point to an extremely short species of tyrannosaur. Regardless, the hypothesized extrapolation of the length and height of Alectrosaurus does indeed appear to indicate that this dinosaur was quite short. Relatively speaking, of course. However, compared to other tyrannosaurs that are well known (e.g. Tyrannosaurus, Tarbosaurus, Nanotyrannus), Alectrosaurus is a very short taxon. The height hypothesized is approximately 2 meters and length is approximately 5 meters. To put that in perspective, Nanotyrannus is approximately 2 meters tall and 5.2 meters long while Tyrannosaurus rex is approximately 4 meters tall and 13 meters long. The overall body design is usually typically tyrannosauroid, but little beyond the feet, tibia, femur, and referred skulls and hindlimbs are known. The referred material has not been assigned without doubt to Alectrosaurus, but that only means that any illustrations of the head and hands, like this one, are somewhat hypothetical, depending on how much assurance there truly is in the referred materials. Regardless, Alectrosaurus is still a rather sleek and dangerous looking tyrannosaur.

29 August 2014

Trudging Through Mongolia

In the 19th Century England, Germany, then North America were centers of paleontological discovery. North America still is, but much of the world has joined the fossil hunt and there have been other centers of discovery as time has gone on.  Different parts of Africa were huge fossil hunting magnets over the past few decades. South America has really come into its own over the past few decades as well. For a time, multiple times actually, China and Mongolia have been big. One of those times was during the roaring 20's, pun certainly intended. In 1923 Walter Granger led the importantly titled Third Asiatic Expedition of the American Museum of Natural History. A young man named George Olsen spent the weeks around April 25 - May 4 of that trip digging in a small area and recovered the bones of what is now known as Alectrosaurus olseni. A couple of years later, during the same expedition, Olsen would find a dozen dinosaur eggs with his colleague, the slightly better known, Roy Chapman Andrews. However, the discovery of Alectrosaurus is much more interesting as it is one of the first Asian tyrannosaurs described. At times Alectrosaurus has been hypothesized to be an Asian albertosaur, but a rather long list of autapomorphies compiled by Charles Gilmore in 1933 and subsequent researchers concerned with tyrannosaurs seems to have cemented Alectrosaurus' place in the tyrannosaur family tree.

From now on Fridays will also include some taxonomy (better late than never?):
Kingdom:                                           Animalia
Phylum:                                              Chordata
Clade:                                               Dinosauria
Suborder:                                          Theropoda
Superfamily:                          Tyrannosauroidea
 Genus:                 Alectrosaurus (Gilmore 1933)
 Specific Epithet:                                        olseni


Alectrosaurus from Planet Dinosaur

28 August 2014

Never A Cast

Aralosaurus has not, as yet, been singled out in dinosaur toy assemblies. It has been written about in scholarly papers, as we know, and Aralosaurus has been mentioned in much of the larger scale technical tomes as well such as The Dinosauria. It has not, though, been the subject of other popular outlets such as made for kids books, popular encyclopedias (think National Geographic rather than the more technical type), or magazine articles. Movies and documentaries are completely lacking Aralosaurus. Kids shows, even Dinosaur King and Dinosaur Train, have ignored the dinosaur. How or what has made its name popular then? The sole reason that I think we have been able to come up with this week is that this dinosaur is from Kazakhstan and very few dinosaurs have been discovered and described from Kazakhstan. Hopefully that number will swell in the future and more examples of this dinosaur will be discovered and described. Until that time, however, hopefully what has been discussed this week will cause Aralosaurus to become better known in the near future; that is kind of the goal of an educational blog like this after all!

27 August 2014

Elephantine Chewing

Aralosaurus has been reported as elephant-sized based on extrapolations from the skull. The most recently updated (2011) appendix for Dr. Holtz's Dinosaurs encyclopedia lists Aralosaurus as rhino-sized. To differentiate the two, using this appendix's weight ranges, rhino-sized is between 1 and 4 tons while elephant-sized is between 4 and 8 tons. The discrepancy, on Rozhdestvensky's part, is most likely due to simple size extrapolation without regard to the actual weight of an elephant. It is quite possible that an Aralosaurus could have been nearly elephant size but in the same weight range as a rhinoceros. Of course, that could be a difficult thing to have happen: squeezing the weight of a rhino into an elephant sized package and not having extra unused space. 

The nasal protuberance, meanwhile, is not an indication of weight, as far as anyone can tell. The wideness and extension of the protuberance has led to speculation that it may have been useful in intraspecific combat and other mating or display rituals. How the protuberance was formed exactly determines how correct the hypothesis of intraspecific combat could potentially be. If the protuberance is more of a horn than a wide, flat, stable surface for butting, than butting could be lethal. If the protuberance is actually a fractional element of a hollow resonating chamber neither hypothesis above would be correct as the structure would be too fragile for any kind of combat. As a resonating chamber it would definitely be significantly useful in display though. My official opinion is that more evidence would be ideal but the evidence present is very inconclusive.
"Aralosaurus skull" by I. Reid (User:Reid,iain james) - Own work. Licensed under Public domain via Wikimedia Commons

26 August 2014

Paper Days

Rozhdestvensky's original papers were written in Russian. Cyrilic is hard to read for non-Cyrilic readers typically. Thankfully, then, we have polyglot paleontologists that are willing to translate and post articles that have been translated! The Hadrosaurs of Kazakhstan is hosted on a site called DinoChecker and describes not only Aralosaurus but all of the other hadrosaurs that Rozhdestvensky discovered or described from Kazakhstan. Since that time, I vaguely mentioned before, many authors have revisited Aralosaurus for one reason or another. Godefroit and Alifanov (2004) revisited Aralosaurus for the sole purpose of describing the dinosaur again. Their redscription declared that Aralosaurus remains a valid taxon and discusses the distribution of the dinosaur during their existence. Averianov (2007) mentions Aralosaurus briefly in a discussion on theropods of Kazakhstan, but as they are not the focus of the paper they are only briefly treated. Two papers are particularly interesting from a cranial anatomy standpoint. Maryanska and Osmolska (1979) and Hopson (1975) both discuss hadrosaur cranial morphology with different emphases, but they also both mention Aralosaurus and discuss the known cranial anatomy of the dinosaur. Maryanska and Osmolska are overall more focused on certain aspects of the cranium and focus most of their descriptions and discussions on Saurolophus, but they do discuss characteristics of Aralosaurus in reference to hadrosaurs in general as well as Saurolophus in particular. Hopson, however, discussed the evolutionary trends of hadrosaur display structures of the cranium. While the majority of Aralosaurus' cranial displays are not known for certain, some inferences are made by Hopson of the Lambeosaurine group in general that could possibly be applied to Aralosaurus. There is a lot of good reading material here if one can access it. The Hadrosaurs of Kazakhstan is available for everyone and should definitely be on the reading list of anyone interested in Aralosaurus.

25 August 2014

Aralosaurus Stagnant

Aralosaurus does not have any movies or even tribute videos. That is okay though. Instead, let us look at Aralosaurus geography today. Aralosaurus is one of very few known and described Kazakhstani dinosaurs. Present day Kazakhstan is a mountainous steppe country that lies in both Europe and Asia; the Ural mountains that separate Asia and Europe pass through the western portion of the country. This, in part, explains why the range of Aralosaurus, though found only in Kazakhstan, is described as existing in both Europe and Asia. Kazakhstan during the Cretaceous, the time of Aralosaurus was quite a bit different from what it is like today. Fossil seeds that have been discovered in Kazakhstan include members of the Magnolia family, particularly Liriodendroid (tulip tree) seeds. These types of trees typically inhabit temperate and tropical areas of Asia, suggesting that Kazakhstan was probably home to either a temperate or tropical climate during the Cretaceous. Overall, Kazakhstan's sites are not as heavily studied as many dinosaur fossil sites in other areas of the globe and this leaves a rather large gap in the known and hypothesized biology of Aralosaurus. However, with the knowledge that flowering trees existed in the general area of Aralosaurus it is not too much of a jump to hypothesize that the primitive lambeosaur may have been eating flowers!

24 August 2014

Children's Kazakhstani Hadrosaurs

Aralosaurus has an absolute plethora of links for the interested children of the world. There are links for all levels of reading ability from the youngest with very brief and easy to read facts to much more involved and longer winded fact pages with more advanced readers in mind. Middle of the ability tree skill levels are also represented in a number of quality pages. Depending on how much your little readers want to read today there are longer paragraphs or there are shorter paragraphs available. Regardless, the interested younger reader is definitely well supplied today by websites catering to different reading abilities.