02 September 2014

Describe and Revise

Mader and Bradley (1989) redescribed Alectrosaurus by revisiting the syntypes of the dinosaur that were unearthed by George Olsen in Mongolia in 1923. Gilmore described the dinosaur as a "Deinodont" (synonymous with "tyrannosaurid") that was similar to Gorgosaurus. Gilmore was very confident in considering this dinosaur a tyrannosaurid, but many more recent phylogenetic and systematics studies have questioned the validity of the assignment based on the fragmentary materials. Mader and Bradley turned the dinosaur upside down, but retained the tyrannosaurid connections. In fact, they considered it close enough to ally it with Tarbosaurus. They added previously unassigned caudal vertebrae (AMNH 21784) while eliminating some of the syntype material (forelimbs labeled AMNH 6368) based on the length of the limbs it portrayed. This places it in the Tyrannosauridae, however, Loewen et al. (2013) places Alectrosaurus in a more basal position outside of the Tyrannosauridae. Part of this study included the information that was compiled in Carr (2005) and is laid out in an easier to read list on Wikipedia. The swaying of assignment for this dinosaur has not been tumultuous at all. The only real swaying that it has done, actually, is in and out of the Tyrannosauridae family. At the moment it is outside of that family and is assigned only into the superfamily Tyrannosauroidea., but it has been considered a true tyrannosaur, an Albertosaur, an ally of Tarbosaurus, and it started out as an unknown theropod. Alectrosaurus has come a long way and, like many other dinosaurs, is still disputed, but is obviously loved by enough people to maintain its popularity.

References:
Carr, 2005. Phylogeny of Tyrannosauroidea (Dinosauria: Coelurosauria) with special reference to North American forms. Unpublished PhD dissertation. University of Toronto. 1170 pp.

Loewen, M.A.; Irmis, R.B.; Sertich, J.J.W.; Currie, P. J.; Sampson, S. D. 2013. "Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans". In Evans, David C. PLoS ONE 8 (11): e79420.

Mader, B.J., and Bradley, R.L. 1989. A redescription and revised diagnosis of the syntypes of the Mongolian tyrannosaur Alectrosaurus olseni. Journal of Vertebrate Paleontology 9(1):41-55.

01 September 2014

Tribute Monday

Alectrosaurus tribute videos seem to be in every corner of the internet. Some of the best, as usual, borrow images that are not always the animal that they are supposed to be showcasing. A lot of them are actually 2D shadow puppet type shorts that are not scientific or really appropriate for our purposes. The Alectrosaurus tribute that matches our purposes best is actually a fairly good tribute video, which is rarely something that gets said with tribute videos. The best place to see Alectorsaurus however is episode 6 of Planet Dinosaur. While neither a strict documentary nor the best pseudo-science out there, the Alectrosaurs in the episode are well modeled (despite sharing a model base with Daspletosaurus) and they have some pretty fantastic interactions with the other dinosaurs of the episode. A small part of that interaction can be seen below:

31 August 2014

Small Tyrannosaurs for Small Humans

As a well known member of the dinosaur community, Alectrosaurus has become a popular internet dinosaur as well. That in turn leads to more websites hosting appropriate reading materials for all ages. Since goal number 1 around here is to make dinosaurs and the science around them more accessible to all ages and all backgrounds, having more links dedicated to different reading abilities and interest levels always makes us happier people! We have today some of the typical websites that are definitely geared toward quick and easy access of facts for any reading ability like the NHM of London's Dino Directory, which happens to sport an outdated but absolutely awesome illustration of Alectrosaurus, and an updated and spiffy looking new About page complete with an updated and energetic looking Alectrosaurus pair from Sergey Krasovskiy. Lesser used pages also include pages on Alectrosaurus such as this one at Dinosaur Jungle and the wiki space for the pseudo-documentary Planet Dinosaur. What is lacking for such a well known dinosaur, actually, are coloring pages specifically dedicated to the small tyrannosaur. That is actually quite surprising!

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