Wednesday, November 13, 2013

SVP LA


As many of you already know, I attended the 73rd Meeting of the Society of Vertebrate Paleontology on Wednesday, Oct. 30 and Saturday, Nov. 2 and it was a positively thrilling experience to say the least. There were so many great discussions, presentations, discoveries, and people. I almost felt overwhelmed by the huge numbers of paleontologists, geologists, artists, and fellow bloggers I was able to meet at the event. I even got a few books signed, which was great. The Awards Banquet on Saturday was also especially inspiring and fun. There was only one downside which I should acknowledge: the cost. But it was really, truly worth every penny and I'm very grateful my parents allowed me to go.

Of course, the talks were the highlight of the event. I sadly missed the Thursday and Friday talks due to school, and thus was not there during the announcement of things like the Therizinosaur nesting colonies, T. rex having an Asia ancestry, an 11-ish meter Abeliosaurid from the late Cretaceous of Kenya, the bizarre new anatomy shown by a brand new specimen of Deinocheirus, and the possible resurrection of the genus Brontosaurus. I was fortunate to get updates on some of the talks by various people who were there the whole time, but I'll refrain from talking about them until properly published. Due to the fact that I saw so much new stuff, I'll try to make everything brief.

New look for Deinocheirus
The neck, ridge, and legs all based on new info from SVP.

Wednesday, Oct. 30: We first saw talks on growth and ontogeny in dinosaurs, such as some new discoveries and methods being used to settle the infamous "Toroceratops" debate, and new juvenile, neonate, and embryonic specimens from some familiar dinosaurs like Chasmosaurus, Troodon, and Allosaurus. Growth, in my opinion, is one of the most interesting things about extinct animals, and the fact that dinosaurs spent so much of their life as juveniles leads to interesting topics about their ecology, behavior, and biology. Thus, I was extremely satisfied to learn about the growth rates, peak performance, and sexual maturity in Troodon, Maiasaura, and Diplodocus respectively. Dial had a wonderful talk about birds and how the locomotor changes in their ontogeny may effect what we know about bird evolution, and finally there was a presentation on multi-niche ontogeny, and how it affected the survivorship ability of numerous animal groups across the K-T boundary.

On the way out of the presentation halls, I was lucky enough to run into and have a short chat with Dr. Darren Naish, who's been a big influence on me to start up blogging and get into the whole scientific community in the first place. Even more of a shock was when he said he had seen my blog before! It was an honor to finally meet him after reading so many of his articles, and later at the Welcome Reception we had a short chat about Jehelornis' cool new tail feathers and he signed my edition of TetZoo Book 1. I was also able to briefly meet Dr. Jack Horner, while a fellow dinosaur pal of mine attended Day One of the conference and chatted with him for quite a bit.

Me (left), Dr. Darren Naish (middle) and my good friend Irlanda (right).
Another pic with Me, Dr. Jack Horner, and Irlanda
We then grabbed lunch, I looked at a few of the posters up in the poster hall, met Dr. Donald Prothero and got a brand new hardcover edition of Abominable Science signed by him, chatted with Luis V. Rey for a bit and bought one of his art pieces, chatted with Paul Sereno about Eoraptor, and introduced myself to Dr. Thomas Holtz before the afternoon session. During that session they covered everything from the evolution of the ankylosaurid tail club, to a new species of basal neoceratopsian from the Cloverly Formation with a really awesome beak, an articulated baby Chasmosaurus with skin impressions, and a talk about pachycephalosaur respiratory turbinates I was excited about just to name a few.

After that we attended the Welcome Reception at the LA County Museum of Natural History (the same one where I volunteer), where we talked with Dr. Luis Chiappe (curator and director of The Dinosaur Institute) briefly before he continued to greet the many guests. I also got to meet artist and fellow blogger Scott Hartman and me, my mom, and friend Irlanda all found people to chat with. After a while the Museum's famous dinosaur puppets came out to greet everyone. They're a T.rex named Hunter and a Trike named Dakota, both of which are juveniles. Everyone was mesmerized by the models. I am lucky I get to see them weekly.

We left the reception tired yet satisfied after having a wonderful experience. Sadly, due to schoolwork I was unable to return to SVP on either Thursday or Friday, and the fact that Halloween was the following day didn't help either. But I worked really hard to get all my work done so that I could return on Saturday, and a lot more fun ensued then.

Saturday, Nov. 2: I faced a dilemma when I got to SVP on Saturday. I couldn't decide which one of the morning sessions I should attend: the one on Polar animals, or the one on paravians and avians. I decided on neither, and ran into the mammal session which was starting. Luckily, the talk was on canids, and I coincidentally had just finished reading Wang and Tedford's Dogs: Their Fossil Relatives and Evolutionary History a few days prior, so I had an interest in the topic. They talked about how the ankle bone could be used to gauge certain species of canid's hunting behaviors and find out if they were ambush, pounce, or pursuit predators. I found the topic very interesting to say the least, and they had some very interesting interpretations about the evolution of modern wolf hunting.

According to the talk given, modern pursuit hunting typical of Grey Wolves
might have been a recent invention. Previous species used other methods of hunting.
After I got mammals out of my system, I started running between the two other halls for the rest of the morning, trying to catch everything that looked of interest from the abstract. I saw everything from new specimens of Anchiornis with new anatomical details, a possibly secondarily flightless Archaeopteryx, the pterosaur from Antarctica that I mentioned briefly in my magazine article from early this year, new species of dinosaurs from both the North and South Poles, and new methods of scanning feathered dinosaurs for melanin preservation. Everything was incredibly interesting, but sadly, the talk about the newly discovered Siberian Ornithischian with feather-like integument was canceled at the last moment, which was disappointing to say the least for everyone.

However, another discovery from Alaska made me perk up once again. A new species of tyrannosaur was discovered in Prince Creek and is the apparent owner of the tooth material that has been discovered up there for the last few years. What's really interesting about it though is that it was suggested that it exhibits insular dwarfism, as it has a 600 mm skull (which is tiny for a tyrannosaur) yet shows signs of being fully grown. What implications this has for its biology and the ecology in the region has yet to be shown, but I find myself really liking this guy so far. Might be my new favorite dinosaur when he's properly named. :)

After the morning talks, we grabbed lunch and looked at all the posters in the poster hall. I got to meet and had a nice chat with Duane Nash from Antediluvian Salad and Southland Beaver, who wrote a post that was a big inspiration for my Kem Kem video I made awhile back. I walked over to a souvenir table with numerous pins of extinct animal skulls on it. I tried to identify them all, but failed horribly when it came to identifying the Champsosaurus skull (I need to read more literature about those guys...). Finally I settled on purchasing an awesome pewter Styracosaurus pin, which now accompanies me every day I work at the museum.


First time I ever misidentified an extinct animal's skull.
Damn you, Champsosaurus...
The last sessions I attended were on a broad range of topics concerning various groups of reptiles from pterosaurs to icthyosaurs to turtles. The first talk was on the first Triassic pterosaur from North America, which was awesome because I always wanted to know what kinds of pterosaurs Ceolophysis was seeing in its environs. (Peteinosaurus is from Italy, not North America, contrary to WWD.) Then there were talks about the diversity of Early Triassic Icthyosaurs, the evolution of large eyes in Icthyosaurs, and many talks about the diversity and evolution of all kinds of turtles, and even some stuff on the Leatherback evolution (and a short bit on conservation, which my mom really enjoyed). They then ended the event on the discovery of the first procolophonid from Tanzania, and although I don't really study procolophonomorphs, I was still thoroughly interested in the topic.

I then walked around for a bit, read some more posters on a possible new species of Edmontosaurus from Prince Creek and a fossil Rhino from Japan, chatted with someone about Dire Wolves, saw Mark Norell but didn't have a chance to say hi, and quickly ran downstairs to freshen up before the Awards Banquet. We sat down at a table with a bunch of students from Florida State University, and I got to chat with one of them about her graduate work concerning South American mega herbivores. They then started the presentation, and it was extremely inspiring for me. They honored paleontologists who had sadly passed earlier in the year, awarded some student scholarships, honored filmmaker Steven Spielberg (although sadly he could not attend) for his support of young paleontologists through his Jurassic Foundation, played clips from old dinosaur movies, handed out more awards, and finally the event ended with a speech given by Dr. Jack Horner, who was awarded thRomer-Simpson Prize for Lifetime Achievement — the highest honor one could receive from the Society.

After the banquet, we stopped into the after hours party but the atmosphere was not very conducive to chatting, so we called it a night. The entire way home I felt inspired and overjoyed to have had the chance to attend a world-class paleontology conference here in my own backyard and to be a member of such a prestigious society. I dream that I'll eventually be up there on a podium one day presenting my discoveries to the world. Until then, you can still catch me blogging here!

Stay sharp everybody!

Saturday, October 19, 2013

Disneyland for Dinosaur Nerds

Stegoceras validum by John Conway
Why didn't you tell me you had respiratory turbinates!?
My loyal readers, I must first start off by apologizing for not writing a post last month. Getting back into the swing of things at school, as well as my docent job at the LA Museum of Natural History and writing a new Magazine article, has made it hard for me to find the time to post here. It also doesn't help that during the short time that I do get on the net, I find myself getting caught up in long discussions with people on Forums or YouTube comment sections, or reading long posts by numerous people in the Paleontology Blogging community. (I'm looking at you, Naish...)

It's been incredibly busy with my Museum job, with our team hosting various events coming up like RAAD (Reptile and Amphibian Appreciation Day) and the Haunted Museum. Moreover, with holidays like Halloween, Thanksgiving, and Christmas right around the corner, I fear my posts will be sporadic on here for a while. But don't fret, when I post it will be because I have something worthwhile to say. In fact, today I have some great news for you all.

The museum I just so happen to volunteer for is hosting the Society of Vertebrate Paleontology (SVP) meeting from October 30th to November 2nd in Los Angeles. I will be attending one day of the conference with a friend and will be able to see first-hand what numerous paleontologists have been working on, before it has even been put in print yet. I'm extremely excited and have already read much of the info concerning the event on the Program and Abstracts, which you can read here.

I plan to be there on the day there will be some interesting discussions on Dinosaur Ontogeny and Ornithischian studies, at the cost of missing the discussions on Theropods and Polar Animals. Still, what I am going to be seeing is a lot of cool stuff that I'll definitely try to write about here as I'm able.

There is going to be information on the peak performance and mortality in Maiasaura, Triceratops growth (including the "Toroceratops" debate), baby Troodons, and *shock horror* Allosaurus eggs and embryonic remains from the Morrison! And that's just the morning! There's also all kinds of info on ankylosaur, ceratopsian, and pachycephalosaur anatomy and evolution in the afternoon, including a major announcement concerning nasal turbinates!!!

Nasal turbinates are a major discovery (well, at least in my opinion) because they are often seen as an indicator of endothermy in animals which have them (although if I'm remembering correctly, ratites and a few other birds lack them). They've so far been said to be absent in dinosaurs, and thus some scientists will often say that this is an indicator that dinosaurs were ectothermic like lizards (however, as they are very fragile and decompose almost as fast as cartilage and other soft tissues, this lack of them in the fossil record may not be a surprise). If there truly are turbinates in Pachycephalosaurs, it would be a major discovery and would suggest that dinosaurs as a whole (or at the very least Pachycephalosaurs) were endothermic, and it would also have implications for the breathing and olfactory abilities in these animals.

So yeah, I'm extremely excited about all this, and do note that this is just the day that I'm visiting. Looking through the whole list, there's a whole lot more presentations on all types of other animals that I'll sadly be missing, but look exciting and interesting nonetheless, and I can't wait to read about them all when they come out in print. The most notable of sessions I'll be missing is the announcement of what seems to be a new species of polar Ornithischian dinosaur from Siberia with *shock horror* preserved  integument showing feathers! We're coming closer and closer to that fuzzy Ankylosaur by the day. :P

Anyway, that's all for now. When I get back from SVP I'll make a follow-up post of everyone and everything I saw. Until then, stay sharp! :)

Friday, August 30, 2013

Thyreophora + Xenarthra = Fuzzy Ankylosaurus?

Beautiful amateur artwork by yours truly. But why the fuzz?
For those of you who have been checking my YouTube page, you may have noticed that I posted a new video, this time about the anatomy of the Ankylosauria. In it I talk about everything ankylosaur, as well as include an image by yours truly showing some speculative interpretations of their hyoids. However, in that same image I also portrayed the ankylosaur, which was based on Ankylosaurus magniventris, with feather-like protofeathers (a.k.a. dinofuzz or whatever it's called these days). Some people might think that this is due to scientists' current preoccupation with taking every dinosaur and slapping some feathers onto it, shattering the hearts of so many JP fans. However, I actually have a very good reason why I believe that not just Ankylosaurus might have had feathers, but also that it might be likely that the entire Thyreophora might've had such fuzz, even more than other large-bodied dinosaur groups. It starts with observations of another living group of animals: the Xenarthra.

Xenarthra are a group of mammals exclusive to the Western Hemisphere. They include freaky animal families like Armadillos, Sloths, and Anteaters, as well as awesome extinct forms like Ground Sloths and Glyptodonts. They are bizarre on so many accounts relating to their anatomy, such as having vertebrae that articulate differently than any other mammal, their lack of tooth enamel, and don't even get me started about some of their unsavory habits, like the recently documented observations of Linnaeus's two-toed sloth drinking from human latrines (Heymann 2010). Yuck...

It suddenly seems a lot less cute after discovering about its drinking habits.
I wonder how Kristen Bell reacted to that discovery...
Anyways, these guys seem to share some aspects of their physiology with thyreophorans, and no I'm not just saying that because they both have members that are complete turtle-mimics. Xenarthra are interesting in that they have the lowest body temperature and metabolic rates of any mammal, being at 40 to 60% what you would expect for mammals of their size (McNab 1980). This low body temperature makes xenarthrans somewhat slow-moving animals, and they have to face problems many people would typically associate with reptiles, such as having to regulate their body temperature and suffer a slower growth rate than other mammals. The latter trait is particularly important, as it's a trait also shared by thyreophorans.

The thyreophoran taxa Scutellosaurus (Padian 2004), Stegosaurus (Redelstorff 2009), and numerous American ankylosaurs (Stein 2013) have all been shown to have slowed growth rates when compared to other dinosaurs. They weren't as slow as reptiles, but definitely not as fast-growing as mammals. This suggests that like xenarthrans, the Thyreophora had a metabolism slower than other dinosaur families. There is, however, the exception of Kentrosaurus, which might have had a faster growth rate (Redelstorff 2013). However, Kentrosaurus seems to have been an exception, and the majority of evidence points towards thyreophorans having lowered body temperatures like xenarthrans. Whether or not their actual body temperatures were at comparable levels to xenarthrans we don't know, but seeing as how many scientists now consider dinosaurs to be warm-blooded on the same level as modern mammals, similar thermoregulatory levels between thyreophorans and xenarthrans might be expected. I'd like to see someone try to test this idea in the future.

So, what does this all have to do with an Ankylosaurus having fuzz? Well, everything really. You see, the main argument made by people against the idea that large dinosaurs had feathers, or any type of fuzz really, is that they wouldn't need it, being large enough to be able to have a stable body temperature, as seen on modern large mammals. I have my own issues with this idea, since it assumes that protofeathers and hair are the same kind of structure (which they are not), and that dinosaurs have a similar physiology to mammals (which is unlikely). However, even assuming such ideas, we still know of large-bodied mammals that live in tropical regions which have thick, shaggy fur, and they're xenarthrans.

The Shasta Ground Sloth, a desert-dwelling sloth that was completely covered in shaggy fur.
Other members of the group were the size of an Elephant and just as fluffy.
Ground sloths are already so famous that they don't need an introduction. They are giant ground-dwelling sloths that were running around on the sides of their feet during the Ice Age, and alongside mammoths, were the largest animals in their environment. However, despite their size, they're often portrayed as being very fuzzy animals with shaggy fur. When in a discussion with someone the other day, they dismissed this as simply an assumption and asserted they were probably hairless like elephants. This is poppycock. We have mummified ground sloth skin from caves in Arizona, Nevada, Argentina, and Chile which show thick fur on the animals. We even have them preserved for Eremotherium, which was the size of a small elephant, and its likely that the fur is present in still larger members like Megatherium.

So this would seem contrary to what people say about large mammals shedding fur at larger sizes. Why did ground sloths keep their shaggy fur in tropical environments at such large sizes while other groups of mammals of equivalent size lost their fur? Our best answer is that this was due to their lowered metabolism, which means they had a harder time holding onto body heat than other mammals. Apparently holding onto that hair was also a pretty smart move, especially since ground sloths back then were perfectly able to extend their range up into temperate regions of North America and even as far north as Alaska during the last Ice Age, while living sloths have trouble tolerating even temperate latitudes. According to McNab, this was probably due to a combination of their thick fur, as well as greater size, larger muscle mass, and a constant food supply compared to their living relatives (McNab 1985).

So assuming that ankylosaur growth rates suggest that they had lowered body temperatures like xenarthrans, might we then expect that these guys were covered in shaggy fuzz, too?

Stegosaurus with tail spines made of porcupine-like filaments. Art by Mark Witton.
Looks like other scientists got the memo, or they're just slapping feathers on everything again...
Thus, even assuming that they had a physiology similar to mammals, and the falsified assumption that protofeathers were similar to hair, our knowledge of their possible xenarthran-like metabolism would still make them candidates for long filaments covering their entire body. We also know that ankylosaurs at least lived in temperate environments, such as Liaoning, and polar environments like Alaska, Australia, and New Zealand. These guys would've needed even longer fur in order to survive the cold snaps, if they were xenarthran-like in their metabolism.

When you take all this into account, it almost makes the picture I drew kind of conservative, showing only short fuzz compared to the longer hair common on ground sloths. Perhaps I'm diving too deep into speculation right now, but I think that my idea holds some merit. What are your thoughts? As always I'd love to hear everyone's opinion on this.

Stay sharp! And make sure you check out my brand new Ankylosaur video on YouTube:



References:

Heymann, E. W., Flores Amasifuén, C., Shahuano Tello, N., Tirado Herrera, E. T. & Stojan-Dolar, M. 2010. Disgusting appetite: Two-toed sloths feeding in human latrines. Mammalian Biology doi:10.1016/j.mambio.2010.03.003

McNab, Brian K. (November 1980). "Energetics and the limits to the temperate distribution in armadillos". Journal of Mammalogy (American Society of Mammalogists) 61 (4): 606–627. doi:10.2307/1380307. JSTOR 1380307.

McNab BK (1985). Energetics, population biology, and distribution of Xenarthrans, living and extinct. In: Montgomery GG (Editor), The Evolution and Ecology of Armadillos, Sloths and Vermilinguas. Smithsonian Institution Press, Washington and London, 219-232.

Padian K, Horner JR, Ricqlès A (2004) Growth in small dinosaurs and pterosaurs: the evolution of archosaurian growth strategies. J Vert Pal 24: 555–571. doi: 10.1671/0272-4634(2004)024[0555:gisdap]2.0.co;2.

Ragna Redelstorff & P. Martin Sander (2009) Long and girdle bone histology of Stegosaurus: implications for growth and life history, Journal of Vertebrate Paleontology, 29:4, 1087-1099, DOI: 10.1671/039.029.0420

Redelstorff, R., Hübner, T. R., Chinsamy, A. and Sander, P. M. (2013), Bone Histology of the Stegosaur Kentrosaurus aethiopicus (Ornithischia: Thyreophora) from the Upper Jurassic of Tanzania. Anat Rec, 296: 933–952. doi: 10.1002/ar.22701

Stein M, Hayashi S, Sander PM (2013) Long Bone Histology and Growth Patterns in Ankylosaurs: Implications for Life History and Evolution. PLoS ONE 8(7): e68590. doi:10.1371/journal.pone.0068590

Friday, July 26, 2013

Pacific Rim and Kem Kem's Water-Loving Theropods

Striker Eureka vs. Otachi in a promotional poster for Pacific Rim
I just went to see the new blockbuster Action/Sci-Fi/Mecha,/Kaiju movie Pacific Rim on Wednesday, and by God it was awesome. It was by no means the best movie ever, being plagued with numerous stereotypes and clichés (and I heard some complaints of bad acting, but I didn't really notice that when I watched it), but for the most part it stood up very well. It had great CGI, cool Kaiju and Jaeger designs, and it knew exactly where, when, and what to do to please the audience, so I found myself thoroughly enjoying the experience, and I recommend the film to everybody even remotely interested in the concept. You won't leave the theater disappointed.

Director Guillermo del Toro took his inspiration from Japanese animes and Kaiju movies, and I could definitely see the resemblance to the former. I watch anime when I can, and many of the characters in Pacific Rim (despite undoubtedly being stereotypes) had an uncanny resemblance to characters in animes I had seen before. This was probably intentional on Guillermo's part. I also noticed some resemblances to Evangelion, an anime series with a similar story of giant monsters called Evas fighting human-powered mechas in order to protect the world. Other people have also noticed the similarities, but apparently Guillermo had never seen Evangelion, so all these parallels are probably coincidental.

Despite having seen numerous animes though, I've barely seen any Japanese Kaiju films before, so I couldn't see if there were any parallels there (other than, well, the fact they both have giant Kaiju in them). Maybe after seeing this movie it will encourage me to start watching some more Kaiju films. Hmm, I have always wanted to watch the original Godzilla movie.

Here's a funny story though. I've been watching another anime right now called Attack on Titan. It's about giant humans called Titans that eat normal-sized people alive just for fun, and how the last piece of humanity has been driven back into the dark ages and forced to retreat behind three giant walls that were built to keep the Titans out, but that's besides the point. The main antagonist's name in that show is Eren Jäger, whose last name has the same root as Pacific Rim's mechas, both being derived from the Germanic word for hunter (Jäger). *Spoiler Alert* This is also ironic seeing as mid-way through the show Eren learns he has the ability to transform into a Titan, and he uses his power in order to fight off the Titans as they slowly try to break their way past the walls to devour the people hiding within. So all in all, Attack on Titan and Pacific Rim are both about giants trying to annihilate the human race and both have heroes named Jaeger that are trying to protect what's left of it. Kind of left me confused...*Spoiler Ends*

There was, however, one HUGE problem with Pacific Rim that seriously brought down the movie for me. Watch this scene and you'll know what it is:


LIES!!!
Eh, I would devote this whole post to ranting about that one scene, but luckily, Darren Naish on Tetrapod Zoology did it for me, as well as talk about a lot of other cool aspects of the movie. Be sure to check that out when you can.

Now, onto important science-y things...

I made another video a few days ago which I posted on YouTube, this one concerning the Kem Kem beds in Morocco. I was inspired to make this due to a lot of work being published on those beds, notably a paper that came out a few months back by Emilie Läng and others, called Unbalanced food web in a Late Cretaceous dinosaur assemblage. I was able to read it about two weeks ago and was inspired to look more into the ideas presented. I then learned that Dale Russel suggested in 1996 a similar theory, I read a post by Duane Nash at another small blog called Antediluvian Salad on the topic, and I had a chance to watch an Attenborough documentary about the effects of the Salmon Run in Canada and what it does to the local predator populations. By the end of that, I had enough info for a video, so I made one. Voila:


It's an interesting idea, and while I'm not completely persuaded by all of its points, nevertheless I do like the theory and I have no particularly big reason to doubt it based on current evidence. Besides, the image of a Carcharodontosaurus ripping a shark out of the water is just dang cool. Land sharks vs. Sea sharks. :P

I've already gotten a lot of attention via PMs and comments about the theory, with people telling me why they agree or disagree with it. I'd like to hear your opinions about it too, so be sure to leave a comment and feel free to make a suggestion for future topics. Until next time...stay sharp, everyone! ;)

Saturday, July 13, 2013

"Porpoise Turtles" and Repenomamus

Well, this goes right up there with Sharktopus, Dinocroc, and Pizza the Hut.
(Are you catching the movie references?)
Marine reptiles are awesome. One of the "big three," as I like to call them, (the other two being Dinosaurs and Pterosaurs), marine reptiles are any group of reptiles that evolved into an aquatic niche. They include a number of unrelated groups, from giant marine squamates like Mosasaurs, to sauropterygian Plesiosaurs, to living Marine Iguanas. I get the honor of seeing some of the best extinct marine reptile specimens in the world every week, at my local museum where I recently began to volunteer. It has both the world's most complete Mosasaur as well as the only known specimen of a pregnant Plesiosaur on display. It's a nerd's paradise. Hopefully I can take some pictures of the specimens to share with you in the future.

While I would like to discuss those specimens in depth, I'll have to do that at another time. Sea turtles are going to be the topic of today's post. What few realize is that sea turtles are the only marine reptile family known to have survived the K-T extinction into modern day. You're probably all familiar with the extinct giant sea turtles like Archelon and Protostega, which are within a family called the dermochelyoidae, whose sole surviving representative is the Leatherback sea turtle (Dermochelys coriacea). However, recently on PLOS, a new member of the giant sea turtle family was announced, named Ocepechelon bouyai, which has to be one of the most awesome sea turtles I've ever seen.

A big, weird, and freaky skull.
Almost hard to believe it comes from a turtle...
Why is Ocepechelon so awesome? Because it is just plain freaky (but in a good way). When I first saw the artist's rendering above, I almost thought it was a fish-eating crocodilimorph like a Phytosaur (by the position of the nostrils), but after reading it was a turtle I was shocked. Its skull (which is sadly the only part we have from this giant) was more than two-feet long, elongated, and tubular, and a horny beak, while probably present, would've been extremely abbreviated and ineffective in capturing prey. The fact that this giant was found in late Maastrichtian rocks of Morocco makes it even more exciting, as we lack virtually any fossils from Late Cretaceous Africa.

Ocepechelon's living habits are even more amazing. The authors make a compelling case that this guy was a suction feeder, and they drew a huge number of adaptations for such a lifestyle. However, he is unique among tetrapods in apparently being a pipette-feeder, like seahorses and pipefish. While most suction feeders alive today have short, wide jaws to maximize water flowing into their mouth, these fish focus on smaller prey and pick them out of the water selectively. Apparently Ocepechelon fed in a similar way as seahorses and, to a lesser degree, beaked whales, which it shares numerous adaptations with as well. The latter features inspired the nickname I posted above: the Porpoise Turtle.

So, great job to the researchers who discovered and described Ocepechelon! He's now officially my favorite Mesozoic sea turtle, and he's just further evidence that the Mesozoic was teeming with reptile diversity. A lot of recent research into other reptile groups outside of the big three also shows that virtually every reptile during the Mesozoic was doing great. We have fossil squamates, snakes, mesosaurs, crocodilians, and sphenodonts running around during the Mesozoic, doing all sorts of things. Almost makes me feel sad for small mammals, as they were the only Mesozoic group that had virtually no diversification. As with most everything, however, there were a few exceptions.

There are a few really cool mammals that lived during the Mesozoic. Repenomamus, the dinosaur-eating mammal found in Yixian, is one of my favorites, as it has guts. These guys reached huge sizes compared to other mammals, exceeding ten pounds, which is a lot for a mammal back then. Not just that but one specimen was found to have a baby Psittacosaurus in its gut, showing that these guys ate dinosaurs. The four-episode Discovery television series "Dinosaur Revolution" had a few clips that included small mammals, such as the beaver-like Castorocauda and flying squirrel-like Volaticotherium. I understand they were also going to include a section on Repenomamus, but it got cut from the project. Nobody knows why the segment got scrapped, but my guess is because it included the now-dubious taxon Raptorex kriegsteini.

Luckily, I was able to find a storyboard sequence of the scene on YouTube. Enjoy, but be warned...I was ROTFL so much after watching this. :)

Until next time, stay sharp!



Click here for Part 2:
References:
Nathalie Bardet, Nour-Eddine Jalil, France de Lapparent de Broin, Damien Germain, Olivier Lambert & Mbarek Amaghzaz (2013) A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods. PLoS ONE 8(7): e63586. doi:10.1371/journal.pone.0063586

Tuesday, July 2, 2013

Awesome Pterosaurs and the Blog's Promo-Video

Well as I said before, since I just finished up with school I am getting more free time to do more things, like write on here. However, recently I've been caught up in reading Mark Witton's new book Pterosaurs (which BTW, is probably the best book on these extinct reptiles to date, and I highly recommend it to anyone even remotely interested in them) and have not had the attention span to tear myself away and write a new post, and during the time that I wasn't reading, I was getting ready to submit my new-and-improved version of my article to AncientPlanet Online Journal.

However, to make up for the lost time, I decided to make a new video, which I posted on YouTube yesterday covering Pterosaur diversity. It includes some new scientific information revealed in the book, as well as coverage of many of the extremes of pterosaur diversity. Enjoy:


After I was done with that, I decided that I needed something to spice up my YouTube channel and get more publicity for my blog, but I couldn't put my finger one what. Then it hit me. I needed something to promote it: a promotion video! So, I decided to throw this together over the weekend and put it up earlier today. It's not the best video I've ever made, and I was limited to using only my Windows Movie Maker program (which isn't the best for these types of videos) but I'm still pretty proud of it and it's a good start.

 
If anyone here has a suggestion for a future blog post or video, or simply has a question they'd like to have answered, feel free to send it by me. As always, stay sharp! ;)

Sunday, June 2, 2013

Psittacosaurus, Allosaurus, Baryonyx, Wulatelong, Aurornis and Torvosaurus. Oh my!

You lying fossil! I believed in you!
It seems that within the last month paleontologists have been publishing a lot of new discoveries about some well-known dinosaurs, as well as discoveries from two new guys guy that I'll get to further down. Some of these discoveries have been of great interest to me, and it has encouraged me to write about it here before school ends and I get more free time to talk about other stuff.

*I don't want this blog to become a sort of news blog where people can come and hear about all the latest discoveries, but if there is something in the news that I find interesting, then I'll post about it. I won't be talking about every little news item, though.

To start off I wanted to talk about a heartbreaking discovery concerning Psittacosaurus. Psittacosaurus is a basal ceratopsian, and also currently holds the record of most known species of any non-avian dinosaur genus. It's also one of the best known dinosaurs, with hundreds of specimens that include details about its internal and external anatomy (even including color!), as well as its diet, ontogeny, and behavior. One of the greatest examples of the latter was the discovery of 34 juvenile Psittacosaurus nested underneath the body of the adult animal, for a long time considered to be one of the greatest examples of parental care among any dinosaurs. Until it was found to be a fake.

A re-analysis of the specimen in question by Zhao and associates found it to be a composite. The 34 juveniles and the 'adult' turned out to be glued together, and the 'adult' specimen in question wasn't even of reproductive age. All in all very disappointing, especially for myself, as the magazine article I've been writing for the last month happened to focus on this particular specimen, and with the news having been published four days before my article was due for publication, I was unable to revise it in time to make the deadline. That was really depressing for me, and I felt like I let a lot of people down. Updates are being made for the next issue, however. Or perhaps I'l focus on less-researched topic than dinosaur parental care, which is what I had originally planned. Perhaps I'll discuss discoveries of juvenile dinosaurs together in nests separate from adults. For instance, although the Psittacosaurus composite is no longer considered an example of parental care, the 34 juveniles still died together, and Zhao also talked about a new specimen which preserves multiple juveniles of differing age groups together, so there certainly are a lot of interesting points remaining to discuss.
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In other news, Witmer Lab has been at it again. This time they reconstructed the neck musculature of Allosaurus using computer models and found that, unlike Tyrannosaurus, Allosaurus did not suffer from as much forward inertia. The lighter head allowed the head to swerve and move around faster than big, boxy-headed Tyrannosaurus and thus the animal was probably more agile. This also brings to mind one of my old predator vs. scavenger posts, where I said that T-rex suffered from a large amount of inertia and likely couldn't turn quickly. This was no problem for Allosaurus.

video
Animation by Witmer Lab. I own nothing. Forever alone....
 
Another interesting observation that they made was that they think they revealed the feeding style of this predator. Apparently unlike Tyrannosaurs, which are thought to have used their jaws to violently shake and tear off pieces of meat, Allosaurus seems to have used its jaw to slice off pieces of meat rather like a predatory bird. This really interests me as a study last year also reported that dromaeosaurids had a predation-style similar to eagles, restraining the prey with the limbs while slicing off pieces of meat with the jaw. Perhaps Allosaurus was doing a similar thing as dromaeosaurids, slicing off pieces of meat on large animals like sauropods and stegosaurs, eating them alive. Extremely gruesome and somewhat revolting, but an efficient feeding strategy nonetheless.
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Baryonyx, perhaps not as much of a fish-eater as we thought.


Onto another fan-favorite, remember my post about spinosaurids a few month back? In it I talked about how Emily Rayfield conducted a study of a number of different theropods, including Suchomimus, and found something odd. Despite its length and lack of any notable features that would resist torsion, Suchomimus has a skull that could resist excessive force just as well as other large theropods. At first I thought that this was odd, and even she noted at the end of the paper that her numbers were inconclusive and required more in-depth studies, but now she and Andrew Cuff have come back with a new paper that backs up this idea.

By using the skull of Baryonyx, a close relative of Suchomimus, they ended up with the same results. Not just that but they also cross-reference the skull with that of living crocodilians (an American Alligator, African Slender-snouted Crocodile, and Gharial) and Spinosaurus and found that Baryonyx could withstand just as much torsion as some crocodilians and theropods, contrary to some studies suggesting that Baryonyx could only withstand as much torsion as a gharial. She also found that Baryonyx's skull reacted very different mechanically than a gharial, contrary to many other studies, including her own. One thing that really shocked me though was that she did find that Spinosaurus' skull reacted mechanically similar to that of a gharial, which again is contrary to some reports that it was better at withstanding mechanical forces than members of the Baryonychinae. Despite this, Rayfield and Cuff firmly state that when size is accounted for, both of the skulls "absolutely outperform all crocodilian taxa”.

I've yet to see how the paleontological community has reacted to this discovery, and it hasn't gotten much press, but now Rayfield and Cuff have suggested that perhaps the Spinosauridae as a whole might not have been obligate piscivores, but instead that perhaps diet was more reliant on size of the individual, as it is in living crocodilians. For example, juveniles crocodiles feed on small animals like fish and insects, mid-sized individuals mostly feed on fish and small game, and larger adult crocs mostly feed on land animals. This is an cool theory, and similar theories have been suggested for other theropods, so it certainly seems likely.
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Note the elevated toe claw.
Bear in mind, this is a oviraptorid, not a Deinonychosaurian.
Wulatelong gobiensis is a new species of basal oviraptorid from the Gobi Desert, and is the fifth new species of oviraptorid to be described this year. It's been a cool discovery not just because it is relatively complete, but it also seems to have died articulated in a relatively natural condition. However, the head and neck are preserved badly, and there aren't any unusual traits about it that make it stand out. It looks just like your average, run-of-the-mill oviraptorid at first glance, until you look down at the foot.

Although the original describers said nothing about it, images such as the one above clearly show that the second toe of this oviraptor has a large claw that is elevated off the ground. As I said, this specimen is articulated in a natural position, so it seems the claw was held in that position in life. If you don't know where I'm going with this, let me help you....

IT'S AN OVIRAPTORID WITH A DROMAEOSAUR-LIKE SICKLE TOE CLAW!

Currently there has been a lot of talk about this specimen, and some scientists are even stating that it might have implications for the evolution of such enlarged hyperextendable claws, that perhaps the ancestor of oviraptorids and dromaeosaurids had such a structure, and even that the trait might be common throughout the Ceolurosauria. It's a bit of a mess right now, but the curious thing that myself and the paleontological community are shocked about is the fact that Xu Xing and the original describers of the specimen don't even remotely bring this up in their paper. It's strange. The animal is found articulated in its natural position showing the claw hyperextending like that, and there's no mention of it whatsoever? I hope we get to hear more about this guy and get a confirmation about such an amazing example of a non-Deinonychosaurian sickle claw. As for why an oviraptorid would need such a claw on its foot, I don't know, but here are some ideas:



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New relationships of basal birds. Time to start rewriting the text books.....
Borrowed from Theropoda.


Aurornis xui (and yes, it is named after Xu Xing, although to my knowledge he didn't work on the specimen) is a new species and genus of basal bird from the mid-Jurassic of China, and has dethroned Archaeopteryx as the "earliest bird" by about 15 million years. It's a pretty awesome discovery, as it provides a snapshot of how birds got their start, and in this case, has also provided a new area of analysis for researchers looking into the question of where Archaeopteryx falls on the theropod family tree. In this case, they found that it is more derived than Aurornis, and that it, along with Anchiornis, Xiaotingia, and Rahonavis(!) are all basal birds. Not just that, but they also found that the troodontidae are not closely related to dromaeosaurids or deinonychosaurians at all! Instead, they seem to be apart on an unnamed sister-group to the avialans, which would explain why troodontids share so many similarities with birds, more so than they share with dromaeosaurids.

However, despite this new find nobody should think of the chapter on
Aurornis xui  as being closed, as I'm sure that in a few months we'll be getting another rebuttal paper stating some alternative ideas. The history of birds is filled with a lot of complex data, and we're at the point that defining birds as a group is harder than it looks, as there is literally no major differences between basal birds and other members of Paraves. We still have a lot more work to do, but having Aurornis with us will hopefully make it easier and not fuzzier.

Perhaps the most shocking find of all in this paper was the discovery that they made with Balaur bondoc. Apparently, it's not a dromaeosaurid; it's a basal bird and sister taxon to Pygostylia! That's a shocker, but there's good reason to think this is the case. The conclusion was based on a direct observation of the specimen, and a new monograph that came out that also came to this conclusion.

So, Balaur is some kind of Cretaceous dual-clawed killer dodo. That's going to take A LOT of getting used to...
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We FINALLY get some big theropod eggs and embryos!
And look at them, such cute little baby Torvosaurus.....
Torvosaurus was the largest predator in the Jurassic (ignoring Epanterias and Saurophaganax as they haven't been properly identified yet). This huge, heavily-built predator with serrated teeth, robust arms, and killer demeanor terrified most around it, but now we know that this species had quite a softer side, as Torvosaurus has now provided the first ever non-avetheropod eggs! Talk about a long wait! Nearly 200 years since the first Dinosaurs were described and 100 years since the first Maniraptor eggs were discovered, and it's only now that we're getting some big theropod eggs? Fossilization is horribly bias sometimes, but I'm happy that we finally found them. Now we just need a thyreophora and neoceratopsian nest and I can die peacefully.

Moving on with this amazing find: These eggs are actually not THAT new; apparently they were first unearthed in 2005 but are only being described now. They were found in a clutch along a hillside and consist of a large number (exact number unknown) in the Lourinhã Formation in West Portugal. For those who are also dino-nerds, you'll remember that a clutch of eggs from the the Allosauroid/Coelurosaur Lourinhanosaurus were also found here. This might suggest that perhaps the area was favorable for breeding theropod females, or maybe that the fossilization process there is biased towards dinosaur eggs. Either way, somebody's got to check out that area for more of these clutches.

The microstructure of the eggs is also unique among theropods, as it has only one eggshell layer, while most theropods have two and birds have three. The eggs also seem to have been buried, as the openings in the eggshell are large to let in air, and the eggs themselves are not disturbed, suggesting that they were already buried by the mother. They were either buried in sediment or plant material, similar to what is seen in crocodiles, so perhaps parental care in this species was also crocodilian-like, but I'll save talking about that for my revised article. ;)

So, what's your favorite discovery in paleo-news recently? Feel free to share, and as always, stay tuned and stay sharp!

References:

Cuff AR, Rayfield EJ (2013) Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians. PLoS ONE 8(5): e65295. doi:10.1371/journal.pone.0065295

Eric Snively, John R. Cotton, Ryan Ridgely, and Lawrence M. Cotton, Ryan Ridgely, and Lawrence M. Witmer (2013) Multibody dynamics model of head and neck function in Allosaurus (Dinosauria, Theropoda). Palaeontologia Electronica Vol 16, Issue 2, 11A 29pp.

Godefroit P., Cau A., Hu D.-Y., Escuillié F., W. Wu, G. Dyke 2013. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds. Nature doi:10.1038/nature12168

Qi Zhao, Michael J. Benton, Xing Xu, and Martin J. Benton, Xing Xu, and Martin J. Sander (2013) Juvenile-only clusters and behaviour of the Early Cretaceous dinosaur Psittacosaurus. Acta Palaeontologica Polonica (in press) doi: http://dx.doi.org/10.4202/app.2012.0128

Ricardo Araújo, Rui Castanhinha, Rui M. S. Martins, Octávio Mateus, Christophe Hendrickx, F. Beckmann, N. Schell & L. C. Alves (2013) Filling the gaps of dinosaur eggshell phylogeny: Late Jurassic Theropod clutch with embryos from Portugal. Scientific Reports 3 : Article number: 1924
doi:10.1038/srep01924

Xu X., Tan Q.-w., Wang S., Sullivan, C., Hone, D. W. E., Han F.-l., Ma Q.-y., Tan L. & Xiao D. 2013. A new oviraptorid from the Upper Cretaceous of Nei Mongol, China, and its stratigraphic implications. Vertebrata PalAsiatica 51 (2): 85–101.
 

Sunday, May 5, 2013

Walking with Dinosaurs: The 3D Movie

First things first, I must apologize for about a month's absence in activity. I have currently been preoccupied by end-of-the-year work at school so my schedule has been really busy, and the rest of my time has been occupied by my magazine article work, family activities, and enlisting to volunteer at my local museum, so I haven't been able to find the time to write. Luckily, during the little free time I have had, I have been reading a lot of new books and scientific papers, so expect when all this is done to have a lot more posts by me.

However, that isn't why I'm here right now. I'm posting to talk about something awesome that was announced by 20th Century Fox on Wednesday. I shouldn't really have to say anything, just look at the trailer:


Yes, a Walking with Dinosaurs 3D movie that will be coming out this Christmas. For Dino-Fans like me, this is a godsend. Quite literally this is what the Dinosaur community has been looking for, for ages. I couldn't believe it when I saw it, as it's almost too good to be true. As for why, I'll list the reasons below.

  • Feathered Raptors!!! - If you look at one of the scenes towards the end, their is a sincere feathered Deinonychosaur (It looks to be a Troodon, but I'm not drawing conclusions yet). I have been wanting to see feathered dinosaurs in a movie for so long, and we're finally getting it. It's 100% scientifically accurate, and much better looking than the 6ft bipedal iguanas in Jurassic Park. 
  • Realistic Dinosaurs - Truly, I have never seen more scientifically accurate looking extinct animals. According to Mark Witton on his blog, he as well as other paleontologists and paleoartists like David Krentz, Tomas Holtz, Scott Sampson, Luis Chiappe, and Victoria Arbour have all been involved in re-creating these animals. Heck, according to him they even consulted Mark about the anatomy on the inside of the pterosaur's mouths trying to get every detail as scientifically accurate as possible. I watched over the trailer about a dozen or so times now and I can find only 1 scientific inaccuracy in it (which I will discus below), but seeing as many documentaries fail at even getting that right, this is truly amazing.
  • Dinosaurs Acting like Dinosaurs - Unlike Jurassic Park, where the animals are nothing but hideous monsters, or Land Before Time and Disney's Dinosaur, which featured talking, human-like dinosaurs, by the looks of it this appears to be what the title suggests: a 3D movie about Dinosaurs, not human-like or Sci-Fi movie monsters, they act like Dinosaurs. Now, there have been some suggestions in the comments of some of the trailers that these animals will talk, but seeing as they don't talk in the trailer (instead making a lot of animal sounds), it's based on the groundbreaking documentary series that goes by the same name, and seeing as the description of the actual movie states that it will be about real-life dinosaurs, I highly doubt the animals will talk.
  • Feathered Raptors!!! - Did I mention how amazing this is?
  • New, Somewhat Unique Story - The story seems to be following the life of a young Pachyrhinosaurus, born young and weak climbing up to become an alpha male in his herd, and the hardship he faces. At least that's what I got from watching the trailer. However, if you do a little research online it seems that it isn't just following the life, it's a rivalry story. Apparently it doesn't just focus on the main Pachyrhinosaurus, but also on another Pachyrhinosaurus, his brother, and about how they grow up together. I'm guessing that the brother is probably the second little Pachyrhinosaurus slightly larger than our hero in half of the scenes, as well as possibly the other big individual shown during the clash towards the middle of the trailer. This is certainly an interesting concept to put into a Dinosaur movie, especially since every dinosaur movie I've ever really watched seems to be (according to my dad) about getting from Point A to Point B and there are meat-eating theropods in-between. In this movie you're following the life of this individual as well as the hardships he face,s not just with vicious predators and a terrifying world he has to live in, but with his own brother and himself. That's a new and interesting concept that I haven't seen before in a Dinosaur movie, and I can't wait to see how they play it out in the film.
So as you can see there are a lot of reasons for me to be excited about this movie. It looks simply awesome that they were able to get this many things right, and I can certainly say that I'm now way more excited about this movie than I am about Jurassic Park 4 (which has crushed the hopes of the paleontological community by saying that feathered raptors will not be appearing in the film) and even Pixar's new film The Good Dinosaur set to come out next year, which is apparently a cartoony film about a human and his Sauropod friend (that is probably going to talk). The later is an interesting scenario, but not anything I'm really that interested in at 16 years of age.

However, being the scientist-in-training I am, I am disappointed about a few things. For one, seeing as they got so many things right in this movie, the one glaring inaccuracy out of the entire movie turns out to be our hero himself. Young Pachyrhinosaurus specimens don't show flat faces like the individual in this show. Instead they have a weird growth sequence where juveniles develop a small horn at a young age which later develops into the horn as they mature. This is seriously an extremely minor thing, and in fact I don't even know why I'm bringing it up. I guess it's somewhat disappointing that in a movie where they got everything so right, the fact they missed one thing kind of annoys me.

I also wish we had feathered Tyrannosaurs, seeing as Yutyrannus was found earlier last year, but according to Witton they designed the Tyrannosaurs before the Yutyrannus discovery came out, so I guess it's acceptable. I also wish the dinosaurs were maybe a little less shrink-wrapped and more speculative, as that's what paleontologists have been trying to push towards nowadays, but again the dinosaurs look great anyways so it's acceptable, and in truth that'd probably be asking for too much.

After hearing the news about JP4 having featherless raptors and getting another new predator appearing, that has definitely lowered my expectations and now I really don't care about the franchise anymore. This on the other hand looks spectacular, so I'm pretty dang excited! Can't wait for this to hit theaters! What's everyone else's thought? Feel free to share!

Tuesday, April 2, 2013

The Plague of the Hesperonychus Meme and its Inaccuracy

That darn Hesperonychus meme again! Trust me, there are plenty more where these came from.
A random collection of pictures by various paleontologists.
I'm not normally one to criticize artwork, but I feel like something needs to be said about this. For those of you who have been keeping up with paleontological blogs (hopefully including mine) you'll remember that All Yesterdays has gotten a lot of praise for pointing out the flaws in modern paleoart, and the memes made by artists who are unfortunately copying other people's work. Darren Naish pointed out some classic memes in his presentations following the publishing of his book, which you can watch here, including the "Freaky Giraffoid Barosaurus" and the black and white Phorusrachus memes, both of which have basically become the norm for the two, but I think I found another.

Those of you who keep up with dinosaur news will remember the discovery of "America's Smallest Meat-Eating Dinosaur" Hesperonychus elizabethae (Currie 2009) (which is technically not true; that title probably belongs to one of our species of Shrike). Hesperonychus was a dromaeosaurid, or more specifically, a member of the subfamily microraptorinae and is the youngest member as well as the first to be discovered outside of Asia. This has made it of particular interest to paleontologists, and has shown that the rather primitive microraptorinae survived close to, if not until the end of the Mesozoic.

However, what is sad about this wonderful little animal is that ever since its description it has been routinely portrayed as holding its tail almost vertically in the air like a lemur (an image further made iconic by the lemur-like tail stripes on many illustrations), with what look to be relatively short arms, standing on the ground with a mostly brownish coloration. Apparently this original "look" was based on a reconstructed model of Hesperonychus following its publication, and it has since been condemned to this appearance. I know there are certainly more dinosaurs that have been condemned to far worse appearances, but I find this to be not just a pressing problem for Hesperonychus because of the "unoriginality loop" it has fallen into, but it also is being portrayed rather inaccurately.

For one, the tail of Hesperonychus has never been found. Indeed, we've only found a partial hip and a few hand bones belonging to the animal, so there is nothing suggesting that it was any different than other microraptorines. Not just that, but you don't see many other raptors holding their tails up in the air, now do you? Might be a fun idea to try, but the majority of fossil evidence currently suggests that microraptorines possessed feathered disks and fronds on their tails. Current research has shown that these tail fronds have an aerodynamic advantage (Habib & al. 2012), and are actually very similar to rhamphorhynchid pterosaur tails (Persons & Currie 2012), which is consistent with the idea that microraptorines were gliding animals. However, even terrestrial dromaeosaurids seem to have had such fronds, showing that they likely had an advantage while on the ground as well. The tails seen on the reconstructions of Hesperonychus, however, much more closely resemble those of primitive Coelurosaurs like Sinosauropteryx, and seem totally un-dromaeosaurid-like.

Given, I know that the tail has not been discovered for this animal, and thus the reconstruction can be based off the artists own personal ideas. But when the reconstruction has been drawn over and over again countless times in the same way with no creativity whatsoever, it gets very annoying. 

And the re-occuring features don't stop there. Often times Hesperonychus tends to be portrayed with what appear to be very short front limbs. This is certainly not always shown; indeed the illustration in the lower right-hand corner in the image above seems to have appropriately-sized arms based on the fossil finger bones and related species, but many of the others just seem to be way too small. The brown coloration has also become routinely shown on this creature, but dinosaur coloration has been shown to have varied widely based on our current melanosome evidence. Again, there is nothing wrong with portraying it as brown, but it's terribly unimaginative after the hundredth time.

Finally, Hesperonychus is almost never shown with the correct large flight feathers on its forearms that are seen in almost all other dromaeosaurids. This is perhaps due to the original description of the animal, as it was described by Longrich and Currie, who believed that because its size more closely matched that of the large microraptorine Sinornithosaurus millenii, it was probably flightless. Sinornithosaurus has a reduced wing, vaned symmetrical feathers, and seems to be too large to be able to glide, and this was also assumed for Hesperonychus.

This seems to be a valid argument, but as for why they decided to make their mount completely lack vaned feathers on the arm when they are still present in Sinornithosaurus does not make any sense, and has definitely contributed to the look of the animal. Also, despite Longrich and Currie's conclusion, it is still possible that Hesperonychus was a gliding animal: another dromaeosaurid, Graciliraptor lujiatunensis is in the same size range as both Sinornithosaurus and Hesperonychus, but feather impressions show that it had large, asymmetrical wing feathers and wings that approached similar proportions to the gliding Microraptor, and thus it too may have been able to glide (Martyniuk 2012). This leaves open the possibility that Hesperonychus would've been able to glide as well, and it certainly would be a nice alternative to the illustrations of walking around on the ground like some Cretaceous lemur or something....

So those are some of my thoughts about this somewhat over-used paleoart meme. Maybe if I'm up to it I'll draw a more realistic Hesperonychus with long arms, large flight feathers, and a horizontally positioned tail climbing through the branches.

Yeah, I draw. Given, I don't normally draw and I'm definitely not the best at it, but that doesn't stop me from occasionally trying. If I'm sucessful at a pic, I'll make another post to show you guys. If it was a failure, I'll never bring it up again. 'Til then, stay sharp!

Refferences:

Habib, M., Hall, J., Hone, D. and Chiappe, L. (2012). Aerodynamics of the tail in Microraptor and the evolution of theropod flight control." 72nd Annual Meeting of the Society of Vertebrate Paleontology, 20 October 2012.

Longrich, Nicholas R. and Currie, Philip J. A microraptorine (Dinosauria-Dromaeosauridae) from the Late Cretaceous of North America. Proceedings of the National Academy of Sciences of the United States of America, 106 (13), (2009). 5002-5007 DOI: 10.1073/pnas.0811664106

Martyniuk, Matthew P. A Field Guide to Mesozoic Birds and other Winged Dinosaurs. Vernon, New Jersey: Pan Aves. (2012) 

Persons, W. S. and Currie, P. J. (2012), Dragon Tails: Convergent Caudal Morphology in Winged Archosaurs. Acta Geologica Sinica - English Edition, 86: 1402–1412. doi: 10.1111/1755-6724.12009