Sunday, August 30, 2015

Acrocanthosaurus: Beast of the Week

This week we are checking Acrocanthosaurus atokensisAcrocanthosaurus was a meat-eating dinosaur that lived in the United States, including Oklahoma, Texas, Wyoming, and even as far east as Maryland, during the Early Cretaceous Period, between 125 and 100 million years ago.  Acrocanthosaurus was a very large meat-eater, at about thirty nine feet long from snout to tail, and was likely the top predator in its environment.  The name Acrocanthosaurus, translates to "High Spine Lizard" and is in reference to this dinosaur's particularly tall neural arches, which gave it a distinctive ridge down its back.

Acrocanthosaurus atokensis life reconstruction by Christopher DiPiazza.

Acrocanthosaurus' spine was interesting in that we haven't found another theropod dinosaur with anything similar.  It is often compared to the unrelated, Spinosaurus' sail-like structure, but Acrocanthosaurus' runs all the way from the back of the skull to the tail, rather than just the back like in SpinosaurusAcrocanthosaurus also has a close relative from Spain, Concavenator, which has a triangular-shaped hump over its hips, but again, this is concentrated to one area of the spine. The purpose of this ridge-like look is a mystery.  Some believe it would have formed a hump rather than a ridge, like what you might see on a modern bison's skeleton.  (Which also have extended neural arches, but only over the shoulder girdle.)   As of now the safe answer could always be that Acrocanthosaurus possessed this ridge down its spine for display purposes to other members of its species.  Maybe they were larger in males than in females and played a role in mate selection?  Perhaps it was significantly shorter in juveniles?  There is still a lot we don't know!

Bison skeleton.  Note the tall neural arches above the shoulders.  The living animal has a hump there.

The skull of Acrocanthosaurus is long, low, and narrow in the front, but the back of the lower jaw become increasingly deep, suggesting there was a lot of muscle there in life, allowing this dinosaur to bite down hard in life.  The teeth of Acrocanthosaurus were slightly curved and serrated.  They were also thicker than the very blade-like teeth of its later relatives, like Giganotosaurus and Cacharodontosaurus, suggesting Acrocanthosaurus was more of a generalist hunter.  This is also further supported by the fact that Acrocanthosaurus' range was so widespread across what is now the United States, which would have consisted of multiple different kinds of habitats.

Acrocanthosaurus skull from the North Carolina Museum of Natural Sciences.

The front limbs of Acrocanthosaurus were short, but powerful and had a decent range of motion to them.  Each hand possessed three hooked claws.  It is difficult to say exactly how Acrocanthosaurus would have utilized these arms since they were so short, but they may have played a part when it was going after large prey, like a sauropod, at close quarters.

Acrocanthosaurus skeletal mount on display at the North Carolina Museum of Natural Sciences.

When alive, Acrocanthosaurus, would have coexisted with many other dinosaurs, including the much smaller predator, Deinonychus, the ornithopod, Tenontosaurus, and a few different kinds of large sauropods.  In fact, there is a dinosaur track way in Texas consisting of large theropod prints that are believed to have been made by Acrocanthosaurus along with those of a large Sauropod.  These tracks show, since at times the theropod prints overlap the sauropod ones, that those of the theropod were made later, and could have possibly been tracking the larger herbivores.  At one point some scientists believe the theropod even attacked the sauropod, since the meat-eater tracks skip for a while where they finally intersect. (did it latch onto the side of its intended prey?)  This hypothesis can't be fully proven, however.  Even though no bones from either dinosaur were found with this trackway, it is predicted the predator was Acrocanthosaurus because the size, location, and age of the find matches with the Acrocanthosaurus bones that have been found in other nearby states.

Photograph of the tracks believed to have been from Acrocanthosaurus possibly stalking a sauropod in the field in Texas.  You can now see these tracks in person on display at the American Museum of Natural History in New York City.

That is all for this week!  As always please comment below or on our facebook page!

References

Currie, Philip J.; Carpenter, Kenneth. (2000). "A new specimen of Acrocanthosaurus atokensis (Theropoda, Dinosauria) from the Lower Cretaceous Antlers Formation (Lower Cretaceous, Aptian) of Oklahoma, USA". Geodiversitas 22 (2): 207–246.

Lockley, Martin G. (1991). Tracking Dinosaurs: A New Look at an Ancient World. Cambridge: Cambridge University Press. p. 252pp.

Senter, Phil; Robins, James H. (2005). "Range of motion in the forelimb of the theropod dinosaur Acrocanthosaurus atokensis, and implications for predatory behaviour". Journal of Zoology 266 (3): 307–318.

Stovall, J. Willis; Langston, Wann. (1950). "Acrocanthosaurus atokensis, a new genus and species of Lower Cretaceous Theropoda from Oklahoma". American Midland Naturalist (American Midland Naturalist, Vol. 43, No. 3) 43 (3): 696–728.

Thomas, David A.; Farlow, James O. (1997). "Tracking a dinosaur attack". Scientific American 266 (6): 48–53.



Wednesday, August 26, 2015

Interview with Paleontologist: Shaena Montanari

Today we have the pleasure of interviewing paleontologist,  Dr. Shaena Montanari!

Dr. Montanari is currently a Newton International Fellow at the University of Edinburgh. She grew up in Connecticut and attended the University of North Carolina at Chapel Hill where she got a B.S. in Geological Sciences. She got her PhD at the Richard Gilder Graduate School at the American Museum of Natural History and before coming to Edinburgh was a Columbia Science Fellow at Columbia University. Shaena uses stable isotopes to discern the diets of extinct animals and learns more about the changes in paleoenvironments and dietary habits over time. She also applies stable isotope analysis to extant vertebrates in order to uncover elusive lifestyles of endangered animals.


Question 1: Let’s start from the beginning.  What was your earliest sign of interest in paleontology that you can remember?

SM: I’ll start off by saying I am perhaps not a typical paleontologist in the sense I only became really interested in paleontology in college. I have always been a “science nerd” though. I loved animals, exploring outside, collecting rocks, twigs, etc. I did not know much about paleontology as a kid but just tried to read anything to do with the natural world I could get my hands on. My favorite place to go as a kid was the aquarium actually!

Question 2: Did you have any professionals or family members who served as role models when you were younger?  Do you still have any now?

SM: None of my family members are academic or scientists in any way, so I was a bit of an odd duck in that respect. I remember really loving nature documentaries and science TV shows—I definitely grew up with Bill Nye always being on the TV. I was lucky to have lots of incredible teachers in primary school all the way through high school who were great role models for me too. I still keep in touch with many primary and high school teachers—some of them were huge influences on my career even all the way back in grade school!

Question 4: Was there anything you did or learned as you were on your way to your current career that you feel got you to where you are?  By this I mean any sort of field experience, a class, networking with the right people, or possibly something different or all three?

SM: Good question…as I described, I didn’t know much about paleontology growing up. I wasn’t really in that “world” from a young age. I came from a non-academic family but just worked really hard to get to a great university. I obtained a competitive internship at a pharmaceutical company in high school that helped me break in to scientific research for the first time. Studying geology at the University of North Carolina was a big break for me because the class sizes were so small I got to know my professors and get solid research experience.  From there, I took a risk and applied to AMNH for graduate school. I didn’t realize when applying to graduate school you should usually be familiar with your mentor before hand! I didn’t know anyone at AMNH at all but I was naïve in that respect and just went for it. I feel getting into AMNH for grad school was my real big break. Without getting into that world, I would never be where I am today.


Question 5: Is the field of paleontology different now than from when you started as far as you can tell?  How about from when you were a child?  What would your advice be to anyone trying to make a career in paleontology (or science in general for that matter) now?

SM: I have only been in the field for about 7 years or so, so I don’t think it has changed in that short period of time. I can speak to how I think academia has shifted from the “good ol’ days” though (even though I wasn’t around). These days, students are expected to publish more and be more productive than ever. We are also expected to have a very diverse, interdisciplinary set of skills. If you want a career in paleontology today I would say examine what an academic career is really like. It is mainly focused on obtaining grant money. It definitely isn’t all fossil digs and fun. Also, even before you get the job, getting a PhD is grueling. You need to make sure you really want it before you try—I recommend talking to friends and other scientists who have gone through it already.

Question 6: What was or is your favorite project in paleontology so far?  Would you be able to tell us about some of your current projects?

SM: I like all of my projects to be honest! I really enjoyed looking at the chemical signatures in dinosaur eggshells from Mongolia. No one has ever done that before and I was able to tell a lot about the paleoenvironment of the Gobi Desert 80 million years ago. Currently, I am also analyzing the chemical signatures in fossils, but this time in teeth from the Paleocene of New Mexico. I am interested in exploring the dietary radiation of mammals after the K/Pg extinction event.

Question 7: You have traveled to a lot of interesting places around the world for your research.  What was your favorite traveling experience so far?  Do you see yourself traveling more in the future?

SM: It is hard not to say the AMNH Gobi Desert expeditions were not my favorite experiences. I went out with the team for two summers and both were just fantastic. That place is incredible and I was so lucky to be able to go out on such a historic dig with my PhD supervisor Mark Norell. One of the best parts of being a paleontologist is the travel! I love doing fieldwork. At Edinburgh, I have gone to the Isle of Skye with Steve Brusatte, and I also plan on heading out to New Mexico with him next year to dig up mammal fossils.

During time doing field work in...you guessed it, Australia!




Question 8: A popular image of paleontologists is that they are constantly out in the field digging up fossils, which is true to an extent.  What people don’t realize sometimes is that a lot of paleontology work is conducted in a lab as well.  In your experience, how much of your projects (in general) take place in the field, and how much are in the lab?


SM: Most of my work is in the lab. I work on specimens that have already been collected most of the time, so I spent time inside analyzing them. I probably only get about 1 month total of fieldwork a year since my work is based in a chemistry lab. Also in general most of our days are spent on the computer!

Question 9: A lot of your work involves chemistry, which is not something many people think of immediately when thinking about paleontology, but in reality it plays a huge part!  How does it allow you to do the work that you do effectively?  Would you say it is a big part in all aspects of paleontology?

SM: I wouldn’t say it is a big part of paleontology in general, but geochemistry and other analytical techniques are surely extremely useful in our field. Looking at bones can only get you so far—there is so much more to say when we examine them closer using methods like stable isotope analysis, SEM, and CT scanning. I just like thinking of new analytical methods to approach old questions.

Question 10: Do you ever get criticized on any of your work?  How do you handle it?

SM: You get criticized all of the time in academia. Either by supervisors, professors, peer-reviewers, mean blog commenters…the list goes on. You have to develop a thick skin because some of the things people say to you about your research are just ghastly! I handle mean peer-reviews by reading them once, getting mad, then taking a break and coming back to it to reply later. Once I’ve cooled off I can sometimes see the point the person was getting at and it might be helpful. If it is just super mean I shrug it off and ignore!

Question 11: Jurassic Park and Land Before Time (opposite ends of the spectrum, I know) were just two of the programs I remember as a kid that helped fuel my obsession with paleontology.  Did you have favorite shows, movies, or even toys growing up that fueled your passion?

SM: I hate to say this but I wasn’t HUGELY into those movies or shows. Sure, I watched them, but I wasn’t obsessed or anything. I mentioned before I liked Bill Nye, that was definitely my favorite science show by far. I also was so excited when my mom would take me to the IMAX theater that showed nature documentaries that was 45 minutes away from our house. I remember seeing the “Tropical Rainforest” IMAX film about 4 or 5 times and just loving it.

Question 12: You have worked with a number of great institutions. (My new place of work is actually your old graduate school, the American Museum of Natural History!) Were there any drastic contrasts in the way work is done between any of these various places that you needed to adjust to?  Do you have a favorite place you have worked at?

SM: The bulk of my true academic career has been spent at AMNH (PhD and postdoc research), so I really cut my teeth there. I’ve only recently moved on for the first time to the University of Edinburgh. It is quite different after spending all of these years at a museum to be back at a “real” university. But luckily I came to work with my old AMNH friend Steve Brusatte, so it isn’t as different as it could be. I still talk about AMNH like it is my home and since I was in the first class at the Richard Gilder Graduate School, I feel like it will always be a big part of me!

Question 13: Possibly my favorite thing about your work is the fact that, in addition to fossil animals, you also do research with living endangered species.  Could you explain in a little more detail how exactly your research helps conservation?

SM: It is often hard to explain to people what I do because while I love paleontology, I really love studying animals over all time periods! I use a lot of the stable isotope techniques I’ve applied to fossils and apply them to conservation issues. Knowing the diets and habits of living animals can help us conserve them and their food sources. I have worked on projects with tigers and snow leopards so far and hopefully I can continue the same sort of work in the UK to learn more about the dietary ecology of threatened wildlife.

Fossil mammal tooth from the Paleocene of New Mexico Dr. Montanari is working on now for stable isotope analysis

Question 14: One of my pet peeves is when people assume paleontology doesn’t really do any real good in the grand scheme of things and is just a “for fun” science.  It’s amazing how many people I have met in my line of work at zoos who are experts on extant animals, but know practically nothing about anything that is prehistoric.  Do you think paleontology has a part to play in preserving endangered species today?  How?

SM: I absolutely do. Studying how organisms have responded to changing climates and environments over millions of years will inform us on what might happen to the biodiversity of our modern planet in the future. Also in order to understand evolution in general we have to examine the fossil record—it is the only way to see how the diversity of animal shapes, sizes, and populations change over time.  

Question 15: Who was the first paleontologist you met?  How was that interaction? 

SM: The first paleontologist I met was probably John Flynn at my graduate school interview at AMNH. It was an amazing interaction because he is an exceptional person, scientist, and mentor. I am lucky he was my co-advisor in graduate school.

Question 16: Why do you think prehistoric animals are so influential to us today?

SM: Besides the scientific importance, it is just so much fun to imagine a time where huge paddle-finned reptiles were ruling the seas and giant winged lizards were soaring through the air. The study of paleontology is a fantastic way to introduce people of any age to science. Sometimes it seems all we do it examine fossils but when you get down to it—to really be a good paleontologist—you have to know about chemistry, biology, evolution, geology, and physics. Paleontology is truly the ultimate interdisciplinary science.

Question 17: What is your favorite prehistoric animal?  Was it different when you were younger?

SM: Not sure I have a favorite actually! Probably Tanystropheus…it’s neck is so confusing!

Question 18: If you could use a time machine to go back and pick only one prehistoric animal to bring back from history and observe alive and in person, which would it be and why?

SM: This is too hard of a question. I would really like to see a Velociraptor though, just to know if they could be trained like the ones in Jurassic World.


Velociraptor

Question 19: Back to the time machine.  This time you can go back to any place and time period and have a look at what the environment was really like.  Which one would you pick and why?
SM: I would like to go to the Permian/Triassic boundary and see what caused that extinction. It is fairly mysterious and perhaps if I was standing there I would be able to see an impact event (if it happened!).


Question 20: Which is your favorite museum?  Why?

SM: I’m sure I sound biased but…AMNH! I have been to many museums around the world and I still think it is the absolute best.  There is nothing like walking into the Rotunda for the first time and laying eyes on the Barosaurus and Allosaurus mount. It will change your life!


Question 21: What hobbies do you have?  (Don’t have to be paleo-related.) 

SM: I actually do a lot of other things believe it or not! I really enjoy yoga, writing, baking, cooking, drawing, watching TV and movies…and now that I live in Scotland I make sure I do a lot of hiking.

Thank you so much, Dr. Montanari!  As always feel free to comment below or on our facebook page.  For more information on Dr. Montanari and the work she does visit her website, here.  

Sunday, August 23, 2015

Megalosaurus: Beast of the Week

This week we will be looking at the dinosaur that started it all. (sort of)  Say hello to the mighty Megalosaurus!  Megalosaurus bucklandii was a meat-eating dinosaur that lived in what is now Oxfordshire, England, during the middle Jurassic Period, about 166 million years ago.  From snout to tail Megalosaurus is estimated to have been about thirty feet long but since a complete skeleton has yet to be found, this number is subject to change.  The genus name, Megalosaurus, translates to "Big lizard/reptile" because at the time of its discovery, its bones were thought to have belonged to a large lizard and not a dinosaur. (The idea of a dinosaur wasn't invented yet!)  Despite the fact that we know dinosaurs aren't lizards now, many are still given "saurus" as part of their names anyway.  The species name is in honor of Professor William Buckland, who studied much of Megalosaurus' bones. 

Megalosaurus life reconstruction by Christopher DiPiazza.

Despite only being known from fragmented remains, consisting of a leg, a hip, some vertebrae, the tip of the snout, and a few teeth, Megalosaurus is a very monumental find because it was the first dinosaur officially named by science.  Megalosaurus was NOT the first dinosaur fossil ever discovered by humans, mind you.  People have been digging up prehistoric dinosaur bones for thousands of years.  They just were not calling them dinosaurs.  It is likely dinosaur, and other prehistoric animals, were the inspiration for many of the monsters seen and told about from the mythologies and folklores around the world.  Megalosaurus was, however, the first dinosaur to be studied and officially referred to as a dinosaur.  It first happened in 1676 when a piece of a leg bone was uncovered that baffled everyone.  It was much too large to belong to any animal native to England at the time.  At first it was thought to belong to a war elephant from ancient Rome and was later re-identified as belonging to a giant human, like the ones described in the Bible. (which have since been confirmed never existed)  This bone fragment was even given a scientific genus and species name, Scrotum humanum.  It means exactly what it sounds like; "human scrotum".  It makes me wonder if the scientists who named the fossil were early incarnates of Beavis and Butthead.
lol
Much later, in 1815, more giant bones from a mysterious creature were discovered in southern England.  They were sort of a mystery to any scientist who looked at them for a few years because they were so unlike anything anyone had ever seen before.  Then in 1818, they were finally identified as belonging to some sort of enormous reptile.  After studying these bones extensively for the next several years, it was officially named Megalosaurus at the Geological Society of London in 1824.  It was concluded that the original bone fragment, which was named Scrotum humanum, was also from Megalosaurus.  However, the original name was ditched in preference for the more informative one.  (and all the perverts cried.)  

Megalosaurus bones on display at the Oxford University Museum of Natural History.

 In the 1840s, life-sized statues of Megalosaurus and several other species of prehistoric animals were erected in the gardens of the Crystal Palace in England.  The palace itself, has since been destroyed, but the grounds where the statues are still remain in the form of a park now.  Back then, since scientists knew much less about dinosaurs, Megalosaurus was represented as a large, lizard-like creature.  We now know it would have looked very different.


Megalosaurus statue at the Crystal Palace gardens.  At the time of its construction dinosaurs were believed to have been much more lizard-like.

When alive, Megalosaurus would have walked on its hind legs as an obligate biped.  (Meaning it could not have walked on all fours even if it wanted to.) Although the front limbs were never found, it is likely, judging by other related theropod dinosaurs, Megalosaurus had three digits on each hand with a hook-shaped claw on the tip of each finger.  Its teeth were sharp and somewhat laterally compressed to better slash the flesh of its prey.  They also had small serrations for cutting meat while feeding.  Although not much of Megalosaurus' anatomy is known, there have been other dinosaurs that share similarities with what we do have of Megalosaurus, like Torvosaurus from North America, which helps us guess what Megalosaurus may have looked like and also what it was related to.  Because Megalosaurus was discovered first, the entire family which includes it and its relatives like, Torvosaurus, is called megalosauridae.  It is also believed that megalosaurids share a relatively recent common ancestor with spinosaurids.

One more fun fact.  The show, Dinosaurs, from the early nineties on the ABC channel here in America, focused around an anthropomorphic family of dinosaurs.  This members of this family were mentioned as being Megalosaurus several times during the series.  (Lots of artistic liberties were taken.)

I know the daughter has a frill but they were still Megalosaurus apparently.
That is all for this week!  As always feel free to comment below or on our facebook page!

References

Benson, R.B.J.; Barrett, P.M.; Powell, H.P., & Norman, D.B. (2008). "The taxonomic status of Megalosaurus bucklandii (Dinosauria, Theropoda) from the Middle Jurassic of Oxfordshire, UK". Palaeontology 51 (2): 419–424.

Benson, R.B.J. (2010). "A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods". Zoological Journal of the Linnean Society 158 (4): 882. 

Buckland, W. (1824). "Notice on the Megalosaurus or great Fossil Lizard of Stonesfield". Transactions of the Geological Society of London. 2 1 (2): 390–396. 

Carrano, M.T.; Benson, R.B.J.; & Sampson, S.D. (2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)".Journal of Systematic Palaeontology 10 (2): 211–300.

Monday, August 17, 2015

Chasmosaurus: Beast of the Week

Chasmosaurus was a ceratopsian (beaks, horns, and frills) dinosaur that lived in what is now Canada, during the Late Cretaceous Period, between 76.5 and 75.5 million years ago.  From snout to tail it measured about sixteen feet long, and it would have eaten plants when alive.  The genus name, Chasmosaurus, translates to "Chasm Lizard/Dinosaur" in reference to the two large holes, called fenestrae, in its large frill.  These fenestrae are present in the frills of most ceratopsians but are particularly large in Chasmosaurus.

Chasmosaurus russelli life reconstruction by Christopher DiPiazza.

In general, Chasmosaurus had three horns on its face, two relatively narrow ones on the brows, and a robust one on the snout.  The frill was extremely long, and somewhat rectangular.  The genus, Chasmosaurus, has accumulated several species within the genus by paleontologists over the years, but some of those, like Vagaceratops, for example, have since been studied further and given their own genus.  Currently there are two official species of Chasmosaurus.  The older of the two is called Chasmosaurus russelli, which had slightly longer brow horns.  The younger of the two is called Chasmosaurus belli, which had smaller brow horns and a deeper, shallow "V" shape to the center of its frill.

Chasmosaurus belli skeleton on display at the Academy of Natural Sciences in Pennsylvania.

The exact function of the frill is somewhat of a mystery.  At first it could be assumed this was a defensive structure against predators, but it was extremely lightweight and the two holes taking up most of its space don't exactly make it a good shield.  (Although the awkward shape could have still made it difficult for predators to bite the neck.)   The second idea is that the frill helped Chasmosaurus thermoregulate, much like the large ears on many mammals do, by pumping blood through it, cooling it off and thus, the rest of the body.  The third idea for the frill is display.  These frills could have served as devices for communication between members of the same species, whether it be species recognition or for attracting mates.  Although there is no sign of males and females having had differently shaped frills, they may have been different colors in life.

There has been skin impressions found from Chasmosaurus' hip region, showing mosaic-like scales of varying sizes, consisting of larger scales, surrounded by smaller ones, forming patterns.  The preserved skin of Triceratops which was found much more recently is extremely similar.  You may see many artists depicting large ceratopsians like Chasmosaurus or Triceratops with long, quill-like structures growing from these scales, but there is no evidence of this and judging by the actual fossils. (although quill-like scale structures did exist on at least certain older relatives of these ceratopsians, like Psittacosaurus, according to fossil evidence.  More on that another time.)

Photograph of fossilized Chasmosaurus skin.

There was also a wonderfully preserved Chasmosaurus baby that was discovered a few years ago.  This almost complete skeleton, missing only the front limbs, measures about five feet long from beak to tail.  The frill is proportionally shorter which is what we have seen so far with other baby ceratopsians on the fossil record, and the legs aren't proportionally long, as is the case with some other species of baby animals.

Baby Chasmosaurus specimen at the University of Alberta.  Photo courtesy of Darren Tanke.  This specimen is usually seen from the side view.  Note how from this angle you can see that even at this early age, Chasmosaurus had finestre in their frills.

That is all for this week!  Feel free to comment below or on our facebook page.

References

Campbell, J.A., Ryan, M.J., Holmes, R.B., and Schröder-Adams, C.J. (2016). A Re-Evaluation of the chasmosaurine ceratopsid genus Chasmosaurus (Dinosauria: Ornithischia) from the Upper Cretaceous (Campanian) Dinosaur Park Formation of Western Canada.

Dodson, Peter et al. "Chasmosaurus". The Age of Dinosaurs. Publications International. pp. 110–111.

Lull, R.S., 1933, A revision of the Ceratopsia or horned dinosaurs. Memoirs of the Peabody Museum of Natural History 3(3): 1-175

Maidment, S.C.R., and Barrett, P.M., 2011, "A new specimen of Chasmosaurus belli (Ornithischia: Ceratopsidae), a revision of the genus, and the utility of postcrania in the taxonomy and systematics of ceratopsid dinosaur", Zootaxa, 2963: 1-47

Ryan, M.J. & Evans, D.C. (2005). "Ornithischian dinosaurs". Dinosaur Provincial Park: A Spectacular Ecosystem Revealed. In: Currie, P.J. & Koppelhus, E.B. (Eds) Indiana University Press, Bloomington. pp. 312–348.

Tuesday, August 11, 2015

Frickn Laser Beams on Dinosaurs

Apparently there is this trend going around where paleoartists edit in laser beams coming out of the eyes of their dinosaurs.  I don't know why.  I don't know how it started.  Quite honestly I'm a little annoyed Buzzfeed already made an article about it before I could join in.  Here are my contributions. 

The first is of Changyuraptor about to ambush a smaller dromaeosaurid....with lasers.


The second is of an Anchiornis pair defending their nest against a thieving Darwinopterus...with lasers. 


The third is a female Tenontosaurus teaching a male of her species that it is rude to catcall as she was just trying to get home from work.  Serieously, guys.  Don't catcall.  It's rude and gross.

Saturday, August 8, 2015

Struthiomimus: Beast of the Week

All birds are dinosaurs, but not all dinosaurs were necessarily birds!  This week's beast is a perfect, yet confusing, example of that.  Let's check out Struthiomimus!

Struthiomimus was a theropod dinosaur that lived in what is now North America, specifically Alberta, Canada, and parts of the Western United States, during the Late Cretaceous Period.  There are currently three recognized species of Struthiomimus on the fossil record, which lived during the span of 75 to 66 million years ago.  The most well-known of the three species, Struthiomimus altus, was the oldest, who's fossils are around 75 million years old.  From beak to tail, Struthiomimus measured about fourteen feet long.  The name Struthiomimus, translates to "Ostrich Mimic" in reference to...well...just look at it!

Sitting Struthiomimus altus life reconstruction by Christopher DiPiazza.

I like to bring up convergent evolution a lot on my site.  In case you haven't read about it before on here, or anywhere else, convergent evolution is when two different species of organisms, in this case animals, look very similar because they live similarly, but do not share a close common ancestor.  They each evolved to look the same way independently.  For a good modern example check out a fish and a whale, or a flying squirrel and a sugar glider, or a monitor lizard and a tegu, or a hedgehog and a porcupine...the list goes on!  Well, Struthiomimus is possibly the best example of convergent evolution in the dinosaur world because it looks so much like a modern ostrich!

You might be thinking "Hey!  But an ostrich is a modern dinosaur!  They probably are directly related to one another!" but they're not!  Struthiomimus, although a theropod, and therefore very closely related to birds, did not go on to evolve into ostriches we see today nor any other kind of bird for that matter.  It went extinct at the end of the Cretaceous like the rest of the non-avian dinosaurs.  In fact, when Struthiomimus was alive, true birds had already evolved and were sharing their habitat with it.  It is amazing how the same design can appear twice, but separated by tens of millions of years!  Evolution is crazy!

Struthiomimus skeletal mount on display at the American Museum of Natural History.

Struthiomimus wasn't the only dinosaur that looked the way it did, however.  It belonged to an entire family, called ornithomimidae.  Ornithomimids typically had long, thin necks, small heads with large, round eyes and beaks, long arms, long fingers with three grasping claws, long tails, and of course, extremely long and powerful legs for running.  It is likely they were the best runners of their time, being able to sprint at high speeds to evade predators when they had to.  It is difficult to say exactly how fast Struthiomimus could have ran, but today's ostriches can sprint close to fifty miles per hour and sustain long distance speeds of around thirty miles per hour.  It is possible ornithomimids could have been similar.

A different Struthiomimus skeleton as found on display at the American Museum of Natural History.

Struthiomimus' diet is pretty mysterious.  Its head and mouth were proportionally very small so it was likely not attacking large animals.  Its actual beak was toothless and had somewhat sharp edges on the sides, which could have been an adaptation for clipping plants or cutting up small animals.  Struthiomimus' arms were long and but didn't have the ability to reach up that high past their normal resting position.  The fingers were all about the same length, which is unusual amongst dinosaurs, and wouldn't have been very dexterous, although many earlier reconstructions of ornithomimids show them holding and carrying items in an almost primate-like fashion.  It is possible Struthiomimus used its forelimbs as hooks, to bend plants closer to its mouth, which it could reach easier with the help of its long neck.

Close up of a Struthiomimus' hand at the Oxford University Museum of Natural History.

In life, Struthiomimus almost definitely had feathers.  We know this because specimens of a closely related dinosaur, called Ornithomimus, was discovered with amazingly preserved long feathers that were attached to its arms.  Struthiomimus likely was the same, making it look even more like an ostrich in life.

That's all for this week!  Feel free to comment below or on our facebook page!

References

Barrett, Paul M. (2005). "The diet of ostrich dinosaurs (Theropoda: Ornithomimosauria)". Palaeontology 48 (2), 347–358. doi:10.1111/j.1475-4983.2005.00448.x

Longrich, N. (2008). "A new, large ornithomimid from the Cretaceous Dinosaur Park Formation of Alberta, Canada: Implications for the study of dissociated dinosaur remains." Palaeontology, 51(4): 983-997.

Nicholls, Elizabeth L.; Russell, Anthony P. (1985). "Structure and function of the pectoral girdle and forelimb of Struthiomimus altus (Theropoda: Ornithomimidae)". Palaeontology 28: 643–677.

Russell D (1972). "Ostrich dinosaurs from the Late Cretaceous of Western Canada". Canadian Journal of Earth Sciences 9 (4): 375–402. doi:10.1139/e72-031.

Zelenitsky, D. K.; Therrien, F.; Erickson, G. M.; Debuhr, C. L.; Kobayashi, Y.; Eberth, D. A.; Hadfield, F. (2012). "Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins". Science 338 (6106): 510–514. doi:10.1126/science.1225376.