Saturday, May 20, 2017

Postosuchus: Beast of the Week

This week we will be checking out a beast that shows us that evolution is capable of truly amazing things and how deceiving looks can really be.  This creature also helps teach us it's okay to change our perceptions as we learn new things, especially in science.  Enter Postosuchus kirkpatricki!

Postosuchus was a pseudosuchian archosaur, more closely related to crocodilians than to dinosaurs, that lived in what is now the Southern United States, specifically New Mexico, Arizona, Texas, and as far east as North Carolina, during the Triassic Period, between 221 and 203 million years ago.  It was one of the largest animals in its environment, with adults measuring between thirteen and fifteen feet long from snout to tail, and ate meat, probably hunting many of the other Triassic animals from the area, including fellow pseudosuchians, Shuvosaurus and Desmatosuchus, and the dinosaur, Coelophysis.  The genus name, Postosuchus, translates to "Post Crocodile", in reference to Post Town, Texas, where the first Postosuchus bones were unearthed.  The species name is in honor of the Kirkpatrrick family, who helped in Postosuchus' excavation.

Postosuchus life reconstruction in watercolors by Christopher DiPiazza.
 
Postosuchus has gone through a few makeovers over the years since it was discovered.  Because the first group of specimens' bones were not always found articulated, and often times among those of other species, early Postosuchus skeletal reconstructions accidentally were partially made of bones from other kinds of animals.  An example of this would be a the pelvis, hand, and toe bones, which would later be found to have really belonged to Shuvosaurus.  Because of this, Postosuchus was often depicted as being able to walk on four or two legs when alive.  However, we now know that it was much more likely to have been an obligate biped, only able to walk on its hind legs, like most theropod dinosaurs. This is thanks to more complete remains of Postosuchus found more recently, proving that the arms and hands were actually much smaller than previously thought, and were incapable of supporting its weight even if they could reach the ground.  The pelvis was much larger than originally thought, too, meaning the animal's center of gravity was over the hips.

Postosuchus brass skeletal mount on display at the Mesalands Dinosaur Museum in Tucumcari, New Mexico.  This mount is actually outdated.  Parts of the pelvis actually belong to Shuvosaurus, and the four-legged stance is improbable.  The vertebrae, especially behind the skull, would have much shallower neural arches in reality.

Postosuchus' skull was tall overall, but narrow laterally in the front, gradually getting wider towards the back.  It had prominent ridges over the eyes, forming an overhanging shelf, perhaps to help block out sun glare in life.  The eye sockets were relatively large, and partially faced forwards, suggesting Postoscuchus may have relied on its sense of site to hunt.  Due to large hollow areas connected to the nostrils, it likely also had a good sense of smell in life.  Postosuchus' jaws were lined with relatively long, pointed teeth that were serrated, for better cutting meat.  Some of the teeth were much longer than the others in certain parts of the jaws, like the tip of the lower jaw, and the mid-section of the upper jaw.  This would have made Postosuchus' mouth act like a deadly trap if it were to bite into a still-living/struggling animal.

Brass cast of Postosuchus skull at the Mesalands Dinosaur Museum.  Note how the longest teeth are in the middle of the upper jaw, and the front of the lower jaw.

Osteoderms have also been discovered with Postosuchus.  Osteoderms are pieces of bone that grow under the skin of an animal.  Modern crocodilians are most famous for having osteoderms, which they use as armor, as well as for built-in solar panels, to better absorb heat from the sun.  The osteodersm associated with Postosuchus appear to have been growing in two rows down the back.  It is still uncertain as to what their purpose was.

Photographs of Postosuchus foot bones from Karin Peyer's 2008 paper, describing the specimen found in North Carolina.  Note how Postosuchus would have walked on four toes on the ground.  This is different from what you'd see in MOST theropods.  (Therizinosaurs walk on four toes.)

Within pseudosuchia, Postosuchus belongs to the family called rauisuchidae.  Rauisuchians all exhibited fully erect posture, and typically had large heads with sharp teeth.  Not surprisingly, they are often mistaken for meat-eating dinosaurs.  They even possessed hollow bones, a trait normally associated with dinosaurs.  However, Postosuchus, like all pseudosuchians, shows some key differences from dinosaurs that give it away as more closely related to crocodilians.  It's ankles are the biggest giveaway because they could rotate, like those of modern crocodilians, rather than the more rigid, one-way bending ankles all dinosaurs have.  It also would have walked with it's first four digits touching the ground and its outermost fifth digit, which was much shorter, out to the side.  Postosuchus was another amazing example of convergent evolution.  In this case, it evolved the same body design you would see in large meat-eating dinosaurs like Megalosaurus or Allosaurus...before large, meat-eating dinosaurs even evolved!

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

References

Chatterjee, Sankar (1985). "Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 309 (1139): 395–460.

Long, Robert A.; Murry, Phillip. A. (1995). "Late Triassic (Carnian and Norian) tetrapods from the southwestern United States". New Mexico Museum of Natural History and Science, Bulletin. 4: 1–254.

Nesbitt, Sterling J.; Norrell, Mark A. (2006). "Extreme convergence in the body plans of an early Suchian (Archosauria) and Ornithomimid Dinosaurs (Theropoda)"Proceedings of the Royal Society B273 (1590): 1045–1048.

Novak, Stephanie E. (2004). A new specimen of Postosuchus from the Late Triassic Coelophysis Quarry, siltstone member, Chinle Formation, Ghost Ranch, New Mexico (M.Sc. thesis). University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Peyer, Karin; Carter, Joseph G.; Sues, Hans-Dieter; Novak, Stephanie E.; Olsen, Paul E. (2008). "A new Suchian Archosaur from the Upper Triassic of North Carolina". Journal of Vertebrate Paleontology. 28 (2): 363–381.

Sunday, May 7, 2017

Zalmoxes: Beast of the Week

This week we will be checking out an unusual ornithopod.  Check out Zalmoxes!

Zalmoxes was a plant-eating dinosaur that lived in what is now Romania, during the Late Cretaceous, between 70 and 66 million years ago.  There are currently two named species, Zalmoxes robustus and Zalmoxes shqiperorumZ. shqiporum is deemed the "larger" species at about eight feet long from beak to tail, but Z. robustus's largest known individuals, at about six feet long, were determined to be sub-adults, so it is likely Z. robustus could have grown more than what the fossil record shows.  The genus name is in reference to Zalmoxis, a character from ancient Dacian (province in Romania) folklore.

Zalmoxes robustus life reconstruction in watercolors by Christopher DiPiazza.

Zalmoxes is considered an ornithopod dinosaur, and is currently thought to be within the iguanodontid clade on the dinosaur family tree.  This would make it a close relative of the more famous, Iguanodon, as well as Mantellisaurus, and Tenontosaurus.  However, within iguanodontidae, Zalmoxes is part of the more specific family, called rhabdontidae.  Rhabdontids were generally smaller, but robust, bipedal dinosaurs.  Despite that they are currently considered most related to iguanodontids, they have also been compared to the even smaller, and more lightly-built hypsilophodontids.

Possibly the most striking feature about Zalmoxes is its skull, which is large when compared to its overall body size.  At the tip of Zalmoxe's triangular-shaped skull, it had a short beak, that would have helped it clip vegetation.  This food would later be processed by its small teeth in the back, which were backed up by a very deep lower jaw.  This deep jaw, paired with the high ridge on the back of the skull, suggests there were large muscles attached in life, and therefore Zalmoxes would have had a very powerful bite.  Perhaps it specialized in eating a certain variety of tough plant?

Zalmoxes shqiporum skeletal mount on display in Brussels. By MWAK - Own work, Public Domain,  Note the high section on the top of the rear of the skull where muscles would have connected to the lower jaw. 

The part of the world that Zalmoxes was found in was an island during the late Cretaceous.  Some scientists have suggested Zalmoxes' smaller size, when compared to other ornithopods of its time is a result of island dwarfism.  Island dwarfism is one of several phenomenons that have been observed when animals from the mainland end up genetically isolated from the rest of their original population on an island.  Over time, this new, smaller population, can evolve smaller bodies to better adapt to their new environment.  Note that Zalmoxes lived at the very end of the Cretaceous, right be fore the mass extinction that wiped all of the dinosaurs (except birds) while the majority of other known iguanodontids flourished during the early Cretaceous.  By Zalmoxes' time, the duck-billed hadrosaurs had taken the niches iguanodontids once held.  Zalmoxes being separated from the rest of the world on an island may have been its saving grace in that it didn't have to compete with the same newer forms of dinosaurs its ancestors on the mainland did, and thus was able to persist up until the end of the Mesozoic.

That is all for this week!  As always feel free to comment below or on the facebook page!

References

Ősi, A.; Prondvai, E.; Butler, R.; Weishampel, D. B. (2012). Evans, Alistair Robert, ed. "Phylogeny, Histology and Inferred Body Size Evolution in a New Rhabdodontid Dinosaur from the Late Cretaceous of Hungary". PLoS ONE. 7 (9): e44318.

Weishampel, D.B.; Jianu, C.-M.; Csiki, Z.; Norman, D.B. "Osteology and phylogeny of Zalmoxes (n. g.), an unusual euornithopod dinosaur from the Latest Cretaceous of Romania" (PDF). Journal of Systematic Palaeontology. 1 (2): 65_123.

Tuesday, May 2, 2017

Interview with Paleontologist: Daniel Barta

Daniel Barta is a Ph.D. Candidate in Comparative Biology at the Richard Gilder Graduate School at the American Museum of Natural History. He grew up in Helena, Montana, and hold Bachelor's and Master's degrees in Earth Sciences from Montana State University. Broadly, He us interested in vertebrate reproduction, growth, and development. His research integrates fieldwork with phylogenetic, histological, and taphonomic techniques to better understand the evolution of ontogenetic trajectories, eggs, and nesting strategies of extinct animals and their living relatives. Fieldwork in the western United States, China, and Mongolia shapes my interests in the faunal evolution and biostratigraphy of the Cretaceous of Asia and North America. Currently he focuses on the post-hatching growth and development of basal theropod and ornithischian dinosaurs. The exceptional sample sizes available at the American Museum of Natural History can provide important insight into dinosaur growth rates and anatomical transformations during development, thereby establishing an essential context for understanding both individual morphological variation and the evolution of the extreme growth and metabolic rates achieved by dinosaurs’ bird descendants. He is passionate about sharing through outreach the thrill of the scientific process and our evolutionary history that it reveals.



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

DB: I’m from Helena, Montana, and my earliest sign of interest came from a family visit to Museum of the Rockies in Bozeman, Montana, when I was about four years old.

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?

DB: My family members, especially my parents, greatly encouraged my interest in the natural world and in paleontology specifically. I still look up to them, and also to so many of my mentors and colleagues who have made great contributions to the natural sciences—there truly are too many to list here!

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?

DB: I’ll highlight three experiences chronologically. The earliest was a “job shadow” experience in sixth grade, when I got to work alongside Jamie Jette, a fossil preparator at the Museum of the Rockies, and learned more about what working with fossils is actually like as a career. This helped solidify my decision to attend Montana State University for my undergraduate studies. The second was my undergraduate research experience in China with Dr. Dave Varricchio of MSU, who later became my master’s thesis advisor. And the third would be a collections visit to the American Museum of Natural History during my master’s research with Dave that introduced me to my current Ph.D. advisor, Dr. Mark Norell, for the first time.

Question 5: You do a lot of work with dinosaur eggs, particularly birdlike theropod eggs.  Did you have a prior interest in this branch of paleontology prior to starting your career? Did it choose you?

DB: It was a little of both. Growing up, I’d always been interested in dinosaur eggs and parental care from reading books and news stories about both Montana’s Egg Mountain locality and the discoveries in the Gobi Desert by AMNH and other expeditions. I thought that they were both just really interesting scientific stories. However, my desire to devote much of my studies so far to dinosaur eggs really grew out of the undergraduate research that I mentioned earlier. I found that there’s a lot of work still to be done to understand the evolution of eggshell microstructure and what fossil egg assemblages can tell us about the biology of the animals that laid them.

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?

DB: This is really hard to pick, as I’ve enjoyed all the projects that I’ve been involved with, but I’ll highlight two projects here. I’m really proud of the paper in Acta Palaeontologica Polonica that I co-authored with Dave Varricchio on some Mongolian Cretaceous bird eggs that we named Styloolithus sabathi. It’s not every day that you get to help describe a new type of fossil egg, and I think the paper stands as a nice tribute to the late Karol Sabath of the Polish Academy of Sciences, who made key contributions to the study of fossil eggs. The specimens in our study help to reveal the very non-avian dinosaur-like reproductive mode of early birds, and may also hold implications for why these early birds went extinct along with the non-avian dinosaurs at the end of the Cretaceous.

My other favorite project is one of my dissertation chapters that I just recently submitted for review, and though I can’t say too much about it here, it involves anatomical study of the hands and wrists of early dinosaurs. I also recently worked on a couple of egg-citing projects related to dinosaur eggshell, but again, you’ll have to wait for the papers to hear more about those!

Question 7: Where have you travelled for your career?  Do you have a favorite destination when it comes to fossils?  Why?

DB: I’ve been really fortunate to travel a lot for my career. I’ve done fieldwork in Montana, China, and Mongolia, and collections visits and conferences have taken me to Europe, Asia, and South America. Mongolia is my favorite fieldwork destination. The quality of preservation and abundance of fossils there really can’t be beat, and we have some wonderful Mongolian colleagues who are incredibly fun to work with.



Question 9: Do you ever get criticized on any of your work?  How do you handle it?

DB: The criticism of my work that I've faced has, without exception, helped to sharpen my thinking and improve the final manuscripts. I’ve been really lucky in my short career not to have encountered anything directed at me that I would consider unfair or mean-spirited. I think it’s really important for everyone in science to work to ensure a collegial academic environment.

Question 10: 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?

DB: Those were two important ones for me as well! I also discovered many of the older dinosaur movies, like "The Land that Time Forgot,” pretty early on and still have a real fondness for those. Another thing that helped spark my initial interest was a blue Brontosaurus toy that my parents bought for me when I was about four (around the same time as my first visit to a museum).

Question 11: 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.  Do you think paleontology has a bigger part to than this?  How?

DB: Paleontology provides us with our only direct record of past biodiversity. Many people say that the current biodiversity crisis represents a sixth mass extinction, and we wouldn’t have any context for understanding what a “mass extinction” is without studying fossils. We would know very little about our modern world and even less about how to predict its future without studying past environments and the life that inhabited them.

Question 12: Who was the first paleontologist you met?  How was that interaction?

DB: The first paleontologist I met was Dr. Jack Horner. I attended a talk that he gave at an elementary school in Helena, and I later got to interview him during my sixth grade “job shadow” experience that I mentioned. Both were tremendously inspiring experiences for me as a young student.



Question 13: Why do you think prehistoric animals are so influential to us today?

DB: Prehistoric animals are ambassadors from a succession of alien worlds ( our own Earth at different points in its past), and as such, are both tantalizingly familiar and startlingly strange. I think they provide one of the most accessible “hooks” for people of all ages to learn about the scientific process.

Question 15: What is your favorite prehistoric animal?  Was it different when you were younger?

DB: My favorite prehistoric animals now tend to be whichever ones I’ve studied scientifically, so currently the early carnivorous dinosaur Coelophysis bauri is one of my favorites. Like a lot of people, I was enamored with Tyrannosaurus rex when I was younger, and still am.

Coelophysis

Question 16: 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?

 DB: I think any of the whole range of extinct reptiles, mammals, amphibians, fish, and invertebrates for which we have no obvious modern analogues would be fascinating to observe, as a time machine might be the only way that we would ever be able to answer basic questions about their structures, functions, and behaviors. Among dinosaurs, I would of course love to answer my questions about Coelophysis growth in real time.

Question 17: 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?

DB: I would pick any time and place during the Triassic Period. One could examine not only the ecologies of the range of bizarre, extinct reptile groups, but also see how the components of the “modern” fauna were becoming established.

Question 18: Which is your favorite museum?  Why?

DB: Based on my answers above, this will probably not come as a surprise: my two favorite museums are the American Museum of Natural History and Museum of the Rockies, as they’ve both contributed immensely to the development of my ideas and interests, setting the direction of my professional life.

Question 19: What hobbies do you have?  (Don’t have to be paleo-related.)


DB: I enjoy hiking, bird-watching, spending time with family and friends, and learning about history, music, and the visual arts.

Sunday, April 30, 2017

Allosaurus: Beast of the Week

This week we will be looking at a well-known, well-loved, and well-understood dinosaur.  Check out Allosaurus!

Allosaurus was a meat-eating dinosaur that lived during the Late Jurassic Period, between 150 and 155 million years ago.  Its bones have been uncovered in the Western United States, Portugal, and in parts of Africa.  An adult Allosaurus, on average, measured about thirty feet long from snout to tail, but some have been found that were slightly smaller or larger.  The genus name translates to "Other Reptile" because at the time of its original discovery in the late 1800s, its vertebrae were what paleontologists used to differentiate Allosaurus from "other" fossil dinosaurs they were finding in the area. (Underwhelming...I know.) There are actually a few currently valid species of this dinosaur, but Allosaurus fragilis is the most commonly found, and the most studied.  In life, Allosaurus would have shared its habitat with (and probably ate) many other known dinosaurs, including, but not limited to Apatosaurus, Brontosaurus, Barosaurus, Diplodocus, Camarasaurus, Stegosaurus, Gargoyleosaurus, Torvosaurus, and Ceratosaurus.  Allosaurus stands out as a very successful meat-eater of its time based on the sheer number of specimens that have been found.  Thanks to this, we know a lot about its anatomy, how it developed and aged, and how it may have behaved, including possible hunting and feeding behavior.

Allosaurus fragilis pair life reconstruction by Christopher DiPiazza.

For starters, Allosaurus had a very interesting skull.  The holes in its skull on either side of its eye sockets (we call those finestra) were large, and the bone walls of the skull, including those surrounding the brain case, were thin.  In addition, it also had hollow chambers in its bones, including its vertebrae and its leg bones.  This suggests Allosaurus was light for its size. It also suggests Allosaurus had an advanced, one-way respiratory system that birds, and some other kinds of reptiles have today.  This would be advantageous Allosaurus endothermic, thus leading an active lifestyle.  These same adaptations would have also helped to keep Allosaurus cool, with easy airflow within the body to shed excess warmth, and preventing the animal from overheating.  It makes sense since we have evidence that the the environment Allosaurus was living in could get rather hot and arid during the Jurassic.

Allosaurus fragilis mount on display at the American Museum of Natural History in New York.

Allosaurus' teeth were curved, flat, and serrated.  They were not extremely large compared to some of its contemporary meat-eaters, like Ceratosaurus or Torvosaurus, which means Allosaurus had a different feeding, and probably hunting style from them.  Allosaurus' teeth were probably best for slicing and cutting, rather than crushing or piercing.  These teeth were backed up by rather slender lower jaws, which means that there was less muscle attached to them in life, and therefore Allosaurus had a proportionally weaker bite when compared to many other meat-eating dinosaurs.  That being said, the jaws of Allosaurus were also able to open much wider than those of other dinosaurs, an impressive 79 degrees wide, to be exact. Also, the back of Allosaurus' skull and its neck bones suggest that there were very large muscle attachments there in life, and its skull, although having weak jaw muscles, was, as a structure, very strong when it came to sustaining impact.  So what does all of this mean?  Some paleontologists think that instead of using just bites to inflict damage or remove flesh from a carcass, Allosaurus likely would have used it's strong neck to swing its mouth, open wide, to hack away at its target like an axe...an axe with teeth.

Section of an Allosaurus leg bone on the left compared with that of a modern bird on the right.  Note how there is a different fossilized mineral inside the Allosaurus bone, showing how it was hollow in life.

It was also discovered that the muscles that would have been in Allosaurus' neck in life would have also allowed for this dinosaur to move its neck in an up-and-down motion very quickly.  Scientists hypothesize that because of this, Allosaurus could also have used it's jaws and teeth like a saw, to hack away mouthfuls of meat off of bones.  Adding to this, there are numerous sauropod bones from the same habitat as Allosaurus that were found with scrape marks that match Allosaurus teeth, on them.  We may never know if Allosaurus actually killed these plant-eaters first, or if it was simply scavenging an already dead animal, but either way we can agree Allosaurus' neck, skull, jaws, and teeth, were together, a great butchering adaptation!

Image from Stephen Lautenschlager's 2015 study comparing the gapes, from left to right, of Allosaurus, Tyrannosaurus, and the therizinosaurid, Erlikosaurus.  Note how Allosaurus was capable of the widest bite.


Allosaurus' mouth wasn't its only weapon.  This dinosaur is most famous for its relatively long, strong arms, and three large, hook-shaped hand claws on each hand.  The first finger of each hand possessed the largest claw, but all were more than capable of dealing substantial damage together and keeping struggling prey in place as the jaws did work on removing flesh from the bone.

Thanks to numerous well-preserved, and complete specimens of Allosaurus, scientists have been able to tell a bit about its lifestyle...and that its lifestyle was rough!  Allosaurus specimens have been found with numerous stress fractures on both the front limbs and the hind limbs, that healed over.  This tells us that Allosaurus was using its arms, which were proportionally long, each ending with three hooked claws to grab onto...something (likely struggling prey but we may never know for sure)...and getting injured in the process sometimes.  It is possible Allosaurus was attacking large prey, like sauropods, with its front limbs, holding on with its hook-like claws, and slashing with its teeth to inflict bleeding wounds until its prey was too weak to stand any longer.  In addition to these injuries, Allosaurus have also been found with bite wounds from other Allosaurus on their skulls, which tells us that there was some intraspecies violence going on.  Also, an Allosaurus specimen was discovered with a nasty puncture wound in its tail that had healed over.  This wound matches the spike of a Stegosaurus, one of Allosaurus' contemporaries, suggesting that the two famous dinosaurs may have fought on occasion.

We also have juvenile specimens from Allosaurus, showing that this dinosaur was more slender, with proportionally longer legs when it was young, and bulked up as it matured into adulthood.  Allosaurus also had two small bony crests, one in front of each eye.  In life these crests likely had a layer of bony material, called keratin, making them even larger.  These were probably display adaptations, communicate within the species who was mature and who wasn't.  It is possible that these crests were different sizes, or even colors between males and females.  Some believe these crests may have also been weapons that Allosaurus would have used to shove each other with in life, to establish dominance.  We may never know for sure!

Drawing of Allosaurus jaw from Darren Tanke's 1998 paper, showing bite wounds that were proposed to have been from another Allosaurus.

Lastly, paleontologists have discovered impressions of some of Allosaurus's skin!  The skin would have been from the dinosaur's side, and had small, bumpy scales.  It is unknown if this kind of skin would have covered the whole body, or if there were different kinds of scales or other body covering elsewhere.  We also can't be sure the skin disproves the presence of feathers, since we know feathers can exist with scales on the same dinosaur.

References

Carpenter, Kenneth (2002). "Forelimb biomechanics of nonavian theropod dinosaurs in predation". Senckenbergiana Lethaea. 82 (1): 59–76.

Gilmore, Charles W. (1920). "Osteology of the carnivorous dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus". Bulletin of the United States National Museum. 110: 1–159.

Holtz, Thomas R., Jr.; Molnar, Ralph E.; Currie, Philip J. (2004). "Basal Tetanurae". In Weishampel David B.; Dodson, Peter; Osmólska, Halszka. The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 71–110.

Lautenschlager, Stephan (2015-11-04). "Estimating cranial musculoskeletal constraints in theropod dinosaurs". The Royal Society. Archived from the original on 2016-03-19.

Madsen, James H., Jr. (1993) [1976]. Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey.

Rayfield, Emily J.; Norman, DB; Horner, CC; Horner, JR; Smith, PM; Thomason, JJ; Upchurch, P (2001). "Cranial design and function in a large theropod dinosaur". Nature. 409 (6823): 1033–1037.

Snively, Eric.; Cotton, John R.; Ridgely, Ryan; Witmer, Lawrence M. (2013). "Multibody dynamics model of head and neck function in Allosaurus (Dinosauria, Theropoda)". Palaeontologica Electronica. 16 (2).


Tanke, Darren H. (1998). "Head-biting behavior in theropod dinosaurs: Paleopathological evidence" (PDF). Gaia (15): 167–184.

Wednesday, April 26, 2017

Prehistoric Beast of the Week Visits Jurassic World: The Exhibition

I have been living in Philadelphia, Pennsylvania, for almost seven months now.  When I first moved here I caught wind of the Franklin Institute opening a seasonal exhibit that simulates visiting Jurassic World with life-sized animatronic dinosaurs.  I knew I had to go see it.  After being open to the public since November, I finally had a chance to go check it out in person.


If you are not familiar with it, simply put, the Franklin Institute is a museum dedicated to science education, especially towards young visitors.  Every exhibit in there has some sort of hands on aspect for everyone to try, all the while pelting you mercilessly with information to fill your brain with for days...if you actually bother to read.  (I will never understand people who just walk through museums and zoos without actually reading things.)  That being said, I was very interested to find out how a place that prides itself on science education would handle an exhibit from a franchise that honestly... kind of hindered science education.  I know that sounds harsh, but it's true, at least when it came to Jurassic Park 3 and the latest Jurassic World.  Too many people have had their image of dinosaurs warped because the Jurassic Park franchise is their only real exposure to the subject.  Too many people don't understand that many dinosaurs, let alone Velociraptor, were just as feathered as modern birds.  Too many people still think Dilophosaurus could spit venom and had a retractable frill.  Too many people still think Tyrannosaurus had vision based on movement....I could go on.  THAT BEING SAID I don't think the Jurassic Park franchise has a responsibility to uphold scientific accuracy.  I will never be one of those nerds blasting on the internet all the inaccuracies of the Jurassic Park movies and how they could have been "better".  There are enough of those folks out there.  I understand the franchise's purpose is to entertain, which it succeeds in doing, and I'm fine with that!  Would I like it if it was scientifically accurate?  Of course.  But I don't expect it to be.  I would much rather attack Discovery Channel, History Channel, and Animal Planet when they mess up paleontology programs because they actually advertise as being educational.  I was simply curious to see how Franklin Institute handled this exhibit.  Will they submit and have something in there that is just for thrills?  Or will they find a way to make it actually educational, even though the dinosaurs would not be?  Let's find out.

First thing I noticed was how long the line to get into the exhibit was.  The line starts on one floor, goes around a few zigzags, goes up a gradual ramp, then up to a different floor...and then you are waiting in a room that is supposed to be the inside of the ferry boat from the movies for a while until everyone fills it.  Then you watch a short introduction movie.  Very reminiscent of something I'd expect to wait on at Universal Studios or Disney World.  Finally the door opens, you push some kids out of the way to get in first, and you see your first dinosaur...

Despite the fact that it's Jurassic World: the Exhibition, this exhibit incorporated elements from all the movies to a certain degree.  A good example of this was Brachiosaurus, which was featured in the first film, but not Jurassic World.  Since Brachiosaurus was so large, and a robot of its whole body couldn't fit inside the exhibit, they cleverly only showed this dinosaur from the shoulders up, and portrayed it as if it were bathing in a lake.  The neck still towers over you and the head comes just low enough so a average-sized adult could be a few inches shy of poking it with an outstretched finger. (not like I tried or anything.)  In front of the dinosaur, were screens, and plaques, with information...good information!  The short movie on loop explained how sauropods likely weren't using their nostrils as snorkels underwater like previously thought, and could probably only wade in water up to a certain point.  They also discussed how sauropod bones were filled with air sacks, making their bodies lighter, which was the key to them evolving so large.

Sorry my photo is blurry.  She wouldn't stop moving.

A few steps further you meet Parasaurolophus, also in the form of shoulders, neck, and head, this time peering out from thick foliage.  This duck-billed dinosaur was in Jurassic World, but it was also in the first movie, seen from a distance with Brachiosaurus, and was most prominent in the second movie, The Lost World: Jurassic Park.  The Parasaurolophus animatronic for this exhibit has a short crest, leading me to wonder if it was based on the Parasaurolopus cyrtocristatus species.  It is also possible it was meant to represent a female of one of the two long-crested species, which some have suggested had shorter crests than males, but this hasn't been proven.

A Parasaurolophus and a fiance pose for a photo. 

The next room showcases beautiful animatronic models of an adult and baby Pachyrhinosaurus.  I'm not sure why they didn't opt for Triceratops, the ceratopsian that was actually featured in all the Jurassic Park movies, but I'm not complaining.  I'm all for lesser-known genera getting public attention.  Pachyrhinosaurus was also the only dinosaur showcased in this exhibit that was not in any of the Jurassic Park movies.  (although it is in the mobile game and was made into an action figure in 2014)  Despite this, I think these were the most well done models in the exhibit.  They were very close to scientifically accurate.  My only nitpicks would be their size was a bit too large, and the fact that their front limbs had claws on all five digits (should be the first three only).  I would have personally changed the skin texture to match that of what we know from mummified remains of other ceratospians, but Pachyrhinosaurus, itself, has never had skin preserved on the fossil record. (that I know of)  Beyond that they were awesome models.  The baby Pachyrhinosaurus was impressive because the horn ornamentation matched what is known from actual fossilized baby Pachyrhinosaurus that have been found, possessing a much smaller nose boss and horns.  To go with this, there was an interactive plaque with light up buttons where you can match the baby ceratopsian skull shape with its adult counterpart.  This was my favorite part of the exhibit from an educational standpoint.  (I'm also biased towards ceratopsians.)

The Pachyrhinosaurus were arguably the best models in this exhibit.

After this you are funneled into a room that is meant to look like a laboratory.  Here, if you bother to read, they actually go into the science of fossilized amber, and how insects get caught in them.  (Nevermind the fact that you almost certainly can't get dinosaur DNA from them.)  There are a number of other fun, interactive, touchscreen activities.  My favorite was one where you can apply your own color scheme to one of several 3D dinosaur models.  Throughout this process, the program explains to you why dinosaurs may or may not have had certain colors and patterns.  In the middle of the room was an incubation chamber with three animatronic sleeping baby Parasaurolophus.  All of them had breathing animatronics and every few minutes the middle one would groggily lift its little noggin, blink, open its mouth, then put its head down to go back to sleep.  As cute as they were, the nerd inside me was disappointed that their crests were too long!  Paleontologists have actually unearthed an real baby Parasaurolophus skeleton, and we now can confirm that the crest started out almost nonexistent (barely a nub on the top of the skull) and would become the shape that the adults had as the individual reached sexual maturity.

Look at those pleepin babies! (I spelled "pleepin" correctly.  This is baby talk.  Learn it.)

Then smaller groups of people are put into a space with a large cage on one side of the room.  This is where you get to come face to face with Blue, the Velociraptor!  Blue comes out in the form of an actor wearing one of those increasingly popular dinosaur puppet-costumes, which are actually really life-like if the actor inside knows what he/she is doing.  Blue will pace around in the cage a few times, sniff/snap at some kids in the front, then go back through a door in the back of the cage, all the while audio of Chris Pratt is being played sating things like "Easy!" and "Back up, Blue!".  During this show, a woman on the monitor (the "head keeper") is saying information about Velociraptor in general.  She uses the term dromaeosaur, to reference the group it belonged to, which is good.  It's mildly annoying hearing people call it the "raptor" group so much.  (I know some professionals who use the term "raptor" to refer to dromaeosaurs, but I personally detest it mainly because of the fact that modern birds of prey were called "raptors" first.  She also mentions that the second toe claw was the its "key to success" and allowed it to slash open prey.  This is possible, but not the only hypothesis for how dromaeosaurs used their toe claws.  Sadly I could not get a decent photo of this.  The room was dark and there were way too many people's heads in the way.

After the Velociraptor encounter you meet Tyrannosaurus.  The huge Tyrannosaurus animatronic (close to life size as far as I could tell...the head was a little large.) looms over the audience off to the side in a dark room, meant to look like her holding pen at night.  Then light affects simulate lightning and audio plays the sounds of thunder and dinosaur stomping as the dinosaur slowly marches out from her hiding spot.  She roars a few times and then appears to bump a parked jeep, which had a set of hydraulics set up under it so when the animatronic bends over and moves its head, the car will shake.  This whole section was definitely a recreation of the famous scene from the first Jurassic Park movie.


Sometime between the Velociraptor and T. rex, we get an "emergency" message on one of the monitors that something went down and nobody should worry. I wouldn't be Jurassic Park World without a dinosaur escape!

Then we get to meet Stegosaurus.  This is probably the most photogenic opportunity in the exhibit because the Stegosaurus model is the closest to you as the guest.  The Stegosaurus is pretty accurate to the movie Stegosaurus, and therefore has the same flaws when looking at it from a scientific standpoint, but it was still very cool and impressive for what it was.

The Stegosaurus is trying not to barf because she's single and bitter about it.

Finally you meed Indominus rex, the main antagonist from the Jurassic World movie.  If you don't know, this large carnivore, was supposed to be a hybrid between a Tyrannosaurus, VelociraptorMajungasaurus, a tree frog, a cuttlefish... and I think a few more.  Anyway, the animatronic for this beast pops up across the path from the Stegosaurus, the lighting in the whole room turns more red (dramatic) and both animatronics begin to thrash around and roar to imply that they are fighting without actually making contact with each other. The Stegosaurus' tail is strategically facing the Indominus from the start, so it really does look like it's warding off the predator with those spikes. Despite the fact that Stegosaurus was in the Jurassic World film, I am surprised they chose not to make a model of Ankylosaurus, instead, since in the movie, that is what Indominus actually had a battle with.  After a few minutes, there are sound effects of gun fire and the Indominous model stops moving, thus ending the walkthrough of animatronic dinosaurs.

Close up photo of Indominus rex after being gunned down.  Poor gal.

The last room before the gift shop was the most educational part, filled with maps and infographs of many different kinds of dinosaurs. (some of which had feathers in the illustrations!)  Ther were also more bone casts from real dinosaurs on display, including those of Plateosaurus, interestingly enough, having not been featured in any Jurassic Park movies, but again I'm not complaining.  Sadly, this is also the room where most of the visitors rushed through the most, having seen all the exciting action-packed parts.

Not the best picture but IT HAS FEATHERS so it's something.

In conclusion I think the Franklin Institute did the absolute best job they possibly could to implement as much educational value into a Jurassic World attraction as possible.  Sadly, most people don't stop to read infographs and plaques when there is a thirty-foot animatronic dinosaur a few feet away.  Nobody's fault!  One thing that I was mildly disappointed at was the fact that there was no love in the exhibit for mosasaur, or any pterosaurs, which had pretty big roles in the Jurassic World movie.  They even had flags and signs with them on it outside the exhibit!  I wasn't expecting them at first, but those stupid flags gave me a glimmer of false hope!

There was also a bin with what were almost certainly 3D printed dinosaur body parts that could be put together and taken apart for the kids to make their own hybrid monstrosities.  I wonder if there is a way to download these and print them, myself.  I'd love to have the Pachyrhinosaurus.

Sadly, at the time of me publishing this, the Jurassic World Exhibition will be finished at the Franklin Institute, but will open at the Chicago Field Museum in May!  If you get the opportunity to check it out, I highly recommend it for a fun, and educational (if you know where to look) experience!

Good thing I gave Indominus my fiance's purse otherwise we'd all be dead.  Not every day you get mugged by a dinosaur.

Sunday, April 23, 2017

Prenocephale: Beast of the Week

This week we will be checking out another dome-headed dinosaur.  Enter Prenocephale prenesPrenocephale was a plant-eating dinosaur that lived in what is now Mongolia, during the late Cretaceous, between 80 and 75 million years ago.  It would have measured roughly between six and eight feet long from beak to tail.  The genus name translates to "sloping head" because of the dramatic shape of this dinosaur's skull. 

Prenocephale life reconstruction by Christopher DiPiazza.

Being a member of the pachycephalosaurid family, the thick, rounded skull is not surprising.  However, within the group, Prenocephale had a particularly egg-like shape to its skull, which sloped dramatically towards the snout, which earned it's genus name.  On the top of the snout, Prenocephale had two rows of short horns that each turn into a wide, bar-shaped ridge above each eye.  This ridge, combined with the fact that it is attached to the rather extensive dome skull, would have given Prenocephale the appearance that it had a furrowed, "grumpy" look in life.  The back of the skull also has rows of small horns on either side.  As is the case with all pachycephalosaurids, it is uncertain as to what exactly Prenocephale was using this kind of skull for.  Perhaps they were using them as weapons?  Perhaps they were purely for show?  Maybe one day we will find out! 

Prenocephale skull cast.  This is part of my personal collection.  Clothespin for scale.

In addition to its dome and horns, Prenocephale has a few other notable features when it comes to its skull.  It's eye sockets are large, and face partially forward.  This tells us that it probably had good vision and could perceive depth in life.  It's beak was small, and very narrow, even compared to other known pachycephalosaurids.  This tells us that Prenocephale may have had a different preference of food, or perhaps had a different style of feeding in life.  Plant-eating animals with more narrow mouths tend to browse for specific leaves more, rather than simply sucking up any vegetation that was closest to their face.  The back of Prenocephale's jaws were lined with small teeth which would have been best at slicing up plants.

Sadly, only Prenocephale's skull was ever actually found, aside from a few small bones.  Therefore we still don't know exactly what the rest of its body looked like.  However, thanks to more complete skeletons of other, closely related, Pachycephalosaurids on the fossil record, it can be assumed that Prenocephale was an obligate biped, walking on two strong back legs, had relatively short front limbs, tipped with five short fingers at the end of each hand, had relatively wide hips for a dinosaur, and a tail that was thick and muscular at the base and thin and stiffened towards the end. 

That is all for this week!  As always feel free to comment below or on the facebook page!

References

Longrich, N.R., Sankey, J. and Tanke, D., 2010. Texacephale langstoni, a new genus of pachycephalosaurid (Dinosauria: Ornithischia) from the upper Campanian Aguja Formation, southern Texas, USA. Cretaceous Research, . doi:10.1016/j.cretres.2009.12.002

Robert M. Sullivan (2003). Revision of the dinosaur Stegoceras Lambe (Ornithischia, Pachycephalosauridae). of Vertebrate Paleontology: Vol. 23, No. 1, pp. 181–207.

T. Maryanska and H. Osmolska. 1974. Pachycephalosauria, a new suborder of ornithischian dinosaurs. Palaeontologia Polonica 30:45-102.

Sunday, April 16, 2017

Byronosaurus: Beast of the Week

Let's check out a little dinosaur that not only taught us about how non-avian dinosaurs laid eggs and made nests, but also further solidified just how close-knit their relationship to modern birds really was.  Enter, Byronosaurus jaffei!

Byronosaurus was a meat-eating dinosaur that lived between 80 and 75 million years ago in what is now Mongolia.  It was a member of the troodontid family, similar to its North American relative, Troodon.  An adult Byronosaurus would have measured roughly four to five feet long from snout to tail, based on what has been found of it.  The genus and species names are in honor of Byron Jaffe, who was an important supporter of expeditions by the American Museum of Natural History into Mongolia.  These expeditions yielded a wealth of important dinosaur fossils, Byronosaurus, being one of them.  When alive, Byronosaurus would have shared its environment with other dinosaurs, like Velociraptor, Protoceratops, Oviraptor, and Citipati.

Byronosaurus life reconstruction by Christopher DiPiazza.

Being a troodontid, Byronosaurus had long legs, including proportionally long metatarsals (foot bones), indicating it was a fast runner in life.  On each foot, like its relatives, the dromaeosaurs, it would have had a retractable talon on each second toe.  These "killer claws" weren't as large as those seen on dromaeosaurs, like Velociraptor, but they would have still been helpful when hunting at least small prey.  Byronosaurus also had large eye sockets, suggesting it possessed good vision and further suggesting it could have been nocturnal or crepuscular.  This would make sense given the fact that where it lived was a desert at the time.  Many desert animals tend to be active when the sun isn't at its brightest to avoid the extreme heat.  Byronosaurus also had a long, slender snout filled with small, needle-like teeth, which were not serrated.  This style of tooth is typically seen in animals that are adapted for grasping and holding small prey.  This is interesting, since other troodontids are known to have had serrated teeth, which were more adept at cutting meat, rather than grasping.  Having good eyesight, a long snout, needle-like teeth, and a proportionally smaller, retractable talon, all suggest Byronosaurus may have specialized in hunting small, bite-sized prey, like invertebrates, mammals, small reptiles, and possibly baby dinosaurs, when available.

Adult Byronosaurus skull from the Mongolian Academy of Science.  Note the small, pointed teeth and large eye socket.

Another amazing thing about Byronosaurus is that paleontologists have discovered its nests, eggs, and babies!  The nests consist of eggs that were partially buried under sand, and were arranged in a cluster.  Eggs laid in clusters like this are also seen today from birds.  This is not the same as other known theropod nests, like those of Gigantoraptor, or Citipati, where the eggs are neatly arranged in a ring, in groups of twos.  Eggs laid in twos tells us that the dinosaur had two functioning oviducts.  Byronosaurus' eggs, which were not laid in twos, suggests, the mother did not have two functioning oviducts.  She likely only had one, like her modern bird relatives.  That, alone, is cool, but this information tells us a LOT more about bird evolution if you dig a little deeper.  For so long, it was thought that the reason why modern birds lost function in one of their oviducts was to become lighter in order to fly.  However, Byronosaurus didn't fly...and its descendants didn't either until finally going extinct.  Remember, when Byronosaurus was alive, during the Cretaceous, flying birds had already evolved.  This means that having one functioning oviduct evolved earlier than the first bird from a common ancestor of both birds and troodontids, and was not for flight originally.  It was simply utilized by the birds, for that purpose at some point later.  Why did troodontids, like Byronosaurus need to loose function of one oviduct if they weren't flying?  We still don't know!

Byronosaurus nest and baby skeleton on display at the American Museum of Natural History in New York.

Relatively newly hatched baby skeletons of Byronosaurus are also on the fossil record.  At first, these tiny skeletons were thought to be baby Velociraptors.  It was then discovered that they were actually Byronosaurus as more material was unearthed.  What's interesting is that as babies, Byronosaurus did not have the characteristic long snouts that the adults had.  Their faces were much shorter, with proportionally large eyes.  This is a trait also seen in modern bird babies, as well.  Animals that look like this as babies are typically taken care of by their parents for a period of time after hatching.  Were Byronosaurus attentive parents, too, perhaps?  Maybe more fossils will tell us one day!

That is all for this week!  As always, feel free to comment below or on our facebook page!

References

Bever, G.S. and Norell, M.A. (2009). "The perinate skull of Byronosaurus (Troodontidae) with observations on the cranial ontogeny of paravian theropods." American Museum Novitates, 3657: 51 pp.

Novacek, M.J., Norell, M.A, McKenna, M.C. and Clark, J.M, 1994, "Fossils of the Flaming Cliffs", Scientific American 271(6), 60-69

Norell, M.A., Makovicky, P.J. & Clark, J.M., 2000, "A new troodontid theropod from Ukhaa Tolgod, Mongolia", Journal of Vertebrate Paleontology 20(1): 7-11

Norell, Mark A.; Clark, James M.; Dashzeveg, Demberelyin; Barsbold, Rhinchen; Chiappe, Luis M.; Davidson, Amy R.; McKenna, Malcolm C.; Perle, Altangerel; Novacek, Michael J. (November 4, 1994). "A theropod dinosaur embryo and the affinities of the Flaming Cliffs dinosaur eggs". Science. 266 (5186): 779–782.