Sunday, November 20, 2022

Beipiaosaurus: Beast of the Week

 Beipiaosaurus inexpectus was a theropod dinosaur that lived in what is now Liaoning, China, during the early Cretaceous period, 125 million years ago.  From snout to tail it measured about 7 feet (2.2 meters) long and would have eaten plants when alive.  The genus name means "Beipiao Reptile" which is in reference to the city, Beipiao, near where its fossils were discovered.  

Watercolor reconstruction of Beipiaosaurus by Christopher DiPiazza.  Note the combination of shorter, shaggy feathers and long, quill-like feathers.

Beipiaosaurus was an early member of the therizinosaur group of theropods, which are famous for being herbivores in an otherwise mostly meat-eating group.  They are also known for having proportionally short legs and long arms, equipped with three extremely long claws on each hand.  Later therizinosaurs, like the more famous, Therizinosaurus, are known for having long, slender necks with proportionally tiny heads, but Beipiaosaurus actually had a very large head, with a skull the same length as its femur.  Beipiaosaurus also had three weight-bearing toes on each foot, while its later relatives had four. 

Beipaosaurus had a long, narrow skull, with a small beak at the tip that was also lined with small leaf-shaped teeth, ideal for shredding plants.  It had long, powerful arms, each equipped with three extremely large, hooked claws.  Since Beipiaosaurus appears to have been a plant-eater, these claws could have been for manipulating branches as it ate, or possibly even for defense against predators.  Thanks to beautifully preserved remains, we know that Beipiaosaurus was mostly covered in shaggy, fur-like feathers that could have been an adaptation to keep the dinosaur warm. (the climate where it lived during the early Cretaceous could get cold at times)  Beipiaosaurus also had a second kind of unusual long, quill-like feather that appear to have been growing out of its body amongst the shorter, shaggier feathers.  We don't know exactly what these quill-like feathers were for. Perhaps they helped keep the animal dry by wicking off rain, or possibly they were for some kind of display among members of the same species? It's difficult to tell without seeing the animal alive. Beipiaosaurus also had a bone on the tip of its tail, called a pygostyle, which modern birds also have where their tail feathers attach.  Beipiaosaurus doesn't show any evidence of those kinds of feathers, however, so the bone, itself, must have evolved first.

Fossil Beipiaosaurus.  Note the feathers that preserved around the neck.

Perhaps the most amazing discovery about Beipiaosaurus, however, is that scientists were able to figure out what colors its feathers were in life.  Be examining the fossilized feathers from Beipiaosaurus' neck under a special kind of microscope, they were able to see cell structures, called melanosomes, which can determine the color of a feather according to the their shape.  Then they compared the shape of Beipiaosaurus' melanosomes to those of living birds and looked for matches.  The modern bird feathers that matched Beipiaosaurus' melanosomes the most were brown, so we can confidently assume that at least some Beipiaosaurus had brown feathers on their necks in life.  

Scientists also found patches of Beipiaosurus' skin!  By looking at its skin under a microscope and then comparing it to other animals, they were able to determine by the amount of keratin (material that feathers, hair, and nails are made of) in the cells, that Beipiaosaurus' body wouldn't have radiated as much heat as many modern birds.  They also were able to determine that Beipiaosaurus would have shed its skin more like modern birds, as dandruff, rather than other kinds of reptiles, like lizards, which shed skin in large pieces or flakes.  (fun fact: modern crocodilians also shed their skin as dandruff!)

Close up of a patch of Beipaosaurus skin from McNamara's 2018 paper.

Before Beipiaosaurus was discovered in 1996, the exact placement of therizinosaurs on the dinosaur family tree was more debated.  Originally, some paleontologists thought they were late-surviving descendants of the early sauropodomorphs from the Triassic and early Jurassic, like Plateosaurus, based on similarities with their small leaf-shaped teeth, long necks, wide bodies, and robust legs.  The discovery of Beipiaosaurus, however, which has more obvious theropod traits while clearly showing a direct connection to the more outlandish, later therizinosaurs, confirms therizinosaurs were indeed theropods.  

That's all or this week!  As always feel free to comment below!

References

Li, Q.; Clarke, J. A.; Gao, K.-Q.; Zhou, C.-F.; Meng, Q.; Li, D.; D’Alba, L.; Shawkey, M. D. (2014). "Melanosome evolution indicates a key physiological shift within feathered dinosaurs"Nature507 (7492): 350–353.

McNamara, M. E.; Zhang, F.; Kearns, S. L.; Orr, P. J.; Toulouse, A.; Foley, T.; Hone, D. W. E; Rogers, C. S.; Benton, M. J.; Johnson, D.; Xu, X.; Zhou, Z. (2018). "Fossilized skin reveals coevolution with feathers and metabolism in feathered dinosaurs and early birds"Nature Communications9 (2072): 2072.

Xu, X.; Tang, Z.-L.; Wang, X. L. (1999). "A therizinosauroid dinosaur with integumentary structures from China". Nature339 (6734): 350–354.

Xu, X.; Cheng, Y.; Wang, X.-L.; Chang, C. (2003). "Pygostyle‐like Structure from Beipiaosaurus (Theropoda, Therizinosauroidea) from the Lower Cretaceous Yixian Formation of Liaoning, China"Acta Geologica Sinica77 (3): 294–298.

Xu, X.; Zheng, X.; You, H. (2009). "A new feather type in a nonavian theropod and the early evolution of feathers"Proceedings of the National Academy of Sciences106 (3): 832–834.

Sunday, November 6, 2022

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.). 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

There are actually three different known species of this Allosaurus that have been identified.  Allosaurus fragilis, from North Ameirca, is the most commonly found, and therefore the most extensively studied.  Allosaurus jummadseni, is also found in North America but was from a few million years before Allosaurus fragilis.  There is also Allosaurus europaeus, which was from what is now Europe.  

Allosaurus fragilis life reconstruction in watercolors by Christopher DiPiazza

Because there have been many specimens of Allosaurus that have been unearthed over the years, paleontologists know a lot more about it and often use Allosaurus as a model to compare to other, less complete dinosaurs for references.  Allosaurus' skull, in particular, is subject to a lot of attention.  The holes in its skull on either side of its eye sockets, called fenestrae, were large, and the bone walls of the skull, including those surrounding the brain case, were thin.  In addition, Allosaurus also had hollow chambers in its other bones, including its vertebrae and its leg bones, like birds.  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, where air initially breathed in via the lungs, was more efficiently circulated around the body, including through some of the bones.  This would have allowed Allosaurus to remain more active for longer periods of time without needing to rest.  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. (this does not mean Allosaurus had a weak bite!  It just wasn't crushing solid bones with its jaws like some other more specialized dinosaurs could.)  That being said, the jaws of Allosaurus were also able to open much wider than those of other dinosaurs, an impressive 79 degrees, 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 its strong neck to swing its open mouth to hack away at its target like 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 allowed for this dinosaur to move its neck in an up-and-down motion very quickly, taking many bites in a smaller amount of time.  Scientists hypothesize that Allosaurus may have used its jaws and teeth like a saw, to hack away mouthfuls of meat off of bones as it fed.  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 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 possibly most famous for its relatively long, strong arms, and three large, hook-shaped 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 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 for something 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.  Another 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.  Lastly, yet another Allosaurus was discovered with a puncture wound through its PELVIS, likely inflicted by yet another Stegosaurus tail spike which appears to have not healed fully and therefore was the death of the unlucky Allosaurus

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 to communicate within the species who was mature and who wasn't.  It is even 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' 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 kinds of body covering, like feathers, elsewhere.

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.

Monday, October 31, 2022

Gargoyleosaurus: Beast of the Week

Ever look up at buildings in the city and see monsters carved out of stone that act as rainspouts?  Those are gargoyles.  Gargoyles are interesting because there are really no rules or guidelines for what they are supposed to look like, unlike a lot of other popular monsters.  Well, our dinosaur this week must have inspired something spooky in paleontologists because it is named after these fantastic stone guardians of the night...that also barf rain.  Check out Gargoyleosaurus parkpinorum!

Gargoyleosaurus fending off a group of Allosaurus.  Watercolor by Christopher DiPiazza.

Gargoyleosaurus lived during the Late Jurassic period between 154 to 150 million years ago in what is now Wyoming, USA.  It measured about 10 feet (3 meters) long from snout to tail and would have eaten plants when alive.  It was an ankylosaur, which means it had heavy bone armor all over its body like its more famous relative, Ankylosaurus.  Gargoyleosaurus is one of the oldest known ankylosaurs, having been from the Jurassic, whereas the vast majority of ankylosaurs on the fossil record lived later in the Cretaceous.  When alive, Gargoyleosaurus would have shared its environment with other dinosaurs, like Stegosaurus and Allosaurus.

Gargoyleosaurus skeleton on display at the Denver Museum of Nature and Science.

Gargoyleosaurus had a long, narrow snout and body was adorned with flat, triangular spikes running down each flank.  Most of the armor on its back consisted slightly keeled scutes, with a wide solid plate, called a sacral shield, over the hips.  The tail had some small spikes running down the sides as well, but lacked a bony club at the tip, commonly seen in more popular ankylosaurs.  Later on during the Cretaceous, we can see two distinct kinds of armored dinosaurs, the ankylosaurids, which had short snouts and bony tail clubs, and the nodosaurids, which had longer, narrower snouts, and typically had sharp spiky plates running down their sides with no tail club.  Gargoyleosaurus appears to have be part of the nodosaurid lineage of ankylosaurs, which suggests that nodosaurids appeared first, with the club-tailed ankylosaurids evolving later in the Cretaceous.

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

References

Carpenter, K., Miles, C. and Cloward, K. (1998). "Skull of a Jurassic ankylosaur (Dinosauria)." Nature 393: 782-783.

Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.

Killbourne, B. and Carpenter, K. (2005). "Redescription of Gargoyleosaurus parkpinorum, a polacanthid ankylosaur from the Upper Jurassic of Albany County, Wyoming". Neues Jahrbuch für Geologie und Paläontologie, 237, 111-160.

Soto-Acuña, Sergio; Vargas, Alexander O.; Kaluza, Jonatan; Leppe, Marcelo A.; Botelho, Joao F.; Palma-Liberona, José; Simon-Gutstein, Carolina; Fernández, Roy A.; Ortiz, Héctor; Milla, Verónica; Aravena, Bárbara (2021). "Bizarre tail weaponry in a transitional ankylosaur from subantarctic Chile"Nature600 (7888): 259–263.

Thursday, October 20, 2022

Interview with Paleontologist: Evan Johnson-Ransom

Evan Johnson-Ransom is a vertebrate paleontologist, currently enrolled at the University of Chicago for his PhD. He received his Master’s from Oklahoma State University Center for Health Sciences in 2021, and his Bachelor’s from DePaul University in 2018. Evan’s research focuses on the functional morphology and feeding behavior of theropod dinosaurs such as Tyrannosaurus, Allosaurus, and Spinosaurus.


Evan with cast of the skull of Carnotaurus at the Field Museum.

Question 1: What was your earliest sign of interest in paleontology that you can remember?


EJ: I’ve been interested in dinosaurs since I was 2 years old. When I was in preschool I always cried when my mother dropped me off in the morning. She noticed my classmates would console me with dinosaur toys. That year for my birthday and Christmas, my family gave me dinosaur toys and I was quickly enamored by dinosaurs. My grandmother and mother took me to dinosaur museums, in addition to me watching dinosaur documentaries, and reading books about dinosaurs.


Question 2: Did you have anyone who served as a role model when you were younger?  Do you still have any now?


EJ: When I was younger, most of my paleontology role models included Drs. Paul Sereno, Thomas Holtz Jr., Phillip J. Currie, Jack Horner, Mark Norell, Xu Xing, Larry Witmer, and Robert Bakker. These were paleontologists who influenced my paleontology journey, growing up. Upon seeing them in-person at the Society of Vertebrate Paleontology conference, was a “dream come true”. 


Question 3: You primarily work with theropods.  Did you choose them or did they choose you? (in a sense) 


EJ: During my undergraduate, I volunteered at the Field Museum as a docent for Sue the T. rex. Most of my talks with the museum guests included discussing Tyrannosaurus’ biology. Upon reading Dave Hone’s “The Tyrannosaur Chronicles”, I was fascinated with the evolution of tyrannosauroids and their feeding behavior. I always pondered how tyrannosauroids evolved their powerful bite forces from the small Guanlong to the large T.rex. During my Master’s, I became enamored with theropod studies that entailed theropod feeding behavior and bite force mechanics.


Evan with the Tyrannosaurus family at the Los Angeles County Museum of Natural History.

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?  What sort of field experience, a class, networking with the right people, or possibly something different?


EJ: During my undergraduate, I initially thought of being  a college professor who taught paleontology and evolutionary biology. Upon taking anatomy classes at Oklahoma State University, I started to notice a “connection” with anatomy and my research in dinosaur feeding mechanics. I was fascinated with the muscles that were responsible for the body’s actions such as biting, walking, kicking, etc, in addition to how muscles impact the skeletal performance. After taking anatomy classes, I currently aspire to be an anatomy professor who teaches anatomy to medical students, but relates the anatomy teaching to research in vertebrate paleontology (e.g., feeding and jaw muscle performance in dinosaurs).


Question 5: What would your advice be to anyone trying to make a career in paleontology (or science in general)


EJ: I would advise someone to partake in outreach events such as volunteering at a museum’s exhibits, contacting the museum curators for possible internships, doing volunteer work in the collections, and attending conferences where paleontologists and other scientists present their work. I highly recommend students attend conferences, which serves as an excellent networking opportunity.


Question 6: What was or is your favorite project so far?


EJ: I am currently publishing my Master’s thesis. One of my Master’s thesis projects involves using 3D models of various tyrannosauroid skulls (e.g., T. rex, Gorgosaurus, Alioramus, Yutyrannus, Dilong, and Proceratosaurus) to evaluate the cranial performance and evolution of feeding function in Tyrannosauroidea. This is my favorite project, because this is the first broad comparative study that looks at the evolution of feeding function in various tyrannosauroids, in addition to the incorporation of small, early tyrannosauroids (Dilong and Proceratosaurus). This will offer insight into the evolution of feeding in a dinosaur clade. 

Evan taking measurements from the Allosaurus at the Smithsonian National Museum of Natural History.

Question 7: Do you have a favorite destination when it comes to fossils?  Why?


EJ: I don’t have a particular destination when it comes to fossils. Every fossil locality such as the Hell Creek Formation, Morrison Formation, and the Kem Kem Beds are unique with the fossil taxa that have been discovered. 


Question 8: A popular image of paleontologists is that they are constantly out in the field digging up fossils, which is true sometimes  What people don’t realize is that a lot of paleontology work is conducted in a lab as well.  In your experience how much time have you spend in the lab and in the field?  What do you prefer?


EJ: With fieldwork, paleontologists will travel to a locality that has previously yielded fossils with the goal of recovering fossils and taking them back to the lab to be prepared for further study or exhibition. The fossil preparation takes months to years, depending on the size and number of fossils brought back to the lab. The preparators and paleontologists will examine the prepared dinosaur(s) and evaluate what features it may have in common with other dinosaurs.


I have had previous field experience in Montana (2014), Wyoming (2018), and Alaska (2021). I was in the field for a week. I mostly conduct lab work. The lab work that I conduct involves scanning the skulls of dinosaurs and converting them into 3D models through imaging software. Following this I run computer simulations to evaluate the cranial performance of the dinosaur’s skull when biting. For one dinosaur skull, the process can take about two weeks. The first week is devoted to the scanning and processing the model for biomechanical analyses, and the second week is devoted to using biomechanical simulations on the dinosaur skull. I mostly prefer lab work as opposed to field work.


Evan scanning the skull of Ceratosaurus at the Smithsonian..

Question 9: Are there any fossils you’d like to work with that you haven’t yet?


EJ: While I have worked on fossil fish and dinosaurs, I would like to work on the feeding mechanics of synapsids such as the sail-backed Dimetrodon. I am currently taking a class on Mammal Evolution taught by Drs. Kenneth Angielczyk and Zhe-Xi Luo. Their lecture on the evolution of synapsids made me realize the unique cranial diversity of early synapsids with implications on the evolution of feeding function in Mammalia. 


Dimetrodon grandis

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


EJ: I have not been criticized for any of my work.


Question 11: A common idea is that paleontology is just a “for fun” science, with no real impact or noticeable effect that helps the world.  Do you think paleontology has a bigger part to play to than this?  How?


EJ: Paleontology allows us to understand the evolutionary history of Earth and the animals and plants that inhabited it. Fossils of animals and plants, as well as sedimentary analyses allows us to comprehend the changes Earth went through, in addition to allowing us to infer what future humans may have on Earth. 


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


EJ: The first paleontologist that I met was Dr. Paul Sereno in 2009. Dr. Sereno was giving a presentation on his new documentary “When Crocs Ate Dinosaurs”. My mother took me to the event, as she was aware that I was a fan of Dr. Sereno’s work. When I saw Dr. Sereno, I talked about how I was a fan of his work and it was a pleasure seeing him in person. Dr. Sereno was flattered by my compliments. 


Question 13: What is your favorite prehistoric animal?  Was it different when you were younger? 


EJ: My favorite prehistoric animal has always been Tyrannosaurus rex. Movies such as “Jurassic Park” portrayed T. rex as a formidable predator which has persisted throughout my childhood and studies.


Evan with "Sue" the T.rex at the Field Museum.

Question 14: 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?


EJ: I would probably bring back Spinosaurus. Spinosaurus has underwent various morphological descriptions where it had short legs with a large paddle-like tail, and spent its life swimming in the water. Paleontologists have debated Spinosaurus’ life history. The idea of seeing a real-life Spinosaurus in the 21st century and observing its feeding and locomotive behavior would be relieving to paleontologists.


Spinosaurus aegyptiacus

Question 15: 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?


EJ: I would look at the environmental aftermath of the Permian Extinction. Paleontologists refer to Permian Extinction as the worst extinction event of Earth’s history. I would be curious as to what animals and plants were able to survive and endure the Permian Extinction, especially in lieu of the appearance of early dinosaurs and early crocodilian relatives.


Fieldwork in Alaska.

Question 16: Which is your favorite museum?  Why?


EJ: My favorite museum would have to be the American Museum of Natural History in New York City. Growing up I found the American Museum of Natural History to be a phenomenal museum because it displays dinosaur fossils from “The Bone Wars”, Barnum’s Brown’s expeditions in the Upper Cretaceous formations of North America, and Roy Chapman Andrew’s fossil expeditions in Mongolia. The dinosaur fossil displays are divided into two different sections, the Hall of Saurischian Dinosaurs and the Hall of Ornithischian Dinosaurs. The saurischian hall displays a comprehensive collection of theropods, sauropods, and sauropodomorphs. The ornithischian hall displays numerous beaked dinosaurs ranging from ceratopsians, thyreophorans, to hadrosaurids. I have visited the AMNH twice (2007 and 2018), but I always yearn to visit it again.


Question 17: What hobbies do you have?  (Don’t have to be paleo-related.)


EJ: My hobbies include playing Pokemon and Yugioh, walking, writing and drawing (paleoart and manga/anime). 


Question 18: You have a book coming out!  Tell us about that.

EJ: The book is called “Dinosaur World”. The details information on every dinosaur that has been discovered to date with information on their size, diet, ecology, and significance in paleontology. In addition to the dinosaur descriptions, the book also talks about the biology of dinosaurs (feeding behavior and anatomy), museums that house dinosaur specimens and biographies of prolific and aspiring paleontologists from diverse and under-represented backgrounds. The book can be pre-ordered on websites such as Amazon, Barnes and Noble, Books a Million, Simon & Schuster, and Indie Bound. It’s best to search for the book by its ISBN: 9781646433162. You can preorder the book now and it will be released February 2023.




Sunday, September 25, 2022

Styracosaurus: Beast of the Week

This week we will be checking out Styracosaurus albertensis, the spike-frilled dinosaur!  Styracosaurus lived in what is now Alberta, Canada, during the late Cretaceous period, between 75.5 and 75.2 million years ago.  From beak to tail it measured about eighteen feet long and was a plant-eater when alive.  The genus name, Styracosaurus, translates to "Spike Reptile" in reference to the eight long spikes growing from the sides of its frill.  When alive, Styracosaurus would have shared its habitat with other dinosaurs like Parasaurolophus, Lambeosaurus, and Gorgosaurus.

Life reconstruction in watercolors by Christopher DiPiazza of two adult Styracosaurus working out a territory dispute. 

After Triceratops, Styracosaurus is possibly the most recognized member of the ceratopsian group of dinosaurs by image if not by name.  As far as dinosaur toys go, if any ceratopsian is going to show up in addition to Triceratops in a package, its almost always Styracosaurus.  (I'm actually genuinely surprised that out of the four ceratopsians that ultimately showed, it never appeared in a Jurassic Park/World movie). It's popularity is probably due to the fact that it has been known about for a lot longer than the majority of ceratopsians, formerly described over 100 years ago, so it's had time to make appearances in books and other popular media.  The other reason is Styracosaurus is just so striking to look at, even among currently known ceratopsian diversity.  Like its genus name suggests, adult Styracosaurus had a series of several extremely long spikes growing from the top edge of the frill.  In addition to these, it also had shorter spikes lining the lower edges of the frill, as well as a long horn growing out of the top of the snout.  We now know that Styracosaurus was capable of exhibiting a decent degree of variation among adults, with the number of long frill spikes ranging between four and eight depending on the individual.  There is even one specimen with seven frill spikes, showing that they were capable of expressing asymmetry in their head ornamentation.  

Front view of the Styracosaurus' skull on display at the American Museum of Natural History in New York.

The evolutionary purpose of Styracosaurus' head ornamentation, like those of most ceratopsians, is somewhat debated.  There's always the likelihood they were for display within the species, but there's also a strong chance they were additionally used as actual weapons, whether for fighting members of its own species for dominance, or against potential predators.  The sideways-facing frill spikes particularly seem like they would be effective at deterring the hungry jaws of tyrannosaurs away from the neck.  A Styracosaurus skeleton described in 2020, possesses proportionally much shorter frill spikes, a shorter nose horn, and an overall smaller body size than most other known Styracosaurus specimens on the fossil record, and is therefore thought to be of a juvenile individual.  Shorter horns in immature animals suggests they had some sort of sexual or social display purpose.  

Photograph of what is thought to be a juvenile Styracosaurus skull from the 2020 paper by Caleb Brown et al. Note the shorter frill horns and nose horn. 

The beak of Styracosaurus was narrow, and the lower beak tip was extremely long and curved upwards.  This would be a good adaptation for clipping specific plants to eat, much like a giant pair of rose trimmers.  Because of this it is likely that Styracosaurus and its relatives were more selective feeders rather than generalists, which are more adept at sucking up any plant material that's infront of them.   In the back of Styracosaurus' mouth were hundreds of small teeth packed together, forming what are called dental batteries.  These structures were good for finely slicing tough plant material, rather than grinding it.

Side view of the same Styracosaurus specimen as above at the American Museum of Natural History.

There have been bone beds comprised of multiple Styracosaurus skeletons discovered, but it is still unclear as to if they were actually herding animals.  The reason for this is because the area in which the dinosaurs seemed to have died was a riverbed at the time of their death.  Frequently, animals, herding or not, will congregate at water sources like this hoping to drink and then drown in flash floods all at once.  Therefore it could be possible Styracosaurus may have still preferred the more solitary lifestyle.  It would be difficult to cuddle with those big spikes anyway.

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

References

Brown, C.; Holmes, R.; Currie, P. (2020). "A subadult individual of Styracosaurus albertensis (Ornithischia: Ceratopsidae) with comments on ontogeny and intraspecific variation in Styracosaurus and Centrosaurus"Vertebrate Anatomy Morphology Palaeontology8 (1): 67–95.

Eberth, David A.; Getty, Michael A. (2005). "Ceratopsian bonebeds: occurrence, origins, and significance". In Currie, Phillip J., and Koppelhus, Eva. Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 501–536.

Holmes, R.B.; Persons, W.S.; Singh Rupal, B.; Jawad Qureshi, A.; Currie, P.J. (2020). "Morphological variation and asymmetrical development in the skull of Styracosaurus albertensis". Cretaceous Research107: 104308.
Lambe, L.M. (1913). "A new genus and species from the Belly River Formation of Alberta". Ottawa Naturalist 27: 109–116.

Ostrom, J. H. (1966). "Functional morphology and evolution of the ceratopsian dinosaurs". Evolution 20 (3): 290–308.

Tait, J.; Brown, B. (1928). "How the Ceratopsia carried and used their head". Transactions of the Royal Society of Canada 22: 13–23.

Tanke, D. H, and Farke, A. A. (2006). Bone resorption, bone lesions, and extracranial fenestrae in ceratopsid dinosaurs: a preliminary assessment. in: Carpenter, K. (ed.). Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs Indiana University Press: Bloomington. pp. 319–347.


Sunday, August 14, 2022

Moros: Beast of the Week

 This week we'll be looking at an important little dinosaur that helps us understand the backstory of the most famous dinosaur ever known.  Check out Moros intrepidus!

Moros was a relatively small meat-eating dinosaur that lived in what is now Utah, USA, during the Cretaceous period, between 97 and 96 million years ago.  From snout to tail Moros is estimated to have measured about 10 feet (3 meters) long based on fragmented remains.  The genus name is after the deity from Greek Mythology, Moros, who was the personification of impeding doom, appearing to those who were about to die. The reasoning for this name is because Moros is thought to be the ancestor of later apex predators, like Tyrannosaurus rex.

Watercolor reconstruction by Christopher DiPiazza of a trio of Moros.

Even though Moros is only known from an incomplete skeleton, paleontologists can deduct that it was indeed a member of the tyrannosaur group based on the leg and foot bones, and the teeth that were uncovered.  They were also able to identify the individual as an almost fully grown adult based on growth rings in the leg bone.  

It may seem odd to associate such a relatively small, lanky dinosaur like Moros, with giant monsters like Tyrannosaurus or Gorgosaurus, but when looking at the fossil record this actually makes sense.  The fossil record actually has many smaller species of tyrannosaurs found in North America, Europe, and Asia, ranging in age from 160 to 96 million years old.  The larger trannosaurids don't start showing up until millions of years later.  Different large-bodied meat-eaters, called the carnosaurs (like Sinraptor in Asia), existed alongside the smaller, earlier tyrannosaurs, and went extinct before the large, two-fingered tyranosaurids appeared in the same places.  It is thought that the smaller, more adaptable, early tyrannosaurs were able to survive whatever  wiped out the carnosaurs in the northern hemisphere, and then went on to occupy their niche as giant predators in the form of the two-fingered tyrannosaurids.  To put it into perspective, Tyrannosaurus is more closely related to birds than to dinosaurs like Allosaurus, and fossils like those of Moros help fill in the gaps that prove it.

Different views of the femur of Moros featured in the 2019 paper by Zano et al., including cross section and growth rings.

Moros had proportionally long, slender legs, which suggest it was a fast runner when alive, and possibly could have hunted smaller prey.  Since paleontologists have found feathers in other tyrannosauroid fossils, it is likely Moros had some sort of feathers in life too.  

References

Zanno, Lindsay E.; Tucker, Ryan T.; Canoville, Aurore; Avrahami, Haviv M.; Gates, Terry A.; Makovicky, Peter J. (February 2019). "Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record"Communications Biology.

Monday, July 18, 2022

Meraxes: Beast of the Week

 Today we'll be checking out a recently described dinosaur that was a giant meat-eater!  Make way for Meraxes gigas!

Meraxes was a large theropod that lived in what is now Argentina during the late Cretaceous period, between 95 and 94 million years ago.  From snout to tail it would have measured about 36 feet (almost 11 meters) long.  The genus name is actually after a dragon from the popular A Song of Ice and Fire fantasy novels. (what the show, Game of Thrones is based on.)  The species name, gigas, translates to "giant" because...this dinosaur was big.  

Watercolor life reconstruction of Meraxes gigas by Christopher DiPiazza.  Note the proportionally small arms and long claw on the second toes.

Meraxes was a member of the family of theropods called carcharodontosaurids, which are characterized by having large, narrow skulls lined with serrated blade-like teeth. (hence the family name which translates to "shark tooth reptiles") Other examples of carcharodontosaurids were the earlier Acrocanthosaurus and Concavenator, and the more famous and slightly larger Giganotosaurus. Meraxus is particularly important because it is the most complete skeleton known of a large charcharodontosaurid, which helps us understand more about their anatomy as a group.  

Like most of its kin, Meraxus had a long, tall skull, filled with blade-like serrated teeth, ideal for slashing and cutting huge chunks of flesh off bone. It also possessed ridges of rough-textured bone on the top of the snout and over the eyes, suggesting it had horn-like crests growing there in life.  These bony crests are actually common in various forms among many kinds of large theropods and may have been for some kind of intraspecies communication or even combat.  

Photoraph of recovered skull material from Meraxus from the 2022 paper by Canale.

Meraxus had three fingers with sharp claws on each hand, but extremely short arms proportional to the body.  Scientists note that despite how Tyrannosaurus is so famous for having tiny arms, this feature is actually not that rare among different kinds of theropods.  In fact, it was noted that proportionally small arms must have evolved at least four different times in theropods, present in tyrannosaurs, abelisaurs (like Carnotaurus), carcharodontosaurs, and the smaller bird-like alvarezsaurs.  If you count modern birds with tiny wings, like Kiwis, it's evolved even more times!  

Possibly the most unique feature about this dinosaur is the fact that it had an elongated claw on the second toe of each foot.  Unlike the specialized toes of dromaeosaurs and troodontids, these claws weren't retractable, so it seems they may have been more similar to the elongated claws on some modern bird feet, like cassowaries.  What purpose these claws served is currently a mystery, but they could have been to help Meraxus pin down a carcass or struggling prey as it tore chunks off with its jaws. (similar to what many modern predatory birds do today with their toe claws) It also could very well have been another instrument in fighting members of its own species. 

Photograph of the foot of Meraxus.  Note the long second toe claw.

Feet of the living Cassowary(bird).  Note the enlarged second claw convergently similar to that of Meraxus.  Unlike Meraxus, Cassowaries eat fruit and seeds, and mostly use their claws for defense.

Lastly before we go, scientists were able to examine certain bones from Meraxes and determine roughly how old it was when it died.  Turns out that individual was over 50 years old at the time of its death!  That makes it the oldest recorded fossil dinosaur known to science! They also were able to determine that like many modern reptiles, even though this Meraxes was an adult, it was still growing at a slow pace right up until it died.  This is a process called indeterminate growth, and it's been observed in a number of fossil dinosaurs, many modern reptiles, but not in modern birds.  

That is all for this week!  As always feel free to comment below!

References

Canale, J.I.; Apesteguía, S.; Gallina, P.A.; Mitchell, J.; Smith, N.D.; Cullen, T.M.; Shinya, A.; Haluza, A.; Gianechini, F.A.; Makovicky, P.J. (7 July 2022). "New giant carnivorous dinosaur reveals convergent evolutionary trends in theropod arm reduction"Current Biology.

Cullen, Thomas M.; Canale, Juan I.; Apesteguía, Sebastián; Smith, Nathan D.; Hu, Dongyu; Makovicky, Peter J. (25 November 2020). "Osteohistological analyses reveal diverse strategies of theropod dinosaur body-size evolution"Proceedings of the Royal Society B: Biological Sciences287