Tuesday, March 13, 2018

Shringasaurus: Beast of the Week

Today we will be looking at a relatively recently discovered creature that was utilizing adaptations famous in different groups of dinosaurs...but wasn't a dinosaur.  Check out Shringasaurus!

Shringasaurus was a plant-eating archosauromorph reptile that lived in what is now India, during the Middle Triassic period, between 247 and 242 million years ago.  It measured a little over ten feet long from snout to tail and would have walked on four short, but robust limbs when alive.  The genus name translates to "Horned Reptile" because this animal possessed two, forward-curving horns on the top of its head.

Male Shringasaurus basking.  If I told you I wasn't a little inspired by Chuckwallas while painting this...I'd be lying.
Shringasaurus belonged to an interesting group of prehistoric reptiles, called allokotosauria.  These early archosauromorphs are characterized by having proportionally small skulls, semi-sprawling quadrupedal posture, and teeth and jaws that suggest they were herbivores in life.  During the middle Triassic, when many of these animals were alive, plant-eating animals are so far relatively rare on the fossil record.  So the more fossils that are discovered from these interesting creatures, the more we can paint an accurate picture of their environment!

Shringasaurus has a number of unique characteristics that set it apart as a beautifully unique animal.  Most notable are those horns.  Lots of reptiles have horns, but few groups of reptiles have forward-curved horns growing over the eyes.  Ceratopsians, the successful group of dinosaurs that includes Triceratops, are the most notable. Many species of modern chameleons also have horns like this.  Shringasaurus seems to have convergntly evolved similar horns, being only distantly related to both of these groups.  The real purpose for evolving these horns is somewhat of a mystery.  But there are clues!  Shringasaurus is known in the fossil record from several individuals.  Among these are smaller, younger individuals, that show smaller horns.  This means that the baby Shringasaurus started off with small, or perhaps no horns, and did not develop them until later in life, probably when they were sexually mature.  This supports the idea that the horns were some kind of an intraspecies display.  Further, there is one individual Shringasaurus skull that had no horns, but was otherwise the same size as other Shringasaurus skulls that had horns.  This strongly points to Shringasaurus having been sexually dimorphic, when the males and females are visibly different.  It is highly possible that Shringasaurus males used their horns to visually intimidate each other, maybe incorporating some kind of "dance" like many modern reptiles will do today, like bobbing their heads around to compete for mating rights.  They may have even used their horns to physically compete with each other, like shoving, or jousting, which is also observable in modern horned animals.

Graphic from Sengupta's 2017 paper describing Shringasaurus.  This image is showing a comparison between Shringasaurus' skull (top left) and the skull of the convergently evolved Arrhinoceratops (top right).  Below, letters d-g and h-k, show the  top and side views of the skulls from various Shringasaurus individuals.  Note how specimen g/k has no horns but is otherwise the same size as specimen f/j.

Another cool characteristic about Shringasaurus is its nostril holes.  They were connected, forming one hole, instead of two, in the front of the snout.  This kind of nose hole opening is not really known in reptiles until Shringasaurus, but is something seen in modern mammals.  Shringasaurus, for whatever reason convergently evolved an external nasal passage more similar to those of mammals from millions of years later!

Shringasaurus had small, leaf-shaped teeth in its mouth, probably for eating plants.  It also had a proportionally small head at the end of a very long neck.  This long neck is often compared to those of sauropod dinosaurs, but it reminds me a lot of Galapagos Tortoise necks too.  Shringasaurus probably used this neck for the same reasons sauropods and tortoises do, too, to help it reach more leaves to eat without moving its body.  Plants provide less energy to the consumer than meat, so plant-eating animals need to conserve as much energy as possible, being able to get as much food for the littlest amount of work is important.


Sengupta, S.; Ezcurra, M.D.; Bandyopadhyay, S. (2017). "A new horned and long-necked herbivorous stem-archosaur from the Middle Triassic of India". Scientific Reports. 7: 8366.

Sunday, March 4, 2018

Lesothosaurus: Beast of the Week

Lets look at an early dinosaur that gives us important insight on how dinosaurs evolved.  Check out Lesothosaurus diagnosticus!

Lesothosaurus was a small, probably omnivorous dinosaur that lived in what is now southern Africa during the early Jurassic Period, between 199 and 189 million years ago.  From snout to tail it measured a little over six feet long.  The genus name translates to "Lesetho Lizard" in reference to Lesotho, the country in Africa in which the first fossils of this dinosaur were found.

Lesothosaurus life reconstruction.  The hair-like feathers are entirely speculative.  However, preserved feathers have been found in other basal onrnithischian dinosaurs that fossilized under different conditions.

Lesothosaurus was originally considered a very early ornithopod dinosaur.  However, as time has passed and more fossils have been found, it has become more likely that this little dinosaur was something even more basal, predating not just ornithopods, but all ornithischian dinosaurs, including the armored thyreophorans (stegosaurs and ankylosaurs) and the horned marginocephalians (ceratopsians and pachycephalosaurs)

Lesothosaururs had interesting dentition that has led paleontologists to believe it was an omnivore in life.  In the front of the jaws it would have had a small beak, probably ideal for picking at leaves to eat.  The jaws, themselves, had mostly small, leaf-shaped teeth that were probably for cutting up plants, but it also had long, pointed teeth growing from the front of its top jaw.  These long teeth may have been an adaptation to help strip leaves off stems and branches, but they also could have been effective at processing animal-based food.  When paleontologists compared the teeth of Lesothosaurus to similarly-shaped teeth of other dinosaurs that were more primarily plant-eaters, Lesothosaurus showed notable less ware on its teeth.  Since processing plants is tougher on teeth than meat, this suggested that it was not eating as much plants as these other dinosaurs, and likely was a meat-eater, too.  Lesothosaurus probably wasn't going after large prey, since its teeth weren't blade-like for shearing off chunks of flesh from carcasses, like those of most primarily meat-eating dinosaurs, but it very well could have gone after small prey, like invertebrates, or any other creature that could be eaten in one or two bites.

Lower jaw of Lesothosaurus showing the teeth that were likely best ad processing plants.  Image from Sciscio's 2017 paper, referenced below.

Lesothosaurus had proportionally very long legs and a long tail that was slightly stiffened in life.  This means that it was a fast and agile runner when alive.  Its primary defense against predators of its time was probably to run away given its anatomy.

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


Barrett, P. M., Butler, R. J., Yates, A. M., Baron, M. G., & Choiniere, J. N. (2016). New specimens of the basal ornithischian dinosaur Lesothosaurus diagnosticus Galton, 1978 from the Early Jurassic of South Africa.

Butler, Richard J.; Upchurch, Paul; Norman, David B. (2008). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology. 6 (1): 1–40.

Butler, R.J. (2005). "The 'fabrosaurid' ornithischian dinosaurs of the Upper Elliot Formation (Lower Jurassic) of South Africa and Lesotho". Zoological Journal of the Linnean Society. 145 (2): 175–218.

Matthew G. Baron; David B. Norman; Paul M. Barrett (2016). "Postcranial anatomy of Lesothosaurus diagnosticus (Dinosauria: Ornithischia) from the Lower Jurassic of southern Africa: implications for basal ornithischian taxonomy and systematics". Zoological Journal of the Linnean Society. in press.

Matthew G. Baron; David B. Norman; Paul M. Barrett (2016). "Postcranial anatomy of Lesothosaurus diagnosticus (Dinosauria: Ornithischia) from the Lower Jurassic of southern Africa: implications for basal ornithischian taxonomy and systematics". Zoological Journal of the Linnean Society. in press.

Sciscio L, Knoll F, Bordy EM, de Kock MO, Redelstorff R. (2017). Digital reconstruction of the mandible of an adult Lesothosaurus diagnosticus with insight into the tooth replacement process and diet. PeerJ, 5:

Saturday, March 3, 2018

Interview with Paleontologist: Jason Poole

Jason C. Poole is a professor at Drexel University and the Dinosaur Hall Coordinator at the Academy of Natural Sciences of Drexel University. Jason has excavated dinosaurs on three continents, Africa, South and North America. Paralititan, Dreadnoughtus and Suuwassea are three dinosaurs worked on by Poole which are new to science, two of which are super massive titanosaurs. Jason can often be
found in the Academy of Natural Sciences Dinosaur Hall Fossil Lab preparing newly found fossils which will spend the rest of their afterlife in museum collections. Mr. Poole is also a Paleo Artist who has published in National Geographic and whose art work appears in many museum and private collections.

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

JP: I collected modern bones and fossils as a kid.

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? 

JP: My folks loved to be outside when we had free time so I got my love of that from them. But I have to say that Dr. Peter Dodson was and still is a huge reason that I am still doing what I do.

Question 3: 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? 

JP: I surrounded myself with people who love science and the outdoors.

Question 4: Is the field of paleontology different now than from when you started as far as you can tell?  What would your advice be to anyone trying to make a career in paleontology (or science in general for that matter) now?  

JP: Now as always I recommend that students who want to become paleontologists become obsessed with science in general and new trends in what new tech can help to explain.

Question 5: What was or is your favorite project so far?  Would you be able to tell us about some of your current projects? 

JP: I love working on Jurassic dinosaurs with the Bighorn Basin Paleontology Institute and the Academy of Natural Sciences! This cooperation gives me the opportunity to educate about paleo in the field to students and volunteers in one of the most beautiful places in the world.   

Question 6: You have traveled to a lot of interesting places digging for dinosaurs.  Do you have a favorite destination when it comes to fossils?  Why? 

JP: I love Montana. My first dinosaur was from there.

Question 7: A popular image of paleontologists is that they are constantly out in the field digging up fossils, which is true to an extent.  What people don’t realize sometimes is that a lot of paleontology work is conducted in a lab as well.  In your experience, how much of your projects (in general) take place in the field, and how much are in the lab?  

JP: My job in Philly is as a preparator and teacher. So 10 months of the year are spent in lab.

Question 8: When it comes to your art, how often are you able to utilize it for paleontology?  

JP: Every day.  It is part of the way I communicate and take notes.

Question 9: What is your favorite medium to use when creating art?  Why?  

JP: Ball Point Pen. It travels well and gives a great line for sketching. 

Jason's reconstruction of the sauropod, Suuwassea.
Question 10: Do you ever get criticized on any of your work? How do you handle it?

JP: I am constantly criticized buy people, the harshest remarks are my own. It is how we grow as artists. Constant pushing and tweaking of our craft due to feedback from people and our own mistakes. I think I handle it well… I have not killed anyone yet.   

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?  

JP: You cannot know the future so you better know the past if you are going to make any informed plans for the future. Evolution and understanding how species react to natural pressures exerted by a changing world is key especially now when we should be looking to science to direct thinking about our future.

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

JP: Bill Gallagher. He is a great guy!

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

JP: Ceratosaurus. Nope.

Ceratosaurus skeleton on display at the National Museum in Washington, D.C.
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?  

JP: T. rex. T. rex gets so much attention and we think we know tones about it. I would love to see how far off we might be. I think it would be a great test of how far off we should expect to be off on other animals. Here is the rub though, When you take an animal out of its ecosystem or habitat you will not know how it naturally behaves.

Question 15: Which is your favorite museum? Why? The Academy of Natural Sciences of Drexel U. in Philadelphia.  

JP: We started this paleo thing in the Americas and we are still going. I am most excited for our future as a public museum and a research institution! Come see why.  

Question 16: What hobbies do you have?  (Don’t have to be paleo-related.)  

JP: Not a lot of time for hobbies. Love to build model kits and skateboard. Family fills most of the free time now.

Sunday, February 25, 2018

Herrerasaurus: Beast of the Week

Today we will be looking at one of the earliest dinosaurs.  Enter Herrerasaurus ischigualastensis!

Herrerasaurus lived in what is now Argentina, in South America, during the Triassic Period, roughly 231 million years ago.  The largest specimen on record would have been about twenty feet long from snout to tail, but all adults may not have reached this size, possibly averaging out at around fifteen feet.  When alive Herrerasaurus would have eaten meat, according to its teeth.  The genus name translates to "Herrera's Reptile", in honor of the goat herder who discovered the first bones of this dinosaur, Victorino Herrera.

My Herrerasaurus ischigualastensis life reconstruction in watercolors.

Herrerasaurus had a boxy profile to its skull, which was armed with a lower jaw that was able to flex back and fourth.  This is an unusual adaptation for dinosaurs, but is common in many modern lizards, like monitors, to help manipulate large chunks of food to the back of the mouth to be swallowed.  (lizards evolved this trait independently of Herrerasaurus, however.)  Herrerasaurus was also armed with extremely long, dagger-like teeth, that curved towards the back of the mouth, another quality of a meat-eater.

Cast of the first discovered Herrerasaurus skull on display at the Academy of Natural Science in Pennsylvania.

Herrerasaurus had strong arms, each armed with three curved claws.  It had proportionally short thighs, and long lower legs and feet, suggesting it was a fast runner in life.  It's tail was not very flexible because of the bony structures in its vertebrae, which is also a characteristic of dinosaurs that were good runners, to aid in maneuverability.  

Herrerasaurus had a number of odd characteristics about its anatomy that have caused scientists to dispute over what kind of animal it really was.  It walked in a fully erect posture, like all dinosaurs, but the socket where its femurs attached to its pelvis was not as open, or "window-like", as it is with later dinosaurs.  It also only had two vertebrae over its hips, called sacral vertebrae, whereas most dinosaurs typically have three.  Lastly the bone int its hip, called a pubis, was angled behind the body, which is typical in ornithiscian dinosaurs, dromaeosaurs, and birds, the last two wouldn't evolve until millions of years after Herrerasaurus.

Herrerasaurus mounted skeleton on display at the Field Museum in Chicago.

Herrerasaurus is one of those fossil creatures that has gone through a few identity crises over the years since its discovery.  Because it lived so early on in the Mesozoic, before dinosaurs started truly diversifying, it has proven tricky to place, genetically.  At first, because of its teeth and long legs, it was classified as a very early theropod.  However, some suggested it had more in common with early sauropodomorphs, like Plateosaurus.  Some have suggested that Herrerasaurus, despite its meat-eating qualities, was actually closest to ornithischian dinosaurs, because of its backwards-facing pubis bone.  It was even proposed to be not a dinosaur, at all, placed just outside the dinosaur family tree and classified as something more closely related to crocodiles due to more basal traits in its skull and hips.  However, as more and more fossils from the Triassic are being unearthed, the latest analysis of Herrerasaurus places it back as a dinosaur,  almost at the very base of the dinosaur line, as a kind of very early saurischian dinosaur.


Benedetto, J.L. (1973). "Herrerasauridae, nueva familia de saurisquios triasicos" (PDF). Ameghiniana. 10 (1): 89–102.

Bittencourt, J.S.; Arcucci, A.B.; Marsicano, C.A.; Langer, M.C. (2014). "Osteology of the Middle Triassic archosaur Lewisuchus admixtus Romer (Chan~ares Formation, Argentina), its inclusivity, and relationships amongst early dinosauromorphs". Journal of Systematic Palaeontology. 0 (3): 1–31. 

Gauthier, J.A.; Nesbitt, S.J.; Schachner, E.R.; Bever, G.S.; Joyce, W.G. (2011). "The bipedal stem crocodilian Poposaurus gracilis: inferring function in fossils and innovation in archosaur locomotion" (PDF). Bulletin of the Peabody Museum of Natural History. 52 (1): 107–126. doi:10.3374/014.052.0102. Archived from the original (PDF) on 2015-09-24.

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 (110): 1–159. 

Nesbitt, S. J.; Smith, N. D.; Irmis, R. B.; Turner, A. H.; Downs, A. & Norell, M. A. (2009). "A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs". Science. 326 (5959): 1530–1533.

Novas (1993). "New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto Formation (Upper Triassic) of Argentina". Journal of Vertebrate Paleontology. 13: 400–423.

 Novas, F.E. (1994). "New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto Formation (Upper Triassic) of Argentina". Journal of Vertebrate Paleontology. 34 (4): 400–423.

Padian, K.; May, C.L. (1993). "The Earliest Dinosaurs". In Lucas, Spencer G.; Morales, M. The Nonmarine Triassic. New Mexico Museum of Natural History & Science Bulletin. 3. pp. 379–381.

Sereno, P.C.; Novas, F.E. (1993). "The skull and neck of the basal theropod Herrerasaurus ischigualastensis". Journal of Vertebrate Paleontology. 13 (4): 451–476.