Tuesday, January 15, 2019

Prehistoric Beast at the Academy of Natural Sciences

I visited Philadelphia's historical natural history museum, The Academy of Natural Sciences, my first weekend after moving to this city, almost three years ago.  I also landed a job working in their education department, and regularly volunteer prepping fossils in their lab.  That being said...for some reason I never wrote a proper post about it.  Let's fix that now.

Outside of the museum.  (Photo by Ashli Lenox)

The Academy of Natural Sciences is the oldest science research institution and museum in the United States.  This is the museum where Edward Drinker Cope worked out of during the infamous Bone Wars in the late 1800s.  It's also the resting place of the first two dinosaurs to be formally described in America, Hadrosaurus and Dryptosaurus.  Needless to say, it's a special place and should be one of the top museums to visit for anyone who likes paleontology or American history.

This awesome life-sized statue of two running Deinonychus, sculpted by Kend Ullberg, was erected in front of the museum in the 1980s.  At the time this was an extremely up-to-date depiction, especially since the idea of light, fast-moving dinosaurs was still novel.  (photo by Ashli Lenox)

When you first walk in the front doors, you are greeted by the skeleton of the giant marine reptile, Elasmosaurus, swimming at you from the ceiling.  This creature has more significance than just looking cool, however.  It was this Elasmosaurus that in some ways started the Bone Wars, the historical event when Othniel Marsh embarrassed fellow paleontologist, Edward Drinker Cope, by pointing out during Cope's debut of this skeleton, that the skull was put on the tip of the tail, instead of the neck.



In the back of the front lobby is a cast and 3D life reconstruction of Tiktaalik, a fossil that helped prove the evolutionary connection between fish and land vertebrates.  The actual fossil of Tiktaalik is currently in Northern Canada, where it was discovered, but it was brought to the Academy of Natural Sciences to be studied and published.

Tiktaalik cast and life reconstruction. (photo by Ashli Lenox)

When you first enter the Academy's fossil hall, you are attacked by a lunging Tyrannoaurus skeleton.  This is a cast of the same T. rex skeleton on display at The American Museum of Natural History, in New York, affectionately referred to by its ID number, 5027.

The T. rex is the central attraction in the Acdemy's fossil hall.  The scapula (shoulder blades where the arms attach) are erected too close together.

Right next to Tyrannosaurus, is a medley of other meat-eating dinosaur skulls, including Acrocanthosaurus, Majungasaurus, Dilophosaurus, Velociraptor, Herrerasaurus, and Eoraptor.  Lots of people come into the museum asking to see a Velociraptor, then get really disappointed when they are shown the actual skull and see how small their favorite Jurassic Park monster really was.  Luckily for those folks, we have a lovely mount of the larger dromaeosaurid, Deinonychus, in all its predatory glory, attacking a family of Tenontosaurus.

Meat-eating dinosaur skulls that are not T. rex!

While we're on the subject of Jurassic Park, the Academy of Natural Sciences showcases almost all of the main dinosaurs featured in the beloved franchise.  This is actually really cool from an educational standpoint because educators giving tours can show visitors the dinosaurs they are already somewhat familiar with and therefore, more effectively implement the real science behind them.  Not sure if having all these specific dinosaurs was on purpose, but it's convenient.

Deinonychus attacking a family of Tenontosaurus.

Another notable skeleton on display is that of the crested hadrosaurid, Corythosaurus.  It's a massive specimen, towering over almost everything else in the room, flanked by the ceratopsian, Chasmosaurus, with two Pteranodon skeletons suspended near its head.  What I really like about this display, is that the Corythosaurus mount is almost all the original fossil bones, not casts.  The only exception is the skull, which is a lightweight cast since the real one was too heavy to be safely mounted up that high.

Corythosaurus

The main fossil hall has a fair share of marine fossils.  Most impressive, in my opinion is a beautifully preserved Ichthyosaurus that spent over one hundred years at the Academy, mostly in the behind the scenes collections.  Only very recently, in 2016, it was realized, upon closer examination, that this specimen was a previously unnamed species.  It was given the full name Ichthyosaurus somersetensis, and is now on full display in the main fossil hall.

Ichthyosaurus somersetensis

The Academy of Natural Sciences has a fossil prep lab, where paleontologists and  volunteers work on cleaning off and assembling pieces of dinosaur bones collected every summer in Montana.  Most of the fossils that are currently being worked on are from the Late Jurassic Morrison Formation.  The sauropod dinosaur, Suuwassia, was discovered, prepped, studied, and scientifically described by folks from the Academy of Natural Sciences.  A glass case with a few bones from this amazing dinosaur is on display right next to the lab.  Visitors can walk right in, look at the specimens currently being prepped, and talk to /ask questions of the scientists and volunteers as they work.

Neck vertebrae of Suuwassia on display in the Academy's fossil lab.  There are more bones from this dinosaur in the museum's collections, and even more in the lab that have yet to be prepped.  We are learning more about this relatively newly discovered dinosaur every day.

Finally, I'd like to share what I am most impressed by at this museum, the first and second American dinosaurs ever described by science! (and they're both from my home state, New Jersey!) Hadrosaurus and Dryptosaurus are both on display at the Academy.  Casts of Dryptosaurus' bones are in a glass case in the main fossil hall, across from a wall mount of casts of the known skeleton of New Jersey's official state fossil, Hadrosaurus foulkii.  On the second floor, however, there is a full skeletal mount of Hadrosaurus on display.  The unknown bones of this skeleton are filled in with the bones of more completely known hadrosaurid dinosaurs, like Maiasaura.  Not only does the Academy have these two important dinosaurs on display, it is also the housing place of their real bones down below in its collections drawers.

Casts of  some of the bones of Dryptosaurus on display in the fossil hall.

Known skeletal elements of Hadrosaurus are mounted in the museum's fossil hall.
On the second floor there is a full skeleton of Hadrosaurus, supplemented with bones from other related dinosaurs to fill in the gaps.  Because of this, the right femur (from a Maiasaura) is longer than the left one (from Hadrosaurus)

There are lots of fossils on display that I did not include in this post.  In addition, there are many other exhibits, other than the fossil hall, that are worth seeing at the Academy.  If you are ever in the Philadelphia area, make sure to go see for yourself!  Stay tuned for part two of my tour of the Academy of Natural Sciences, where we will take a look behind the scenes and see fossils that you don't get to see on a regular visit!

Sunday, January 6, 2019

Macrocollum: Prehistoric Beast of the Week

This week we will be checking out a newly discovered dinosaur that is currently the oldest known member of its family. Check out Macrocollum itaquii!

Macrocollum was a plant-eating dinosaur that lived in what is now Brazil, during the late Triassic period, about 225 million years ago.  When alive, it would have measured about sixteen feet long from snout to tail.  The genus name translates from Greek to "long neck".

Macrocollum life reconstruction in watercolors by Christopher DiPiazza.

Macrocollum is an important find because it is the oldest known member of the group of dinosaurs known as the basal sauropodomorphs, or "prosaurpopods" as they have also been called.  These dinosaurs were common during the late Triassic and early Jurassic and are characterized by having long necks and tails, and proportionally small heads.  Many of them walked on their hind legs primarily, but others could also have dropped down to all fours, as well.  Plateosaurus, Massospondylus, Mussaurus, and Ingentia, are also members of this group.  There is evidence to suggest that this group of dinosaurs would later give rise to the gigantic sauropods, like Brontosaurus and Apatosaurus.

Close up photograph of a Macrocollum skull.  Note the down-turned tip of the snout and the small, leaf-shaped teeth.

The fact that Macrocollum is from as old a time as it is, combined with its anatomy, is what makes it extremely interesting, and tells us a lot about sauropodomorph evolution.  Macrocollum had a very long neck, and proportionally small head, just like later members of its family.  This tells us that, since it is so far the oldest-known member, that the sauropodomorph body type must have happened even earlier, from an ancestor that didn't have a long neck and proportionally small head.  Many paleontologists agree that the common ancestor to dinosaurs was a meat-eater.  Macrocollum's proportionally small head, small, leaf-shaped teeth, and long neck are all adaptations for eating plants, which proves that being a plant-eater must have evolved much earlier in the dinosaur family tree, too.

Multiple skeletons of Macrocollum were discovered very close to each other.  Each individual animal's remains are highlighted in a different color.  Image from Federal University of Santa Maria.

Macrocollum is also interesting in that multiple individual skeletons were discovered nearby each other.  This suggest that this dinosaur may have been social, perhaps living in groups, or sticking with family members as an adult, which is exciting to think about and rarely supported by fossil evidence.  That being said, keep in mind it is also possible that these dinosaurs may have just congregated at a riverbed in search of a resource, like water, during a time of drought, and all died at about the same time from lack of that resource.

References

Rodrigo Temp Müller; Max Cardoso Langer; Sérgio Dias-da-Silva (2018). "An exceptionally preserved association of complete dinosaur skeletons reveals the oldest long-necked sauropodomorphs". Biology Letters14 (11)


Tuesday, December 4, 2018

Interview with Paleontologist: Nathan Van Vranken

Today we will be interviewing paleontologist,  Nathan Van Vranken.  Nathan has been a friend of mine for many years.  I have had the honor of providing artwork for many o f his scientific papers, research posters, and presentations.

Nathan is a paleontologist based out of the Dallas-Fort Metroplex in Texas. He specializes in Cretaceous interior seaway animals such as ichthyosaurs and mosasaurs and also has an interest in biostratigraphy. He holds as BS in interdisciplinary studies from the University of Texas at Arlington and a Msci from the University of Texas of the Permian Basin. Currently, he teaches introductory Earth Science courses at different Dallas-based colleges when not doing research. Nathan has worked on several projects during his academic career and is an advocate for public outreach on social media (Facebook) along with helping develop the computer model for the Mosasaurus found in the popular video game, Saurian.

Nathan with one of the Tylosaurus specimens he's worked on. 

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

NV: I think my first memory of doing anything paleontology related was my mom took me to the Peabody museum in Connecticut. I Think looking at the giant slabs of dinosaur tracks being mapped and documented got me interested in the field. This was sometime in the early 90s during the famous dinosaur craze. After that, visiting the dinosaur halls at the American Museum of Natural History and New York state museum for some large mammals really propelled me into thinking about this being a possible field of enjoyment. My first dig site experience was helping Skidmore college in middle school excavate artifacts in Saratoga Springs, New York along a place called Fish Creek. Admittedly it was archaeology but it still got me thinking about what is buried under my feet.

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?

NV: I was always a Jacques Cousteau, Bob Bakker and Don Lessem fan growing up as far as my science background is concerned. Still, my biggest role model was Derek Main, he taught me about perseverance and how to go above and beyond to help the paleocommunity out and take risks.

Nathan and Derek Main.

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?

NV: I think its a mixture of the three. Get yourself out there by helping the community out either getting some field or lab experience which helps bridge the gap between interested fossil collectors and researchers. Classes can help you know the current concepts and how to improve your critical thinking skills and understand some of the background concepts in our field. I think some of the best things that helped my career is to go to a professional conference such as SVP or GSA. Attend them and network with the professionals and ask questions to them about their research or talk to them about some ideas you had dealing with a topic. Pick a topic either big or small and present it at a conference either as an oral or poster presenter this is a great way to get noticed.

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?

NV: I think paleontology is undergoing a lot of changes. Some really good ones. Back when I started we didn’t have the open access journals or being able to convert fossils into digital scans to do research on. Or at least that I was aware of. Now, I think that is the new normal and we should encourage it because most of it can help early career researchers produce and collect data and promote their projects. Again, think the best way to get started is be active in the community, social media is a great example and don't forget to branch out into other topics. 

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

NV: Think my favorite project so far was working on my Texas ichthyosaur paper where I cataloged and updated the descriptions of the ichthyosaurian remains found in Texas. I also have a few fish and mosasaur papers I am working on and should be published soon.

Still unnamed species of Platypterygius, one of the Icthyosaurs included in Nathan's recent paper.

Question 6: Do you have a favorite destination when it comes to fossils?  Why?

NV: I think my favorite destination would be here in Texas. My state has a variety of paleoenvironments, fossils, and segments of geologic time. You can also go from populated areas to collect in such as the Dallas-Fort Worth metroplex to about as rural as you can get, in places outside of the Big Bend region. Outside of the state I do have other favorite places like southeastern Montana which I haven’t been to since 2015 but I do miss that area. As long as I can look at the deep time and sample some local food I feel that would always be a favorite destination.

Nathan finding a dinosaur bone at the Arlington Archosaur site.

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?

NV: I think most of the work I have been doing recently is in the collections and labs. While I do love fieldwork and being an urban paleontologist I have to adapt. That's why I prefer being a meta-analyst and go though the collections and help clarify or update the records.

Question 8: You are most known for your work on marine life, like mosasaurs, ichthyosaurs, and fish.  Did you choose these subjects for your work or did they “choose you” in a sense?

NV: Well seeing I got myself started in Texas, the work pretty much picked me. I had always been interested into the interior seaway and seeing carbonate rocks are the most common in the state I worked with them. Working on the Arlington Archosaur Site project and walking the famous Glen Rose tracks got me interested into the coasts of the interior seaway and when I got into graduate school at the University of Texas of the Permian Basin I was given a mosasaur to study, one of the more common vertebrates found in the seaway. I worked with that specimen and was able to reach out to larger collections and their experts at SMU and the Sternberg to learn more about the seaway itself overtime. The ichthyosaurs I would have never thought to be working on them for being obscure in the state and actually enjoy them as much as mosasaurs.

Tylosaurus has the been the subject of several of Nathan's papers.

Question 9: Is there a subject you’d like to work on that you have not yet?

NV: Yeah, ceratopsians. 

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

NV: I think it’s a norm now in social media to be criticized for any work. I admit I’ve been on the receiving end of some critics as much as the next guy. How do I handle it? I address their comments as best as I can and also be skeptical of their claims as the critic can be skeptical of mine. This is a skill that I am constantly improving on. It’s really just another type of peer review.


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?

NV: Yes I think it does apply to the grand scheme because it allows us to look at the data given and apply it to the trends we see today. I was once taught that Earth’s history is much like a Shakespearean play, the plot and characters change but the themes will always linger. If we can identify those themes we can apply it to our lives to see where we are going and where we came from and understand big picture concepts. Our field does do good not on a philosophical level but paleontology also is a great medium to communicate to kids and adults and it makes science accessible. If I can get a person off the computer or iPad and looking at the ground or natural world and ask questions then I think I’ve done some good. Paleontology helps bridge that gap and helps promote the idea that citizens can contribute and become scientists at any level.

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

NV: I think the first true paleontologist I ever met was my old mentor Derek Main. Our first conversation was very influential as he told me the same advice I tell everyone which is to get out there and be active in the community and be a risk taker. The conversation I had was very welcoming and gave me the confidence to pursue this as a career. 

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

NV: Well my favorite prehistoric animal is probably Herrerasaurus. Probably had something different when I was younger like Stegosaurus or something. Still will always love my marine reptiles.

Herrerasaurus

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?

NV: Probably something from the Pleistocene. My first shot at de-extinction would be a Bison latifrons. I think it’s just because it’s a big Bison and I always liked them.

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?
Question 16: Which is your favorite museum?  Why?

NV: Think the best museum I have ever gone to would have been the TELLUS museum in Georgia. Felt the displays for some of the local gulf coast fossils were pretty cool and atmospheric.

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

NV: Ahhh well, this will out me. I admit, I do enjoy watching my anime and I am also an avid gamer. I like to collect Magic the Gathering cards and play various table top games like Dungeons and Dragons. I also enjoy video games, mostly strategy or fighters.  Other hobbies consist of collecting antique books and being a foodie.

Sunday, November 25, 2018

Nasutoceratops: Prehistoric Beast of the Week

Today we take a look at a really cool looking plant-eating ceratopsia called Nasutoceratops titusi.

Nasutoceratops titusi life reconstruction by Christopher DiPiazza.

Nasutoceratops measured about fifteen feet long from beak to tail when it was alive.  It lived in what is now Utah, USA, during the late Cretaceous period, between 75 and 76 million years ago.  Nasutoceratops translates to "Big Nosed Horned Face" because of its extremely thick snout.

Nasutoceratops was an early member of the centrosaurine branch of the ceratopsian family of dinosaurs.  Centrosaurines are characterized by having short, very tall snouts.  Nasutoceratops has perhaps the most extreme case of this feature, which is how it got its genus name.  This huge nasal cavity may have served a number of purposes, from sound amplification, to a structure for maintaining moisture.  The big nose may have also been for visual display within the species.

There have been a lot of interesting ceratopsians over the last several years, many of which have very unique horn and frill structures.  That being said, I personally think Nasutoceratops is the coolest out of this bunch.  It doesn't really have much on its nose, but its brow horns were a different story.  They grew outwards to the sides of the animal's face then curved inwards towards the middle, very similar to the horns of some modern bulls.  These horns are also interesting because Nasutoceratops' later relatives from the centrosaurine group, like Centrosaurus, StyracosaurusPachyrhinosaurus, or Sinoceratops, possessed very short brow horns, or no brow horns at all, but typically had large horns or bony structures on their snouts and even their frills.  Nasutoceratops implies that long brow horns may have been an ancestral trait to the large ceratopsians, but the centrosaurine branch turned them in for more elaborate nose structures as time went on.

Nasutoceratops' frill was relatively small and circular shaped, with prominent scallop-shaped horny structures growing out of the edges.

Nasutuceratops skull


Not only bones are known from Nasutoceratops.  This dinosaur is one of the few that we actually have skin casts from!  A small patch of skin, thought to be from the arm, shows mosaic-like scales, similar to those we can see on modern crocodilians.  We have a small record of skin impressions from a few other kinds of ceratopsians, including Triceratops, Chasmosaurus, and Centrosaurus, but those are all from different parts of the body, mostly the back and hip area.

Nasutoceratops skin cast.   Note the different sized scales.  Photo used with permission courtesy of Brian Switek.

Nasutoceratops is an interesting and important dinosaur because Ceratopsids in the centrosaurine group (thick-snouted ones also including Diabloceratops, Styracosaurus and Pachyrhinosaurus) are rare in the Southern United States.  Many of them are actually found farther north in Canada.  Nasutoceratops provides us with more clues (and questions) about ceratopsid evolution and geographical distribution.


References

Sampson, S. D.; Lund, E. K.; Loewen, M. A.; Farke, A. A.; Clayton, K. E. (2013). "A remarkable short-snouted horned dinosaur from the Late Cretaceous (late Campanian) of southern Laramidia". Proceedings of the Royal Society B: Biological Sciences 280 (1766): 20131186. doi:10.1098/rspb.2013.1186

Tuesday, November 13, 2018

Microraptor: Beast of the Week

This week we shall check out a tiny dinosaur that has taught us more than we ever could imagine we'd learn about any fossil animal.  Enter Microraptor gui!

Microraptor was a small, feathered, meat-eating dinosaur that lived in what is now China, during the early Cretaceous, 120 million years ago.  Adults ranged in size between 2.5 and 3 feet long from snout to tail.  The genus name, Microraptor, translates to "Small Hunter/Thief".

Microraptor was a tiny member of the dromaeosaurid family of dinosaurs, and therefore was related to creatures like Deinonychus, Dakotaraptor, and the extremely popular Velociraptor.  Like it's larger cousins, Microraptor had and long thin tail for balance, three long claws on each hand and of course, the signature retractable "killer claw" on the second toe of each foot.  Microraptor had large eye sockets, indicating it had good vision, and a mouth armed with pointed teeth, some of which were serrated.

Watercolor life reconstruction of Microraptor gui  hunting a scorpionfly by Christopher DiPiazza.

Microraptor's real claim to fame is the fact that its feathers were preserved during the fossilization process, giving us a much clearer vision of what it looked like when alive.  Microraptor would have been as covered in feathers as most modern birds, and even had proportionally very long primary feathers growing out of its arms and hands, forming wings.  More amazing, Microraptor also had long wing feathers on its legs and feet!  There were actually other kinds of dinosaurs that evolved to have primary feathers on their lower limbs we now know of, like Anchiornis or Changyuraptor, but Microraptor was the first of these to be discovered and described back in 2003.

So why the extra set of wings?  At first it was proposed that Microraptor would have lived in trees and glided from branch to branch with its legs outstretched behind it, like a modern flying squirrel, using the leg wings to form a kite-like shape as it did so.  It was later determined that despite the fact that the fossilized skeleton had the legs in this position, that it was crushed flat in a position not true life during the decomposition and fossilization process.  Other known dromaeosaurs and living birds can't position their legs that way without breaking them, and Microraptor likely was the same.  Instead, it is possible Microraptor's leg feathers could have provided extra lift when jumping or taking off.  Many paleontologists now think that Microraptor may have been capable of actual powered flight, and not just gliding.  It had a fused sternum, like most modern flying birds have, and its wing feathers were extremely long to the point where they, combined with its leg wings, almost certainly could have provided Microraptor the ability to get and stay off the ground if it needed to.  It's arm sockets, however, prevented Microraptor from lifting its arms above its shoulders, unlike modern flying birds can to perform a strong upstroke when flapping.  This doesn't mean that Microraptor still couldn't fly, it just means it wasn't as adept a flier as a lot of modern flying birds.  It would have been common to see Microraptor flying short distances, possibly from tree to tree, or from the ground to a tree to roost, but probably not soaring up in the sky like an eagle.

There are many specimens of Microraptor on the fossil record and several of them actually preserved food that had been ingested shortly before the Microraptor died.  Because of this wealth of fossil information, we know that Microraptor was a meat-eater, but wasn't picky or specialized in going after one kind of prey.  Among the known last meals include lizards, mammals, birds (yes, there were true modern-style birds back then) and even fish.

Cast of the skeleton and feathers of Microraptor gui on display at the American Museum of Natural History for their Dinosaurs Among Us seasonal exhibit.

For a long time, we always assumed that no matter how many fossils we found, we'd never know what colors prehistoric animals were.  Not the case with MicroraptorMicroraptor's feathers preserved so well, that when viewed under a microscope, organelles called melanosomes were found to still be present.  Melanosomes are responsible for determining what color waves reflect back when light hits the feather.  Whichever waves are reflected is the color we see.  Even though the color, itself, was not visible anymore, by comparing the shape of the fossilized Microraptor melanosomes to melanosomes of modern bird feathers, paleontologists were able to deduct what colors Microraptor would have had when it was alive.  As it turns out, Microraptor feathers were iridescent blackish bluish, like those of modern crows, grackles, and starlings!  Since the iridescence of feathers like these can only be noticed in the sunlight, this also supports the idea that Microraptor would have been active during the day and not at night, otherwise there wouldn't have been a reason for it to have evolved such reflective colors.  This being said, keep in mind these melanosomes were only observed in one specimen of Microraptor.  This doesn't mean that all Microraptors were this color throughout their whole lives.  It is entirely possible that only adults, or one sex was this color.  Or maybe Microraptor molted feathers, becoming a different colors depending on the season.  There is still room for imagination!

Modern Boat-Tailed Grackles have feathers that may have been similar to those of Microraptor.  Notice the shiny blue-black coloration.
That is all for this week!  As always feel free to comment below!

References

Chatterjee, S.; Templin, R.J. (2007). "Biplane wing planform and flight performance of the feathered dinosaur Microraptor gui"(PDF)Proceedings of the National Academy of Sciences104 (5): 1576–1580.

Jingmai O'Connor; Zhonghe Zhou & Xing Xu (2011). "Additional specimen of Microraptor provides unique evidence of dinosaurs preying on birds"Proceedings of the National Academy of Sciences of the United States of America108 (49): 19662–19665. 

Li, Q.; Gao, K.-Q.; Meng, Q.; Clarke, J.A.; Shawkey, M.D.; D'Alba, L.; Pei, R.; Ellision, M.; Norell, M.A.; Vinther, J. (2012). "Reconstruction of Microraptor and the Evolution of Iridescent Plumage"Science335 (6073): 
1215–1219. 

 Lida Xing; et al. (2013). "Piscivory in the feathered dinosaur Microraptor". Evolution67: 2441–2445.

Senter, P (2006). "Scapular orientation in theropods and basal birds, and the origin of flapping flight". Acta Palaeontol. Pol51: 305–313.

Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). "Four-winged dinosaurs from China." Nature421(6921): 335-340, 23 Jan 2003.

Sunday, November 4, 2018

Harpymimus: Beast of the Week

This week we will be checking out a bird-like dinosaur that was named after a fearsome mythical creature.  Let's check out Harpymimus okladnikovi!

Harpymimus was a theropod dinosaur that lived in what is now Mongolia, during the early Cretaceous period, between 107 and 100 million years ago.  It measured a little over six feet long from snout to tail and would have almost certainly been covered in feathers when alive.  The genus name, Harpymimus, translates to "harpy mimic" in reference to the harpy, a monster from Greek mythology with the head of a human and body of a bird.  I'm not sure why this dinosaur, in particular was named after a harpy other than the fact that it was bird-like, which isn't really a unique feature among dinosaurs.

Harpymimus life reconstruction in watercolors by Christopher DiPiazza.

Harpymimus was a very early member of the group of theropod dinosaurs, called the ornithomimosaurs.  These dinosaurs are known for having had long legs, long, slender necks, and relatively small heads with beaks.  The late Cretaceous-living Gallimimus and Struthiomimus are more famous members of this group, and Deinocheirus was a very large member.  Since Harpymimus lived so much earlier than most of the other known ornithomimosaurs, it also showcases a number of features in its anatomy that would change as its descendants became more specialized.  This is a great example about how studying fossils allows you to see how the evolution of many kinds of organisms changed over millions of years, which also tells us a lot about organisms that are still alive with us today!

Harpymimus skeleton on display at the Mongolian Academy of Sciences)

Harpymimus had relatively large eye sockets, suggesting it could see well, and had a long, slightly down-turned snout.  It had teeth on the very tip of its lower jaw.  Teeth in general are considered an ancestral trait for this kind of dinosaur, since all the late Cretaceous ornithomimosaurs were completely toothless.  Harpymimus teeth were tiny and cylinder-shaped.  They would have been hardly noticeable unless you were to look directly into Harpymimus' mouth up close.  What these teeth were exactly for is a mystery.  Many hypothesize that Harpymimus could have been an omnivore, eating plant material as well as hunting for small prey, like invertebrates or other kinds of small animals it could snap up.

Harpyimimus had long arms tipped with three fingers on each hand, but the first digit was significantly shorter than the other two.  This is typical for most kinds of three-fingered theropods, but would eventually change in later-living ornithomimosaurs, which had three fingers of equal lengths on each hand.

Harpymimus had long, powerful legs, which would have enabled it to have run quickly.  While later ornihomimosaurs only had three toes on each foot, Harpymimus possessed a fourth (but digit 1) tiny toe, called a hallux, which was on the inside of each foot.  This is also a trait common to most theropods, but evolved out as ornithomimids became more specialized later in the Cretaceous.

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

References

Barsbold, R. and Perle, A. (1984). [On first new find of a primitive orithomimosaur from the Cretaceous of the MPR]. Paleontologicheskii zhurnal2: 121-123

Kobayashi, Y. and Barsbold, R. (2005). "Anatomy of Harpymimus okladnikovi Barsbold and Perle 1984 (Dinosauria; Theropoda) of Mongolia." In Carpenter, K. (ed.) The Carnivorous Dinosaurs. Indiana University Press: 97-126

Thursday, October 25, 2018

Caelestiventus: Beast of the Week

This week we will be checking out a newly discovered creature that is one of the oldest known pterosaurs to date.  Let's check out Caelestiventus hanseni!

Caelestiventus lived in what is now Utah, USA, during the late Triassic period, about 208 million years ago.  It was a meat-eater, and based on the bones that have been found, would have had a wingspan of almost five feet.  The genus name, Caelestiventus, translates to "heavenly wind" and the species name, hanseni, is in honor of geologist, Robin Hansen.

Life reconstruction of Caelestiventus in watercolors by me.

Caelestiventus is particularly amazing because it is the oldest known pterosaur from North America.  On top of this, it lived in an arid, desert-like environment, which is not common in currently-known pterosaurs.  Even more amazing is that the bones from Caelestiventus are beautifully preserved in three dimensions.  Most pterosaur bones tend to become flattened during the fossilization process because they are so delicate.  The fact that Caelestiventus preserved as well as it did allowed paleontologists to get a better idea of the shape of he skull.  According to what was found, Caelestiventus would have had powerful jaws, due to ridge-like structures on the top of its skull where muscles would have attached in life.  Since paleontologists were able to scan the inside of the skull, including the space its brain occupied, they found that its eyesight would have been powerful, but the senses of smell and taste less so.

3D printed cast of Caelestiventus' skull.  This pterosaur is known from an almost complete skull and a piece of the wing.

Caelestiventus was a very close relative of the more famous, and slightly later-living pterosaur, Dimorphodon.  Both of these pterosaurs had proportionally gigantic skulls that were tall and armed with differentiating kinds of teeth, which is also unusual among known pterosaurs, let alone reptiles in general.  Caelestiventus, specifically had long, pointed teeth in the front of its jaws, which would have been ideal for capturing prey, and smaller, more blade-like teeth in the back of its jaws, which appear to have been more for processing food once in the mouth.

Exactly what Caelestiventus was eating is still mostly a mystery, but we do know there were a number of small reptiles, like sphenodonts (relaitves of modern tuataras),  pseudosuchians (relatives of modern crocodilians), and even some dinosaurs, that at least as babies, could have been food items for this pterosaur.   There were almost certainly a variety of insects alive back then, as well, that could have been a staple food source for Caelestiventus.

References

Britt, B. B.; Dalla Vecchia, F. M.; Chure, D. J.; Engelmann, G. F.; Whiting, M. F.; Scheetz, R. D. (2018). "Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years"Nature Ecology & Evolution.

Britt, B. B.; Chure, D. J.; Engelmann, G. F.; Shumway, J. D. (2016). "Rise of the erg—Paleontology and paleoenvironments of the Triassic-Jurassic transition in Northeastern Utah"Geology of the Intermountain West3: 1–32.