Ichthyosaurus: Prehistoric Animal of the Week

This week we shall be looking at a reptile that once called the oceans over what is now Ireland, in addition to a lot of other places, home.  Enter Ichthyosaurus!  Ichthyosaurus was a genus of marine reptile that lived during the early Jurassic, about 190 million years ago, in the oceans that covered much of Europe at the time.  Many good Icthyosaurus remains have been found in Germany, Belgium, Switzerland, and England.  A few have also been found in Ireland!  This animal measured only about six feet long from snout to tail and its diet consisted of fish and cephalopods.  The genus, Itchthyosaurus, translates to "fish lizard" and includes several species.

Ichthyosaurus communis life reconstruction by Christopher DiPiazza

The first Ichthyosaurus fossils were discovered by a twelve-year old girl named Mary Anning during the early 19th century in England along with many other important Jurassic marine fossils.  We know a lot about Ichthyosaurus thanks to a myriad of well-preserved remains of it and its close relatives that have been unearthed since then over the years.  We know that Ichthyosaurus would have had a dorsal flipper and vertical tail fluke, much like a fish, thanks to some fossils that preserved a soft-tissue outline of the dead animal.  We also know, thanks to the remains of a closely related ichthyosaur, that these animals gave birth to live young rather than laying eggs like most reptiles do.  Scientists used to assume that all prehistoric marine reptiles would have hauled out on land to lay eggs like sea turtles do prior to this discovery.  We also know what they ate belemnite (squid-like cephalopod) and fish thanks to remains found in Ichthyosaurus stomach cavities and coprolites. (fossilized poop)

Ichthyosaurus communis skeleton.

Ichthyosaurus was very similar looking to fish and modern dolphins.  This is yet another excellent example of convergent evolution- unrelated animals evolving similar body plans and adaptations to suit similar lifestyles.  Because of this we know Ichthyosaurus was likely a very fast swimmer.  Unlike fish, however, Ichthyosaurus would have needed to come to the water's surface to breathe air since it was a reptile with lungs.  The eye sockets on Ichthyosaurus were very large so this animal likely had superb vision, especially in the dark.  This could mean that Ichthyosaurus was either mostly active at night, and/or it was able to hunt in lower depths where it was dark.  In some specimens, the skulls even preserved scleral rings, which are bony rings inside the sockets that supported the large eyes.  Similar to some dolphins, it also had a long, skinny snout lined with many cone-shaped teeth for catching swift-swimming prey. 

That's all for this week!  Hope you enjoyed our St. Patrick's Day Irish (and the rest of Europe pretty much) creature!  If you want to see me review and paint a particular beast feel free to comment below or on our facebook page.  Also special thanks to Dr. Adam Stuart Smith for helping me out with this post!

Works Cited

Martill D.M. 1993. Soupy Substrates: A Medium for the Exceptional Preservation of Ichthyosaurs of the Posidonia Shale (Lower Jurassic) of Germany. Kaupia - Darmstädter Beiträge zur Naturgeschichte 2: 77-97

Smith, Adam S. "Rare Ichthyosaur and Plesiosaur Material from the Lower Jurassic of Ireland." Irish Journal of Earth Sciences 28 (2010): 47-52. Web.

Interview with Sculptor and Toy Designer: David Silva

Today we have a really fun interview!  David Silva is one of my favorite sculptors mainly because he does dinosaurs and all things beastly so well. 

After graduating art school with a BFA in both Sequential Art and Illustration at the Savannah College of Art and Design in 2003, David Silva began working in the toy industry just three weeks later as a freelance designer for McFarlane Toys. A year and a half later this design job would lead to an in-house sculpting job which would last until David left in 2008 to go work for Hasbro as both a temporary in-house sculptor and a freelance sculptor. During this time, David completed his first dinosaur sculpt for what would later become Creative Beast Studio- a small side business of prehistoric and fantasy model kits. In January of 2010, David cut ties with Hasbro to sculpt in-house at NECA where he still remains today. All the while, Creative Beast Studio has continued to grow with new products and a supportive fan base.

David Silva surrounded by some of his creations at Wonderfest 2013.

Question 1: At what age did you become interested in dinosaurs?  Were they always a subject of your art?

  

DS: While I don't remember the exact age, I do recall dinosaurs being an influence as far back as I can remember. Seems like I always had a little bag of plastic dinosaurs with me when I was younger. I probably drew my first dinosaurs in preschool back when I first discovered my love for creating art. However, I got away from dinosaurs for a while as a teen as I became more interested in comic books and super heroes. That lasted until my adult years. It wasn't until working on the McFarlane Dragon toys did I rekindle my passion for prehistoric reptiles.

David's Scavenger Dragon design and sculpt for McFarlane's huge line of dragon figures.

Question 2: What medium do you most prefer to use for your art?  Any particular reason why?  Do you ever try digital sculpting or do you prefer to work with actual materials?

DS: I almost exclusively work in castilene wax clay for all of my sculpting work- personal or professional. It's a material that is very common in the toy industry and it's what I had to learn when I began sculpting for McFarlane Toys back in 2005. I have dabbled a little with digital sculpting and while I can appreciate it's benefits, I am very partial to traditional methods.

David's sculpt of Leo for McFarlane's zodiac line.

Question 3: Is there any particular artist who particularly inspired you growing up?  How about today?

DS: My artistic influences have varied depending on age and what I was into at the time. I think the first time I felt inspired by another artist was when I got a dinosaur calendar as a kid - I think I was eight maybe nine years old. I didn't know who's artwork was on the calendar at the time but I later discovered it was John Sibbick, who's work I still greatly admire today. These days I am very much inspired by the paleoart of James Gurney, Shane Foulkes, David Krentz, and Sean Cooper just to name a few.

Question 4: When did you decide to pursue a career in art?  How did it happen?

DS: I suppose it was around third or fourth grade. Ever since then, a career in art seemed inevitable and was the only path I'd considered since. The short of it is, I went to art school with a focus on comics and illustration, earned a job as a freelance toy designer three weeks after graduating, and that led to sculpting toys. The rest just fell into place.  (Include some design work- cyber spawn)

 

Question 5: Have you ever received any negative feedback on any of your work?  How do you respond to that?

DS: Occasionally yes- but who doesn't? I think I've always dealt with criticism fairly well outwardly, but when I was younger it was much harder to deal with inwardly. These days I welcome the negative feedback and critiques. Having your mistakes pointed out to you not only offers a fresh perspective but I've found that it is also the fastest way to grow as an artist.

Predator Dog sculpted by David Silva.

Question 6: Art and illustration is such a diverse field.  It has also changed dramatically within the past decade or so.  What advice would you have to give an aspiring artist today?

DS: Do what you genuinely love, find what you want to say and be humble when you are shown how to say it. Commitment and persistence are essential to effective creative productivity. Expect to make mistakes along the way- this is the best way to learn. And know that your greatest obstacles will likely be created by your own ego, not others. Once these things are understood and mastered, success is sure to follow.

David's Jabba the Hutt sculpt for Hasbro's Star Wars line.

Question 7: Out all of the sculpts you have done do you have a favorite? 

DS: My favorite sculpt is often, and should be, my most recent. Right now I am finishing up my second Acrocanthosaurus sculpt. I'd have to say it is my favorite dinosaur sculpt to date. I can tell how far I have come since my first Acro sculpt back in 2010. I am also very fond of my Dragolina Dinosaur Slayer piece. It was a great experience because I created that character back in high school, even sculpted her a few other times. So finally bringing that character to life properly with the skills I have now felt like the end of a journey. I'm very please with how that tuned out. 

Dragolina.  I guess the Masiakasaurus oogled her a bit too much.

Question 8: You have sculpted for many well-known companies in the field of toys.  Was there a particularly fun experience with any of these that stands out? 

DS: There have been a lot of great projects that I've had the pleasure of being a part of. No particular one stands out as my favorite but there are a few that come to mind. With McFarlane Toys it was the Scavenger clan dragon from series 6. That was great because I got to design and sculpt it. It was a very vulture-like dragon design. With Hasbro it was easily Jabba the Hutt for obvious reasons. And with NECA so far, I guess my favorite would be the Pacific Rim kaiju- Axehead, Knifehead, and one more yet to be announced. I'm a huge Pacific Rim fan so working on the toys was a dream for me. I'd love to do more, but time will tell.

Pacific Rim kaiju figures sculpted by David Silva.

Question 9: You are famous for portraying lots of subjects in addition to dinosaurs.  Do you prefer any over the others?  Why?

DS: 'Famous'? Wow. Well although I was trained in human anatomy studies, I've always had a preference for animals and creatures. At McFarlane I would always try to get my hands on the animal-like creature designs like the dragons and fantasy creatures. At Hasbro my favorite projects were again the more creature oriented ones- the dewback and Jabba the Hutt come to mind. The Jurassic park projects were cool as well, but a bit constricting. At NECA I've really enjoyed working on the predator figures as well as the occasional kaiju (Pacific Rim or Godzilla). 

Dewback from Hasbro's Star Wars line of toys, sculpted by David Silva.

Jurassic Park!  I wonder if anyone reading this would be interested to know more about that?  How was sculpting for them restricting? 

DS: In my particular case, I had sculpted two dinosaurs that we're not in the movies (Pachyrhinosaurus, and one that shall remain anonymous ). In both cases I was made to follow line drawings done by the Hasbro design team. I am not familiar with the process they went through for creating these designs, but they were to be followed by me explicitly, to the point that the images of the sculpt had to line up the the drawing when overlapped in Photoshop. I found this to be very constricting because the drawings were not scientifically accurate - I can only assume that modifications were made to appeal to a younger audience, though some details seemed to simply be incorrect. In either case, already having knowledge of these beasts actually worked against me. Most of the revisions I had to make were due to me attempting to make a more accurate a realistic dinosaur. However if it contradicted anything in the drawings, it had to be changed. Eventually I had to resign to the fact that I wasn't sculpting a dinosaur, but a dinosaur-like fantasy creature. The experience left me feeling disappointed and exhausted, but it also made me realize how important my own personal work really is to me.

David's prototype of a fantasy creature loosely based on a real genus of dinosaur, Pachyrhinosaurus.

Question 10: What was your favorite dinosaur (or other prehistoric creature) growing up?  How about today?

DS: I've always liked the large meat-eating dinosaurs best and at the risk of sounding predictable, T. rex was my favorite growing up. Now days I'm more of an Acrocanthosaurus guy. Dilophosaurus is way up there for me as well (sans neck frill).

 

Acrocanthosaurus sculpted by David Silva.

Question 11: Jurassic Park and Land Before Time (opposite ends of the spectrum I know) were the movies I remember as a kid that fueled my passion for dinosaurs. What was your most memorable movie?

DS: I don't recall too many dinosaur movies growing up, but Land Before Time may have been my earliest dinosaur influence as far as movies go. Jurassic Park was great as well. As a kid though, I think what got me most excited about dinosaurs was the Dino Riders toy line. I had a lot of the toys and the VHS cartoon for it as well. Someday I hope to get all of those back- they were so cool!

Question 12: Dinosaurs and other prehistoric animals were amazing. Why do you feel they continue to fascinate us?

DS: Most likely it's the large scale of the creatures that grabbed peoples attention initially but despite all of the recent discoveries, there is still a lot of mystery surrounding these animals. And now that we all know that dinosaurs weren't just giants but came all sizes, I think it's this mystery that is now the most intriguing aspect. It's just really fun to try and imagine how each one may have looked, sounded, or behaved. No matter how much information is uncovered, there will always be unknown variables and that's very exciting.

"Dragon vs Raptors" sculpted by David Silva.

Question 13: What is your favorite time period?

DS: Nothing really beats the Cretaceous period for me. It's when dinosaurs were in their evolutionary prime and were the most diverse. Permian and Triassic are of interest as well, but I always come back to the Cretaceous.

Question 14: Do you have any other hobbies or interests? 

DS: While I try to sculpt as often as I can, professionally and for myself, I also enjoy drawing as well. But as far as non-art related activities go, I really enjoy toy collecting. I have a pretty big collection of everything from vintage Transformers and He-Man, to Hot Toys. Aside from this, I'm also a bit of an exercise nut. With a job like mine it's important to find ways to stay active- it just make everything run more efficiently. And if I feel better I can work better.

Thank you so much David!  

Opabinia: Prehistoric Animal of the Week

This week marks the very first invertebrate Prehistoric Animal of the Week after two years.  This is totally inconsistent with the biodiversity of the world considering the fact that 98% of all animals actually don't possess backbones.  I guess we are just biased towards dinosaurs.  Even so, I must admit that this week's critter is a cool one.  Enter Opabinia regalis!

Opabinia lived all the way back 500 million years ago during the Cambrian age in what is now Canada.  Most of the world, including Opabinia's habitat, was in the ocean at the time.  According to the fossil record, it is during this time that the first multi-celled animals flourished...a lot.  In fact there was such a boom in biodiversity from what paleontologists can tell during this era, it has been nicknamed the "Cambrian Explosion".  Opabinia was one of the products of this...explosion.

Opabinia regalis reconstruction by Christopher DiPiazza.  Seriously, why has there not been a pokemon based on this yet?

 
This critter was small, only about 2.5 inches long, and would have swam around using paddle-shaped lobes lining the sides of its flattened body.  It also had six lobes surrounding its tail which may have helped it steer.  On its head it possessed five, large, spherical eyes and its mouth was underneath...and faced backwards. (evolution was in one of its weird experimental phases I guess)  Finally, in the front of this animal's body, there was a long tube that ended in a little grabber which was probably used to forage and bring food to the mouth.  H.P. Lovecraft would be all over this thing.

So we know what it looks like, we know where it lived, when it lived, and we know what it's called.  Still...what was it?  Well scientists were wondering that too.  There is some debate as to where exactly Opabinia falls on the family tree but most scientists can agree that it is at least closely related to arthropods. (jointed legs, exoskeleton...horseshoe crabs and scorpions for example)  Opabinia doesn't actually show any real evidence of having an exoskeleton or real jointed legs itself, though.  It does, however, have a segmented body, which led other scientists to think that it may be more closely related to annelids. (segmented worms like earthworms and leeches)  Finally, another group of scientists believe Opabinia is most closely related to a group of animals called tardigrades.  The most famous kind of tardigrade is called the Water Bear. (They are actually pretty bad-ass. Look them up after you read this)  Soooooo where does that leave Opabinia?  Latest research puts it at the base of the arthropod branch. 

Beautifully preserved Opabinia fossil from British Columbia, Canada.

Hope you enjoyed this week's Prehistoric Animal of the Week!  Not only was it the first invertebrate, but it is also the oldest animal, and probably the weirdest one we have reviewed to date.  It was also a request!  If you have a request of an animal you would like to see me review and paint leave a comment below or on our facebook page!

References

Budd, G. E. (1996). "The morphology of Opabinia regalis and the reconstruction of the arthropod stem-group". Lethaia 29 (1): 1–14. doi:10.1111/j.1502-3931.1996.tb01831.x.

Whittington, H. B. (June 1975). "The enigmatic animal Opabinia regalis, Middle Cambrian Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society B 271 (910): 1–43 271. Bibcode:1975RSPTB.271....1W. doi:10.1098/rstb.1975.0033. JSTOR 2417412. Free abstract at Whittington, H. B. (1975). "The Enigmatic Animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society B 271 (910): 1. Bibcode:1975RSPTB.271....1W. doi:10.1098/rstb.1975.0033.

Science Symposium: Arizona 2014

This past weekend the Jersey Boys flew to Mesa, Arizona for a science symposium.  We were there presenting our research on a bone that our team dug up a few summers ago in Tucumcari, New Mexico.  I just updated my blogpost on our trip to Tucumcari.  I highly recommend you go there and read it first.  Go ahead...

Read it?  Good.  Okay so the bone we were presenting research on is a femur from a poposauroid.  Originally we were calling the poposaurid remains we found from that area Shuvosaurus.  After all, Shuvosaurus was alive at the time and would have been strikingly similar.  After checking out this bone more closely, however, we found out it was closer to another poposauroid called Effigia.  HOWEVER, it wasn't identical to Effigia, either.  This poposauroid might be something new.  Only more research and more good fossil finds will tell!

Ross Geller and Ted Mosby present their poster.

You may be thinking...

"How can you tell all that from just one bone?  Those little differences could mean nothing!"

Unfortunately when you work with fossils there is very little to go off of and often times we need to make the best, most logical assumptions based on the facts that we DO have.  What we have is a femur that is very similar to some known animals but not quite the same.  It is safe to say that it is definitely from a poposaurid.  Given the fact that there were likely many more species alive back then that we may never discover, it is most logical to assume this femur belonged to something new instead of something that is already named. Remember a LOT of differences can be in the soft tissue of an animal, none of which were found for this guy, let alone other bones!  So the differences that we can see in the bones are important.

From left to right: Tiger and Lion.  SO SIMILAR but we all know they are very different animals.  Related, yes, but still different.

We had some fun while there too.  As always I took every opportunity to photograph animals.  This time i got some birds.  Oooh Ground Doves!

These guys actually exhibit some sexual dimorphism.  Female is on the left and male on the right.

We also met up with our friend Andrea.  If you read this blog two years ago you would recognize her as one of our original authors. 

Left to right: Dr. Axel Hungerbuehler, Gary, Andrea, Chris

That is all for this week!  Join me on Sunday for a long-anticipated Prehistoric Animal of the Week! 

That bar had Nintendo 64s hooked up at all the tables and I was too distracted by the thought of playing Cruisin USA to make an adorable selfie face.  Sorry.

Brendan Schaffer: Snow Stegosaurus

Let me start out by saying that I hate the snow.  I hate it so much.  I used to like it when I was a little kid and it meant no school but now that I actually have to drive into work most of the time regardless and shovel the driveway, I have learned to despise the stuff.  Plus it's cold.  Seriously I hate this time of year.  Winter is funny.  Up until Christmas everyone loves the snow.  "Oooh Aaah!  Pretty winter wonderland!"  Then every time it snows after that it's more like "UGGGHHHHHH EVERYTHING IS WET AND GROSS WE WANT SPRING!"

Well the snow doesn't bother my friend, Brendan!  Brendan and I went to Rutgers together and took an ornithology class where we bonded over identifying birds.  He studied Ecology and Marine Science, but also paints, draws, and sculpts whenever he can, trying to capture how beautiful and colorful nature can be.  Only in the past year has he discovered that he can sculpt snow!  Whenever the forecast calls for even a light dusting, he can be found with his father and brothers out in their front yard creating the next "masterpiece".  From dragons to dinosaurs, Brendan sculpts whatever may be relevant (holidays and mascots included), sometimes what they think will look cool or funny off the top of their heads. They like to make their community happy with their snow sculptures and hope it brings joy to people during the dreary winter months.

So recently I got a message from Brendan asking for my help.  He had sculpted a life-sized snow Stegosaurus and wanted to know if there was anything he could do to make it as scientifically accurate as possible.  Needless to say, the piece was already awesome!

Now before any of you hardcore science fanboysandgirls start nitpicking every single freaking thing that could possibly be not 100% scientific for the sake of flexing your intellectual muscles and looking like a total ass pro on the internet keep in mind that snow is NOT an easy medium to work with!  If the sculpture sacrifices some anatomical accuracy for the sake of...I dunno, staying together as a sculpture then so be it.  There are some things that Brendan and I decided could be changed to make this guy even more realistic, however.

We started at the head and worked our way back.  I'd say change the shape of the head by making it more narrow and angular.  Stegosaurus had an almost wedge-shaped noggin.  Also let's add on a little throat pouch with gular armor!  The snow plates are delicate but we thought it would be good if they were made a little more broad on the bottom.  Lastly, the we decided to change the position of the spikes on the tail.  They can't be held out completely to the sides because they would fall off, however.  I suggesting using giant icicles for spikes but those are hard and dangerous to come by.  Oh well!

Check out the improved sculpture!  Brendan is standing next to it so you can see just how huge this thing really is.

It looks great!  Brendan even went so far as to paint it with water mixed with food coloring!

Now it just needs one more thing...ah!

PERFECT.

Great job, Brendan!  Want to see more?  Check out and like his facebook page.  There are really awesome pieces on there. 

That's all for this time!  Just so everyone knows Gary and I will be flying to Arizona this weekend to present a research poster on possible new species of Shuvosaurus we helped to dig up last Summer.  That being said I may not be able to do a Prehistoric Animal of the Week on Sunday.  I'll try my best though! 

Prehistoric Valentines

It's Valentines Day tomorrow!  Ever wonder what it would be like if valentines were a thing in prehistoric times?  What would an Ankylosaurus say to woo a mate?  Would Gryphoceratops say anything special to that special someone?  Well I decided to make some prehistoric themed valentines.  Feel free to print them out and give them to your loved ones...or people who you really want to creep out. 

I bet some dinosaurs would be sweet, witty, or flirty...

  

Oh Unenlagia, you could go dancing with me any day.

Linguistics joke!

I actually don't have a tail so...

Some would probably be more aggressive with their advances...

Now that's dedication.

A bit too kinky for me, thanks.

Of course, let's not forget that most animals are pretty direct when the time is right. Sometimes blunt is best.  (Although I don't think I would use any of these lines, myself.)

Honesty is a good quality!

If you want to read about how dinosaurs may have courted check out my post from last year and if you would like to know about what it would be like to date a T. rex check out Gary's post from two years ago.  Happy Valentines Day everybody!

Glyptodon: Prehistoric Animal of the Week

This week we are checking out a really heavily-protected prehistoric mammal.  Enter Glyptodon!  Glyptodon was a member of a family of mammals called xenarthra, which also includes modern anteaters, armadillos and sloths.  Glyptodon resembled a gigantic armadillo with a high, dome-shaped shell covering most of its body.  This beast measured ten feet long and would have lived in what is now South America during the Plestiocene era which spanned from a few million years ago up until only ten thousand years ago.  The genus, Glyptodon, translates to "carved tooth" and includes a few different, but similar species. When alive, Glyptodon would have coexisted with many other prehistoric beasties including Sabre-toothed cats, giant, flightless terror birds like Titanis, mammoths, giant ground sloths like Megatherium, and even humans. 

Glyptodon by Christopher DiPiazza.

In life, Glyptodon's shell was comprised of wide sheets of bone under the skin covered in a layer of horny keratin. (same stuff as our fingernails)  Modern armadillo armor is like this as well but varies in thickness and flexibility depending on the species.  Modern armadillos also have segmented shells with bands in the middle.  The number of bands is different depending on the species and the higher the number of these bands, the more flexible and maneuverable the armadillo can be.   

Above are two modern examples of armadillos that I work with.  On the left is the Six-Banded Armadillo (Euphractus sexcinctus) who's armor is thicker and stiffer than the surprisingly fast-running Nine-Banded Armadillo's (Dasypus novemcinctus), on the right. 

Glyptodon, however, had a shell that comprised of one solid dome covering the entire body, except for the head and tail.  When faced with a predator, Glyptodon wouldn't have been able to run away quickly.  Instead it would have simply lowered it's head and stood firm, making it's body into a seemingly impenetrable fortress. The shell was so strong and big that some believe early humans would have used hollowed out Glyptodon armor as shelter sometimes. Glyptodon also had armor on the top of its head like a cap as well as the tail which was covered in rings of armor. 

Somebody is about to get a sexy wake-up surprise!

Glyptodon's body design has evolved separately many times in other kinds of animals throughout history.  This idea of different, unrelated animals evolving similar adaptations for similar purposes is called convergent evolution.  The group of dinosaurs, the ankylosaurs, the crocodile relatives, the aetosaurs, and the testudines (turtles and tortoises) all are examples of other vertebrates that independently developed bony armor for protection.

Glyptodon skeleton.  Note the high shell and the short face.

In addition to being much larger, Glyptodon differed from modern armadillos in other ways, too.  Most notable is the skull.  Modern armadillos all posses long, pointed snouts with small teeth designed for crunching up insects and other food items.  Glyptodon, on the other hand, had a very short, robust skull with a huge lower jaw where a lot of muscle would have been attached in life.  Glyptodon teeth are also more designed for chewing grass, suggesting that this prehistoric xenarthid was a herbivore and not an omnivore or insectivore like its modern relatives.

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

References

Fidalgo, F., et al. (1986) "Investigaciones arqueológicas en el sitio 2 de Arroyo Seco (Pdo. de Tres Arroyos, prov. de Buenos Aires, República Argentina)" In: Bryan, Alan (ed.) (1986) New evidence for the Pleistocene peopling of the Americas Peopling of the Americas Symposia Series, Center for the Study of Early Man, University of Maine, Orono, Maine, ISBN 0-912933-03-8, pp. 221-269, in Spanish

Politis, Gustavo G. and Gutierrez, Maria A. (1998) "Gliptodontes y Cazadores-Recolectores de la Region Pampeana (Argentina)" ("Glyptodonts and Hunter-Gatherers in the Pampas Region (Argentina)") Latin American Antiquity 9(2): pp.111-134 in Spanish