Thursday, August 30, 2012

Living Fossil: The Dinosaur's Archosaur Relative

A few weeks ago I wrote about a living fossil, the horseshoe crab.  Today I will be going over another type of modern prehistoric creature that is near and dear to my heart, crocodilians.  Crocodilians (including crocodiles, alligators, caimans and gharials) have been wildly successful since the Triassic.  They started to become successful right alongside the first dinosaurs.  Unlike the dinosaurs, however, (many)crocodilians have remained virtually unchanged since the Mesozoic.  Dinosaurs, on the other hand, evolutionarily experimented with countless different body types, sizes and niches only to end up with just one variety adaptable enough to survive into today (birds).

In the workplace I get the pleasure of dealing with the Dwarf Caiman (Paleosuchus palpablrosus), the smallest and most heavily armored member of Crocodilia.


During the Mesozoic era there were crocodilians that were more or less the same as the ones living today.  Some, however, did evolve a bit differently.  There are a number of strange and different kinds of crocodilians on the fossil record.  Some were more land-adapted, some had wildly different skulls for functions scientist can only guess at today and some, like Sarcosuchus and Deinosuchus, grew to epic sizes and more than likely were preying upon dinosaurs much like smaller modern crocodiles prey on land mammals today.

During the late Cretaceous, crocodilian, Kaprosuchus, threatens the dinosaur, Nigersaurus.

Today, crocodiles and their kin remain one of the most adaptable and successful reptiles, but why?  Here is an animal that has remained virtually unchanged for 250 million years.  They must be doing something right

Lets start by looking at a crocodilian's lifestyle.  They don't require much.  They spend time in and out of the water (which doesn't need to be that clean) and tend to be generalist predators all around.  A crocodilian won't hesitate to eat any kind of animal, including rotting carcasses other meat eaters would pass on.  Furthermore, like many reptiles, crocodilians are cold blooded or ectothermic.  Because of this their metabolisms are much slower than an endothermic animals's and therefore don't require as much food in order to stay alive.  In fact, after a large meal, a large crocodile can go to a year's time without eating if it has to.

Come on in!  The water's...um...actually don't. 

When compared to other modern reptiles like testudians and squamates, crocodilians have a few advantages.  The tough scales on their backs, called scutes, function like solar panels, allowing the animal to absorb energy from the sun and warm the body up much more quickly than most other modern reptiles.  Crocodilians have a four chambered heart and the functional equivalent of a diaphragm.  They also have a one-way breathing system much like their closest living relatives, the birds.  This means that instead of mixing inhaled and exhaled air in the lungs when breathing (like we do) fresh air is continuously being taken through the body (more efficient).  Fun fact: alligators have the most powerful jaws of any living animal ever recorded (over 2,000 pounds per square inch).

Alligator mouth.  Yes, I took this picture.  No, there was no zoom. 

American Alligators (Crocodilus mississipiensus) have recently become the interest of medical doctors because of their immunity to a vast variety of pathogens.  In a lab setting, alligator serum and human serum were both exposed to twenty three types of harmful bacteria including MRSA (methicillin-resistant staphylococcus aureus), E. colli and Salmonella.  The Alligator serum fought off all of them with flying colors.  The human serum only managed to fight off eight.  Furthermore, the protiens in alligator blood were also discovered to be totally resistant to Candida albicans (fungus), HIV and Herpes (viruses).  This could be due to the fact that alligators commonly live in environments where the water isn't exactly the cleanest.  Lets just say if a human were to go wading around in there with any open wounds there is a solid chance that individual would get an infection of some kind.  Alligators, however, get bloody injuries all the time due to fighting amongst themselves for dominance.  Its a fundamental part of their social behavior.  Its not uncommon to see alligators missing body parts from fights with rivals.  Yet despite these seemingly mortal wounds, the alligators almost always heal up no problem even with the bacteria and other nasty pathogen-infested water they are constantly swimming around it.  Jaws, armor and metabolism aside, the crocodilian's immune system very well may be its secret to success.  Sadly, even the mighty crocodilians were found to be sensitive to pollution caused by humans.

Alligator that had lost it's tail in a fight.  The wound healed over no problem.


Who knows?  If scientists manage to sequence the proteins in alligator blood, we may have some powerful new medicine in the future to fight off seemingly incurable diseases!  

Works Cited

Bird, July. Antibiotics from alligators. Nature Publishing Group 8.5 (2008): 326-26.

Merchant, Mark. Differential protein expression in alligator leukocytes in response to bacterial lipopolysaccharide injection. Comparative Biochemistry and Physiology: Genomics and Proteomics 4.4 (2009): 300-04.

Fleshler, David. Alligators' 'ferocious' immune system could lead to new medicines for people. Sun-Sentinel. 14 Aug. 2006.

Avasthi, Amitabh. "Alligator Blood May Lead to Powerful New Antibiotics." National Geographic

Farmer, C. G., and Sanders, K. (January 2010). "Unidirectional Airflow in the Lungs of Alligators". Science 327 (5963): 338–340. doi:10.1126/science.1180219. PMID 20075253. http://www.sciencemag.org/cgi/content/abstract/327/5963/338.

Thursday, August 16, 2012

Animals Then and Now: Choose Your Weapon

This week I'm going to go back into my comfort zone of comparing extinct dinosaurs to modern animals in order to better understand them.  Specifically, I would like to talk about animal weaponry.  Many animals, alive and extinct, have weapons to either help defend themselves from being eaten or to help them catch/kill other animals for themselves to eat.  At work I get to see some of these dangerous animals up close (sometimes too close!).

Dangerously Cute!!!  (Baby Arctic Foxes)

If you notice, predatory animals tend to all have similar weapons to help them catch their prey regardless of whether or not they are related to each other.  This is because the ultimate goal of every predator is the same: catch the prey.  Check out this claw from an African Lion.

African Lion front claw (cast)

See its shape?  Its hooked.  Hooks are great for catching things.  They are sharp at the tip to pierce the skin of whatever they are hunting and they are curved to prevent whatever they are catching from pulling away.  Even us humans use hooks to catch fish.  Its a simple yet highly effective design.  It isn't designated to claws either.  Predatory animals that can't use claws many times use teeth instead like snakes.

Now check out THIS weapon.

Allosaurus hand claw (cast)

Same structure as the lion just a lot bigger right?  Its from an animal not remotely related to lions though.  That's a hand claw from an Allosaurus.  Even though Allosaurus and African Lions don't share much in common when it comes to their DNA.  They have many of the same adaptations thanks to convergent evolution (which I talked about in my very first post!).  So what does this tell us about dinosaurs like Allosaurus?  Well, a lion will use its hooked claws to hold on to struggling prey that is many times larger than the lion itself.  It can be safe to assume that Allosaurus was doing something similar with its claws.  Since Allosaurus was much larger than a lion and its claws were also much larger than a lion's, it makes sense that it could have been hunting animals that were also much larger like the myriad of other dinosaurs it shared its habitat with during the Jurassic.  

Allosaurus

Extinct predators that didn't really have dangerous claws (or any claws) would have used other things.  Check out Tyrannosaurus rex.  Tiny arms, HUGE head with teeth...that are curved!  Not really related to snakes that closely but similar adaptations none the less.

Tyrannosaurus rex

Not all predatory weapons HAVE to be hooks either.  As long as they catch prey they are successful.  Crocodillians don't really have curved teeth but they do have powerful jaws that do a good job of locking down on prey hard enough so that it can't escape.  Many turtles and fish create a vacuum under the water to suck prey into their mouths.  Amphibians don't have much in the way of teeth and absolutely nothing when it comes to claws yet they are highly effective predators in their own right thanks to their sticky tongues and fast mouths.

With a tongue like this Palm Salamander's who needs teeth?

What about the prey?  They certainly aren't interested in catching any other animals.  The weapons they DO have are usually designed to keep predators as far away as possible.  Think about an animal like a porcupine.  They have many sharp quills coming out from their backs.  Most predators have to deal with the dilemma of working around those things which requires them to keep a distance between the two of them.  Not an easy prey animal.  Other animals have things like armor on their hides like armadillos and tortoises to discourage predators from attacking.  How about dinosaur weapons?  Here is a tail spike from a Stegosaurus.

Stegosaurus tail spike (cast)

Its sharp.  But it isn't curved or hooked.  Without ever seeing the animal alive I can guess that it's first line of defense against something like Allosaurus would be to keep the predator away and discourage it from attacking in the first place.  If it HAD to stab with the spikes, they could easily be removed after the damage is done because they are straight.  The last thing a prey animal wants to do is hold on to its attacker!

Stegosaurus


Works Cited

Holtz, Thomas R., and Luis V. Rey. Dinosaurs: The Most Complete, Up-to-date Encyclopedia for Dinosaur Lovers of All Ages. New York: Random House, 2007. Print.

McGhee, G.R. (2011). Convergent Evolution: Limited Forms Most Beautiful. Vienna Series in Theoretical Biology, Massachusetts Institute of Technology Press, Cambridge (MA). 322 pp.

Sabuda, Robert, and Matthew Reinhart. Dinosauria. Kbh.: Carlsen, 2007. Print.

Thursday, August 9, 2012

Living Fossil: A New Jersey Native

Living fossils are a really important factor when studying paleontology.  The term "living fossil" shouldn't be taken literally (since fossils are mostly made of rock and therefore can't be alive).  The term is used to describe an organism that exists today that existed in the same form a very very very long time ago.  Lets say over ten million years since that's how long it usually takes for most species to rise and go extinct.  As far as animals are concerned there are plenty of living fossils around us.  Many of them you may be familiar with already such as crocodiles, sharks, cockroaches, scorpions and even opossums haven't really changed much since the Mesozoic.  Today, however, I am going to talk to you about an animal that was around long before the first dinosaurs even and just to add a little kicker, its native to the shores of New Jersey as well.  Ladies and gentlemen, please welcome Limulus polyphemus or the Atlantic Horseshoe Crab.  



When it comes to living fossils, horseshoe crabs put other animals to shame.  To put it into perspective, the oldest known dinosaur fossils are from about 250 million years ago (nothing to scoff at).  The oldest known horseshoe crab fossil?  455 MILLION YEARS OLD.  That's four hundred and fifty five...times a million.  455 million!  That's almost double the age of the oldest dinosaur fossil!  The impressive part is these fossils don't look different at all from their modern descendants.  If an animal that hasn't changed its design in 455 million years isn't considered a successful animal then I don't know what is. 

A painting I did of a prehistoric creature that was alive hundreds of millions of years ago...with a dinosaur.  (Baby Dryptosaurus to be exact.)


455 million year old horseshoe crab fossil.  It was named Lunataspis aurora.

Lets learn a little about this hugely successful creature shall we?  Luckily for you I get to work with Atlantic Horseshoe Crabs for my job at the zoo.  First off, despite the name, they are not crabs.  They aren't even crustaceans.  Horseshoe crabs belong to a subphylum called chelicerata and are therefore more closely related to arachnids like spiders and scorpions than they are to crabs.  However, the horseshoe crab's closest relative is an animal that is long extinct, the trilobite. 

Trilobite fossil

Another common misconception about horseshoe crabs is that they possess a stinger on the ends of their tails.  Horseshoe crabs are actually completely harmless to humans and only use their rather blunt tails to steer while swimming or to flip themselves over if turned on their backs.  This misconception could be due to the horseshoe crab's superficial resemblance to a stingray which does have a dangerous barb on its tail.  Stingrays are fish, however and aren't related to horseshoe crabs nor do the two animals share anything in common beyond living in the ocean together.

Stingray: a type of fish.  Not even close to a horseshoe crab.

The horseshoe crab's scientific name, Limulus polyphemus, literally translates to "side-looking cyclops" and refers to the cyclops from the Greek myth "The Odyssey", who's name was Polyphemus.  Ironically enough, horseshoe crabs actually possess ten eyes while the cyclops is only said to have one.  Oops.  

Hey, Polyphemus!  No, not you.  The other Polyphemus.

There is a LOT more I could discuss with you about this fantastic animal but I really want to keep my posts on here short and sweet.  If you have any inquiries about this subject feel free to do some research of your own including checking out some of the sources I included under my works cited for this post.  Also as you should know, myself as well as the other members of the Jersey Boys Hunt Dinosaurs crew are always more than willing to talk and answer questions on here or on our facebook page as well.  Let me know what you think about this post.  I have a lot of other cool living fossils I work with that I could do posts about in the future!  

From left to right: Atlantic Horseshoe crab, yours truly, Gary Vechiarelli's son, Joey. 


Works Cited

"Oldest Horseshoe Crab Fossil Found, 445 Million Years Old." ScienceDaily. ScienceDaily, 08 Feb. 2008. Web. 09 Aug. 2012. <http://www.sciencedaily.com/releases/2008/02/080207135801.htm>.

"About the Species." Natural History: The Amazing Horseshoe. N.p., n.d. Web. 09 Aug. 2012. <http://www.horseshoecrab.org/nh/species.html>.


Thursday, August 2, 2012

Interview with Scientist/Artist: Bruce J. Mohn

I have a special post for you all to enjoy today!  Bruce J. Mohn is a paleontologist specializing in the study of small carnivorous dinosaurs, early birds and pterosaurs.  He is also an artist, best known for his three dimensional, bone by bone reconstructions of the skeletons of Compsognathus, Archaeopteryx, Pterodactylus and Rhamphorhynchus.  He has also done illustration work for several major museum exhibits, books, magazines and television and life reconstructions and dioramas.  I had the pleasure of getting to know Bruce through the past few years since he worked in the biology department at Rutgers University when I was an undergraduate there.  He was always very supportive and more than happy to answer any questions I emailed him about paleontology and would let me come visit him in his office to check out the department's collection of dead (stuffed) animals, bones or sometimes just talk paleo.  Most important of all, however, Bruce was kind enough to mentor me through a lot of my own paleo-artwork and was never afraid to rip them apart (metaphorically) if they weren't scientifically accurate.  This is something I especially appreciated since it did nothing but drastically improve my own work.

Bruce Painting the teeth on an Archeopteryx model he sculpted.

On to the Questions!

Question 1:
How long have you been interested in paleontology?  Who did you admire
growing up?

I have been interested in paleontology most of my life.  I remember sculpting a Triceratops in kindergarten and doing dinosaur illustrations and sculptures in grade school.  The librarian at the local children’s library used to order books especially for me on the subjects of evolution and paleontology.

My paleontological interests hit a snag when my family got religion in a big way around the time I was 9.  I attended a Creationist seminar when I was 11 and was encouraged to believe that all fossils were fakes and that the world was very young.  I had doubts, but it wasn’t until I attended a seminary in upstate New York that my doubts were clarified.

Upstate New York is loaded with marine fossils, which I assumed were evidence of the Great Floodas they seemed to be encrusting rocks, much as modern barnacles or mussels do today.  But as I hammered them out, I realized the fossils were actually weathering OUT Of the rock.  It became obvious that the rock was not just a random boulder, but achunk of seabed that had turned to rock and then been broken off a bigger bed of rocks, weathered and worn down to reveal the fossils inside it.  That was my first realization that there was ample evidence for the Earth being very old and if that was the case, then there was plenty of time to allow evolution to work.

I dropped out of seminary and embarked on a course of self-study and college studies that led to where I am today, a biologist specializing in evolution and anatomical studies.

I wasn’t really aware of any paleontologists when I was growing up.  The paleo-artist who most inspired me was Charles R. Knight.

Question 2:
At what age did you get inspired to pursue a career in paleontology?

I was inspired to pursue a career in paleontology when I was in college.  I had thought that dyslexia and associated problems with math would keep me from a career in the sciences, but was counseled otherwise by Roger Wood, a professor in evolution and anatomy at Stockton College.  He encouraged me to push through the courses that were tough and helped me design independent study courses in ecology, fossil preparation and reconstruction of extinct animals.

 Question 3:
When you were a child, what was your favorite dinosaur?  What dinosaur is your favorite now?

My favorite dinosaurs when I was a child were Triceratops, Stegosaurus and Struthiomimus.  My favorite dinosaurs now are the dromaeosaurids and compsognathids.  I have a special fondness for Compsognathus as it was the first dinosaur for which I sculpted the entire skeleton, an educational and also a profitable experience.

Bruce's Compsognathus model.


Question 4:
Paleontology is such a diverse field these days involving many
disciplines.  What advice would you give to an aspiring paleontologist today?

Most paleontologists today are employed in fields other than paleontology.  A lucky few work in universities and museums as paleontologists, but most paleontologists teach biology, geology or anatomy and pursue their paleontological research on the side.  A few are employed as consultants in the private and public sectors.  If you are determined to work exclusively as a paleontologist, be prepared for a struggle.

I am a paleontologist, but am employed as a laboratory operations coordinator at Rutgers University.  I have worked as a field biologist, environmental consultant, exhibit consultant, designer and fabricator, sculptor, illustrator, television consultant, specimen collector, skeleton and fossil preparer, even done botanical studies and soils sampling.

Question 5:
Going to college these days and then on to grad school has become a
daunting task.  Many people are unaware of how long it takes to make
it to the finish line.  The rewards are great, but what would you say
to someone pursuing professional studies after college?

Good luck!  If you want to be employed as a paleontologist, you need an advanced degree if you hope to get a job which will provide a decent wage.  Graduate school is a big commitment of time, energy and funds.

Question 6:
What was or is your favorite project?  What are some of your current projects?

My favorite museum project of all time was developing, creating and assembling the elements of the dinosaur exhibit at the Delaware Museum of Natural History.  The staff and professionals were great to work with, the money was good and the final result is still satisfying.

My favorite personal projects have been the four skeletons I sculpted; Compsognathus, Archaeopteryx, Pterodactylus and Rhamphorhynchus.  All four species are known from fossils that are mostly preserved in two dimensions, very tiny, too fragile or too important to ever prepare the bones completely away from the surrounding rock.  I sculpted each skeleton mostly bone by bone with all of the joints articulating properly.  I then had the sculptures molded and cast for sale to museums, universities and private collections around the world.  I made reasonable amounts of money, quite good for a hobby, but not enough to quit my day job.

I’m currently working on a full sized skeleton of Velociraptor mongoliensis and restoring the exoskeleton of a Japanese giant spider crab that was collected over a century ago.


Diorama at the Delaware Museum of Natural History featuring many elements created by Bruce.

 Question 7:
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 movie inspired you the most?

I really didn’t see many movies as a kid and at the time there really weren’t many dinosaur themed movies other than some terrible B films and worse Japanese monster movies.  I was most inspired by books and particularly enjoyed the illustrations of Charles R. Knight, one of the earliest paleo-artists.  I tried to sculpt a few dinosaurs based on his work, but mine were only pale reflections.

Prehistoric Beast done in 1985 was the first dinosaur movie I saw that really thrilled me.  It’s a short film by Phil Tippett with gorgeously sculpted stop motion animation dinosaurs moving through an authentic landscape.  I think it was the first dinosaur depiction I had seen which put them in a deep forest, rather than on a tabletop landscape.  They were real animals in a real landscape, rather than monsters.

Question 8:
Do you remember the first paleontologist you ever met?  Were you a
nervous wreck?

The first paleontologist I ever met was Roger Wood, who became my undergraduate advisor in college.  Roger is an expert in the study of extinct and extant turtles and one of the nicest people you could hope to meet.

The first famous paleontologist I met was John Ostrom, who I met while I was an undergraduate student.  John was the describer of DeinonychusThe first fossils of Deinonychuswere discovered by Barnum Brown years earlier, but not recognized for what they represented until Ostrom found additional specimens in 1960).  No, I wasn’t nervous.  John was soft spoken and kindly answered all of my questions while he was giving my class a tour of the Yale Peabody Museum of Natural History.

After I became a member of the Society of Vertebrate Paleontology and attended conferences, I met a large number of the paleontologists working in a variety of fields today, including a bunch who are known through the media.  Can’t say as any made me nervous.  They’re just people and generally want to talk to other people about the things that fascinate them.

Question 9:
Why do you feel dinosaurs continue to fascinate us?

They’re big and strange looking!  Except for the tiny ones of course, which are the ones I am most interested in.  They are aliens that we can study and try to understand.  Their bones are beautiful and terrifying.  And they’re dead!

Each new find tells us so much more about them.  Feathers on dinosaurs were completely unknown until 1996 and now there is evidence of feathers in a number of specimens.  Some specimens have revealed soft tissue details and others such as the various dinosaur mummies have revealed skin texture.

Question 10:
What is your favorite geological time period?

Pretty fond of the Holocene!  I like a variety of species acrossthe range of geological time.  I can’t think of one single time or place I would like to visit if time travel was possible.  But there are a bunch of places where unusual preservation allows us to do the next best thing to time travel.  I visited Drumheller in Alberta, Canada in 1998 and saw dinosaur bone beds for the first time.  It was enthralling to be walking in a place where the bones were so thick I had to watch my step.  The only dinosaur bones I had seen in the field before that had been in Gloucester County, NJ and I only found two chips after several hours of looking.  More amazing were the specimens being prepared in the labs at the Royal Tyrell Museum.  There were two specimens being removed from the matrix, an ornithomimid and a Gorgosaurus.  Almost every bone was still in its proper place and the animals looked like the scavengers had just finished picking the meat off their bones.

Sculpting a Pterodactylus skull.