Sunday, September 14, 2014

Dreadnoughtus: Prehistoric Animal of the Week

This week we will be looking at a recently discovered behemoth of a dinosaur.  Make way for Dreadnoughtus schrani!  Dreadnoughtus was a huge plant-eating dinosaur that lived in what is now Argentina, during the Late Cretaceous, roughly 77 million years ago.  It was one of the largest land animals of all time, measuring eighty five feet long from snout to tail.  It is considered a titanosaur, which was a kind of sauropod (long-necked dinosaurs) that survived all the way to to the end of the Mesozoic Era.  The genus name, Dreadnoughtus, translates to "fears nothing".  This is in reference to this animal's immense size and that it probably had no predators to fear once it reached adulthood.  Dreadnought is also the name of a kind of giant, armored battleship which were first launched during the early 1900s.  Two of these massive ships were also in the Argentine navy making this dinosaur's name that much more appropriate. (and badass) 

life reconstruction painting of Dreadnoughtus schrani by Christopher DiPiazza.

Dreadnoughtus is an exciting discovery for a few reasons.  One reason is between the two individual animals found, a lot of bones were unearthed, more than what is typical for large dinosaurs.  In fact, going by types of bones (Once you have the left humerus, for instance, you can safely assume the right one is the same, just mirrored even if it was never found.), over 70% of Dreadnoughtus' anatomy is known.  This is extremely rare for a large dinosaur since in order for fossilization to take place, the animal's remains need to be buried rapidly after death.  This is more common with small animals. Its more likely for mud or sand to completely cover a dead pigeon-sized Anchiornis' entire body, for instance, within a matter of minutes.  But what are the chances eighty five feet of dead dinosaur would have been rapidly buried?  Normally when large animals, especially sauropods, die, the remains would have sat there for a while, scavengers would pick at them, maybe even scatter them around to different places.  Millions of years later, paleontologists are lucky to find one vertebra that fossilized to study.  (Doesn't stop scientists from naming new species though!)  Because of this Dreadnoughtus is considered the largest, well understood, dinosaur known to science.  What I mean is that there are other dinosaurs that have been discovered that may have been bigger than Dreadnoughtus, but they are only known from highly fragmentary remains and scientists tried to hypothesize their full sizes by scaling imaginary skeletons around the few bones that were actually found.

Image from the 2014 paper by Kenneth Lacovara, referenced below.  Note the size compared to an average human diagram and how many bones (shown in white on the diagram) were actually discovered!

Dreadnoughtus' bones gave scientists a lot of answers as to how large titanosaurs would have looked and possibly walked.  Its front limbs were shorter than its hind legs, so it is likely that its neck was held more parallel with the ground nomrally.  It could have raised its neck for short periods of time for eating the tops of trees or displaying for members of its own species possibly, however.  Dreadnoughtus' neck was extremely long and was about half the animal's total length.  The tail, however, was relatively short, only thirty feet long.  (only a thirty-foot tail...I feel weird saying that.)  Most Titanosaurs, like Dreadnoughtus' smaller cousin, Saltasaurus for instance, had a pretty wide stance with reference to to their legs and bodies.  Dreadnoughtus, however, although having a still pretty wide stance, held its legs more underneath its body in comparison to its kin.  We know this because of the angles at which the leg and arm bones attach into their sockets.  These extremely powerful limbs would have acted like pillars, supporting Dreadnoughtus' immense bulk as it walked, and stood and...did pretty much everything I guess.  Other titanosaurs, like Saltasaurus, are known to have had bony armor embedded in their skin.  There is not evidence that suggests this in Dreadnoughtus so it is a mystery as to whether or not it had such a defense adaptation.  It wouldn't surprise me, however, if an animal as large as Dreadnoughtus, lacked armor as its size alone (as an adult, at least) would have made it impossible to kill for any known predator.

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

References

Lacovara, Kenneth J.; Ibiricu, L.M.; Lamanna, M.C.; Poole, J.C.; Schroeter, E.R.; Ullmann, P.V.; Voegele, K.K.; Boles, Z.M.; Egerton, V.M.; Harris, J.D.; Martínez, R.D.; Novas, F.E. (September 4, 2014). "A Gigantic, Exceptionally Complete Titanosaurian Sauropod Dinosaur from Southern Patagonia, Argentina". Scientific Reports. doi:10.1038/srep06196. Benson, Roger B. J.; Campione, Nicolás E.; Carrano, Matthew T.; Mannion, Phillip D.; Sullivan, Corwin; Upchurch, Paul; Evans, David C. (May 6, 2014). "Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage". PLOS Biology. doi:10.1371/journal.pbio.1001853.

Wilson, Jeffrey A.; Carrano, Matthew T. (June 1999). "Titanosaurs and the origin of "wide-gauge" trackways: a biomechanical and systematic perspective on sauropod locomotion". Paleobiology 25 (2): 252–267. Retrieved 31 August 2014.

Wilson, J. A. (February 2006). "An Overview of Titanosaur Evolution and Phylogeny". III Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno: 169–190.

Sunday, September 7, 2014

Euoplocephalus: Prehistoric Animal of the Week

Sorry for the delay.  (Not really though because I had no choice in the matter.)  This week we will be looking at a well studied, but until recently not so well understood armored dinosaur.  Check out Euoplocephalus tutus!

Euolpocephalus tutus life reconstruction by Christopher DiPiazza.

Euoplocephalus was a heavily-armored, plant-eating dinosaur that lived in what is now Canada, during the late Cretaceous period, about 77 to 75 million years ago.  It belonged to the ankylosaurid family, which also includes the larger, "more famous", Ankylosaurus.  (I say "more famous" because many depictions in pop culture or in toy form that are labelled as Ankylosaurus are usually based on Euoplocephalus because it is more completely known.)  The genus name, Euoplocephalus, translates to "well-armed head" and the species name, tutus, translates to "safely protected" because this dinosaur had a LOT of armor.  It was twenty feet long from snout to tail and would have co-existed with many other dinosaurs like Chasmosaurus, Styracosaurus, Parasaurolophus, and Corythosaurus

Euoplocephalus mount on display at the Senkenberg Museum of Natural History in Germany.

Euoplocephalus' body had a series of bone chunks embedded in the skin, separate from its actual skeleton, called osteoderms.  Osteoderms have been discovered in a number of other kinds of dinosaurs like the titanosaurs, and stegosaurs.  They can also be observed in modern animals, like crocodilians.  Ankylosaurs, however, were the most heavily armored.  This armor most likely would have protected the animal from predators or possibly from rivals of the same species if they ever did engage in such behaviors over dominance, territory, and/or mating rights.  Some of the armor on Euoplocephalus took the form of small osteoderms, along the back and sides, but other osteoderms were keeled, and almost blade-like, higher up on the back.  Euoplocephalus also had two rings of keeled osteoderms on its neck, called cervical rings, and a flat, wide sheet of bone covering the entire dorsal portion of its extremely wide pelvis, called a sacral shieldEuoplocephalus's head was armored, too, including the eyelids, and it had horns on the back of its skull and its jugal bones (under the eyes).  Although armor from the tail was never found, it is likely that Euoplocephalus had rows of osteoderms down there, as well, since they are known from a related ankylosaur from Asia, called Pinacosaurus.  As if all that armor wasn't enough, Euoplocephalus was armed with a mass of solid bone on the tip of its tail that it could have swung around as a serious weapon against other dinosaurs.  The tail just in front of this bony club was stiffened and fortified to support it and absorb shock when it smashed into things like wimpy theropod legs.  The base of the tail was not stiffened to give the weapon some range, and would have been supported by large muscles.

Euoplocephalus possessed a wide, flat beak which was a good adaptation for grasping low vegetation.  Because of the broadness of the beak, it wasn't likely a picky eater and probably acted like a giant, reptilian lawnmower, just sucking up any plants it walked in front of.  The plants would then be shredded by its small teeth, located farther back on the jaws.

Euoplocephalus skull on display at the American Museum of Natural History in New York.

 Inside the skull, Euoplocephalus had a series of long passages running through its skull which were attached to it's nostrils.  It was first believed that these had something to do with a heightened sense of smell.  It was later found out that Euoplocephalus had an inner ear that was capable of picking up extremely low-frequency noises.  Because of this, it is also possible that Euoplocephalus used these hollow passages inside its skull to make ultra-low sounds to communicate with members of its own species.  This behavior can be observed in animals alive today, like Elephants.  Euoplocephalus also had tiny eye sockets, but this doesn't mean it would have had poor vision.  In fact, it is likely it could see pretty darn good.  Remember, all of those spikes, horns, and armor were likely just as much for display within the species, as they were defense against predators, so being able to see them on a rival/potential mate was important to Euoplocephalus.

Another Euoplocephalus skull.  This one is from the University of Alberta.  Photo was taken and provided by Victoria Arbour for her latest paper on ankylosaur taxonomy.  (more on that soon!)

That is all for this week!  Special thanks to Dr. Larry Witmer and Victoria Arbour for providing their expertise for the information and life reconstruction in this post.  Feel free to comment below or on our facebook page!  

References

Arbour V.M. and Currie P.J. (2013). "Euoplocephalus tutus and the Diversity of Ankylosaurid Dinosaurs in the Late Cretaceous of Alberta, Canada, and Montana, USA". PLoS ONE 8 (5): e62421. doi:10.1371/journal.pone.0062421.

Arbour, V. M. (2009). "Estimating Impact Forces of Tail Club Strikes by Ankylosaurid Dinosaurs". PLoS ONE 4 (8): e6738. doi:10.1371/journal.pone.0006738. PMC 2726940. PMID 19707581..

Coombs W. (1972). "The Bony Eyelid of Euoplocephalus (Reptilia, Ornithischia)". Journal of Paleontology 46 (5): 637–50. JSTOR 1303019..

Coombs W. (1979). "Osteology and myology of the hindlimb in the Ankylosauria (Reptilia, Ornithischia)". Journal of Paleontology 53: 666–84. JSTOR 1304004.

K Carpenter (1982). "Skeletal and dermal armor reconstruction of Euoplocephalus tutus (Ornithischia: Ankylosauridae) from the Late Cretaceous Oldman Formation of Alberta". Canadian Journal of Earth Sciences 19 (4): 689–97. doi:10.1139/e82-058.

Miyashita T, Arbour VM, Witmer LM, Currie PJ, (2011). "The internal cranial morphology of an armoured dinosaur Euoplocephalus corroborated by X-ray computed tomographic reconstruction". Journal of Anatomy 219 (6): 661–75. doi:10.1111/j.1469-7580.2011.01427.x.

M. K. Vickaryous, A. P. Russell (2003). "A redescription of the skull of Euoplocephalus tutus (Archosauria: Ornithischia): a foundation for comparative and systematic studies of ankylosaurian dinosaurs". Zoological Journal of the Linnean Society 137 (1):

Thursday, September 4, 2014

Reunited: Pleistocene Texas

I actually forgot I made a lot of paintings featuring animals that have been individually featured on here for Prehistoric Animal of the Week.  Today we will be reuniting some mammals!  Remember Bison latifrons from last month? 


How about Neochoerus


Well if you read each of my posts about them you would have noticed that they actually coexisted with each other.  Nowadays, capybaras, known from tropical regions, and bison, known from dryer, cooler areas, wouldn't really seem to go together, but these two did thousands of years ago!  Here they are in the full painting.  There are also prehistoric muskox in the background, and a dinosaur and the giant prehistoric beaver, called Castoroides, in the foreground. 


If you go by these animals' modern relatives, the proportions in this painting are going to seem off.  Remember, however, these creatures were different!  The capybaras were man-sized (six feet), the bison had a seven-foot wide skull (including the horns), and the beaver was about eight feet long. 

This painting was commissioned to me for the Dallas Paleo Society's Occasional Papers and will be the cover for volume 11.


Sunday, August 31, 2014

Mesozoic Movies: The Dinosaur and the Missing Link (1915)


Today, Thomas Edison’s fingerprints are everywhere. Yet his legacy’s loaded with asterisks. As many people know, the man’s business tactics were often despicably underhanded, leaving a trail of alienation and resentment in their wake. However, nobody can dispute the awesome impact this amazing tinkerer’s had upon modern life as we know it. Paleontology fans are particularly indebted to his storied career. Why? On top of his better-known accomplishments, Edison—it turns out—helped introduce dinosaurs to the silver screen.  

Here’s a delightful short released by Edison’s film company that’s available freely online through the miracle of public domain. So heat up some microwave popcorn & enjoy 1915’s The Dinosaur and the Missing Link: A Prehistoric Tragedy


Despite the title, this flick’s only dino gets little more than a brief cameo during its climax. Instead, most of its runtime is dedicated to a razor-thin love story which happens to get rudely interrupted by an obnoxious hominid and some no-nonsense sauropod.

Our tale begins on a quiet, prehistoric morning. Miss Araminta Rockface (an eligible bachelorette) suddenly finds herself surrounded by hopeful suitors. There’s a clumsy oaf simply called “The Duke”, his boorish rival Stonejaw Steve, and one Mr. Theophilus Ivoryhead, whom the film cites as its designated hero. At this point, I should note that the short’s sense of humor might fall flat with modern audiences. Consider, for example, this timeless thigh-slapper Araminta delivers at the 1:43-mark:

“Won’t you come into the drawing room? I should offer you tea, but tea has unfortunately not yet been discovered.”

Oh, my sides. Anyway, we’re then introduced to the “Missing Link” known as Wild Willie: a scrawny, bad-tempered ape-like beast who closely resembles another, far more famous simian.  More on that later.

Willie busies himself by making off with Araminta’s hard-earned supper. She responds by informing her male guests that if they’d like any dinner, they’ll have to “go out and get it” themselves. Meanwhile, Willie’s appetite remains unquenched. Regrettably, while hunting near the local river, he winds up mistaking a distracted sauropod’s writing tail for a tasty snake. After bashing it with a rock, the enraged dinosaur attacks and—after a brief scuffle—kills poor Willie.

A few moments later, who should arrive upon Willie’s broken corpse but the dashing Theophilus? When everyone else shows up at the crime scene, our hero boasts “Yes, yes—a mere trifle. He irritated me and I was forced to kill him!” Apparently, Araminta finds this swoon-worthy, showering him with kisses as the screen fades. The end.  

To be sure, The Dinosaur and the Missing Link is a silly piece of entertainment. And, though cinematic dinosaurs weren’t exactly common at the time, this certainly wasn’t the first short film that starred one. Vaudevillian Winsor McCay’s hand-drawn cartoon Gertie the Dinosaur (1914) had delighted audiences the previous year with its personable titular “Brontosaurus”

But, having said all this, The Dinosaur and the Missing Link nicely foreshadowed the next twenty years’-worth of dinosaurian filmmaking. This is largely thanks to its innovative animator, Willis O’Brien (1886-1962).

Genius is rarely celebrated in its own time. Stop-motion animation had been in existence since the 1890s, long before O’Brien started tinkering with it. However, this talented California native can be credited with inventing the technique independently as a young man. O’Brien discovered, quite by accident, that by systematically projecting still images of stationary models in various positions, he could create the illusion of movement.

Naturally, O’Brien adored sculpting. A very different subject also enamored him, one which would—in almost equal measure—help guide his new career path: paleontology

The Dinosaur and the Missing Link ranks among the first of several prehistory-themed projects O’Brien added to his resume. Completed in 1915, it greatly impressed Edison, who decided to redistribute it two years later and eventually collaborated with O’Brien on many subsequent short films, including 1917’s Prehistoric Poultry


O’Brien quickly transitioned into feature-length movie-making and brought his love of dinosaurs along for the ride. Filmography highlights include The Ghost of Slumber Mountain (1918), The Lost World (1925), & The Giant Behemoth (1959), all of which pitted human characters against Mesozoic monsters.

And then there’s King Kong (1933). Notice that, decades before the eighth wonder of the world arrived, O’Brien was already experimenting with fights between dinos and scrappy simians. Furthermore, Willie’s on-screen death in The Dinosaur and the Missing Link indirectly sets the stage for Kong’s iconic demise.

All things considered, despite its campy dialogue, this short stands as an invaluable prelude for what was to come. 

Sunday, August 24, 2014

Neochoerus: Prehistoric Animal of the Week

This week we will be looking at one of the largest rodents to ever live.  Check out Neochoerus pinkneyi!  Neochoerus was a species of giant capybara that lived during the Pleistocene epoch, as recently as 11 thousand years ago, in what is now the Southern United States.  Like its modern relatives, this massive rodent would have probably eaten water plants.  It measured about six feet long from snout to rump and could have weighed as much as two hundred pounds!  The genus name, Neochoerus, translates to "new pig".  It wasn't a pig though...it was a rodent...like I already said.

Neochoerus herd.  Reconstruction by Christopher DiPiazza.

Even though the Pleistocene is famous for being an ice age, filled with woolly beasts majestically roaming snowy tundras, parts of the world, especially near the equator like Neochoerus' habitat, were still relatively warm.  In fact, the area of the Southern United States that Neochoerus was roaming around in at the time was mostly floodplain, similar to the everglades in Florida today.  This makes sense for a giant capybara since we know their modern relatives thrive in wet environments.  They are adept swimmers and even have semi webbed toes.  Neochoerus would have coexisted with many other giant beasts like Glyptodon, giant ground sloths, mammoths, giant bison, a species of giant beaver, and even humans!  Back in the Pleistocene, seeing a R.O.U.S. wouldn't really have been unusual at all!




Modern capybaras are known to be social animals and are often found in large groups.  Unlike those of many animals, capybara jaws can chew side to side, which helps since they eat so much tough plant material.  Capybaras are also commonly hunted by all sorts of predators.  Jaguars, anacondas, and even humans frequently rely on the large rodents for food on a regular basis.  Back in the Pleistocene, Neochoerus may have been preyed upon by many predators as well.  Pumas and sabre-tooth cats are known to have lived during that time.  Prehistoric humans also likely hunted them.

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

References

Baskin, Jon A.; Thomas, Ronny G. "South Texas and the Great American Interchange". Gulf Coast Association of Geological Societies Transactions 57: 37–45.

Kurtén, Björn and Anderson, Elaine. 1980. Pleistocene Mammals of North America. Columbia University Press, New York, p. 274. ISBN 0-231-03733-3