The Biggest Carnivorous Dinosaur Part 1: Move Over, T-Rex (Kind Of)

Tyrannosaurus rex, the "Tyrant Lizard King," has long been a dinosaurian favorite the world over.  He is quite the interesting animal, and simply massive; the publicity received by him and the giant-sized Velociraptor in Jurassic Park helped a bit, I'm sure!  However, T-rex is no longer thought to be the largest carnivorous dinosaur.  Well, yes he is.  But he isn't.

A picture of the Tyrannosaurus rex specimen Stan at the Morrison Natural History Museum.

Imagine someone who has never heard of the giraffe and elephant asks you which one is biggest.  You might say the elephant, because the elephant is much heavier and has more bulk.  But what if they mean which animal is taller?  Somewhat of a dilemma.  So using words like "biggest" (as I have done here) is not the best way to go.  So Tyrannosaurus still seems to be the heavyweight champion, there are other dinosaurs that, while more slender, were probably longer.  Kind of confusing, I know.

The fact that T-rex has some serious competition has put barely a dent into his popularity, and some of the other larger carnivores are receiving a lot of attention, too. The longest of these carnivores, which we will learn about on Wednesday, was possibly around 20% larger than Tyrannosaurus Rex!  Today, we are going to look at another enormous killer, of South American origin; the massive, the monstrous, Giganotosaurus.

A Giganotosaurus on display at Fernbank Museum, in Atlanta, Georgia

Giganotosaurus is an estimated 46 feet long, comparable in length to the average Tyrannosaurus!  We do have some specimens of Tyrannosaurus that are around the same size as Giganotosaurus, but either way: Giganotosaurus was a massive animal! Of course we don't actually know for sure what the maximum size for any dinosaur is as, unlike for most living animals, we generally have a relatively small sample set, but we can make close estimates based on the finds we have.  And these estimates indicate that Giganotosaurus grew to simply massive proportions.  One of the largest terrestrial animals that we know of is Argentinosaurus (who, like Giganotosaurus, was also found in Argentina), a sauropod dinosaur that lived at the same time as Giganotosaurus.  For Giganotosaurus to prey on even the juveniles of such a large herbivore, it would similarly need to grow to massive proportions.

Giganotosaurus vs. Argentinosaurus at Fernbank Museum, in Atlanta, Georgia

Giganotosaurus vs. Argentinosaurus at Fernbank Museum, in Atlanta, Georgia

This pattern repeats itself all over the world, the pattern of gigantism evolving in sauropods, along with the subsequent evolution of gigantism in the theropods (meat-eating dinosaurs), is a pattern repeated throughout the world, and throughout the Jurassic and Cretaceous Periods of the Mesozoic Era, the two periods in time when the rule of the dinosaurs was absolute.  Here are some more of the predator-prey, giant-sized carnivore/giant-sized herbivore relationships seen throughout the Mesozoic.  The first animal named will be the predator, and the second will be the sauropod.

Asia, 160 MYA: Sinraptor, Mamenchisaurus
Europe, 125 MYA: Neovenator, Ornithopsis
North America, 150 MYA: Allosaurus, Diplodocus
North Africa, 95 MYA: Carcharodontosaurus, Paralititan

In tomorrows post, we will look at the last relationship, and focus on another larger (or longer) than life carnivore, Carcharodontosaurus.

Fossil Hunting 6/30

Yesterday, my friend Masaki Kleinkopf and I went to check out a fossil site that I had found with another friend a couple of days ago. It looks to be Laramie Formation (towards the end of the death of the dinosaurs, in the Late Cretaceous), and a river seems to have been in this area. The most exciting fossilized things we found was a bunch of fossilized wood, as you can see below.

Fossilized wood

More fossilized wood

However, the most exciting that we saw of the day was definitely a wolf spider, probably three inches across. We saw the web first, and I was going to try and get the spider to come out with a long piece of grass (didn't want to get too close!) when I accidentally startled a grasshopper into the web. It couldn't get out, and suddenly the wolf spider appeared, and attacked it. It ran up probably ten or fifteen times, stabbing the grasshopper with its mandibles (I think that's what it was doing, anyways) and with its two front legs held up in the air. After awhile, the grasshopper was still alive, and the wolf spider retreated back down its hole. When we came back fifteen or so minutes later, the grasshopper was gone; probably dragged down by the wolf spider into its burrow to be devoured. I took a pic of the spider, but I think the  spider moved when it saw my phone, so all you can see is a blurry shot of the burrow.

Wolf spider burrow.  I think that the darker black in the burrow might be the  spider.

Besides wood, the Laramie Formation has yielded a number of dinosaur remains as well, among them being Edmontosaurus, Ornithomimus, Thescelosaurus, Triceratops, and Tyrannosaurus.  But first, here is a map of where the Laramie Formation is in Colorado.  Many of the dinosaurs that I mention below were found up in the north, near Fort Collins I believe.

We Interrupt Our Previously Scheduled Programming: RIP, Lonesome George

Well, we managed to get a whole day without me changing the programming!  I decided to let you all know about a saddening death that occurred a week ago today in the Ecuadorian-owned Galápagos Islands.

A picture of Lonesome George that my grandparents took several years ago on a visit to the Galápagos.  Apparently he was a little camera shy.  Photo Credit: Ted and Gail Neher

Lonesome George was the last survivng member of his supspecies. Ten of the fifteen known subspecies of the Galápagos Giant Tortoise survive in the wild. However, and eleventh subspecies survives in captivity, Chelonoidis nigra abingdoni. Consisting of a sole member, Lonesome George, it is easy to see where George got his name!

Researchers at the Charles Darwin Research Station, a biological research station in the Galápagos, have offered a $10,000 bounty on anyone who can find a suitable mate for Lonesome George. So far, all attempts at getting Lonesome George to breed with a member of another sub-species have been unsuccessful.

A herd of turtles (yes, Michael Scott, I'm looking at you).  These Galápagos turtles would belong to a different sub-species than Lonesome George.  Photo Credit: Ted and Gail Neher

Here is a brief snippet from a news cast regarding his death:

"Scientists had expected him to live another few decades at least.

Various mates had been provided for Lonesome George after he was found in 1972 in what proved unsuccessful attempts to keep his subspecies alive.

Attempts were initially made to mate Lonesome George with two female tortoises from Wolf Volcano. But the eggs they produced were infertile.

Two females from Spanish island's tortoise population, the species most closely related to Pinta tortoises, were placed with him last year."

The majestic hindquarters of Lonesome George.  Photo Credit: Ted and Gail Neher

Unfortunately, with his death, the world's most endangered animal has passed on the mantle to some other animal, unknown to me at this time, and perhaps even unknown to science.  Regardless, it is a sad day for people the world over with the loss of this titan; literally, as he was over 100 years in age, and was about 5 feet long and weighed 200 pounds!  He seemed to pass away from old age, though, so at least he went in a nice way.

And don't worry, we can get back to teeth and dental anatomy some time next week.  See you tomorrow.

Puerto Ayora on Dwellable

Another Living Fossil: The Coelacanth

400 millions years ago (MYA), during the Devonian Period, life had already gained a foothold on land.  However, in the seas, unless you were at the top of the food chain, there were a lot of predators to contend with.  If you were a fish in the middle of the food chain during the Devonian, you not only had to deal with ancestors of the modern day shark, but a now-extinct group of armor-plated fish, called the Placoderms.  Some of these Placoderms, like Dunkleosteus, grew to simply enormous proportions, around 30 feet in length!  One type of fish that lived during the Devonian and was most likely preyed upon by the sharks and the Placoderms was a fish known as the Coelacanth.

The Coelacanth (SEE-lah-canth) was a relatively unassuming fish, its closest living relative being the lobe-finned fish.  Fossils of the Coelacanth have been discovered ranging from 400 MYA to around 65 MYA, coinciding with the death of the dinosaurs.  In 1938, however, when one was hauled in on a fishing net off the coast of South Africa, the temporal range of this animal was extended by 65 million years!  Today, by studying the living Coelacanth, scientists have found that the fish gives birth to live young, unlike other fish.  Further discoveries both in Africa (off the coasts of Mozambique, Madagascar, Kenya and Tanzania) as well as Asia, around Sulawesi, Indonesia, of living Coelacanth specimens have further widened the current geographical range of the Coelacanth.

A specimen of the Cretaceous coelacanth Coccoderma nudum from Germany.  On display at the Mace Brown Museum of Natural History on the campus of the College of Charleston in South Carolina.

Unfortunately for this living fossil, it is labeled "Critically Endangered" by the IUCN, much like yesterday's living fossil, the mountain pygmy possum.  Just like the mountain pygmy possum, conservationist groups are working towards it's protection, trying to keep fisherman from fishing in the Coelacanth's habitat.  Hopefully, humans won't be the final nail in the coffin, so to speak, for this 400 million year old fish.

Animal Spotlight: The Mountain Pygmy Possum

You've probably never heard of the mountain pygmy possum (Burramys parvus); few people have, it being one of Australia's many lesser known marsupials.  One of five extant (opposite of extinct, or still living today) species of pygmy possum, the mountain pygmy possum has a very interesting story about its discovery, a story that we will now look at.

The genus Burramys, the genus the mountain pygmy possum is a part of, also contains three extinct species of possum.   In fact, prior to 1966, the mountain pygmy possum had been described solely from fossils dated from the Pleistocene Epoch.  (The Pleistocene Epoch dates from around 2.5 million years ago to around 10,000 years ago, when the last Ice Age ended.)  It was first described from these Pleistocene fossils by the famous geologist/zoologist/paleontologist Robert Broom in the year 1896, and was assumed to be extinct, just like the other three members of the genus Burramys.  That is until 1966, when one showed up in a ski hut on Mount Hotham, a mountain in New South Wales, southern Australia, and home to the Hotham Alpine Resort.

Since this surprising discovery, scientists have located three populations of the Mountain Pygmy Possum in different spots in southern Australia.  Although it is exciting to discover a species that was previously thought to be extinct, it is saddening to find out that this animal has a wild population of a mere 2,000 individuals, and is labeled "Critically Endangered" by the IUCN.  Means have been taken to protect the mountain pygmy possum, including the so-called "Tunnel of Love," a little possum-path that granted the males better access to the female habitat, and helping to reduce fatal encounters with automobiles.

Works Cited:

Mountain Pygmy Possum. (n.d.). - Just another global2.vic.edu.au weblog. Retrieved June 29, 2012, from http://teacherrsc.global2.vic.edu.au/

Dinner Plain on Dwellable

Digest This: Or Can You? A Koala Could

I've been reading some interesting things about the koala (Phascolarctos cinereus) that I thought you might be interested in hearing.  As we all know, koalas are one of the sleepiest animals, and can be found sleeping and resting around eighteen or nineteen hours a day.  That means that out of their thirteen year life span, they are sleeping for around ten of those years. By comparison, a human with a lifespan of seventy-five years that sleeps an average of eight hours a day would sleep around 25 years of their life.  While a lot more than twelve years for the koala, keep in mind that humans only sleep around 33% of their life, while koalas sleep around a whopping 75-80%. But why do they sleep so much? The answer lies in what they eat: Eucalyptus leaves.

The leaves of the Eucalyptus trees are incredibly hard to digest.  Not only are the leaves very fibrous, much like celery (think about how hard celery is to chew), but they are also chock-full of toxins that very few animals can digest, with especially high concentrations of volatile oils and phenolic compounds.  What does that mean in English?  Well, phenolics are a type of organic chemical that naturally occur in plants, where they can act as deterrents against predatory browsing at the hands (or rather the mouths) of herbivores.  As stated before, the concentration of phenolics in the Eucalyptus leaves are so high that most animals would simply be unable to digest the leaves.  The koala decided not to take this lying down (ironic, as that is most of what koalas do in a day), and have evolved in a few key ways to help them deal with these toxins.

A fascinating moment of a koala's life: being awake.  Quite the statistical anomaly.

The first is simple; they have teeth that are great for chewing.  The broad, high-cusped molars possessed by the koala help it to thoroughly mash the food in its mouth prior to further digestion.  In our own mouth, we also have molars, along with a wide assortment of other types of teeth. When you are chewing your dinner, you tear bite-sized chunks off with your front teeth, or incisors and canines. Then, you move the food to the back of your mouth for further processing, and you further chew the food with your molars. The cusps on our teeth make it so the food is crushed fairly thoroughly. However, the koala doesn’t eat food like lettuce that can be torn up fairly easily. Thus, the koala has higher cusps on their molars, allowing for the Eucalyptus leaves to be ground up quite nicely.

A koala skeleton on display at the American Museum of Natural History in New York, New York.  Note the molars in the back.

The second major evolutionary adaptation is that the koala has a very long cecum, a pouch of sorts that is considered to be the first part of the large intestine.  In fact, at four times its own body length, the cecum of the koala is proportionally longer than that of any other mammal on the planet! The bacteria in the cecum help to break down the tough tissues in plants, such as cellulose, an important structural component of the cell wall in plants.  This gives our fuzzy marsupial friend a whole lot more time and space for that tough plant material to be digested.  Apparently, it takes a whole lot of guts to be a koala.

Believe it or not, I don't have a picture of a koala cecum on file.  So instead, take a look at this other interesting adaptation of the koala.  Instead of having a single thumb like we humans have, it has two!  Its first two digits are both functional thumbs, and are opposable to the other three digits on their hand.  You can see part of the hand skeleton the picture above this one.

Koalas aren't born with those important cecum bacteria, though, and to my knowledge no animals really are.  After five months of suckling from mom, the koala joey starts to enjoy the "partially digested leaf material produced from the female's anus" (MacDonald, 1984), or, as I like to call it, "Mom's Butt Leaves."  This delicious meal is actually thought to come from the cecum, giving the joey those essential bacteria and microbes, not to mention a delightful, pre-digested meal of Mom's Butt Leaves.  (Check out our other post about butt bacteria and eating poop HERE.)

Get yours at your local King Soopers today!

A fourth innovation of the koala is simply the exorbitant amount of time that the marsupial spends sleeping.  When you sleep, you are burning fewer calories than you would be if you were running around or hunting, or moving through a Eucalyptus tree browsing on its leaves.  Therefore, the more time the koala spends sleeping, the more energy it saves in exchange.  (The popular myth that the koala gets "stoned" by the Eucalyptus leaves is nothing more than that: a myth.)  The koala is able to delicately walk the line that we all desire to find: the maximum amount of sleep that one can get without dying.  It's truly a marvelous achievement, one which the koala handles with much grace and aplomb.

During the Pleistocene, there existed a larger species of koala, Phascolarctos stirtoni, a slightly larger koala than the modern species, P. cinereus.  Based on dentary measurements of both species from Price et. al., I came up with an approximate size increase of 1.4.  That is, take the length of a body part of P. cinereus, the modern koala, and multiple that value by 1.4, and you should get the approximate length of the same body part for the robust koala, P. stirtoni.  Not exactly the most precise method, but one that'll work for our purposes.  Below, you can see an approximate size comparison that I made of the two koalas, our modern species in gray and the extinct species in brown.

An approximate size comparison between the modern Phascolarctos cinereus (right) and the extinct P. stirtoni, with a can of Mom's Butt Leaves for scale.

More recently, scientists have realized that there is actually no evidence that does not support the idea that the hypothetical Laser-Eyed Koala (Phascolarctos oculaser) could have maybe possibly existed.  Scientists have been quoted as saying "We have never found it but that's not to say that who's to say that we aren't all koalas."  Below is the first unrefuted photographic evidence of the Laser-Eyed Koala in action.

That incredible, hands-on natural history museum in scenic Morrison, Colorado never stood a chance against that koala.  Fortunately, repairs to the facility should be completed on time for tomorrows 10:15 AM tour, which is included with your admission fee and well worth the time.  Talk about great free advertising, am I right?

Works Cited:

Hättenschwiler, S., & Vitousek, P. (2000). The role of polyphenols in terrestrial ecosystem nutrient cycling. Trends in Ecology & Evolution, 238-243.

Logan, M., & Sanson, G. (2002). The effect of tooth wear on the feeding behaviour of free-ranging koalas (Phascolarctos cinereus, Goldfuss). Journal of Zoology, 63-69.

Macdonald, D. (1984). The Encyclopedia of mammals. New York, NY: Facts on File.

Nagy, K., & Martin, R. (1985). Field Metabolic Rate, Water Flux, Food Consumption and Time Budget of Koalas, Phascolarctos Cinereus (Marsupialia: Phascolarctidae) in Victoria. Australian Journal of Zoology Aust. J. Zool., 655-655.

Piper, K. (2005). An early Pleistocene record of a giant koala (Phascolarctidae: Marsupialia) from western Victoria. Australian Mammalogy Aust. Mammalogy, 221-221.

Price, G. (2008). Is the modern koala (Phascolarctos cinereus) a derived dwarf of a Pleistocene giant? Implications for testing megafauna extinction hypotheses. Quaternary Science Reviews, 2516-2521.

Price, G., Zhao, J., Feng, Y., & Hocknull, S. (2009). New records of Plio-Pleistocene koalas from Australia: Palaeoecological and taxonomic implications. Records of the Australian Museum Rec. Aust. Mus., 39-48.

Hello There

Hello, my name is Zack Neher.  I hope to be able to use this blog as a platform to help share my love of nature with the world, and talk about some things that I find interesting, and hopefully, you will too.  Enjoy!