Online Submission by Helen Chang-Zhao
“Ground-breaking” discoveries are not uncommon in Paleontology (the study of fossils) – but a truly spectacular discovery is reshaping our understanding of Dinosaurs.
It was early last year when a hapless farmworker in rural Argentina stumbled across a strangely shaped rock formation. Curiosity having gotten the better of him, he put down his tools and decided to investigate. As he pushed aside the red soil of the region, a large bone started to take form.
The excavated bone turned out to be the size of a small car, and it was only a single piece of a massive dinosaur skeleton buried deep underground. As experts from Argentina’s National Museum arrived, and began formal excavations (to the great inconvenience of the farmer) they discovered that this was not simply just another dinosaur – but was in fact the largest dinosaur ever found, meaning it also earns the tittle of the largest creature to ever walk the earth.
In deference to its great size, the creature was named Titanosaurus, and last month scientists finally completed assembly of the skeleton. The creature is in fact so new and so bizarre that it has yet to be given a formal scientific name.
This is obviously a fascinating find, yet it also raises an intriguing puzzle: why are there no more creatures of this size? The current heavy-weight champion of terrestrial animals is the African Elephant, which narrowly beat its Asian cousin as the largest living animal to walk the earth. Yet, Titanosaurus is larger than 17 elephants, being over 130 feet long, and over 65 feet high. As a matter of perspective, that means it’s longer than most airplanes and taller than a 6 story building!
So why are things on Earth today so much smaller?
This is a difficult question for scientists to answer because unlike ‘current’ science, we cannot simply measure what’s around us. Studying the past means that we must devise ways to look back in time – which is a tremendous challenge when there are no records to look back on. However, we can make some simple assumptions. First, we know that things deeper in the ground must be older than things buried closer to the surface. We also know that the characteristics of a layer of soil must reflect the conditions of the environment it was made in. These two simple assertions underpin the science of geology, and we can use them to answer our question.
So, taking a look at the soil and rocks in the same depth as where our bones were found – scientists found unusually high levels of complex molecules as well as very rich sediment. This must mean that unlike today’s barren landscape, the Argentina in the days of Titanosaurus was a dense and rich forest – teeming with life. This is a good start as we know that for anything to grow as big as Titanosaurus, there must have been an abundance of food.
Yet, a closer look at the exact composition of this soil also reveals unusually high levels of Carbon Dioxide. Today, CO2 is making headlines because our gas powered engines have spewed out so much of it that we’re beginning to affect the global temperature. However, in the age of Titanosaurus, global volcanic activity had expelled so much gas that carbon dioxide levels were thousands of times greater than it is today.
However, being the astute reader you are, you’ll note that this still doesn’t answer our question. If more carbon dioxide is all it takes to grow bigger, then why aren’t we all growing as the todays CO2 levels are increasing?
The answer surprisingly does not lie with Titanosaurus, but rather in the plants that it ate. We all know that plants use Carbon Dioxide to grow – and so it’s logical that if there is more CO2 then plants will grow more. Indeed, this is exactly what happened, we can see fossilized evidence that plants grew larger and faster than they do today, relentlessly fueled by the massive amounts of atmospheric CO2. However, as a plant grows larger so quickly, the nutrition in the individual leaves would decrease.
It’s a bit like eating a soup which someone is progressively diluting. You’d need to eat more and more of it to simply get the nutrients you need to survive. This is precisely what happened 100 million years ago. Because the nutrition was so poor, Titanosaurus had to eat more and more to simply get the nutrients it needed to survive. As it ate more and more, it would need a bigger gut to digest all of this new food. Therefore over successive generations its gut would get bigger and bigger. As its gut grew, it would need a bigger body, which means it would also require more nutrition. This means that it would need even more food, starting the cycle all over again.
In other words, the reason Titanosaurus grew so big is that it grew out of control – it had to keep growing to survive. This also explains why animals today are a lot smaller: our modern atmosphere (despite the pollutants) is rich in oxygen and nitrogen – meaning that though plants grow more slowly, they are rich in nutrients and we can manage without constantly increasing our body size.
The story of Titanosaurus also portends one of the more intriguing inevitabilities of climate change. As we continue to pump tons of carbon into the atmosphere, forcing plants to gradually grow faster and less nutritious, we may soon see a day where giants once again roam the earth. Though perhaps interesting to behold, it makes you wonder what our planet may become…