I expect that everyone’s favourite dinosaur is Tyrannosaurus rex. Well, maybe not favourite, but always recognizable. An adult T. rex could grow to 42 feet – about the length of a transit bus – stand 15 to 20 feet tall, and weigh 6 or 7 tons. T. rex, the King of dinosaurs, started out as a hatchling, emerging from an egg perhaps the size of an inflated football, but would grow quickly – gaining as many as 1700 pounds a year.
I was attracted to the subject of dinosaurs while listening to a CBC radio interview with Steve Brusatte. Dr. Brusatte is an American paleontologist who received his PhD at Columbia University and who currently teaches at the University of Edinburgh. I was so intrigued by the interview I went out and bought Dr. Brusatte’s latest book, “The Rise and Fall of the Dinosaurs.” And that brought me to this blog entry.
Here are some interesting observations about T. rex, according to Dr. Brusatte:
- T. rex made its appearance in western North America some 68 to 66 million years ago (I will dwell on references to “millions of years” later on).
- T. rex had bone crushing jaws and teeth set in a disproportionately large skull; massive thighs and somewhat incongruously, very small arms. But what need of arms when T. rex had jaws that could probably bite through a car?
- This dinosaur had very acute senses of smell and sight and sound, and contrary to what the Jurassic World movies suggest, standing still and silent would not necessarily save you from a T. rex.
- Tyrannosaurs like T. rex were pretty smart. Dr. Brusatte refers to a measure of intelligence called the encephalization quotient (EQ) – a measure of the size of the brain compared to body size. Humans like you and I have an EQ of about 7.5; dolphins are 4.0 to 4.5; chimps 2.2 to 2.5; and T. Rex 2.0 to 2.4. Not bad. Dogs and cats range from 1.0 to 1.2. Some politicians might come in at 2.2 to 2.5 (my estimate – not Dr. Brusatte’s).
- Dr. Brusatte calls T. rex the “James Dean of dinosaurs; it lived fast and died young.” Maybe a life span of thirty years. Scientists look at bone rings, much as one might look at tree rings, to determine the age of a dinosaur.
I will come back to dinosaurs, but I thought it reasonable to go off on a tangent for a while. The earth may be more than 4 billion years old, and as recent as 240 million years ago there existed Pangea – a supercontinent that welded together all of earth’s current land masses (as depicted in the image following). There were no Atlantic and Pacific Oceans, just one ocean that wrapped around Pangea. Eventually Pangea started to crack and the continents that we know today gradually began to form. When I say gradually, this may have happened over 40 million years. There were massive volcanic eruptions producing lava and the release of noxious gases, followed by intense global warming. According to Dr. Brusatte this caused a mass extinction, with perhaps 30% of all species wiped out. But this seemed to be a signal for dinosaurs to thrive. Despite the break-up of Pangea and environmental chaos, dinosaurs diversified, multiplied and grew bigger, simply edging other species, such as a once dominant crocodile-like reptile that never survived the break-up. Thus began the Jurassic Period.
The Rise of the Dinosaurs
It was the Late Jurassic Period when dinosaurs became dominant on earth. A mere 150 million years ago. As impressive as T. rex might have been, the plant-eating Brontosaurus cannot be ignored. This “sauropod” came in at perhaps thirty tons – a figure arrived at through bone analysis and computer modelling.
Not sure who the guy is, but he gives you an idea of the size of a Brontosaurus.
As the Late Jurassic Period transitioned into the Cretaceous Period, about 125 million years ago, cooler climates, some fracturing of the Pangea, lower sea levels that produced more exposed land, all helped to produce a different set of dinosaurs. The beloved Brontosaurus (below) went extinct, replaced by even larger sauropods.
For example, the Argentinosaurus was 100 feet long and weighed in at 50 tons – the weight of a Boeing 737! Over time – and again, time measured in the millions of years – there emerged giant carnivores (lots of fattened sauropods to eat it would seem) called carcharodontosaurs, that spread around the world (as the Pangea had not fully fragmented).
These hypercarnivores remained on top for a while, before being displaced by smaller, faster, smarter (remember EQ) tyrannosaurs. In 1902 in Montana, the bones of the first Tyrannosaurus rex were uncovered, and estimated to be 66 million years old.
Not sure how to pronounce “Chicxulub” and when I first saw it my immediate impression was it must be a chain of Mexican car lube businesses (think “Jiffy Lube”). Chicxulub though, is a small town on the Yucatan Peninsula of Mexico very close to the massive crater caused by the impact of either a comet or asteroid or meteor that struck earth about 67 million years ago.
According to Dr. Brusatte, among others, the asteroid/comet/meteor was 6 miles wide – approximately the size of Mount Everest – and moving at 67,000 miles per hour. A Boeing 747 moves at about 570 miles per hour and will fly from New York City to London, England in 6 hours and 25 minutes. Riding this asteroid/comet/meteor would get you to Heathrow from NYC in the time it would take to fasten your seatbelt.
And then there was the impact. Dr. Brusatte says the asteroid/comet/meteor hit the earth with more than a billion times the force of 100 trillion tons of TNT, or the energy of a billion nuclear bombs. It penetrated the earth’s mantle to a dept of 25 miles and left a crater 100 miles across. Importantly, he says, the effects on wildlife on earth, with few exceptions, were almost immediate. The impact produced changes in weather patterns, including extreme rains and winds that exceeded 600 miles per hour; and earthquakes that resulted in massive tsunamis and volcanic eruptions. These all came together to accelerate the demise of the dinosaurs. There remains ongoing controversy about this single event extinction theory – for example, about the same time there were massive volcanic eruptions in what is now India – but regardless, in short order (and in the context of millions of years, it is difficult to define “short”) the land dwelling dinosaurs were gone. Birds (and they are dinosaurs) and small burrowing or water-oriented animals were all that remained.
The Chicxulub crater is re-produced in the preceding image.
This has been called the Cretasceous-Paleogene extinction event, and of course leaves a multitude of questions, even with those of us who are amateur observers. First and foremost; would a single catastrophic event such as this lead to the demise of most of the living things (plants and animals) on earth? Would this event, and in the context of dinosaurs having roamed and ruled the earth for millions of years, caused their almost immediate extinction? And would this object from space, considering its size and the velocity with which it hit earth, have moved the earth from its axis and/or re-routed its solar path, possibly and almost certainly, affecting serious changes of climate? And, perhaps most intriguingly, were it not for this event, would the dinosaurs still dominate? Would there have been a time or room for man?
So here we have “Lucy.” A reproduction and obviously not a dinosaur. Known as Australopithecus afarensis, Lucy dated back some 3.2 million years ago. The remains of Lucy were discovered in Tanzania in 1974. Lucy was petite – just under 4 feet tall and weighing only 64 pounds, and with an EQ of 2.4 (think politician again – male politician I might add). She was an important archaeological find as her skeleton was the most complete among early human relatives at that time. Lucy was bi-pedal (walked on two legs) and derived her name from the Beatles’ song “Lucy in the Sky with Diamonds.” The discovery of Lucy signalled to many archaeologists and paleoanthropologists that man split from his primate ancestors far later than previously assumed.
And what has this to do with dinosaurs, you might ask? Absolutely nothing. But I started to think that dinosaurs were around for hundreds of millions years while hominids and finally humans, by contrast, for maybe a couple of million or several hundreds of thousands of years. Homo sapiens may be just 200,000 years old. Truly, dinosaurs were the most dominant of creatures on earth.
It also brings me back to “millions” and how to put millions of years in perspective. Is a year like a grain of sand on an endless beach? Or a star among an endless galaxy of stars? Hard to fathom. And aside from those questions, there is again the all-important question, “would man have evolved if not for the cataclysmic event, or events, that brought on the demise of the dinosaurs?”