Most people would say that dinosaurs were the biggest creatures to walk the Earth. A few of the biggest dinosaurs might have been longer than the Blue Whale, but they didn’t compare to the actual body size of the Blue Whale. At up to 110 ft in length and 200 tons or more in weight, it’s believed to be the largest animal ever to have existed. It’s as big as an entire town of 2700 people. It has to eat a million calories a day. Their diet consists mainly of small crustaceans known as krill, as well as small fish and sometimes squid. The blue whale’s tongue weighs more than an elephant and its arteries are big enough for a man to swim through. Its heart, which has to pump the whale’s entire supply of eight tons of blood, weighs 1,000 pounds.
But why and how is this possible you ask?
Well, “when the dinosaurs and their marine cousins went extinct 65 million years ago, mammals took the opportunity to take advantage of the space these creatures had previously occupied”, says Evans from the Proceedings of the Royal Academy of Sciences.
It took nearly 10,000 million generations for a mammal to get 5000 times bigger, and over twice as long to evolve form the size of a mouse to the size of elephant. Elephants have been the largest land animal for the past 10 million years, and before that the record was held by a now-extinct “rhino-like animal”, says Evans.
Researchers believe one reason for this faster evolution in size among marine animals is that it’s easier to grow bigger in the sea. With the water holding you up, fewer body modifications are required to handle the increase in weight. Interestingly the new study found that almost all mammals are smaller today than they were in the last major ice ages or a million years ago. Evans says, “this may be because the biggest animals have been hunted to extinction, or because the weather is warmer and there is less advantage to being big.”
But not all mammals got larger after the demise of the dinosaurs. Some, especially those isolated on islands, got smaller. including now extinct dwarf mammoths off the coast of California and dwarf elephants in the Mediterranean. You see, getting smaller can have advantages too, including helping animals to adapt to a smaller food resource. Interestingly, these animals evolved smaller size much faster than those evolving larger size, the researchers found.
But that makes me wonder the reverse: were there any dinosaurs bigger than whales or at least came close?
Bruhathkayosaurus, (a more recent contender for largest dinosaur as well) was named in 1989 on the basis of limb, hip and backbone elements found in the 70-million-year-old strata of India. At first, the remains seemed to represent one of the biggest predatory dinosaurs of all time, but paleontologists later recognized that the bones had come from a sauropod (lizard-hipped dinosaurs). These bones indicated that this dinosaur was even larger than the roughly 100 foot long Argentinosaurus—the creature often cited as being the current record-holder for the biggest dinosaur of all time.
So we’ve come full circle, are blue whales the biggest animals ever? Again, in terms of mass, almost certainly yes. The biggest whales weighs more than 200 tons, and even mass estimates for the biggest dinosaurs don’t come close to this. But dinosaurs may have whales beat when it comes to length. Supersaurus—one of the many confirmed giants—might have been a little longer than the 110 foot benchmark set by whales, and perhaps Amphicoelias was even longer.
If only someone could find a good skeleton of such a giant. Your Thoughts?