September 5, 2024
Are Birds Living Dinosaurs?
Are Birds Living Dinosaurs?
I was asked to examine an emu the other day. Now, if you’re wondering what an Emu is - it looks like a small ostrich, native to Australia. Why I was asked to examine this large, flightless bird is another story. But what I want to talk about this week is why it looks like a dinosaur. I was struck by how the bird moved - carefully picking its way around the field with large goose steps. Moving it’s small head back and forward with a hesitant, darting motion. It reminded me of the movie Jurassic Park (and it’s many sequels). This bird moved like a velociraptor. Which is appropriate, because scientists think that they are cousins. The emu is in fact one of our only living fossils - a living dinosaur.
Now, of course, no-one has ever seen how a dinosaur would walk. The movie makers extrapolated how they thought the dinosaurs would move by studying their fossils and consulting experts in anatomy. So that’s where we will start - the fossil record. Fossils are the petrified remains of dinosaurs preserved in stone forever. They are found everywhere, from Donegal, to Dorset to China. The fossils are like a shadow of what the dinosaurs looked like. And the skeleton of some dinosaurs bears a striking resemblance to the skeleton of our modern birds.
The limbs of mammals - hands and feet, are based on five digits - in our case four fingers and a thumb, or five toes. This is known in anatomy as the pentadactyl limb (penta = 5). However, this structure is not unique to mammals, it is found in birds, and dinosaurs. In birds, the five digits have become very thin and support feathers to allow for flight. If we x-ray a bird’s wing, it looks just like a splayed human hand, only longer and thinner. Now, the exciting thing is, if we look at some dinosaur fossils e.g. Archaeopteryx, we can see the same structure - 5 digits forming wings. In fact some scientists think that these dino-bird hybrids had feathers on their legs as well as “arms”. So they perhaps flew through the air with four wings rather than the more usual two. Which must have looked a bit, well, prehistoric.
So now to the final piece of the puzzle. We have fossils that look like bird skeletons. The limb structure is strikingly similar to the modern bird wing. So what about feathers? In the early part of the twenty-first century, fossils were uncovered in China that had what appeared to be the outline of feathers attached to the limbs. So it would appear that some dinosaurs had feathers. Some scientists have even been able to speculate on their colour - ginger! These fossils are almost identical to the modern bird in every respect. Some have even been found nesting over eggs in the manner of a modern bird. So our emu friend is a living, breathing dinosaur whose ancestors have walked the earth for millions of years more than ours have, and perhaps he will be here long after we have gone.
