Updated: Oct 11, 2022
Ok, this seems like a silly question at first, but hear me out...
During a palaeoecology module, I gave a presentation on the fauna effects and changes of the K-Pg mass extinction (specifically on dinosaurs). The question I asked myself when writing it was, 'are dinosaurs still thriving as much now?'.
In case you didn’t know, dinosaurs aren’t actually extinct. This isn’t the start of a conspiracy theory, there aren’t still sauropods still lumbering in the Congo (though we do have a post on that here). Whilst the dinosaurs that we typically think of definitely went extinct ~66 million years ago, there is one group that survived: birds. Those annoying things that wake you up at 5am and relieve themselves all over your car are scientifically classed as dinosaurs. Even their scientific class name, ‘aves’, is a derivative of ‘avian dinosaur’. It was the NON-avian dinosaurs that went extinct. This does make sense when you think about it, especially when comparing skeletons.
Birds are highly derived theropods, related to the likes of T.rex and Velociraptor. They are actually one of two only surviving groups of archosaurs (the other being crocodilians…...yes a crocodile has more relation to a penguin than a lizard). You can see it in their limbs especially, with their characteristic theropod feet and their three front digits which have fused into a wing. If you ever treat yourself to chicken wings, you can even find a tiny dinosaur claw! (maybe don’t start dissecting at a family gathering though…). Of course, the classifying characteristic is the hip structure. If you’d like more info, how to classify a dinosaur will can be found here!
So, now you know that dinosaurs are indeed still alive and are living as modern birds, you can start to imagine just how many dinosaurs still roam the Earth! There are modern day raptors such as hawks and eagles, extraordinarily fast land animals such as ostriches, semi-aquatic fishers like penguins or even animals that fully transverse land, water and air like ducks!
Dinosaurs first arrived on the scene around the mid-Triassic. During this time they were…..well to the average non scientific onlooker….quite boring. They were just getting started, with modest sizes and basic dinosaurian body plans.
The ‘exciting’ species didn’t start arriving until the mid-late Jurassic, such as sauropods, bigger theropods, stegosaurians and so on. One of these emerging groups was the birds, as seen by the ‘missing link’ and Darwin’s mascot, Archaeopteryx.
Birds soon thrived like any other dinosaur group in the Mesozoic. By the end of the Cretaceous, some very familiar body plans were more than common. Soon the extinction came around when the infamous asteroid struck, throwing debris and dust into the air, blocking the sun and killing off plant life, then subsequently anything that ate them, then anything that ate the plant eaters. You can find more on this extinction in an upcoming post!
None of this happened in a day, in fact, it most likely took place over hundreds or maybe even thousands of years. As with any extinction event, it was the exciting specialists that died first. Being a massive specialist apex predator might mean that you’re top of the food chain, but you don’t have a huge amount of adaptability when a change occurs. It’s like coming to a restaurant when you only like chicken nuggets…..but they've run out of chicken nuggets. Small generalists fared a much better chance since they were happy to eat anything that wasn’t chicken (gross oversimplification, I know).
This is the reason that a much higher proportion of mammals survived, because they couldn’t specialise into niches that were already filled. Small theropods such as birds with less derived body plans were much the same. After the natural arms race that occurred after the K-Pg mass extinction (where each animal was competing for newly available niches, a characteristic event that happens after any mass extinction), many reptiles and mammals soon started to explore their capabilities.
If you look at examples such as phorusrhacids (terror birds), dinosaurs even made a small comeback as top predators of their area.
Fast forward to today and you’ll find that birds have diversified the most out of any of the non-mammalian amniotes, much more than that of other reptiles. In fact, there are more species of dinosaur alive today than we have discovered in the fossil record. Granted, that is down to preservational bias (which is the acceptance that the fossil record is showing a different picture to how things actually were due to only certain things being preserved), but it does go to show that you have probably seen more living dinosaurs than extinct ones you can actually name.
There are a great many more weird and wonderful dinosaurs that are yet to be discovered, some probably more derived and diverse than any bird we know of. There is much more to a faunal groups success than size, derivation or how many niches it occupies alone, but if we look at the global distribution, body plan diversity, wide array of niche occupation and just sheer skill at what they do (they’ve been perfecting it for a long time), avian dinosaurs are doing just as well as their predecessors, if not better. How many raptors can you name that can walk, swim and then fly halfway across the world? Not many I wager.
How can we look at a giant theropod with bone crushing teeth and decide that the exciting times are long behind us? Although prehistoric, non-avian dinosaurs capture the imagination of the child in us, we owe it to our modern world to appreciate just how weird, wonderful, fascinating and downright beautiful it truly is. They do say it is a window to the past after all.