I know this is off-topic, but I’m working on a new script that has encouraged me to reconnect with one of my oldest passions: dinosaurs. Now my hair stands up on the back of my neck whenever I see a major discovery published in the news, just like when your small, rodent-like ancestor realizes that there’s a deinonychus watching it from right… over… there.
This time it was a story suggesting that dinosaurs were already going extinct by the time a “catastrophic event” occurred 66 million years ago and wiped them out for good. The paper, titled “Dinosaurs in decline tens of millions of years before their final extinction,” is published in the Proceedings of the National Academy of Sciences. You can read the abstract here. This paper upends part of the traditional narrative we tell ourselves about dinosaurs, which goes something like this:
Way back when, roughly 250 million years ago, Planet Earth was reeling from the largest mass extinction event on record. The Permian mass extinction killed off 70% of all life on land and 96% of life in the oceans. As life clawed its way back during the Triassic Period of the Mesozoic Era, a new kind of reptile emerged as the top dog.
These were dinosaurs– terrible lizards. We throw the word “dinosaur” around as something archaic and old fashioned, but it’s worth pointing out that one of their defining characteristics was the ability to hold their hind limbs directly underneath their bodies-
quite an innovative adaptation.These early Triassic dinosaurs, like sleek Coelophysis, grew and diversified into massive sauropods like apatosaurus, and thagomizer wielding stegosaurs from the Jurassic Period.
There were fearsome predators like Tyrannosaurus rex, locked in life-or-death combat with rhinocerous-like Triceratops at the end of the Cretaceous Period. There was Maiasaurus, which cared for its young in densely packed nesting colonies. And there were smaller creatures, like Velociraptor, the glorified turkeys we try to pass off as villains in summer blockbusters.
Supposedly, dinosaurs were going strong until something happened 66 million years ago that made them go extinct. There were many suspects- climate change, volcanic activity, disease. Now, of course, we realize that there’s no way you can wipe out the coolest frakking monsters that ever walked the Earth with some measly plague. No, you cut them down in their prime with a space rock the size of Mount Everest traveling 12,400 miles per second that crashes into the Yucatan Peninsula and starts global forest fires, leading to a decades-long ashen winter, collapsing the food chain by cutting off photosynthesis.
That’s how you kill off the dinosaurs. If you’re writing the screenplay.
Here’s where the new research comes in. It turns out that dinosaurs were not diversifying into new species the way they once had been when the asteroid hit. I just wish all the news articles had pointed out that this is not the same as saying dinosaurs were going to go extinct on their own.
If the health of a species is measured in the number of individuals running around, the health of a clade like dinosauria is measured in the orders, families, genera, and species that are a part of it. There might have been billions of dinosaurs all over the Earth, but only from a few species. The low diversity means that the larger group is more vulnerable to extinction if anything happens to the remaining species. The dinosaurs might have weathered the impact event better if there had been more species to absorb the blow.
Of course, the dinosaur narrative has a silver lining, in that these fearsome, magnificent beasts never really went extinct. They live on, as the eagles, vultures, cassowaries, pigeons, flamingoes, and songbirds we see around us every day.
And hey, it’s not like our own genus, homo, has seven billion individuals in only one species left. Right? I mean, there’s no way anything like that could ever happen to us…