Chicxulub Stragglers: How Long did the Non-Avian Dinosaurs Survive?

Greetings. The Cretaceous/Paleogene extinction event is perhaps the most well-known such catastrophic event in the long history of complex life on Earth. Whilst not the most destructive, that particular distinction being held by the End-Permian extinction event, colloquially known as "The Great Dying," the event that extinguished so many iconic forms at the end of the Cretaceous is the one that holds the fascination of humans worldwide. 

While all the specific causes of the Cretaceous/Paleogene extinction event have not been firmly determined by paleontologists as of this writing, the Chicxulub impactor is certainly the prime candidate, or at the very least, was the final nail in the Triceratops' coffin, so to speak. The subsequent impact winter was a form of slow death for the survivors of the initial impact, providing a cold, dark, and barren landscape for the animals endlessly wandering the Earth's continents in a valiant and fruitless search for sustenance. With photosynthesis rendered virtually impossible by the planetwide blanket of dust, soot, debris, and acid-rain filled clouds, the flora of the planet died out within weeks of the initial impact, at least those few plants that were not burned by the worldwide wildfires brought on by the hot ejecta particles that slowly descended to the surface after the massive Chicxulub explosion. As a result of this, the herbivorous dinosaurs were deprived of food sources, resulting in a slow extinction of the lonely and unlucky survivors. Only their corpses were left behind, food for the predatory dinosaurs to take advantage of, food to keep the meat eaters alive for a few more months more. 

Paleontologists have long debated about how long the Earth's impact winter lasted, a few months, two years, or even longer. The newest ideas posit that the winter lasted for two years, full sunlight only becoming a reality fifteen long years after the Chicxulub impactor made contact with the planet. If the timescale of two years is accurate, then some interesting possibilities present themselves. Were some theropods able to make it through the worst of the winter? If such survivors did indeed make it through the worst of the destruction, how many and where? Let's take a measured and speculative look. 

It seems reasonable that some Cretaceous predators might have made it into the Paleogene, albeit in low and widely scattered numbers. Which ones? In my humble opinion, the most likely reptilian candidates are the endothermic, feathered, and smaller-bodied species; animals that could sustain themselves on far less than what the massive Tyrannosaurus rex needed to stay alive. (One such unlucky T-rex is pictured above, searching in vain for food in the darkness.) Which dinosaurs specifically? Well, the Dromaeosauridae immediately come to mind, a family of feathered coelurosaurian theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period, attaining a high level of diversity and evolutionary advancement; all being endothermic, all possessing large brain cases, all being active and highly social bipedal creatures. Think of a bipedal, reptilian version of today's wolves. Magnificent. Dromaeosaurid fossils have been found across the planet in North America, Europe, Africa, Asia and South America, with some fossils giving credence to the possibility that they inhabited Australia as well. The earliest fossils of the family are known from the Early Cretaceous, and they survived until the very end of the Cretaceous, existing until the Cretaceous/Paleogene extinction event. But, did they all die out? 

No.

I hold the position that a few dinosaurs managed to make it into the Paleogene, certainly not enough animals to perpetuate their individual species, but enough nonetheless. I find it heartwarming to consider that they witnessed the dawning of a new world, a new biosphere, not the one they were charter members of, but a renewal of biodiversity and all the wonderful opportunities such a warm, sunlit environment offers. 

At least the dinosaurian survivors saw the sun rise once again, after years of bleakness. They certainly deserved that, after the cruel hand they were dealt by random chance from above. 

Thank you for your time and consideration.