The Last Dinosaurs [GPT]

We sometimes hear that birds descend from dinosaurs. The idea intrigues, amuses, or raises doubt… but above all, it deserves a closer look. What exactly does it mean? Is it simply an evolutionary relationship, a distant kinship? A superficial resemblance, inherited from a distant past? In reality, the answer is quite simple: birds are not only the descendants of dinosaurs—they are their last living representatives. They belong to a very specific branch of these extinct animals, that of the theropods, which also included the famous Tyrannosaurus rex and small predators such as the velociraptor. It is within a lineage close to the latter that the ancestors of birds emerged, a light, fast, feather-covered lineage that survived the great extinction at the end of the Cretaceous. For this reason, some now refer to birds as “avian dinosaurs,” in contrast to their ancestors described as “non-avian dinosaurs.”

Some may then ask: “What about those large flying creatures, like the pteranodon we often see in movies?” Well, they are not exactly dinosaurs. Animals like the pteranodon belong to another group: the pterosaurs, flying reptiles that evolved alongside dinosaurs, but outside of their lineage. They do share a common ancestor, of course, but it is older, and therefore they are not part of the group scientists call Dinosauria. In other words, a triceratops and a blackbird are more closely related to each other than a pteranodon and a tyrannosaur are.

This kind of distinction may seem subtle, but it illustrates how the evolution of life follows complex paths, with branches that stretch, diverge, or disappear. In this great tree of life, birds are the only leaves still green at the end of a long branch that has otherwise withered. And among them, some species carry this ancient memory more clearly than others. Not because they visually resemble a movie dinosaur, but because they retain certain traits now considered direct inheritances from their ancestors. Scientists have highlighted many characteristics shared between modern birds and theropod dinosaurs: a backward-pointing pelvis, hollow bones, a three-toed foot, fused clavicles, an S-shaped flexible neck, a bipedal posture… and of course, feathers. The latter are not unique to birds: several species of non-avian dinosaurs already had them, likely for thermal insulation. Flight, however, would have appeared later, within a particular group.

Among today’s birds, it is the species of the paleognath group that best illustrate this ancient connection. Ostriches, emus, cassowaries, and kiwis have a more massive skeleton, a terrestrial gait, and conservative anatomical traits that recall the first birds that appeared at the end of the Jurassic (long before the extinction of non-avian dinosaurs). Other birds, although more evolutionarily distant, can also evoke these echoes of the past. The sandhill crane, for example, with its upright posture, long neck, and harsh call, easily brings to mind the predators that marked the end of the Cretaceous.

Today, no tyrannosaur, no triceratops, no stegosaur remains. Their world has vanished, swept away by a cataclysmic event that reshaped life on Earth. And yet, every blackbird, every vulture, every crane that rises into the sky still carries within it a part of that history. Birds are not the heirs of a vanished past—they are its living continuation. It is often said that the disappearance of the dinosaurs paved the way for mammals, which have since become the dominant group on Earth. This is true, in part. But while our distant ancestors were still creeping in the shadows, birds were already taking flight. Today, they have conquered every continent, from equatorial forests to icy poles, from oceans to the highest mountain peaks. They are found in cities, deserts, marshes, and wind-beaten cliffs. They live in places where even humans do not always dare to settle. Birds are everywhere. And although they often appear in a discreet, light, familiar form, they still carry within them the resilience of a reign that never truly ended.