New Scientist: Birds Are Dinosaurs — Evolution, Fossils, and the Rise of Modern Birds with Steve Brusotti

In this New Scientist interview, paleontologist Steve Brusotti explains that birds are dinosaurs, tracing their origins from feathered relatives and the fossil record to the dramatic diversification of modern birds after the Cretaceous asteroid impact. The conversation traverses Archaeopteryx, the evolution of flight, the competition with pterosaurs, and the rise of giants like Terror Birds and Elephant Birds, culminating in the intelligent, adaptable birds we know today. Brusotti also discusses how DNA and development illuminate dinosaur ancestry and what the future may hold for birds amid current global changes.

• Birds as dinosaurs: deep evolutionary links and fossil evidence
• How flight evolved from feathered dinosaurs through display to powered flight
• The post-extinction explosion of bird lineages and megafauna birds
• Modern bird cognition and the ongoing hunt for older true-bird fossils

Introduction: Birds as Dinosaurs

Steve Brusotti, a paleontologist at the University of Edinburgh, discusses the central thesis that birds are dinosaurs, explaining the evolutionary genealogical relationship and how birds are the only dinosaur lineage to survive the mass extinction that ended the reign of T. rex and Triceratops. The conversation frames the idea that birds have dinosaur DNA and that modern birds are living relatives of the dinosaur family, a notion that reshapes how we view every day feathered creatures.

Evidence for a Dinosaurian Bird Lineage

Brusotti outlines the main lines of evidence for birds evolving from dinosaurs: fossil anatomy that links birds and reptiles, the discovery of transitional fossils with feathers, wings, and wishbones, and the fact that DNA data place birds within the reptiles, with crocodiles as close relatives. The discussion also touches on the limitations of ancient DNA, noting that Jurassic-era dinosaur DNA has not been recovered, but modern genomic data robustly supports the dinosaur-bird connection. The development of the embryo and how bird development preserves echoes of their dinosaur ancestry is highlighted as a key line of evidence.

The Fossil Record and Archaeopteryx

Archaeopteryx is presented as the oldest known bird, about 150 million years old, a mosaic of dinosaur and bird features. Brusotti explains its significance in Darwin’s era and in the ongoing search for older true birds, particularly in locales like Scotland’s Isle of Skye where Jurassic rocks preserve relevant fossils. He describes the transitional nature of Archaeopteryx, with teeth and claws alongside wings and a wishbone, illustrating the gradual shift from dinosaur to bird form.

From Feathers to Flight: How Winged Birds Evolved

The talk delves into feather evolution, from simple, hair-like structures to branching, quill-feathers that could form wings. The idea that early feathers were used for display and sexual selection is proposed, with color evidence from preserved melanosomes suggesting flamboyant patterns. A threshold concept is introduced: incremental improvements in wings could cross a physical boundary that enables powered flight, leading to an explosion of avian diversity.

Pterosaurs vs Birds: A Sky-ward Competition

The relationship with pterosaurs is explored, noting that pterosaurs predated birds and occupied the sky for millions of years. Birds were the interlopers who eventually diversified and, following the end-Cretaceous asteroid event, filled many ecological niches left vacant by the extinct dinosaurs and pterosaurs.

The End-Ccretaceous Extinction and Bird Diversification

After the asteroid event, birds rapidly diversified to fill new ecological roles. Brusotti uses molecular clocks and fossil records to explain how major modern bird groups—birds of prey, songbirds, penguins, ostriches, and others—originated in the wake of the extinction, illustrating why certain traits such as rapid growth, flight capability, beak specialization, and versatile lifestyles were advantageous in a post-catastrophe world.

Megafauna Birds and the Aftermath

Among the most striking outcomes are giant, flightless birds that filled predator niches once occupied by dinosaurs, including Terror Birds, Elephant Birds, and Demon Ducks. The discussion emphasizes that these lineages thrived in isolated regions like South America and Madagascar, later giving way to modern birds as ecosystems shifted again due to climate and mammal competition.

Intelligence, Cognition, and the Modern Bird World

The conversation turns to bird intelligence, noting remarkable cognitive abilities in crows, ravens, and parrots. Brusotti highlights that, relative to body size, birds have had large brains for a long time, sometimes rivaling primates in certain cognitive tasks. A collaborative project that analyzes neuron counts across species and uses fossils to infer brain evolution is described, underscoring the multidisciplinary nature of modern paleontology.

Future Prospects: What Might Happen Next?

Brusotti offers a cautious look at the future, acknowledging the possibility of another mass extinction driven by rapid climate change but expressing confidence in birds’ adaptability. He muses about potential future forms, including speculative large flightless birds in altered environments, while stressing the importance of conservation in the face of human-induced environmental change.