Birds flying in today’s skies are descendants of dinosaurs that once ruled the Earth. In The Story of Birds, Steve Brusatte, a paleontologist and professor at the University of Edinburgh, UK, and consultant on the Jurassic Park films, traces their evolution— from Archaeopteryx and feathered theropods to demon ducks and the birds we know today. Along the way, he reveals how discoveries in palaeontology have transformed our understanding of one of nature’s greatest success stories. Excerpts:
Recently, the dinosaurian nature of birds received startling support from unexpected sources. Developmental biologists in the early twenty-first century invented new techniques for visualizing how embryos mature before hatching. These were marshaled by the brilliant young paleontologist Chris Griffin—who was taking a break from his PhD work on dinosaurs to study embryology with Yale anatomist Bhart-Anjan Bhullar.
Chris showed that if you follow the growth of a quail or chicken, tucked up in its egg, it starts off looking like a tiny dinosaur before morphing into a bird. Gander at a six-day quail embryo and you see a pelvis that, to me as a dinosaur anatomy specialist, is a dead ringer for the hips of a theropod.
There is a big forward-facing pubis bone with a large muscle attachment at its end, like in T. rex or Allosaurus, but a couple days later it shifts backward and loses the muscle scar, assuming the characteristic retroverted pelvis shape of birds. Meanwhile, the tail starts off long and slim, comprised of many individual vertebrae just like in an average theropod, and then gradually shortens and fuses into the pygostyle bone of birds. Other embryologists even showed that some mutant chickens are capable of growing pointy little teeth that look, for all the world, like those of a typical theropod…
This excerpt was originally published in the August 1-15, 2026 print edition of Down To Earth