Review of "The Story of Birds: A New History from Their Dinosaur Origins to Today" by Steve Brusatte

 

Steve Brusatte is an American paleontologist, dinosaur hunter, science writer, professor, and consultant for Jurassic World. Brusatte has written books about mammals and dinosaurs, and this discourse on birds adds to his impressive paleontology oeuvre.

Rather than pen a dry science chronicle, Brusatte laces his book with fanciful zoological scenarios and anecdotes about researchers, which makes the book fun as well as informative.


Author Steve Brusatte

Brusatte starts out with an observation that might surprise some people. "Dinosaurs, those great icons of extinction, aren't really dead. Birds are dinosaurs. That is the evolutionary story I am going to tell in this book. The complete journey of birds, from their origins among small carnivorous dinosaurs, through the twists and turns of volcanic eruptions and asteroid impacts and drifting continents, to the more than ten thousand species that persist today."



There's been debate about the dinosaur-bird connection since the mid-1800s, but the case was substantially proven in the 1960s when Yale professor John Ostrum found fossils from a dinosaur along the Wyoming-Montana border. Ostrum named it Deinonychus, and it had a neck, pelvis, head, and arms that Ostrum had seen before....in birds.


Deinonychus

Deinonychus inspired Ostrum to take a closer look at Archaeopteryx, the extinct Jurassic bird first discovered in 1861. What Ostrum saw now astounded him. Archaeopteryx looked just like a coelurosaur - a small predatory dinosaur.



In this book, Brusatte explains in detail how dinosaur traits morphed into what we think of as bird characteristics. He also provides proof of dinosaur-bird associations discovered by researchers and experts. I'll give a few examples for the general reader, but keep in mind Brusatte's explanations are MUCH MORE extensive, scientific and detailed.

⚫ The link between dinosaur scales and bird feathers

Both reptile scales and bird feathers are made of corneous beta-proteins (CPB), and research with embryos proves that bird feathers are basically elaborate scales that developed from the substances that make up reptile claws. In fact, many dinosaurs had feathers, as seen in fossils found in China and elsewhere. Feathers did not evolve for flight. It's much more likely feathers originated for insulation and became more elaborate/colorful for sexual selection (attracting mates). Only later, did feathered wings evolve, and become airfoils used for flying.


Fossil of feathered dinosaur Zhenyuanlong suni found in China (top); Artist's depiction of Zhenyuanlong suni (bottom)

⚫ Some dinosaur embryos are distinctly bird-like

In 2019, a fossilized dinosaur egg containing an embryo was discovered in China. Brusatte could tell from the shape of the skull that it was a type of small coelurosaur theropod - one of the feathered dinosaurs. As Brusatte's group analyzed the fossil - which they named Baby Yingliang - they felt like they were studying a bird. The fossil egg had the shape of a chicken egg, and the posture of the embryo was distinctly birdlike.


Fossilized dinosaur egg containing Baby Yingliang

Brusatte points out that much about the eggs, reproduction, and parenting strategies of coelurosaurs were birdlike. He notes, "If you squint at Baby Yingliang's spinal cord, you'll notice minuscule holes that pierce the vertebrae and expand inside the bones as caverns. These bones are largely hollow, as are many bones in modern birds.

⚫ The evolution of flight

Archaeopteryx had wings, but could it fly? Archaeopteryx had asymmetrical feathers, a sign that it had lift-providing wings that could withstand the rigors of propulsion through the air. Also, observation of Archaeopteryx skeletons with intense X-rays show that the density of the wing bones and the thinness of their walls correspond to those of modern-day birds that flap their wings to fly in bursts, for short distances. So Archaeopteryx probably flew.



There are two opposing theories, however, about how dinosaur flight evolved. One group posits flight evolved from the ground up, as fast-running dinosaurs used their proto-wings to catch insects, or leap onto their prey, or turn, etc. Then they somehow started to generate a little lift as well, and took to the skies.

The opposing group prefers a trees-down scenario. These proponents suggest the proto-wings were used by tree-dwelling dinosaurs to extend jumps and provide stability as they leapt between branches, which eventually led to flight.

To resolve the controversy, scientists will need to find fossils of the very first birds, to study the structure of the wings. In any case, much is already known about the evolution of wings, and Brusatte discusses this in some detail.

⚫ From reptile teeth to bird beaks

The most recent common ancestor of modern birds, called crown group birds, lived in the late Cretaceous (around 65 million years ago). A late Cretaceous avian fossil named Asteriornis (aka Wonderchicken), looks something like a half-duck, half-chicken with a large toothless beak.


The skull of the Wonderchicken

Brusatte writes that the late Cretaceous appearance of the Wonderchicken marks the appearance of full-on modern-style birds. He notes, "They changed their teeth for beaks. Now their entire body was that of a bird...Different Cretaceous birds probably lost their teeth for various reasons...Some might have adapted to eat new foods, like nuts or crunchy insects, which could better be crushed by a beak...others might have [discarded] a bit of extra weight from....useless teeth, to unburden themselves further for flying...All it probably took was a few genetic mutations, and the teeth would disappear, leaving the jaws free for new functions." For interested readers, Brusatte provides a thorough discussion of the evolution of the bird beak.


Nearly modern Cretaceous birds


Archaeopteryx beak with teeth (top); Modern fowl beak with no teeth (bottom)

⚫ Birds survive the extinction event at the Cretaceous-Paleogene (K-P) Boundary

Sixty-six million years ago, an asteroid about six miles (10 kilometers) wide smashed into what is now the Yucatán Peninsula of Mexico. It smashed with colossal force, "triggered tsunamis and earthquakes, propelled hurricane-force winds, and activated volcanoes. It turned the atmosphere hotter than an oven, sparking wildfires and liquidating rocks that cooled and fell back down as glass....The dirt and dust from the collision, and the grime and soot from the fires, drifted into the atmosphere and blocked out the sun. It was a global nuclear winter."


Chicxulub crater resulting from the meteorite strike

Most plants and animals died in the mass extinction event, including non-avian dinosaurs. But some birds made it through. Scientists speculate the survivors were ground birds that ate seeds, which can remain in the soil for decades.


Scientists speculate some ground birds survived the extinction event at the K-P Boundary

Brusatte writes, "No matter how they did it, once some crown group birds made it through the nuclear winter and greeted the returning sun, they would have looked out at an empty world. Most niches in the food webs were vacant...Opportunities abounded. And these birds took advantage - they diversified with gusto, evolving into many new species, reconquering the trees, expanding into new environments, and in some cases, moving into the niches of their departed dinosaur brethren."

Brusatte proceeds with an extensive discussion of bird evolution from the Paleogene Era forward, a must-read for bird aficionados. This includes references to the 'eighth continent' Zealandia, most of which is now underwater, with New Caledonia and New Zealand poking up. These regions are known for their large flightless birds, called rattites.




Richard Owen, 19th century English biologist and paleontologist, with the skeleton of a moa from New Zealand

In a fun anecdote, Brusatte recalls, "One of my proudest moments as a father was when my boy Anthony, who was four at the time, proved himself to [paleontologist] Jack Horner." Jack asked Anthony, 'Son, what's your favorite dinosaur?' And Anthony immediately said 'penguins.'


Anthony Brusatte, at five-years-old, next to a montage of penguins at the Prague Zoo

When Anthony heard there were gigantic penguins that lived long ago - taller and heavier than his Dad - he was mesmerized, and informed much of Edinburgh's under-six population.


The ancient colossus penguin was as tall as a basketball player

⚫Bird Intelligence

Brusatte observes, "Birds are smart. Many use tools, recognize themselves in mirrors, have sharp memories, and can plan ahead. And some, like crows and parrots, boast problem-solving skills otherwise seen only in primates like us."

How is this possible? The basic computational unit of the brain is the neuron, and scientists discovered that bird brains are packed with neurons. "For example, a goldcrest, Europe's smallest bird at a mere sixth of an once (4.5 grams), has 164 million neurons, double that of a two-hundred-pound (90 kg) Nile crocodile.



In fact, "pound for pound, [birds] have more cognitive power than mammals, or indeed any other animal." Brusatte expounds on the evolution of bird brains, and the remarkable abilities of these feathered creatures.


A pair of adult ravens transferring a tool between them

⚫ The Future of Birds

Brusatte notes that birds are not doing well. Many modern bird species have gone extinct, and it's the fault of humans. Brusatte writes, "The reasons are varied. We hunt birds, clear their habitats to make farmland and cities, poison them with pesticides, and introduce rats and dogs and other invasive species that crowd them out. And especially over the past couple of centuries, we've been changing the climate so quickly and thoroughly that some birds struggle to cope." It's sad. 😪


The dodo went extinct by the late 17th century

At almost 450 pages, Brusatte covers MUCH MORE territory in the book, which also contains informative endnotes and references. Photos enhance the narrative, and Brusatte's copious acknowledgments add a warm note.

I found the book informative and enjoyable, and highly recommend it.

Thanks to Netgalley, Steve Brusatte, and Mariner Books for an ARC of the book.

Rating: 4.5 stars