Alternately admiring and critical, unvarnished, and a closely detailed account of a troubled innovator. As natural selection got to work, one population accrued adaptations that would eventually give rise to mammals. Chief among them was a single opening behind the eyes – allowing for bigger, stronger jaw muscles – and teeth specialised for different purposes.

Mammals Modernize: the Eocene period would be populated by mainly placental mammals that were now larger. They are also recognizable when compared to modern day mammals. Modern DNA analysis can now be used to generate the family tree of mammals. They showed that the first placental mammals to appear were the hoofed animals and primates, followed by the rodents and carnivores. South America would have its own host is mammals different from the northern continents, including predatory marsupials. But DNA would show that South American rodents and primates were from Africa, probably arriving via drifting vegetable rafts from Africa. I had a similar reaction to The Rise and Reign of the Mammals, paleontologist Steve Brusatte’s sweeping history of the animals that have, for the moment, inherited the Earth. Moving generally forward in time, the book describes how the mammalian line progressively acquired a range of features that have come to define what a mammal is.Out of this long and rich evolutionary history came the mammals of today, including our own species and our closest cousins. But today's 6,000 mammal species – the egg-laying monotremes including the platypus, marsupials such as kangaroos and koalas that raise their tiny babies in pouches, and placentals like us, who give birth to well-developed young – are simply the few survivors of a once verdant family tree, which has been pruned both by time and mass extinctions. I am not a paleontologist nor any other kind of scientist, but recently I have become obsessed with books that explain how the world became what it is today. That obsession led me to listen to this book. Beginning with the earliest days of our lineage some 325 million years ago, Brusatte charts how mammals survived the asteroid that claimed the dinosaurs and made the world their own, becoming the astonishingly diverse range of animals that dominate today’s Earth. Brusatte also brings alive the lost worlds mammals inhabited through time, from ice ages to volcanic catastrophes. Entwined in this story is the detective work he and other scientists have done to piece together our understanding using fossil clues and cutting-edge technology. Soon, hair began sprouting, brains grew in size, and higher metabolisms developed. “When you look in the fossil record, you see there was this long story [over] tens of millions of years, when mammals were essentially assembled by evolution, piece by piece,” says Brusatte.

I absolutely ADORED Steve Brusatte's last book, The Rise and Fall of the Dinosaurs: A New History of a Lost World, which came out in 2018. I read it in November of 2019 and was absolutely captivated. When I saw that Brusatte had a new book releasing in June of 2022, I couldn't wait to get my hands on it. About half the this book covers the time period preceding the Cretaceous-Paleogene extinction with the balance of the book describing mammal life afterward. Only one chapter is devoted to primates and humans. I've previously read Brusatte's book The Rise and Fall of the Dinosaurs: A New History of a Lost World. As he tells in the beginning of this volume, he was lured into paleontology by dinosaurs, those fearsome extinct creatures that have enraptured generations of children. I was one of those kids, so his dinosaur book was retreading well known territory for me. It was written in an accessible style and I was delighted when I realized that he had penned a similar book about early mammals. There is plenty of science in this book, and Brusatte doesn’t skimp on the use of those incredibly complicated animal names, but he adds just enough personal anecdotes and downright story telling to keep the narrative going. His highly fictionalized but factual tale of the little pregnant mini horse who fell into a lake and became a fossil is a delight. So is his encounter with a legendary Polish bone digger. His explanation of the infamous asteroid extinction event 66 million years ago, and other less catastrophic but life altering incidents, are so well told I listened to them twice. The number of mammal species continued to expand and diversify through the Paleogene era. South America, Australia, and Madagascar experienced some unique species because of their isolation. About three million years ago the drifting continent of South America made connection with North America which resulted in the extinction of many of the South American mammals because of new predators moving in from the northern continent.

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The really widespread extinction of megafauna occurred in the last 100,000 years (much of it in the last 10,000 years) when humans spread throughout the world. One of the weirdest extinct species worth mentioning is the Chalicothere which is so unlike anything alive today that it required DNA analysis to figure out its ancestry. This creature, as well as many other extinct mammals, lived recently enough to allow the acquisition of DNA samples. But Steve Brusatte of The Rise and Fall of the Dinosaurs: A New History of a Lost World fame does not think so. As a matter of fact, he tells is that after all the dinosaur adventures he has had an about-face and now is very much into prehistoric mammal fossils. And he’s clearly very passionate about this. Forget the brontosaurus and the triceratops — below their feet a fascinating parallel world of mammals was just waiting for its chance. But another type of creature was also on the rise: dinosaurs. And as these beasts went big – a diplodocus was roughly the length of a basketball court – mammals went small. Brusatte is keen to stress that the pressure went both ways. “You never saw a triceratops the size of a mouse. And that’s because the mammals were keeping the dinosaurs big,” he says. Terrific. ... In one engaging chapter after another, Brusatte takes readers through the long story of the little mammals that took over the world from those tyrannosaurs. It’s a fascinating story, and Brusatte fills it out with plenty of digressions about some of the people who dedicated their time to learning it." — Christian Science Monitor