Evolution: tracing the rise of the mammals (Introduction)

by David Turell , Tuesday, June 07, 2022, 21:31 (688 days ago) @ David Turell

A new book review reveals much interesting material:

https://www.sciencenews.org/article/mammal-world-evolution-innovation-dinosaurs-paleo

"Some of the moments of evolutionary invention that led to what we now think of as a mammal are remarkably subtle. There’s the hard roof of the mouth that created a dedicated airway to the lungs, allowing mammal ancestors to eat and breathe at the same time. There’s the change from a spine that bends from left to right (which produces the classically reptilian side-to-side gait) to one that enables bending up and down, which ultimately allowed mammals to take in more oxygen as they moved, helping them run faster. And there’s the variety of tooth shapes — incisors, canines, premolars and molars — that made it possible for mammals to eat many kinds of food. A reptile, by contrast, tends to have just one tooth type.

"Some mammalian characteristics are very familiar: milk production, warm-bloodedness, hair. But there’s one less–well-known evolutionary advance that was in its humble way quite profound, setting “us apart from amphibians, reptiles, and birds,” Brusatte writes. It’s a joint in the jaw that makes chewing possible. The ability to chew was “a major evolutionary turning point,” he writes. “It triggered a domino chain of changes to mammalian feeding, intelligence, and reproduction.”

"Brusatte also describes a second small, curious adaptation: the transformation of two bones in the reptile jaw, which migrated to the inner ear to become two members of a famous trio, the hammer and anvil (the third is the stirrup). These inner ear bones are the basis for yet another key mammalian feature: the ability to hear a wide range of frequencies, particularly in the upper register.

"The story of the Age of Mammals is often told as the flip side to the dinosaurs’ demise. But the fossil record reveals that mammals were hardly newcomers: They arose around the same time as the dinosaurs, over 200 million years ago. Even during the Age of Dinosaurs, “in the smaller and hidden niches, it was already the Age of Mammals,” Brusatte writes. “Mammals were better than the dinosaurs at being small.” (my bold)

"Within just a few hundred thousand years of the asteroid impact that wiped out all nonbird dinos some 66 million years ago, mammals moved in to fill the vacancy, rapidly getting a lot bigger, ballooning from, say, mouse-sized to beaver-sized. Pretty soon, they got a lot smarter too. In a geologic blink — a scant 10 million years — mammals’ brains caught up with their brawn, and then the Age of Mammals was off to the races."

Comment: from the standpoint of design, the story fits perfectly. Their waiting in the wings sounds exactlyliike pre-planning. What is the driving force that chance mutations could create? IT doen't exist. Only a desinging mind could direct mutations to produce a big-brained human