After the extinction of dinosaurs came the age of mammals. A new book brings readers into this world with well-researched species profiles by Aaron Woodruff, collection manager for vertebrate paleontology at the Florida Museum of Natural History. The book also includes stunning illustrations by paleoartist Julius Csotonyi.

In “Prehistoric World: Over 1,200 Incredible Mammals and Discoveries from the Mesozoic and Cenozoic,” readers will learn about the warm-blooded animals that rose to prominence once the dinosaurs were gone. Woodruff offers incredible facts about each species, including what they ate, where they lived and how they behaved.

While the book includes new information about popular animals like woolly mammoths and saber-toothed cats, it also features many more recent discoveries that many people may not have heard of before.

“Bear-dogs are some of my personal favorite carnivores,” Woodruff said. “Before large cats evolved, they were the top predators across the Northern Hemisphere and Africa.”

The book also introduces readers to prehistoric mustelids, a family of carnivores that includes weasels, badgers and wolverines. These ancient mammals were far larger than their modern relatives. Some species that lived during the Oligocene and Miocene epochs grew to the size of today’s wolves and jaguars and were able to hunt animals the size of deer and horses.

Illustrator Csotonyi recreated these animals and many more in consultation with Woodruff. “The way [Csotonyi] brought these animals to life was really good,” he said. “I think the artwork will pull many people in and get their minds going.”

Woodruff spent seven months doing the research and writing for this book before finally completing “Prehistoric World” on his birthday. Throughout the project, he remained committed to his full-time job at the museum, often using his weekends and holidays to work on the book.

“This is the kind of book that 10-year-old Aaron would have been looking at all the time,” Woodruff said. As a little kid, he was so enthusiastic about the dinosaur books his parents gave him that he would try to recreate them. “I would draw pictures of dinosaurs and write little descriptions about them and staple the pages together at the end.”

For a few of the mammals featured in “Prehistoric World,” Woodruff had very little information to work with. Some species were first discovered centuries ago and were given scientific names without an accompanying etymology, leaving Woodruff to decipher their meaning with Greek and Latin dictionaries.

He also assigned common names to animals that didn’t already have one, using information discerned from the scientific name. The extinct cat Miopanthera lorteti, for example, is called Lortet’s cat in its description and the bear Tremarctos floridanus is called the Florida spectacled bear.

“For a lot of extinct mammals, all we have are just isolated teeth,” Woodruff said. “We’re lucky if those teeth are still connected to jaws.” Fortunately, that is often enough for paleontologists like Woodruff to get an idea of a mammal’s diet, age and sometimes even sex.

Had he known that he would one day publish a book on paleontology, Woodruff says his “younger self would be over the moon with excitement.”

While “Prehistoric World” is officially marketed to children, Woodruff says readers of all ages will enjoy it. He hopes readers will come away with not only new information about prehistoric mammals, but also a deeper appreciation for those both living and extinct.

UC Santa Barbara neuroscientists have reconstructed the entire anterior visual pathway of a fruit fly, a complex series of connections between the insect’s eyes and the navigation center of its brain.

With the help of artificial intelligence and manual proofreading, systems biologist Sung Soo Kim’s research group and collaborators worked out the relationships between more than 3,000 neurons with unprecedented detail.

These insights into the fruit fly’s anterior visual pathway contribute to a suite of nine papers reporting the neuronal wiring of the entire fruit fly brain, published in the journal Nature.

Led by Princeton neuroscientists Mala Murthy and Sebastian Seung, this landmark achievement—an account of the largest, most complex brain to be so thoroughly mapped so far—brings us closer to understanding the intricacies of animal brains and is a stepping stone toward ultimately understanding how the human brain is wired.

“In systems neuroscience, the question is how neurons interact and generate perception, cognition, motor commands and so on,” said Kim, a co-author of two studies (one as a co-corresponding author) appearing in the journal Nature. “But the major problem here is that we don’t know how the neurons are connected to each other. So it’s difficult to understand what’s really going on in the neural network.”

Indeed, depending on a variety of contexts, a single stimulus can result in a wide array of responses, as the information moves from the initial, sensory stage to the deeper, cognitive and motor stages of the brain.

For instance, if you feel something pressing into your skin, your peripheral neurons will be the first to pick up the pressure, Kim explained. But, as that touch information rapidly makes its way through the brain, it is modified by myriad other factors, including mood, activity and the source of that pressure, just to name a few. As a result, your reaction to that touch can vary wildly.

“There are so many different connections and feedback connections that the brain is processing, so that this single touch could have totally different representations in the brain,” Kim said.

Such is the case with navigation, a fundamental, goal-oriented behavior that most animals engage in. Using a constant stream of sensory cues and feedback information, we make representations of our environments and decisions about how to get to where we want to go.

In fruit flies, approximately 50 “compass neurons”—neurons that tile together to form a ring within the donut-shaped “ellipsoid body” deep in their brains—are responsible for encoding a fly’s sense of direction. This relatively simple structure makes their brains a good candidate for working out the neural circuitry between what they see with their eyes, and how that information travels to the deeper areas of their brains.

“It’s a lot easier to look at these pathways in the fly’s brain,” said co-lead author Dustin Garner, of the Kim Lab. A few years ago, scientists at the Janelia Research Campus at Howard Hughes Medical Institute took 7,050 sections of a single fly’s brain, took 21 million electron microscope images, and compiled them into a publicly available database.

Groups at Princeton University took this data and trained an AI to recognize sections of individual neurons across these images, which then led to a 3D reconstruction of the entire neural network of that fly’s brain. But it was not perfect and still needed human eyes to confirm it. Garner’s job was to proofread the AI’s output with regard to the fly’s anterior visual pathway.

“It was great to be able to see the individual neuron-by-neuron specifics,” he said. “And we actually found multiple parallel pathways that had similar types of neurons, but were slightly different in both form and function.” Garner’s analysis included classifications of these different types of neurons, and predicted their functions from the connectivity.

Meanwhile, Kim Lab colleague and co-lead author Jennifer Lai confirmed some of these predictions experimentally, using the lab’s virtual reality arena for flies, a highly controlled environment projecting light in the fly-visible spectrum (UV to amber), in order to apply stimuli to a tethered fruit fly and observe its brain activity.

In particular, they watched for which neurons fire based on what is being presented to the fly’s visual system, be it multiple small dots or vertically oriented objects.

“We had two major predictions,” she said. “One was the shape of the visual area that each neuron responds to. Some of them respond to vertically elongated visual areas, like columns in a Greek temple, whereas others respond to smaller and more circular visual areas, which we presented in this paper.”

The other, she said, is the color sensitivity of the “ring neurons,” which are the last relay in the anterior visual pathway before visual information is integrated by the compass neurons to generate a directional sense. That, she said, is still a work in progress.

This detailed connectivity data can be used to create computational models that may shed light on how animals navigate and could serve as a model for autonomous vehicle navigation, without relying on GPS.