All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals (Irregular Books, 2012) is a small art book by vertebrate paleontologist Darren Naish and paleoartists John Conway and C. M. Kosemen. When the book was first released in 2012, it got a lot of attention online on the “speculative” illustrations of extant animals. This portion of the book, “All Todays,” attempts to “reconstruct” modern animals from their skeletal diagrams with some knowledge of musculature, but no information about soft tissue or behavior. This approach yields both hilarious and horrifying results. The “All Todays” illustrations serve to poke fun at the “shrinkwrapped” approach to illustrating dinosaurs, but also shows just how little can actually know about dinosaur appearance and behavior on the fossil record alone. So many of the distinctive features of modern animals would be lost when only presented with skeletal remains. This is actually the inspiration of the first half of the book.

In the Introduction, Naish notes that “the process of reconstructing a fossil animal involves a marriage of both ‘hard’ data as well as a degree of informed speculation.” Each dinosaur illustration is accompanied by short text explaining both what is known from the fossil record and what we know from modern zoology and ecology. This science informs new and speculative representations of dinosaurs that challenge dominant imagery. One of my favorites is the sleepy T. rex.

While we’re accustomed to seeing the T. rex roaring and brutally hunting prey, the text explains that most modern predators only spend a small amount of time hunting, in fact, they spend a lot (if not most) of their time resting, sleeping, and digesting.

The cover image, Mesozoic Goats, features protoceratops in a tree, inspired by some modern goats which climb trees to graze. The text explains that while there is often a correlation between anatomy and behavior, that is not always the case. “Animals do what they do, not necessarily because it is what they are good at, or even because their anatomy is suited to it, but simply because they can. As a result, unexpected behaviours are commonplace.”

The success of All Yesterdays is how thoroughly it captivates the imagination. Dinosaurs were almost certainly much more than vicious meat-eaters and docile, helpless herbivores. In all likelihood, dinosaurs and other prehistoric animals were just as complex, interesting, and full of surprises as modern animals. Reading this book, I couldn’t help but wonder about all the possibilities of dinosaur natures. All Yesterdays really highlights what is both intriguing and so maddening about paleontology — we know just enough to understand just how much we really don’t know.