All Yesterdays

All Yesterdays is a book by John Conway, C.M. Kosemen and Darren Naish; the book is about how we see dinosaurs and other prehistoric animals by challenging our notions of how prehistoric animals looked and behaved. The book asks questions on what is probable, possible and what is commonly ignored when viewing and discussing these creatures.

The book makes connections of behaviors of animals today to what could happen to prehistoric animals. A lot of media such as films, documentaries and even children’s books on dinosaurs show them as vicious monsters which is a factor of attracting people to the study of dinosaurs. There are a number of factors that are apart of the predator and prey relationship such as curiosity, fear, intimidation and exhaustion, which make their relationships far more complicated then we could imagine.        

“In this scene, set in the Late Jurassic, a herbivorous Camptosaurus is seen approaching a resting Allosaurus in what appears to be a curious social gesture. While Allosaurus was certainly a regular predator of Camptosaurus, this encounter seems to be a peaceful exception to the norm. In today’s ecosystems, predatory big cats and herbivores have also been observed interacting in similarly non-violent ways.”  

One of the most important behavior traits that all animals engage in is play. Play helps animals learn how to attack, defend and even social ques. Even creatures such as lizards, turtles, crocodiles and fish have been reported to engage in play like behaviors. If even these creatures could develop and perform the act of play, then prehistoric animals should be able to do so too.

“Here a sub-adult Camarasaurus is shown enjoying the soothing feeling and antiparasitic properties of a good roll in the mud.”

Popular depictions such as films show predators like the Tyrannosaurus changing at its prey while roaring. However, we know from predators today that they wait silently, hiding within vegetation. Todays warm blooded predators also spend a lot of their time sleeping after spending a lot of their energy chasing, killing and digesting their prey. For dinosaurs such as Tyrannosaurus, there is a lot of speculation and fascinating of where, when and how they slept.

“In this picture, Stan has just finished a big meal and is sleeping soundly as he digests his fill. A tyrannosaurus like Stan was probably capable of eating tonnes of flesh in a single hunt, and would have eaten relatively infrequently. It could of taken Stan several days to sleep off the exhaustion and torpor of a meal.”  

“Since the old view of dinosaurs as lumbering and shapeless piles of stocky lard was discarded, paleontological artists have been keen to portray most dinosaurs as slim, sleek animals where every contour of the limbs, every muscle and even every bone can be clearly discerned. No living mammal, reptile or bird has such an illustratively visible anatomy. Living animals are replete with skin flaps, fat and saggy bits that obscure the exact lines of their bones and musculature.”

This book wants to show the Lambeosaurus as a more solidly built creature with a throat pouch. This is pushing the boundaries of what paleontological artists can create rather than sleek to the skeleton designs.

This creature has mystified scientists and artists alike by its strange anatomy. There have been many theories and hypothetical identities as to what this creature could look like; early ideas being gigantic, turtle-like beasts or vicious predators that used its 70cm long claws to attack its prey. Newer discoveries show that the Therizinosaurus was a plant eaters and closely related to birds.  

This book also illustrates what artists would think and create if they found the remains of animals today. This is a really interesting insight into the thought process of how we illustrate and imagine creature design from the small clues of bones.

“Only the skull of the Hippopotamus is known, yet even that is enough to tell that this apex predator was the most dangerous hunter of its period. Its long teeth and heavy jaws were strong enough to chew right through the metallic armor of cars.”      

“The Cow was a lithe, graceful herbivore that despite its size, could easily outrun pursuing hunters.”

“The Spider Monkey was a small, possibly arboreal species of Human with extraordinarily long fingers and big eyes. Unlike their cursorial relatives, the Spider Monkeys were efficient, stealthy predators.”

“Two Swans are seen with their long, scythe-like forelimbs, which they must have used to spear small prey items. One of them has just caught a Tadpole, one of the mysterious fish of the past.”  

Since 1999, Kent Stevens and his colleagues argued that vertebral joints of Sauropod dinosaur necks could be modeled within software designed to show the anatomy abilities of that creature, it was called Dinomorph. This software showed that Sauropods had restricted movements in their necks and held them at a horizontal pose. Other researchers argued that the software cannot take soft tissue into account as well as virtually all living terrestrial amphibians, reptiles, birds and mammals hold their necks in an elevated pose.

“Perhaps, not realizing that neck posture in living animals is not reflected properly in the way neck bones fit together, future paleontologists will model such living animals as rabbits in the same way, concluding that they, too, held their necks horizontally. This illustration thus serves as a warning against overly mechanistic approaches to anatomy.”

Overall, this book has been fascinating, funny and insightful. This has given me a different outlook on animals and especially extinct animals such as dinosaurs and their possible behavior.  

All images in this blog post I have scanned myself from the referenced book below:

Hartman S. 2012. All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. Irregular Books.