Impressions

I was inspired to buy this book after hearing the author’s conversation on Armchair Expert. His enthusiasm for dinosaurs and the mysteries of earth 66 million years ago was contagious. I was hoping for a creatively written book about dinosaurs that helped me learn a lot about their origin. I wasn’t disappointed with that notion in mind, but I also wasn’t thrilled with the book. At the end, I still felt there was a lot of information missing about how dinosaurs were created, but perhaps that because no one actually knows. Either way, I think Brusatte is a good writer and is able to mix academic knowledge with engaging writing, but I was hoping for more academic knowledge and less engaging writing. That said, it was a fun book and I’d recommend it to anyone wanting to learn a bit about dinosaurs, their evolutionary processes, and what the hell happened to all those magnificent creatures.

Notes

• 252 million years ago, the Permian period of the world ended with a massive mass extinction underneath Siberia. It wiped out 90% of the living things in the world and lasted for a few million years.
• Body fossils, the most popular type, are when parts of the actual animal or plant become fossilized. Trace fossils are when a footprint, bite mark, or something of the like become fossilized. These are valuable because they show how the animal interacted with the environment around them.
• Dinosaurs lived through three periods of geological history: the Triassic, Jurassic, and Cretaceous, which are together known as the Mesozoic Era.
• The earth formed around 4.5 billion years ago. Around 1.8 billion years ago is when we start getting our first complex organisms. They finally started to emerge onto land about 390 million years ago.
• One of the first species to evolve after the end-Permian extinction were the archosaurs. From them, two lineages branch off:
  • First, pseudosuchians, later gave rise to crocodiles
  • Second, the avemetatarsalia developed into pterosaurs, dinosaurs, and the birds we now see today. This group is called the bird-line archosaurs.
• True dinosaurs first entered the picture around 240 and 230 million years ago. The hesitation in accuracy is because its difficult to radiometric date
• The dinosaurs grew up on a one-continent, one-ocean world. Pangea and Panthalassa.
• The high carbon dioxide in the Late Triassic period started a chain reaction: huge fluctuations in temperature, wildfires and humid spells. This made it very difficult for plants to establish themselves in an ever-changing world. Consequently, plant-eating dinosaurs had a difficult time establishing themselves as well, even 20 million years after they first arrived on the scene.
• Convergence – When different types of animals end up resembling each other because of similarities in lifestyle and environment.
• Morphological disparity – A type of comparison done to analyze diversity based on features of anatomy. A bird is more diverse than a jellyfish because birds have a much more complicated system than jellyfish, who are basically just sacks of goo, do. This technique is so effective because so many functions of biology, diet, behavior, growth, and metabolism, are all governed by anatomy.
• Some 30 million years after dinosaurs first came about, they still hadn’t had world domination like we think of it. They were being outmanned and outgunned by their crocodile-like adversaries, pseudosuchians.
• At the very end of the Triassic, some 201 million years ago, Pangea, after 40 million years of slow tugging and drifts, finally cracked. This caused magma and lava from underneath the earth’s surface to erupt in a massive volcano, the end-Triassic eruptions. In the end, some three million square miles of central Pangea were drowned in lava.
• The end-Triassic eruptions were the best thing that could have happened for dinosaurs. Afterwards, they became more diverse and more adaptive and bigger – outnumbering now the previous crocodile-like pseudosuchians. (Not sure why though, – yet at least.)
• Most 3D models of dinosaurs today are created using photogrammetry. They’re able to take pictures of fossils, import them into a computer program and let it build out a skeletal model. From there, you can add organs, muscles, and skin and create a life-like dinosaur, complete with the ability to make it move. Pretty crazy.
• The key to brontosaurs massive size:
  • 1.) Their neck – it allowed them to reach high above the trees, higher than any other plant eating dino. It also allowed them to camp in one spot and gobble up plants from all around, expanding very little energy while doing so.
    1. The rate at which they grew was very fast
    1. Their lungs were different from all other lungs and it was much more efficient.
       • Unidirectional lung
    1. Their bones were hollow, filled with air sacs much like honeycombs and not solid bone.
• Niche partitioning – When coexisting species avoid competing with each other be behaving or feeding in slightly different ways.
• Tyrannosaurs are actually a group of dinosaurs that are all similar to the T. Rex and are who the T. Rex evolved from. They started to take shape around the middle Jurassic, when sauropods and other dinosaurs were making their big debut. The first ones were very small.
• Kileskus was the first tyrannosaur we know of. It was around more than 100 million years before T. Rex.
• T. Rex finally rose to the top of the food chain at the dawn of the Campanian subinterval of the latest Cretaceous period. We’re not sure why. There is a theory that volcanic ash and poisonous gas spewed up and made the planet toxic for a while, killing off a bunch of species (that’s fact) but we don’t know if that helped the T. Rex takeover or it’s just a mere coincidence.
• T. Rex lived about 69 to 66 million years ago and thrived in Western North America – which was covered in forest-y coastal plains.
• Encephalization quotient – A measure of the relative size of the brain compared to the size of the body. Bigger animals will have bigger brains because their bodies are naturally bigger, but that doesn’t mean they are smarter.
• Rex had large olfactory bulbs – the lobes at the front of the brain that control the smell. This led to their very keen sense of smell.
• Birds are dinosaurs – just like theropods and sauropods, birds are just another one of the many branches from the dinosaur family tree.
• Natural selection works by favoring certain heritable traits that aid in surviving longer. If a group of offspring all have slightly different colors and one is darker and that helps them camouflage better, and the trait is inheritable, they will pass that on.
  • If a population is somehow divided enough and each subset goes its own way, evolving its own features until the two groups are so different that they can no longer mate with one another, then they have developed into a new species.
• It’s no doubt birds evolved from theropods. But they didn’t evolve wings to fly at first. Most likely, they evolved to show off and get mates, like the tails of peacocks. Since bigger wings were more impressive, wings kept getting bigger and bigger relative to the size of the body. Eventually, the wings got big enough to support the bird’s body in the air.
• The food they ate and their size had a lot to do with why dinos died and why some mammals and reptiles went on to live after the Cambrian explosion.
• The asteroid/comet hit right on the edge of the Yucatan Peninsula.