''The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction'' is a 1986 book written by

Robert T. Bakker Robert Thomas Bakker (born March 24, 1945) is an American paleontologist who helped reshape modern theories about dinosaurs, particularly by adding support to the theory that some dinosaurs were endothermic (warm-blooded). Along with his mentor J ...

. The book sums up the extant evidence that indicates that

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

s, rather than being cold-blooded and wholly lizard-like, were

warm-blooded Warm-blooded is an informal term referring to animal species which can maintain a body temperature higher than their environment. In particular, homeothermic species maintain a stable body temperature by regulating metabolic processes. The onl ...

, agile creatures more similar to modern

birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

than to

lizards Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia althou ...

or other

reptiles Reptiles, as most commonly defined are the animals in the Class (biology), class Reptilia ( ), a paraphyletic grouping comprising all sauropsid, sauropsids except birds. Living reptiles comprise turtles, crocodilians, Squamata, squamates (lizar ...

. Although controversial on publication in 1986, much of ''The Dinosaur Heresies'' now represents the prevalent view in paleontological circles (although other parts have been outdated by more current research). The main arguments used to show that dinosaurs were warm-blooded are: * Almost all animals that walk upright today are warm-blooded, and dinosaurs walked upright. * The

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide t ...

s of warm-blooded animals can pump much more effectively than the hearts of cold-blooded animals. Therefore, the giant

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their bo ...

dinosaur ''

Brachiosaurus ''Brachiosaurus'' () is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 154to 150million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in th ...

'' must have had the type of heart associated with warm-blooded animals in order to pump blood all the way up to its head. * Dinosaurs such as '' Deinonychus'' led a very active life, which is much more compatible with a warm-blooded animal. * Some dinosaurs lived in northern

latitudes In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

, where it would have been impossible for cold-blooded animals to keep warm. * The rapid rate of

speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

and

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

found in dinosaurs is typical of warm-blooded animals and atypical of cold-blooded animals. * The predator/prey ratio of predatory dinosaurs to their prey is a signature trait of warm-blooded predators rather than cold-blooded ones. * Birds are warm-blooded. Birds evolved from dinosaurs, therefore a change to a warm-blooded metabolism must have taken place at some point; there is far more change between dinosaurs and their ancestors, the

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...

s, than between dinosaurs and birds. * Warm-blooded metabolisms are evolutionary advantages for top predators and large herbivores; if the dinosaurs had not been warm-blooded, there should be fossil evidence showing mammals evolving to fill these ecological niches. No such evidence exists; in fact, mammals by the end of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

had become smaller and smaller from their synapsid ancestors. * Dinosaurs grew rapidly, evidence for which can be found by observing cross-sections of their bones.

References

1986 non-fiction books Dinosaur books {{dinosaur-book-stub