The Dinosaur Heresies

{{Short description|Book by Robert T. Bakker}}

{{refimprove|date=April 2011}}

{{Infobox book|

| name = The Dinosaur Heresies

| title_orig =

| translator =

| image = Heres.JPG

| image_size = 200px

| caption = Paperback edition front cover,
Illustration by John Gurche (1985)

| author = Robert T. Bakker

| illustrator =

| country = United States

| language = English

| series =

| publisher = Citadel Press (current edition)

| release_date = 1986

| media_type = Print/Hardcover

| pages = 481 pp.

| isbn = 0-8217-5608-7

| oclc= 36439291

}}

The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction is a 1986 book written by Robert T. Bakker{{cite web|title=BOOKS OF THE TIMES; Dinosaur Mysteries|url=https://www.nytimes.com/1986/11/08/books/books-of-the-times-dinosaur-mysteries.html|first1=Michiko|last1=Kakutani|authorlink=Michiko Kakutani|date=1986-11-08|accessdate=2015-01-06|work=The New York Times}}{{cite web|title=Review of The Dinosaur Heresies by Robert T. Bakker|website=Kirkus Reviews|date=21 November 1986|url=https://www.kirkusreviews.com/book-reviews/robert-t-bakker-3/the-dinosaur-heresies-new-theories-unlocking-th/}} exploring extant evidence indicating that dinosaurs, rather than being cold-blooded and wholly lizard-like, were warm-blooded, agile creatures more similar to modern birds than to lizards or other reptiles. Although controversial on publication in 1986,{{cite journal|last1=Horner|first1=John R.|authorlink=Jack Horner (paleontologist)|title=The Dinosaur Heresies. New Theories Unlocking the Mystery of the Dinosaurs and Their Extinction. Robert T. Bakker|journal=The Quarterly Review of Biology|volume=63|issue=2|year=1988|pages=210–211|issn=0033-5770|doi=10.1086/415850}} much of The Dinosaur Heresies now represents the prevalent view in paleontological circles (although other parts have been outdated by more current research).{{Citation needed|date=April 2008}}

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 hearts of warm-blooded animals can pump much more effectively than the hearts of cold-blooded animals. Therefore, the giant sauropod dinosaur Brachiosaurus 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, where it would have been impossible for cold-blooded animals to keep warm.
• The rapid rate of speciation and evolution 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 archosaurs, 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 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.