Dinosaur renaissance

**Dinosaur renaissance** is a term coined in a 1975 issue of _Scientific American_ by Robert Bakker to describe the renewed interest in paleontology. This has lasted from the 1970s to the present. It was caused by a great increase in dinosaur discoveries, and by new ideas about how they lived.

The "renaissance", a word which means "rebirth", changed how dinosaurs pictured both by professional illustrators, and in the public eye.

## Discovery of _Deinonychus_

John Ostrom's 1964 discovery of _Deinonychus_ is one of the most important fossil finds. _Deinonychus_ was an active predator that clearly killed its prey by leaping and slashing or stabbing with its "terrible claw". Evidence of a truly active lifestyle included long strings of tendons running along the tail, making it a stiff counterbalance for jumping and running.

According to Ostrom's student, Robert Bakker, some dinosaurs had a high metabolism, so in some cases, they were warm-blooded. Bakker popularized this theory. The impression of dinosaurs as being slow, cold-blooded, small-brained reptiles needed to be rethought, at least for some of the carnivores.

## Scientific debates

Scientists have differing opinions about what dinosaurs were like. Here are some of the main arguments.

### Warm-bloodedness & activity level

Robert Bakker argued that dinosaurs were warm-blooded and active animals, capable of long periods of high activity. Scientists have fiercely debated whether Bakker's methodology was correct..

Scientists now think that many dinosaurs had higher metabolic rates than living reptiles; however, the situation is complex and varied.

Many dinosaurs could have had intermediate metabolic rates. The discovery of feathers on dinobirds clinched the argument for the smaller theropods.

### Social behavior

Fossil tracks suggest that sauropod dinosaurs moved in structured herds, with the adults surrounding the juveniles in a protective ring. Studies of dinosaur nests suggested that duckbilled dinosaur _Maiasaura_ cared for its young.

Dinosaurs are a natural monophyletic group (they descend from a single common ancestor).

### Movement

The dinosaur renaissance changed the way dinosaurs are portrayed by artists. Bakker's illustration of _Deinonychus_ is one of the most recognisable and iconic of dinosaur restorations.

Another result of modern fossil finds is the balance of bipedal dinosaurs. Dinosaurs, we now know, moved with their body almost horizontal, balanced over the hips by a long and often heavy tail. This tail is kept stiff by tough tendons running along the vertebrae. In many adult dinosaurs the tail tendons became ossified (partly bony), keeping the tail more rigid.

### New extinction theories

In the past, some scientists assumed that dinosaurs became extinct because they could not compete with other mammals. This is wrong.

Iridium, a metal found mainly in meteorites, was found in the Cretaceous-Tertiary boundary layer. Scientists then found the Chicxulub crater. This suggested the extinction had been caused by a meteor impact. Later, the existence of the Deccan Traps at the same time showed that enormous flood volcanism was also at work.

### Cultural impact

The dinosaur renaissance revived the general public's interest in dinosaurs. A flood of books, films, television programmes and general publicity has followed. Jurassic Park is the best-known example of this.

## Chinese lagerstätten

The discovery of new feathered dinosaurs in China has kept the field in the forefront of research and popular attention. Lower Cretaceous geological formations in the northeastern Chinese province of Liaoning are especially noteworthy. The animals found there are known as the Jehol biota.