What did feathered dinosaurs decorate their nests with?
– pub quiz trivia question (award points for creative answers)

Whether or not modern-day birds are descended from dinosaurs has been a matter of much debate ever since the very first fossilised bones were unearthed in the early 19th Century.

Scientists have compiled a 'Dinosaur supertree' to consolidate what has been discovered about known species of dinosaur (more than 1,000 at the time of writing). Fossils of feathered dinosaurs leave an imprint which can be discovered by palaeontologists and, once excavated, later studied by scientists. The oldest known bird, dating from the late Jurassic Period¹ around 150 million years ago, is Archaeopteryx ('ancient wing'), discovered in the part of Europe which is now Germany. Some researchers believe birds and dinosaurs had a common ancestor far further back in the geological record of life on Earth.

We are reasonably confident that avian dinosaur Confuciusornis ('Confucius bird') could fly because it had a wishbone and large quilled flight feathers². Fossils suggest that the breastbone was robust enough for flight muscles to attach to, and the wingspan suggests that flight would have been successful. Although the bird apparently would not have been able to raise its wings above the shoulder like modern birds do, this doesn't rule out flight.

Other creatures were more ambiguous; just as today we have birds which can't fly (like the ostrich, the kakapo and penguin species), so there are feathered dinosaurs which found other uses for their (no doubt, brightly-coloured) appendages. Just a few feathered dinosaurs are mentioned in this Entry: true avian dinosaur species are not included.

Some Feathered Dinosaurs

Bambiraptor ('baby thief') sounds more like a cute name for a cuddly Disney character than this 75 million year old North American denizen. Bambiraptor was about the size of a squirrel, but that's where the similarity ends. Attached to Bambiraptor's long, feather-covered arms were hands with opposable digits³ which would have been useful for holding its prey securely prior to delivering the coup de grâce and then while eating its prize.

Compsognathus ('elegant jaw') was the smallest known dinosaur when first discovered, but tinier ones are now known. Fossil remains of Compsognathus have been excavated in France and Germany, and it lived around the same area and epoch as Archaeopteryx. Compsognathus was a long-necked bipedal carnivore which probably fed on insects and small reptiles. It possessed a long, feathered tail for counterbalance which also gave it stability when turning and dodging during chases. Computer simulations have shown that it could run at approximately 40km an hour (25mph), which probably helped it escape the clutches of bigger, bulkier predators.

Deinonychus ('terrible claw') grew to over 3 metres (about ten feet) including its long, feathered tail. It lived in the Americas about 115 million years ago, during the Cretaceous Period⁴. This creature would have been a good runner with its strong hind legs similar to those of a modern-day ostrich. Deinonychus had a perfectly-equipped head with powerful, hinged, vice-like jaws complete with a plentiful supply of flesh-tearing teeth for ripping its prey to shreds once caught. A lifesize model of Deinonychus is on display at the Natural History Museum in Vienna, Austria.

Epidexipteryx ('display feathers') was unearthed at a dig in the Daohugou beds in Nincheng County, Inner Mongolia in 2008. The mid-Jurassic fossil had a combination of physical features not seen before. Its body was covered with fluffy down, but its sharp teeth and talon-like claws belied the cuddly toy appearance. Epidexipteryx had four elongated tail feathers for ornamental display, making it the earliest known creature to possess this feature. Scientists are intrigued about this particular find:

This fossil [Epidexipteryx] is the latest in a string of feathered dinosaurs emerging from China, but is especially exciting for two reasons. Firstly, whereas other feathered dinosaurs date from after the appearance of the first known bird, this fossil appears to be much closer in age, so it opens a new window on the evolutionary events at the critical transition from dinosaurs to birds. Secondly, it has an exquisite set of ornamental tail feathers, suggesting that feathers were used in show even before they were used in flight.
– Dr Graham Taylor of Oxford University's Animal Flight Group

Erlikosaurus ('Erlik's lizard') was a huge herbivore which lived during the late Cretaceous Period. Fossil remains of 6m (20') tall creatures have been discovered in Mongolia and Canada. A fully-grown adult Erlikosaurus weighed around 160kg (25 stone). Its short-legged skeleton reveals that this was a sloth-like creature which probably dug in the ground for its food, turning over and raking the earth with its large claws.

Microraptor ('small thief') was about the same size as a pigeon. On its feathered forelimbs it had curved, pointed claws seen today in creatures which climb tree trunks, like squirrels. Microraptor also had a back-facing perching toe on each hind leg, like modern-day parrots. If Microraptor couldn't fly perhaps it could perch up high in a tree to watch and wait for lunch to amble along below, then launch itself from its vantage point in a manner similar to today's flying squirrels, and glide down to make its kill.

Oviraptor ('egg thief') was unfortunately named due to a misconception that it was raiding the nest of another dinosaur for its food when it was killed and its bones preserved for posterity. Further investigation produced evidence that Oviraptor was in fact attending its own nest when it died, possibly shielding the eggs or hatchlings from a sandstorm with its protective feathers. The first Oviraptor skeleton was discovered in Mongolia by palaeontologist Roy Chapman Andrews⁵ (1884–1960) and his party, but larger specimens have since been unearthed in South Dakota, USA.

Sinosauropteryx ('Chinese lizard wing') - a small (about the size of a modern-day turkey) ginger and white carnivore of the early Cretaceous Period. It had a hooped tail and a feathered Mohican running along its back and head. The feathers evolved for temperature control and mating display, not flight. Sinosauropteryx was a fast runner and would have chased small prey like lizards for dinner.

Troödon ('wounding tooth') was equal in size and weight to a modern-day tiger with similar retractable claws. Even though Troödon (pronounced true-oh-don) was covered in feathers, it would have been a fearsome spectacle and not something you'd want stalking you. It is regarded as the most intelligent dinosaur due to its large brain capacity. Troödon inhabited North America around the same time as Bambiraptor, which hopefully was clever enough to keep out of Troödon's way.

Tyrannosaurus Rex ('tyrant lizard king') has its own Edited Entry as befitting the most famous dinosaur. No 'T.rex' feathers have been preserved but some scientists suspect that it could have had them because it belonged to the same family group (Coelurosauria) as other feathered dinosaurs like Sinosauropteryx. There's no doubt 'T.rex' couldn't fly; a fully-mature adult weighed several tons so if it did have feathers they were for display purposes only, either as a warning to other adults, or during a mating ritual to attract a member of the opposite sex (or both).

Velociraptor ('fast thief') - its feathers may have been useful for display and insulation, and also to shield nests. Specimens unearthed in Mongolia indicate that the creature itself could not fly because they had short arms. An adult Velociraptor weighed about 15kg with a length of 1.5 metres - somewhat smaller than the intelligent stalkers of Jurassic Park fame, which were shown as being the same height as their human prey.

A Quilled Dinosaur

Ornitholestes ('bird robber'), a close relative of Compsognathus, is thought to have had a crest of quills running along its skull reaching down as far as the base of its neck, and also on the end of its tail. It had bird-like skeletal features like flexible wrists which meant it could fold its hands up close to its body in a similar way to how a bird tucks its wings when resting. Ornitholestes measured over two metres (6'6") in length and was an agile bipedal predator/scavenger which fed on eggs, lizards, small mammals and carrion during the late Jurassic Period. Fossil remains have been discovered in Wyoming, Utah and Colorado, USA since the early 20th Century. Ornitholestes, complete with its nasal bone crest (which probably only males had for the purpose of attracting a mate), appeared in the BBC's Walking with Dinosaurs and The Ballad of Big Al.

American sculptor and painter Charles R Knight (1874-1953) was possibly the best historical palaeoartist and his 1914 charcoal representation of Ornitholestes capturing its prey, Archaeopteryx is outstanding.

Charles R Knight's wonderful interpretations of prehistoric creatures were the basis of my models. Long before Obie [Willis O'Brien], myself and Steven Spielberg, he put flesh on creatures that no human had ever seen. His dinosaur and prehistoric animal paintings and sculptures had more than just a realistic surface quality; they also possessed scientific reality and natural beauty. He was the first to reconstruct prehistoric life in a romantic form and the first to work in close collaboration with palaeontologists to attempt to achieve scientifically accurate anatomy. His long experience in drawing and painting live animals in zoos, together with his romantic and vivid imagination, helped to instill his prehistoric reconstructions with a 'charisma' only found in living creatures... At the LA County Museum I vividly remember a beautiful Knight mural on one of the walls depicting the way the tar pits would have looked in ancient times. This, plus a picture-book about Knight's work my mother gave me, were my first encounters with a man who was to prove an enormous help when the time came for me to make three-dimensional models of these extinct beings.
– American film producer and special effects creator Ray Harryhausen

Dinosaurs vs Birds

We still don't know for sure whether dinosaurs were hot-blooded (endothermic) like mammals and birds, or cold-blooded (ectothermic) like reptiles. Dinosaur hunters continue to search for fresh specimens and new species are constantly being discovered. Until a skeleton miraculously containing a DNA fragment which can be analysed is unearthed, the debate will continue. The controversy over whether modern-day birds are evolved dinosaurs remains, but evidence is piling up that the instigators of our glorious dawn chorus can claim heritage from the infamous Hollywood stars 'T.Rex' and Velociraptor.