Did all dinosaurs have feathers?
30 years ago, when people heard the term "world of the dinosaurs", they imagined a misty, swampy world similar to the one depicted in the mural below.
The creatures ruling this world were sluggish, scaly giants, barely able to drag their tails behind them. Now, thanks to the Jurassic Park film/book franchise, that mental image has morphed to more closely resemble the picture below.
This representation is fairly accurate, except for one crucial detail. It is now known that many species of dinosaur had feathers, either covering their entire bodies or in select places as display structures. The image of the world that these animals inhabited has also changed dramatically. During the Mesozoic (the time era in which the dinosaurs lived), the world was much warmer, meaning there were no polar ice caps. This led to a rise in sea levels on a global scale. So while there were swamps and moss plains (grass would not evolve until the very end of the Cretaceous period), many areas were still cold enough to be covered in snow during the winter months. This means that the world of dinosaurs more closely resembled the picture below.
However, the mental image that most people hold of "the time of the dinosaurs" is stuck in the late 20th century visuals. Why is it so challenging for us to accept this environmental and physical change?
Why do people find it hard to accept feathers on dinosaurs?
Another reason feathers are unaccepted is because of the selective and incomplete reporting of scientific discoveries by the mainstream media. Scientific papers are complicated and lengthy to read, making them difficult and challenging to distill down in to a short, bite sized story understandable to the "average Joe" and eye catching. More often that not, in their haste to get a hook out quick, the news media communicates the science poorly. An excellent example of this is the recent paper about Tyrannosaurus rex not having feathers.(http://rsbl.royalsocietypublishing.org/content/13/6/20170092) This paper more or less confirmed what was already thought and in no way completely disproved the idea. However, news media blew the paper completely out of proportion, and gave many people the idea that depicting feathers on Tyrannosaurus rex was completely false.
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Lastly, feathered dinosaurs have lagged in popular support because of the absurd and visually unappealing early artistic renderings. The two pictures below demonstrate this.
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On the left, you can see a model of a Tyrannosaurus rex. It possesses feathers, but looks like a half plucked chicken. The image on the left is one that was made when the evidence for feathered tyrannosaurs was almost non-existent. It is almost silly in its lack of appeal. People took one look at pictures like that and decided that feathers on all dinosaurs were ugly and weird. On the right is another image of a Tyrannosaurus rex. It also possesses feathers but looks far more natural.
It is hard to know whether all dinosaurs at all stages of growth had feathers. For some types of dinosaur, like Yutyrannus (you-tie-ran-us) and Velociraptor, there is direct evidence such as full body skin impressions and quill knobs, that these dinosaurs had feathers. However, other species like Carnotaurus (car-no-tore-us) and Edmontosaurus (Ed-mon-toe-sore-us) show evidence that as adults, these animals had pebbly, scaly skin covering most of their bodies, as shown in fossil skin impressions. This does not mean that these animals did not have feathery down as juveniles or display feathers on their heads, arms or tails. Understanding the ancestry of dinosaurs requires us to keep an open mind about feathers on dinosaurs. Since all dinosaurs descended from a common feathered ancestor, it is entirely possible that at some point in their lives, all dinosaurs had some type of feathers. Each dinosaur family may have expressed that ancestry differently in their body coverings.
Stegosaurs and Ankylosaurs
No fossil impressions of feathers are known from either stegosaurs (steg-O-sores) or ankylosaurs (an-kye-low-sores). Combine this with the bony armor of ankylosaurs and it seems highly unlikely that ankylosaurs had feathers at any age. Stegosaurs are a different matter. It is possible that stegosaurs could have had primitive, quill-like feathers going down their backs and tails. However, their is no evidence to suggest the presence of these quills besides the feathered common ancestor of all dinosaurs.
Ceratopsians and Pachycephalosaurs
There is evidence of feathers in ceratopsians (s-air-a-top-see-ans)(the group that includes Triceratops). This evidence comes from a creature called Psittacosaurus (sit-taco-sore-us) which had a tail that looked like the end of a broom. Long, quill-like feathers gave Psittacosaurus' tail this appearance. This creature was an ancestor to both ceratopsians and pachycephalosaurs (pack-E-sef-O-low-sores), meaning that members of both groups could have had brush tails or even full body coverings in cold climates.
Iguanodonts, Hadrosaurs, and Other Ornithiscians
It is because of small ornithiscians (or-nith-ski-ans), like the one shown on the right, that we know that all dinosaurs shared a common feathered ancestor. Fossils have shown that these turkey to man size creatures were covered in feathery down, even as adults. However, it would appear that their later descendants the iguanodonts (i-guan-O-don-ts) and hadrosaurs (had-row-sores) did not possess this covering as adults. However, it is still possible that species living in colder climates retained the feathers. It is also unknown whether young animals in these groups had feathers or not.
Feathers
Primitive Theropods
It is largely unknown whether many of the primitive theropods (ther-o-pods) possessed feathers. However, many of these creatures were ancestors of creatures that are known to have feathers, meaning it is highly likely that these primitive dinosaurs had feathers at some point in their lives.
Ceratosaurs and Abelisaurs
There are several fossil skin impressions from both ceratosaurs (sair-a-toe-sores) and abelisaurs (a-belly-sores). These skin impressions show that these animals were covered in scaly skin and some even had crocodile-like scales to give them extra protection. Because of these fossils, it has always been thought that all ceratosaurs and abelisaurs entirely scaly. That changed with the discovery of Limusaurus (lim-oo-sore-us). Limusaurus was a ceratosaur unlike any other in the group. First off, it was a herbivore. All other ceratosaurs were carnivores. And secondly, Limusaurus was covered in downy feathers. This raises the possiblity that other ceratosaurs and their descendants the abelisaurs also had feathers, either for use as a display structure or when they were juveniles.
Carnosaurs
For a long time, it was thought that because they did not lay on the evolutionary path to birds, carnosaurs (car-no-sores) like Allosaurus (al-low-sore-us) and Giganotosaurus (gig-a-note-O-sore-us) were completely featherless. Then the creature Concavenator (con-kay-ven-ator) was discovered. Careful analysis of its arm bones revealed that Concavenator had quill knobs. Quill knobs can be found on some modern birds and are attachment points for feathers. Combine this fact with the shared common ancestor of all dinosaurs, and it seems likely that at some point in their lives, most carnosaurs had feathers.
Megalosaurs and Spinosaurs
Like the primitive theropods, there is no direct evidence of feathers on either megalosaurs (mega-low-sores) or spinosaurs (spy-no-sores). However, it is possible that young animals had downy coats, with mature animals only having feathers for display.
Prosauropods and Sauropods
There is no evidence that sauropods at any age possessed feathers covering their bodies. However, it is possible that some sauropods had feathers that functioned as display structures on the head, neck, body, or tail.
Raptor Dinosaurs
The evidence for the raptor dinosaurs having feathers is more abundant than in any other group of dinosaur except birds. This evidence can be found in a variety of species. Quill knobs have been found on the bones of Velociraptor, and entire skeletons of the tiny Microraptor (my-crow-rap-tore) have been found surrounded by fluffy feather impressions. These fossils show that many of these raptor dinosaurs had feathers that would have been capable of flight. This makes sense, given that raptors are the direct ancestors of birds.
Oviraptorsaurs and Ornithomimids
Like the raptor dinosaurs, the evidence for oviraptorsaurs (oh-vee-rap-tore-sores) and ornithomimids (or-nith-oh-my-mids) having feathers is abundant. Recently, a fossil of the North American ornithomimid Ornithomimus (or-nith-oh-my-muss) was found with feather impressions surrounding it. It has even been deduced that most oviraptorsaurs had a large fan of feathers on the end of their tails, most likely for display purposes. This was revealed by careful analysis of the end of the tail, which ended in a bone called a pygostyle. This is the same bone that the tail feathers of modern birds attach to.
Tyrannosaurs and Therizinosaurs
Evidence for feathers in tyrannosaurs (tie-ran-O-sores) and therizinosaurs (th-air-E-zin-O-sores) comes from various creatures in both families. However, in both groups, there are very large animals that are covered in feathers as adults. This raises the possibility that the largest members of each of these groups, Tyrannosaurus and Therizinosaurus (th-air-E-zin-O-sore-us), could have been covered with feathers as adults.
Conclusion
It is understandably that it is hard to accept new facts, especially when the new facts threaten cherished memories. However, we should accept these facts with open arms and put away the pitch forks and fire.
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Image Credits
All images have been cropped to fit the space required
All images are used under Fair Use laws
Image credits are listed from top to bottom and from left to right
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Tyrannosaurus rex
Original artwork by: RJ Palmer/arvalis
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The Age of Reptiles
Original mural by: Rudolph F. Zallinger
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Life, finds a way
Original film by: Universal Studios
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Yutyrannus
Original artwork by: Brian Choo
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Schleich Therizinosaurus
Original picture by: Schleich
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Schleich Velociraptor
Original picture by: Schleich
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Owen with Velociraptors
Original film by: Universal Studios
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JP Raptor Feathers 2
Original image by: Constantijn Van Cauwenberge
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ARK Tyrannosaurus
Original screenshot by: Liekeze
Taken in game: ARK: Survival Evolved
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Highlands Tyrannosaurus
Original screenshot by: Liekeze
Taken in game: Prehistoric Kingdom Demo
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Tyrannosaurus rex
Original model by: Robert? Sorry, I can't read the signature.
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Tyrannosaurus rex
Original artwork by: Fred the Dinosaur Man
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Giant Porcupine
Original artwork by: Chris Masna
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Wooly Pachyrhinosaurus
Original artwork by: Mark Witton
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Resting Pachycephalosaurus
Original artwork by: oghaki
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Rudolph the Red Nosed Hadrosaur
Original artwork by: Maija Karala
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Valdosaurus
Original artwork by: Mark Witton
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Cryolophosaurus
Original artwork by: H. Kyoht Luterman
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Limusaurus
Original artwork by: Sorry, but I could not find an original creator.
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Feathered Carnotaurus
Original artwork by: Ashley Patch/PLASTOSPLEEN
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Allosaurus fragilis
Original artwork by: Connor James Lachmenec/TheMorlock
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Concavenator
Original artwork by: Raúl Martín
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Megalosaurus
Original screenshot by: Liekeze
Taken in game: ARK: Survival Evolved
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Feathered Spinosaurus
Original artwork by: Tena/ImagineCorgis
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The Giant and Company
Original artwork by: R.Nicholls
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Dakotaraptor
Original screenshot by: Liekeze
Taken in game: Saurian
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Oviraptor
Original screenshot by: Liekeze
Taken in game: Primal Carnage: Extinction
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Gallimimus
Original screenshot by: Liekeze
Taken in game: The Isle
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Tyrannosaurus rex
Original artwork by: RJ Palmer/arvalis
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Therizinosaurus
Original screenshot by: Liekeze
Taken in game: The Isle
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Dr. Robert Bakker
Original artwork by: Chris Masna
One reason for the stubborn adherence to the reptile-like imagery is the representation of dinosaurs by the entertainment industry. Film, video game, and toy makers don't follow the scientific facts despite the abundance of evidence for feathered dinosaurs. Thus, people end up becoming attached to scaly movie monsters, not real animals. A good example from the toy industry are the dinosaur toys produced by Schleich. They are highly selective as to which dinosaurs they make scientifically accurate, and which ones they don't. This can be easily seen by comparing their Therizinosaurus (th-air-E-zin-O-sore-us) toy to their Velociraptor. Velociraptor, despite the direct evidence for it possessing feathers, looks like it was ripped straight out of Jurassic Park. On the other hand, Therizinosaurus, for which there is no direct evidence of feathers, is shown with a fluffy, feathery back.
An excellent example from the film industry is the recent film, Jurassic World. The first three films in the Jurassic Park franchise generally tried to follow the most recent scientific knowledge at the time. This meant that in 2001, with the release of Jurassic Park III, the famous Velociraptor got a complete redesign to match the view of raptor dinosaurs at the time. When Jurassic World was announced, people were excited at the idea of seeing the latest scientific knowledge brought to life. However, the film quickly dashed those hopes. Instead of having a fluffy and ferocious pack of Velociraptors, viewers were shown animals that were outdated by twenty years. According to some sources, Steven Spielberg did not feel that feathered dinosaurs were scary enough and approved the scientific inaccuracy. The image on the right shows just how scary looking feathers can be. Hopefully, Jurassic World: Fallen Kingdom will help bring Velociraptors back to the 21st century.
To give an example from the video game industry, one has to look no further than one of the most popular survival games of 2017, ARK: Survival Evolved. ARK is notoriously bad for their representations of dinosaurs and other prehistoric creatures. ARK's Tyrannosaurus is inaccurate in four key areas. The first is its size; it is over twice as large a the real animal. The second is its arms. No dinosaurs could rotate their wrists, restricting their hands to a "Clapping" position, palms facing each other. Third is the proportion of the head in comparison to the rest of the body, with the head being almost as large as the animal's torso. The final and largest inaccuracy is the body covering. Not only does ARK's Tyrannosaurus lack feathers, but it instead has weird, rock-like scales that give the animal a spotty appearance. It is this image of T. rex that is being imprinted, reinforcing the outdated view of dinosaurs. Thankfully, games like Saurian and Prehistoric Kingdom (shown on the right) are consulting with scientists prior to release and will hopefully help to change the view of dinosaurs in video games.
