Re: With enough information, would it be possible to grow/create a baby dragon?

This is a really fun question. In the title to your question, you ask "with enough information, wouldn't it be possible to grow/create a baby dragon."

The premise of your question then becomes whether we currently know enough to say whether or not this is possible, if we were able to get additional information. For purposes of answering this question, we will assume that money is no object, and that we have as much money as we need to do this.

The answer really depends on what you mean by dragon. Dragons are mythological creatures that have never existed. They fulfill some kind of human psychological need in myths and legends. They are something powerful, terrifying, and rarely seen. A hero who slays one, or even outwits one, has done an epic deed.

Western dragons, as depicted in artwork going back centuries, and going back decades in film, have specific characteristics that everyone generally agrees upon when showing them.

1. They breathe fire.
2. They are large flying reptiles.
3. They have four legs.
4. They have long necks, and teeth that are usually more like those of a mammal rather than a reptile.
5. They are intelligent, often portrayed as more intelligent than people.
6. They live a long time.
7. They are very fast, very strong, and very hard to kill.

I think that is pretty much the list. Some of it might be negotiable. Let's see if there is anything in modern biology that rules out any of this.

Fire is the real showstopper here. There is no biological mechanism that would explain an animal breathing fire. It has never, ever been seen in nature. Is this something that we could create if we had sufficient knowledge?

We know that fire needs three things (think of the "Fireman's Triangle"). To have fire, you need fuel, oxygen, and heat. Remove any one of those things and you snuff the fire (or it never starts).

A fire-breathing animal would have to eject some kind of flammable liquid or gas (fuel) into the air (oxygen). The oxygen part is easy. There is plenty of oxygen in the atmosphere.

What biological mechanism would allow an organism to store flammable liquid or gas?

We know that living organisms produce methane (natural gas) due to fermentation by bacteria in the gut. Cows exhale a lot of methane when they burp. It is actually a serious source of a major greenhouse gas. There is current work to attempt to formulate feed for cows that will reduce methane production. Please see:

http://www.nytimes.com/2009/06/05/us/05cows.html

A Google search will turn up more articles along these lines.

So imagine that our knowledge of biology is sufficient to create an animal that has a special methane-sequestering bladder that leads to its upper respiratory tract. When the animal wants, it can exhale a puff of pure methane. You wouldn't want any oxygen in the puff, or if the methane ignites, the whole animal would blow up like the Hindenberg. You would want the animal to have a good set of reflexes or other mechanism to make sure that it didn't inhale right after it did this.

Does that solve the problem? No, we still need heat. How much heat does it take to ignite a fuel-air mixture for various fuels? That temperature is called the auto ignition temperature. Here is a table:

http://www.engineeringtoolbox.com/fuels-ignition-temperatures- d_171.html

For methane, it's 1076 F or 580 C. There is no part of any living animal that has ever been anywhere close to that temperature. Looking through the table, there are a lot of fuels, some with lower auto-ignition temperatures than methane. All of the temperatures are far above any temperature ever reached in a living organism that wasn't holding something already on fire.

So, if your definition of a dragon means that it has to breathe fire, you are not going to get one no matter how much we learn about biology.

If you are willing to give up on the fire breathing, we move on to the next most difficult part of making a dragon: making a four-legged reptile with wings.

This is a difficult problem, because all terrestial vertebrates (animals with backbones) are variations on a single body plan, the tetrapod (four-limbed) body plan. The first tetrapods were lobe-finned fishes, appearing in the late Devonian period, about 380 million years ago.

A Google search on tetrapod evolution will turn up a wealth of information on this subject. This is not really my area, so I suggest that you just look around for basic information on the web, or visit a Natural History museum or your local library.

Right away you might think that you can think of animals that don't have four legs, birds for example. However, the wings of a bird are its front legs. If you look at the skeleton of a bat it will be immediately clear that the wings are its front legs. You can see that the "fingers" are actually the spines that run down a bat's wings.

What about snakes? They don't have any limbs at all. Or do they? In some snakes, there is a pair of rudimentary hindlimbs that is apparent on close inspection. Some species of snakes have a pelvic girdle.

This is a big problem in making dragons. The body plan for a dragon includes a pair of hindlimbs (back legs) which is easy. There is a pair of front legs, which is also easy. It is our heritage as tetrapods!

The really big problem is having both front legs and wings. There are no vertebrate animals, including extinct species, that ever had six legs, or more specificially, both wings and front legs.

You are asking for a variation in the body plan of vertebrates that has never existed in vertebrates. It is not entirely beyond our knowledge, however. Can we find any animal that has both wings and front legs? More generally, can we find any example of an animal that has two appendages in the same segment?

That is very easy. Having two appendages in the same segment is common among arthropods. Arthropoda is the biggest phylum in the animal kingdom, with more species than just about everything else put together. The average animal species is an arthropod. An arthropod is an invertebrate animal with an exoskeleton. Arthropods include many extinct forms, but also spiders, insects, millipedes, and crustaceans (crabs, shrimp, etc.).

There is a concise summary of arthropods on Wikipedia. A Natural History museum or your library can provide more information.

I raise the subject of arthropods because early arthropods, and many living ones, have biramous appendages, that is, there are two appendages per segment. The dorsal appendage is a gill branch (in early marine forms) and the ventral appendage is a leg branch. In later arthropods the appendages are absent in the posterior segments, and the gill branch may be specialized into a wing. If you look at a dragonfly, you will see that anteriormost thoracic segment, with the most anterior of three pairs of legs, has a set of wings as well. The next segment back has both wings and legs as well. Look at a housefly or a Drosophila (fruit fly) and you will see that there are only two wings instead of four (which is why they are called Diptera, two wings). There is a tiny vestigial wing called a haltere in place of the mesothoracic wing.

There is a short description of biramous appendages in arthropods on a site at Berkeley.

So, it is not impossible to have two appendages in the same segment. Vertebrates last shared a common ancestor with arthropods around 600 million years ago. By way of comparision, the mammalian lineage diverged from the avian (bird) lineage about 300 million years ago, not that long after the first tetrapods (380 million years ago).

Because your question gives us the possibility of getting all the knowledge that we need, I will say that it is not impossible to make a vertebrate with both forelimbs and wings. It is far beyond our current knowledge, however.

I am afraid that I will have to say that it is a real stretch of the imagination to say that any animal proportioned like a fantasy dragon would ever be able to fly. There have been flying reptiles, well known in the fossil record and to fans of movies featuring dinosaurs. Do a Google search for pterosaur and you will see some good images.

Look at how small the body is compared to the wingspan. Look at birds and bats. None of them are proportioned anything like fantasy dragons with the dragon's massive body and relatively small wings. The big flying reptiles in Avatar are proportioned slightly more realistically, but also live on a planet with lower gravity.

Some of the rest of the stuff on our list of dragon traits is relatively easy. A Komodo Dragon is about the right size for a small dragon, about ten feet long, but the head is like a monitor lizard's instead of like a fantasy dragon's. The teeth are wrong, too. The neck is too short. This is all minor stuff.

Most reptiles don't seem to be very smart, though. If you are willing to give up on this, we might get somewhere.

In summary, if you want something that looks more or less like a fantasy dragon, that isn't very smart, that can't fly, and doesn't breathe fire, it could be done. Given these limitations, the hardest part would be making a vertebrate with two pairs of forelimbs, both wings and legs.

Thank you for a great question!

Yours,
Paul Szauter
Mouse Genome Informatics

Admin note: A wyvern, which is similar to a dragon, has two wings and two legs. There are only 4 limbs in total, as opposed to 6 for a traditional dragon. A wyvern would probably be easier than a dragon, if you don't mind the lack of separate arms.

See: http://www.mythicalrealm.com/creatures/dragon-wyverns.html

Sanjida Rangwala, MadSci Moderator