Short answer: Because all artists paint with presumptions.
Scripture Reference: None
As part of my Noah’s Ark: Beyond Flannelgraph presentation, I typically show kids a Powerpoint slide of one of the more famous paintings of Noah’s Ark by Edward Hicks and ask the kids: What’s missing? Eventually, they realize that dinosaurs are missing. [It helps when Billy Behemoth, our sauropod sidekick, appears in the painting in the next Powerpoint slide transition!]
Well, keep in mind that paintings aren’t photographs. The distinction is important! No one photographed the animals going aboard the Ark, so the artist has to give us his interpretation of what it looked like.
There are actually 3 reasons dinosaurs have been left out of Ark scenes.
1. Evolutionary bias: Museums, children’s dinosaur books and media sources all assure us that there was an Age of Dinosaurs, when dinosaurs roamed the Earth millions of years ago; therefore, man and dinosaurs could not have co-existed. Compare this with the Biblical view that God created everything in 6 literal days a few thousand years ago, that all land animals including dinosaurs were created on Day 6 [the same day man was created]; therefore they must have co-existed. Since fossils were formed in the Flod of Noah’s day and we have dinosaur fossils, dinosaurs lived at the time of the Flood. And since God told Noah to bring aboard 2 of every unclean animal after their kind, dinosaurs would have been on the Ark as well. Unfortunately, artists have allowed evolutionary biases to determine which animals they put into the Ark scenes. Incidentally, this is also why a lot of paintings of Adam and Eve surrounded by animals do not show dinosaurs or pterosaurs!
2. Dinosaurs were re-discovered just prior to 1841 when Sir Richard Owen coined the word “dinosaur.” Before that, large reptilian creatures [and small winged reptiles!] were called dragons. Fossils had always been around and were considered  either curiosities formed by geological processes by God’s whim or  the remains of giants who perished in the Biblical Flood. Neither explanation was completely accurate. When fossils began to fascinate man scientifically and he began to realize they were the remains of creatures that no longer existed upon the Earth [except perhaps tucked away in some remote corner], the fossil boom began. One after another, new dinosaurs were discovered and sent to museums.
In Biblical perspective, Answers in Genesis has asked us to consider that there was not an Age of Dinosaurs. Rather there have been seven ages of dinosaurs, alliterated as 7 F’s.
- Formed – Dinosaurs were created on Day 6 with Man
- Fearless – Man and dinosaurs co-existed without fear in God’s perfect Creation.
- Fallen – Due to the effects of the Fall, carnivory begins. Since some dinosaurs eat meat now and since man is essentially meat, well…. the honeymoon is over!
- Flood – The Great Flood destroys all life except that aboard the Ark. The majority of fossils are formed at this time.
- Faded – The dinosaurs leave the Ark. Due to changes in climate and other factor [an Ice Age, for example] dinosaurs slowly go [mostly] extinct. Memories of dinosaurs as dragons take on some fantastical elements as the real creatures begin to fade from observable ecology.
- Fossils – As noted, scientists begin to discover dinosaur bones and realize they were a distinct class of creatures no longer seen on Earth.
- Fiction – he age in which we now live, where secular scientists, textbooks and museums tell us that dinosaurs lived millions of years ago, that they evolved into birds and other fictions.
This brief history of dragons/dinosaurs gives us another clue as to why dinosaurs were not included in Ark depictions: Namely, they had faded from memory and had been replaced [by degrees of storytelling!] by the iconic dragon which most folks thought of as fantastical and, well, made-up. Edward Hicks well-known painting was created sometime before he died in 1849 [just 8 years after the word dinosaur was coined and well before folks were even relatively sure what they might have looked like] and like most Ark paintings of that time and prior, Hicks simply painted the animals of his day. [Keep in mind that many folks still believed fossils were the bones of giants or odd rock formations made at God's whim for some time after dinosaurs were officially named by Owens and Hicks may have been one of these].
3. Ark depictions have become standardized. Truth be told, people have a certain image in their heads when they think of the Ark – and not all of it is accurate! Not only are dinosaurs and pterosaurs left out of the picture, often the Ark itself is drawn in these rather cutesy bathtub toy dimensions rather than the more realistic ones given in the Bible. So when you ask somene to draw Noah’s Ark, they typically paint or draw the one that most everyone thinks of, the one that has imprinted into our culture, whether it’s accurate or not. Fortunately, a lot of Creationist illustrators are trying to correct this cultural notion of the Ark.
So the next time you see a painting of Noah’s Ark, remember: it’s not a photograph. We should base our ideas of what the Ark looked like and what animals went aboard it based on what the Bible, God’s revealed Word, says – not the flawed opinions [and drawings!] of man.
-Rev Tony Breeden
For more information on the 7 F’s of Dinosaur Ages, I suggest the excellent book, Dinosaurs for Kids by Ken Ham. My kids really enjoyed this book. It not only got them talking about dinosaurs, but Heaven, salvation and the Gospel itself! It really shows how dinosaurs can be used as “missionary lizards.”