(birds chirping) - [Mark] I think your fascination for dinosaurs certainly sets in as a child.

And if you're lucky, it never goes away.

(door creaking) (mellow music) Dinosaurs are bigger than life.

(door closing) They were creatures that were strange, that were fierce, that were scary, scary in a delightful, exciting way.

- [Narrator] Mark Hallett has spent decades bringing dinosaurs to life.

- [Mark] We can't produce any photographs of T-Rex.

We can certainly document the fossil finds with photography, but I think we need paleo art to be able to show what these things looked like when they were alive.

- [Narrator] He's earned his reputation in the world of paleo art, a term he's credited with coining.

- [Mark] Paleontological art combines both science and art in a very felicitous way.

You're basically using observable things and combining with the intuition and the inspiration of an artist to create things that no one has ever seen before.

I love this idea very much.

(soft upbeat music) I am creating a life restoration.

It was a saber-tooth cat found several years ago in South Dakota.

The cranium, or the upper part of the skull, it's very badly crushed.

However, we have the lower jaw.

This gives me a pretty good idea about size, but also each of these little bumps and grooves have meaning.

Scientific sleuthing and paleo art is a tremendously appealing thing for me because I love deducing what something would look like based on known observable facts.

This combined with the intuitive quality in being an artist is the best of both worlds.

It's a very grubby, beat-up book, but it's the original.

This book had a tremendous effect on my psyche as a child.

To me, they look almost like photographs of actual existing animals.

And it was a great shock to me when my father told me that dinosaurs were extinct.

But that was one of the things that made me draw them.

So I could, in my mind, make them real and make them understandable.

- [Narrator] The work of an earlier generation of paleo artists taught Mark that the art improves alongside the science.

- Our knowledge of prehistoric animals has changed quite a bit.

We know now that T-Rex holds its body in a horizontal mode rather than the more vertical one that we thought it was.

And it's quite possible that T-Rex had some kind of feather light body coverings that help keep heat in.

So it's very important to keep up with this kind of new information.

- [Narrator] With a career spanning nearly a half century, some of Mark's most beloved pieces have, well, gone the way of the dinosaur.

- A depiction of the Mamenchisaurus that I did for the Los Angeles County Museum of Art in 1986.

At the time, it was thought that it was a close relative of the so-called Diplodocus.

Well, as it turns out, it was not a Diplodocus at all.

The head that I've done for that particular painting is entirely wrong.

At some point, I want to change it.

That's the way it is in scientific illustration.

Nothing will ever stay the same, which is a very good thing.

- [Narrator] It's ironic then that the very painting Mark needs to fix is the one that caught Hollywood's eye.

(dinosaur roaring) - [Mark] Well, I was very happy when I got asked if I'd be interested in being a consulting artist.

The project was the first "Jurassic Park."

(uplifting music) I worked with the digital effects people on doing the very first concepts of dinosaurs, including T-Rex, including the so-called Raptors.

I wasn't the only person working there, but I filled in a necessary gap.

And it was a wonderful experience because I got to learn from these people.

I think I was able to help them understand what dinosaurs may have really looked like and how they may have moved.

Spielberg wanted to create the entity of the so-called spitter dinosaurs.

I kept being asked to refine my drawings and refine my drawings and make them smaller, but make them really scary.

And of course, making a dinosaur that could spit venom was considered a really cool idea.

And I think the results were pretty good, even though there was never any such dinosaur that existed.

(dinosaur roaring) - [Narrator] Mark also worked on Disney's "Dinosaur" and several documentaries on paleo life.

But his success didn't come easy.

- [Mark] What I have is a congenital birth defect.

My lower left arm and right lower leg are missing.

It's the way I came into the world.

So it really hasn't stopped me from doing what I want to do.

(film projecting clicking) (mellow music) When I was probably about six years old, my mother took me to the Natural History Museum in Los Angeles.

I had a impossibly uncomfortable and heavy prosthetic right leg.

The museum's main entrance had a series of steps that seemed to go on forever.

And I just looked at it and didn't think I could make it.

I just decided that I would overcome the discomfort.

I saw hulls of North American, African, Asian mounted animals and natural habitats.

And I was profoundly glad that I made the decision to overcome my discomfort in getting up there.

And it really awakened me very much.

Being a double amputee restricted my ability do some things, but then made me go in the direction of others.

Very much like water.

When it's blocked in one direction, seeks another.

(mellow music) (brush clanking) My newest book will be called "In Search of Big Cat Origins."

The book will take us from the earliest origins of cat-like animals, tracing their evolution and how they adapted as a master predators to become lions, tigers, leopards, and Jaguars that we know now.

- [Narrator] Now in his seventies, Mark is showing no signs of slowing down.

He'll soon start a book about horse fossils, and he'll finish work on that newly discovered saber-tooth cat.

And he spent the end of 2019 in India as a visiting lecturer at a school in the foothills of the Himalayas.

(mellow uplifting music) - [Mark] Clouds, because they're dimensional, you want to make sure that they have shadows.

Now I have a chance to show people how they can actually make careers out of science and art, which excites me very much.

I often liken myself to some kind of little fox or ferret snuffing around a series of doors.

And then I wait for one to open a crack, and then I put my nose in and see what kind of opportunity I can come up with.

Being able to have a unique career in science and art has been an extraordinary adventure.

I feel very fortunate that I could really do these things.

(mellow music)