It was 53 feet long from snout to tail, 9 feet longer than the largest known dinosaur, Tyrannosaurus rex. The enormous dinosaur — named Spinosaurus after the ridge of bony spines on its back — has remained elusive, until now.

In 1912, German paleontologist Ernst Stromer von Reichenbach discovered Spinosaurus fossils in the Sahara desert, shipped them home, and put the assembled bones on display until the skeleton was destroyed in an Allied bombing raid in 1944. Since then, efforts to find another specimen have been unsuccessful. Fortunately, Stromer kept detailed, illustrated records, which led to a new discovery in the cliffs of Morocco.

The Nova/National Geographic documentary "Bigger Than T. rex," which premieres on Nov. 5 on PBS, tells the fascinating story of this lesser known dinosaur. With technology funding from the National Geographic Society, researchers have created a digital model of Spinosaurus, revealing what the carnivorous behemoth looked like, what it ate, and how it lived. 

Paleontologist Nizar Ibrahim, whose detective work was instrumental in solving the Spinsaurus mystery, shared his story with MNN.

MNN: When were the first new Spinosaurus bones found? What was your reaction when you heard they existed?

Nizar Ibrahim: I saw the first bones of the new skeleton in 2008. At the time I suspected that they might belong to Spinosaurus, but it was only when I saw other parts of the same skeleton in an Italian museum that I knew for sure. Realizing that we had a new skeleton of Spinosaurus in our hands was incredible. For me, it was a very special moment. Spinosaurus had become something of an obsession for me. I first read about this dinosaur when I was 6 or 7 years old and was determined to find a new skeleton one day. Ernst Stromer von Reichenbach has always been something of a "science hero" for me. When I began my life as a scientist, I decided to follow in his footsteps. I wanted to rediscover his lost world of Saharan dinosaurs, and that includes the "holy grail" of Saharan dinosaurs, Spinosaurus. The odds really were stacked against me when I tried to locate the man who found the new Spinosaurus skeleton. It was like looking for a needle in a haystack — or, better, a desert. So you could say luck was important. But I had "earned" that luck. I traveled back to the Sahara, attempting to do the impossible, and I was rewarded.

Why is North Africa such a good source for finding fossils?

Well, it is and it isn't. In the case of Morocco, some fossils, such as ammonites and shark teeth, are common. Partial skeletons of dinosaurs on the other hand are rare finds. One of the reasons North Africa has produced interesting fossils is that the lack of vegetation means that the rocks that entomb extinct animals are exposed at the surface and more easily accessible. On the other hand, the desert heat, sandstorms, snakes and scorpions make field work in North Africa very challenging at times.

What besides its size was so different about Spinosaurus?

Spinosaurus is the first — and only — dinosaur that spent a substantial amount of time in the water. Spinosaurus has long slender jaws, a giant sail on its back and powerful forelimbs. We are talking about an animal that looked very different from T. rex and other more "typical" predatory dinosaurs.

We all know about T. rex. Why haven't most of us heard about this dinosaur and Ernst Stromer's original discovery?

The only other partial skeleton was destroyed in World War II. Stromer and his work, faded from the scientific literature and, because no other partial skeleton was discovered for about 100 years, Spinosaurus never achieved the same kind of notoriety as T. rex.

What is the significance and impact of this discovery?

Spinosaurus is a reminder that dinosaurs are more adaptable and diverse than we give them credit for. Spinosaurus shows us that at least this one dinosaur invaded a world that no other dinosaur invaded, the world of rivers and deltas.

A model of the Cretaceous predator Spinosaurus gets rock star treatment at a photo shoot

A model of the Cretaceous predator Spinosaurus gets rock star treatment at a photo shoot. (Photo: Mike Hettwer, assisted by Mark Thiessen/National Geographic; dinosaur provided by GeoModel)

What can this fossil tell us about life in the Cretaceous that we didn't know before?

The new find shows us that the many predators that lived in the Cretaceous of Africa could coexist at the same time because they exploited different food sources. Spinosaurus was avoiding direct competition with the other giant predators by living in a different ecological niche.

What has computer technology enabled you to do that wouldn't have been possible before?

Adjusting the bones, reconstructing missing parts and so on was only possible by working with a digital skeleton. A digital skeleton also allows researchers to "put muscles on the bones" and estimate the shape, weight and weight distribution of the body.

Are there even bigger dinosaurs yet to be discovered?

Spinosaurus is the largest predatory dinosaur — about nine feet longer than the next largest predatory dinosaurs. That is a pretty good margin. But of course it is not impossible that one day we will find an even larger predator.

Nizar Ibrahim at a dig site

Paleontologist Nizar Ibrahim's research was key in unearthing the secrets of the Spinosaurus. (Photo courtesy of Nizar Ibrahim)

Tell us more about how your childhood interest in dinosaurs got you into paleontology. What do you love about it?

Yes, it all started with a book on dinosaurs. In paleontology, you get to combine different areas of research (zoology, geology, anatomy) and you can become a real life time traveler. You have an opportunity to discover lost worlds from the deep past of our planet, reconstructing the greatest story out there: the history of life on Earth. A story that leads to all living things alive today, including us.

Now that Spinosaurus has been found, is there a new 'holy grail' for you?

Sure, I have a few other projects in mind. It is difficult to top the Spinosaurus saga, but the Sahara is still full of treasures. Can't tell you about my new holy grail yet, though.

What do you hope viewers of the special take away?

I hope that they will see that real science and exploration can be far more exciting than any Hollywood adventure movie. The Spinosaurus story is one of risk taking, facing multiple challenges--and one of international collaboration. The Spinosaurus story is also one taking viewers on a journey through "deep time," to a "river of giants" flowing through what is now a barren desert. Understanding these incredible changes also acts as a reminder that our presence on this planet is a fleeting moment in a long sequence of events. Finally, I hope that people appreciate that dinosaurs were incredible successful, adaptable animals, not the lumbering, slow and stupid behemoths of old dinosaur books.

If you want to find out more about Spinosaurus, Ibrahim suggests these links:

Rare, ferocious and 'Bigger Than T. rex'
The enormous dinosaur — named Spinosaurus after the ridge of bony spines on its back — has remained elusive, until now.