[Lusotitan grumbling] -[Narrator] Lusotitan was a towering dinosaur that ruled Portugal in the late Jurassic, one hundred and fifty million years ago.

[grumbles] Known only from partial remains, it has rewritten the record in European palaeontology and posed a major mystery.

[slow, heavy steps] This Jurassic long necked titan is almost identical to dinosaurs found in the United States.

Despite the two countries being separated by thousands of miles of ocean.

So what was it doing here?

The most recent discovery of this colossus was made in the quiet Portuguese town of Pombal.

And it’s given experts their most complete picture yet of this island giant.

[metallic clank against rock] It’s remains are now being stored at a local school [machine whirring] where paleontologist Elisabete Malafaia is examining them in more detail.

And one stands out from all the others, a newly discovered enormous rib.

-[Elisabete Malafaia] When we start to excavate the ribs, the rib continue and continue and it seems that this rib never end and for the late Jurassic therapods this is the largest rib that we know in the world.

-[Narrator] The sheer size of these bones cement Lusotitan [Lusotitan bellows] as one of Europe’s largest dinosaurs but its features bear a striking resemblance to Brachiosaurus, another colossal long necked 40-ton goliath that roamed the Western United States.

[Brachiosaurus bellowing] [flying dinosaur screeches] It’s part of the sauropod family which also includes the titanic Diplodocus and Brontosaurus.

Brachiosaurus appears to be closely related to Lusotitan.

[crunch and gulps] And it’s this connection that has puzzled scientists for years.

It’s a mystery that has only deepened with another remarkable discovery.

[keys jingle] Housed at the Natural History Museum in Lisbon, is the near complete skeleton of an iconic American predator.

[dinosaur hisses] Also unearthed in Portugal.

Allosaurus, a therapod and relative of T Rex.

[guttural growl] -[Elisabete] Allosaurus is one of the most common therapod dinosaurs.

North American, but not in Portugal, this specimen was the first evidence of Allosaurus outside North America.

-[Narrator] The discovery of a Portuguese Allosaurus was the first time one single species of dinosaur was found in both America and Europe.

When it was unearthed, it amazed dinosaur experts across the world.

Along with Lusotitan, it led paleontologists to examine all the fossils discovered in Portugal for intercontinental relatives.

-[Elisabete] We discover other dinosaurs such as Stegosaurus, [dinosaur snarls] we have also Torvosaurus, we have Ceratosaurus we have almost the same dinosaurs we know with North America.

-[Narrator] With so many dinosaur species appearing on both sides of the Atlantic, [dinosaur grumbles] it’s led to an intriguing theory.

-[Elisabete] This suggests that during the late Jurassic, the land masses were connected by land bridges when these dinosaurs lived.

-[Narrator] Though America and Europe were once a single land mass by the start of the Jurassic they had been split by the newly formed Atlantic Ocean.

But Elisabete thinks these land bridges could have continued to connect the two continents for millions of years.

-[Elisabete] Land bridges could allow the dinosaurs to cross between what is now North America and Portugal.

-[Narrator] The Atlantic Ocean would eventually expand further and with rising sea levels these land bridges would be lost beneath the waves.

But they may ultimately be the key to solving the prehistoric mystery of how Portugal became home to the colossal Lusotitan.

[Lusotitan bellowing]