With mere days left until the gates to Jurassic World swing open, could there be a better time for scientists to discover the first evidence of fossilised dinosaur blood? (No!) Researchers from Imperial College London recently used state-of-the-art techniques to investigate eight ordinary-looking dinosaur bones. But what they discovered was anything but ordinary.

Materials scientist Sergio Bertazzo, palaeontologist Susie Maidment and their colleagues examined 75-million-year-old dinosaur specimens from the Natural History Museum in London. The fossils were pretty unexceptional – just scraps of bone from North America's ancient dinosaur graveyards that weren't even particularly well preserved. On closer inspection, however, the specimens revealed something remarkable.

By training the beam of a high-powered microscope on fragments from the claw of an unknown carnivorous theropod (beast-footed) dinosaur, the team found evidence for structures that closely resembled red blood cells.

In order to peer at the internal structure of these cells, Bertazzo and Maidment used a beam of ions – think James Bond-style lasers – to strip away minute atom layers one by one. Next came a method called serial sectioning, which was applied to a small sample of dinosaur bone. The technique actually destroys the sample by grinding it away one layer at a time, photographing each layer, and then using these photographs to reconstruct what the insides of the bone look like in 3D.

Even more hi-tech prodding revealed that these structures were almost identical in their chemical makeup to blood cells taken from a living emu, a bird that's thought to be a relatively close dinosaur relative. Taken together, the shape and chemistry of the cells confirmed that the team was looking at nothing less than the fossilised remains of dinosaur blood!

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The internal structure of the cell after several layers had been stripped away using the focused ion beam. Image: Susie Maidment

Alongside the blood cells, Bertazzo and Maidment also found evidence of collagen, a fibrous protein found in animal bones, cartilage, tendons and other connective tissue. Chemical analysis of the collagen showed that even some of its building blocks, 75-million-year-old fragments of amino acids, had been preserved!

This is the first time that such a combination of methods has been used to peer deep inside the remains of dinosaur tissues and investigate their chemistry. Findings like this, however, often generate debate among experts. Many members of the palaeontological community are convinced that soft tissues can't withstand the ravages of time for more than a few million years before decaying beyond recognition.

In recent decades, scientists have discovered everything from the original material of skin, to feathers, colour-bearing organelles and even muscle fibres preserved for millions of years in the fossil record – but the published reports of these findings have generated controversy. (Perhaps some of the best known and most controversial findings have been blood vessels and cells known as osteocytes in Tyrannosaurus rex.

But the authors of the new study are optimistic that the tide of scepticism is turning. “I think there's been a mounting body of evidence to suggest that soft tissues and original components are present in the fossil record. Although it's right that people are sceptical – that's part of the scientific method, after all – there comes a point where so many different lines of evidence point towards something being true that it becomes impossible to refute any more," says Maidment.

"I think there's an appetite for this right now and I think most people will accept our findings," she adds.

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Dino DNA? Not quite. Image: Universal Pictures

Palaeontological controversy aside, there's one important question that all Jurassic World fans will be bursting to ask: do these findings bring us any closer to discovering fragments of preserved dinosaur DNA? While Maidment is quick to dash our dreams of dino DNA, she's not ruling out the possibility. “Although we have identified structures we believe to be nuclei in the red blood cells, there is no evidence that there is any DNA in there. However, I think it is generally unwise in science to say 'never'." 

"Increasingly, studies like ours are showing that original components can be preserved over geological timescales. So perhaps one day DNA fragments might be found in an exceptionally preserved dinosaur fossil,” she adds.

And just because these particular bone samples didn't yield any DNA doesn't make the finds any less valuable. In fact, they're set to provide the groundwork for exploring how dinosaurs behaved and functioned as living, breathing animals like never before. For example, the discovery of red blood cells belonging to dinosaurs that aren’t closely related to their living descendants – birds – may help solve the long-debated riddle of whether they created their own heat (like mammals), or relied on the sun for warmth (like reptiles).

This is just the latest in a series of exceptional palaeontological discoveries that pushes the boundaries of what we thought possible for history to preserve. And the fact that it lay hidden in a collection of ordinary, apparently unexceptional bones is a hint that more discoveries await detection if we just look closer.

The new findings are reported in the journal Nature Communications.