Sergio Bertazzo, a biomedical physical scientist at Imperial College London, examines a fossil containing structures that appear to be red blood cells. (Lauren Mekul via Reuters)

They looked, as one researcher said, like “rubbish,” eight seemingly inconsequential dinosaur fossils from the Cretaceous Period that sat in a London museum’s collection for more than a century after being found in Canada’s Alberta province.

But a fresh examination revealed the 75 million-year-old fossils to be quite remarkable, boasting microscopic structures that appear to be red blood cells containing nuclei as well as ropelike collagen fibers, scientists said last week.

It is extraordinarily rare for such ancient soft-tissue structures to be preserved as fossils, and some of the few similar discoveries in the past have been greeted with doubt.

It is even more surprising considering that these fragmentary fossils, from a number of different dinosaurs, are not especially well preserved, as were the earlier ones that harbored soft-tissue remains, the researchers said.

They conducted a series of examinations using sophisticated microscopes and sliced samples using a focused-ion beam to check the internal structures.

“We have attempted to apply the correct amount of skepticism, but, yes, I think it’s fair to say that neither of us can think of anything else that these structures might be,” said paleontologist Susannah Maidment, referring to her study co-leader at University College London, biomedical physical scientist Sergio Bertazzo.

Apparent red blood cells were found in a claw that may be from the forelimb of a gorgosaurus, a meat-eater that was 30 feet long. Other fossils from the collection at London’s Natural History Museum appeared to preserve remains of collagen, the main structural protein in various types of tissues including bone and skin, and fragments of the protein’s constituent amino acids.

But do not expect the findings to lead to the creation of live dinosaurs via cloning, as in the new “Jurassic World” film. “Although we have found dense internal structures that we have interpreted as nuclei in our cells, and the cells we found appear to preserve original components of blood, there is no evidence of any organelles or DNA within the nuclei,” Maidment said.

“But even if one was to find some fragments of DNA, we would not be able to reconstruct a dinosaur ‘Jurassic Park-style’ because we would need the complete genome to figure out where the holes in the DNA are,” Maidment said.

The research appears in the journal Nature Communications.