In a scene similar to the Jurassic Park film, scientists at the Imperial College London have found what seem to be remnants of connective tissue and red blood cells in fossils of dinosaurs dating back to 75 million years ago.
Researcher Dr. Susannah Maidment and her colleagues at Imperial examined a fossilized claw of a dinosaur. A chemical analysis of the specimen revealed small ovoid structures with a dense inner core which, according to the scientists, resembled red blood cells.
The researchers also studied a fragment of a fossil that had fibrous features with a banded structure that resembled collagen found in the skin, tendons and ligaments of most present-day animals.
While this may not be the first time such evidence was found in unearthed dinosaur fossils, Maidment said that what makes their findings different is the quality of soft tissue components in the specimens.
She explained that previous studies presented soft tissues that appeared to be exceptionally fossilized, leading scientists to question how they became that well preserved.
The fossils featured in their study, however, were left mostly in a poor state of preservation as they were kept in the collections of the London Natural History Museum for over a century.
"They're very scrappy, individual broken bones. I can't even tell you what dinosaur they come from," Maidment said in a recent interview.
"If you're finding soft tissues in these kinds of fossils, maybe this kind of preservation might be more common than we realized, and might even be the norm."
The structures on the specimens were not fossilized, but instead they appear to be genuine soft tissue remnants.
In their chemical analysis of the remains, the researchers used a mass spectrometer to identify the presumed collagen protein as well as the blood cell remnants. They discovered that the collagen contains a substance that resembled amino acids, which are the basic components of all proteins in living organisms.
The chemical composition of the red blood cells closely resembled the red blood cells recovered from an emu. This provides an interesting insight as emus, just like most birds, are considered direct descendants of dinosaurs.
Maidment pointed out a well-known trait among individual groups of vertebrate: the smaller the red blood cell, the faster its metabolic rate is.
She said that animals with faster rates of metabolism are often warm-blooded, whereas those with slower metabolism rates tend to be cold-blooded.
For decades, paleontologists have tried to determine if dinosaurs were warm-blooded or cold-blooded as this can provide vital information on the lifestyles these pre-historic animals had.
The researchers noted that red blood cells obtained from the specimen were smaller compared to the red blood cells from an emu, but dinosaur blood cells would have reduced in size and curled up over a long period of time.
Scientists also need a larger sample of dinosaur blood cells in order to study the potential connection between the red blood cells from the specimen and the metabolic rate of dinosaurs.
"If we can find red blood cells in lots of different dinosaurs and measure them, we might be able to start to understand which dinosaurs had fast metabolic rates, which were approaching warm bloodedness, which were truly warm-blooded, and which were cold-blooded," Maidment said.
Further study on the collagen fibers is needed to help explain the relationships between different species of dinosaurs.
The unique structure of its collagen molecules could be determined through a process called collagen fingerprinting.
Maidment said closely related animal species tend to have similar collagen structures compared to those that are distantly related.
If they could retrieve collagens from different dinosaur species, according to Maidment, then they could identify a form of relatedness within the family tree of the dinosaur.
"We still need to do more research to confirm what it is that we are imaging in these dinosaur bone fragments," Dr. Sergio Bertazzo, co-author of the study, said.
"If we can confirm that our initial observations are correct, then this could yield fresh insights into how these creatures once lived and evolved."
The Imperial College London study is published in the journal Nature Communications.
