The researchers, from the Department of Geology at the University of Leicester, UK, devised a new method for extracting information from 500 million year old fossils.
They studied the way fish decompose to gain a clearer picture of how our ancient fish-like ancestors would have looked.
Their results indicate that some of the earliest fossils from our part of the tree of life may have been more complex than has previously been thought.
According to Dr Rob Sansom, lead author of the research paper, "Interpreting fossils is in some ways similar to forensic analysis. We gather all the available clues to put together a scientific reconstruction of something that happened in the past."
"Unlike forensics, however, we are dealing with life from millions of years ago, and we are less interested in understanding the cause or the time of death," he said.
"What we want to get at is what an animal was like before it died and, as with forensic analysis, knowing how the decomposition that took place after death altered the body provides important clues to its original anatomy," he added.
Fish-like fossils from half a billion years ago are recognized as being part of our evolutionary history because they possess characteristic anatomical features, such as a tail, eyes and the precursor of a backbone.
"It seems contradictory, but decomposition is an important part of the process by which animals become preserved and fossilized, so by knowing how these important anatomical features change as they rot, we are better able to correctly interpret the most ancient fossils representing the lowest branches of our part of the evolutionary tree," Sansom said.
"These fossils provide our only direct record of when and how our earliest vertebrate ancestors evolved," said Dr Mark Purnell, one of the leaders of the study.
The results show that some of the characteristic anatomical features of early vertebrate fossils have been badly affected by decomposition, and in some cases may have rotted away completely.
Knowing how decomposition affected the fossils means our reconstructions of our earliest ancestors will be more scientifically accurate.