"These fossils provide our only direct record of when and how our earliest vertebrate ancestors evolved" adds Dr Mark Purnell, one of the leaders of the study. "Did they appear suddenly, in an evolutionary explosion of complexity, or gradually over millions of years? What did they look like? in what ways did they differ from their worm-like relatives and how did this set the stage for later evolutionary events? Answers to these fundamental questions - the how, when and why of our own origins - remain elusive because reading the earliest vertebrate fossil record is difficult."
The scarcity of branches in this part of the evolutionary tree could reflect rapid, explosive evolution or the simple fact that, because they lacked bones or teeth, the earliest vertebrates left few fossils.
This is the area in which Dr Sarah Gabbott, who with Purnell conceived the Leicester study, is an expert: "Only in the most exceptional circumstances do soft-tissues, such as eyes, muscles and guts, become fossilized, yet it is precisely such remains that we rely on for understanding our earliest evolutionary relatives: half-a-billion years ago it's pretty much all our ancestors had."
The results published today in Nature, 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.
|Contact: Dr Mark Purnell|
University of Leicester