The Cambrian explosion was an extraordinary phenomenon in the evolution of life on the planet that led to the emergence of many animal phyla and the diversification of species. During this period, some 530 million years ago, most of the basic body plans of organisms that have survived to the present day emerged. However, this great explosion of life that changed the evolutionary landscape on Earth may have occurred millions of years earlier than previously thought, a hypothesis now reinforced in a study published in the journal Geology .
This is a main conclusion of a new study that analyses the body profiles of organisms - symmetry, segmented bodies, exoskeletons, etc. - from around 545 million years ago by analysing trace fossils, which are the fossilized marks in rocks and sediments left by the activity of organisms in the past.
The authors of the article are the experts Olmo Miguez-Salas, from the Faculty of Earth Sciences at the University of Barcelona, and Zekun Wang, from the Natural History Museum in London (United Kingdom).
Fossil traces of extinct animals
The Cambrian explosion is a unique period in the history of life that poses many unanswered questions. To delve into the biodiversity of this period, most studies in palaeontology tend to focus on the study of organisms that had hard parts. However, the study of trace fossils (or ichnofossils) opens up the possibility of discovering what the activity of hard-bodied, soft-bodied or skeletally deficient organisms preserved in the stratigraphic record was like.
"The trace fossil record provides valuable information about evolutionary periods when soft-bodied fauna were dominant", says Olmo Miguez-Salas, a Beatriu de Pinós postdoctoral researcher at the UB's Department of Earth and Ocean Dynamics. "Fossil traces reflect the behaviour of the organism that generates them, which is determined by habitat and responses to environmental stimuli. Therefore, they are an indicator of the palaeoecological conditions in which the organisms that generated them lived".
