"The evolution of segments may have led to a transformative innovation" in animal movement that paved the way for an explosion of life in the Cambrian period
that followed, the paper argues.
Furthermore, this also proves that even before the Cambrian period
, animals have already gained the ability to move across the seafloor.
We know this, at least in part, through the fossil record of marine invertebrates left behind since the Cambrian period
. Remarkably, extreme events of diversification and extinction happen more frequently than a typical, Gaussian, distribution would predict.
This is a fossilized trilobite Aldonaia from the Cambrian Period
We have proved that this happened in the middle of the Cambrian period
, at the time when the first terrestrial animals appeared, "says Jennifer Morris of Bristol University.
"Our results show the ancestor of land plants was alive in the middle Cambrian Period
, which was similar to the age for the first known terrestrial animals."
Paleontologists from the Royal Ontario Museum and the University of Toronto have revealed more insight into the Habelia optata--a sea predator which belongs to the arthropods and lived during the middle Cambrian period
about 508 million years ago--from fossil records found in the Burgess Shale fossil deposit in British Columbia.
The search for fossils from such ancient times, 60 million years before the Cambrian period
and its burst of multicellular evolution, has yielded tantalizing bits but nothing with details like this specimen.
The prior oldest known primitive sponge fossil only dated to 530 million years ago, in early Cambrian period
Although the evolutionary origins of fish and fishlike animals can be traced all the way back to the Cambrian Period
(about 515 million years ago), those earliest primitive vertebrates were soft-bodied and lacked many of the features (including scales, bony bits, and jaws) that characterize the later fossil record.
To say that the fauna of the Cambrian period
appeared in a geologically sudden manner also implies the absence of clear transitional intermediates connecting the complex Cambrian animals with those simpler living forms found in lower strata.
Fossilized records from the Cambrian Period
, which occurred between 540 million and 485 million years ago, provide glimpses into evolutionary biology when the world's ecosystems rapidly changed and diversified.