Stunning fossils of the Grand Canyon reveal strange experiments of evolution

A stunning new find from the Grand Canyon fills some of the gaps from the time when evolution began to experiment with strange new forms.

About half a billion years ago, life on Earth really began to prepare for the case, which we now call the Cambrian explosion. The fossils of that time show a surge of strange, complex creatures appearing over a relatively short period of time, laying roots for most of the main animal groups that exist today.

It is disappointing that fossils of the later Cambrian period are less common, so we do not have a clear image of the second experimental album of evolution.

But a recently discovered batch of extremely well-preserved fossils can patch this gap. They are about 505 million years old - 3 million years younger than the Burgess slate, the layer in which fossils from the Cambrian explosion appear.

Related: The first explosion of life on Earth struck deep below the surface

The team, led by researchers from the University of Cambridge, discovered more than 1,500 small carbon fossils in samples from the Bright Angels Formation (BAF) of the Grand Canyon, which was once a shallow marine environment. The vast majority of fossils are apulid worms, along with a couple of hundred crustaceans and several mollusks.

Although there were many environmental resources at that time, competition also grew, rewarding species that exploited new niches. Analysis of these fossils revealed many devices to do just that.

For example, it was discovered that a species of worms called Kraytdraco spectatus was covered with teeth occupying complex threads, which differed in shape and length depending on where they were on the body. Researchers suggest that they used their simpler teeth to scrape and rake surfaces, knocking out food particles that they could then filter out of the water with longer threads.

The crustacean fossils had signs of feeding suspension through tiny hairs that pushed food particles to the mouth to be crushed by molar structures.

Meanwhile, the mollusks had rows in the shape of a shovel of teeth that could be dragged from front to back to scrape algae or microbes from surfaces.

The Cambrian explosion attracts a lot of attention because it is so well represented in fossil records, but it was only the beginning. The recently described fossils, with their exceptional level of preserved details, give a fascinating idea of the time shortly after, when the difficult life was established and comfortable, and had the stability to start innovating with new forms.

And we should be glad that this happened: most of the main groups (or types) of animals originated during the Cambrian. This includes arthropods, which include all insects, arachnids and crustaceans. And there is a chordate that includes us and the rest of our brothers.

The competitive period of the late Cambrian could strengthen the strategies that helped animals remain successful half a billion years later.

"If the Cambrian explosion laid the foundations of modern adaptive solutions of metazoa, it was the scaling of their competitive interactions that may have provided targeted, long-term trends of functional innovations in the Fanerozoic biosphere," the researchers write.