Ordovician faunas of Burgess Shale type

Dudley Smith

It appears paleontologists have discovered another amazing fossil location in the world where soft-bodied animals from the early radiation of animals are preserved. Before the Cambrian explosion (ca. 530 million years ago, Mya) life as indicated by the fossil record was apparently, largely unicellular and then suddenly and abruptly highly diverse lifeforms appeared.

The new early animal fossils are early Ordovician (500-440 Mya) in the period following the Cambrian and are preserved in exquisite detail similar to the famous, and previously considered unique, Canadian site - the Burgess shale - that Stephen Jay Gould wrote about in Wonderful Life (1989). At the Cambrian explosion all the early bauplan (German for building plan, blueprint) of animals were laid down for subsequent elaboration and seemingly a bizarre reduction in complexity from the initial highly diverse Cambrian lifeforms. It had been considered that after this diverse assemblage of life was generated then many lineages quickly went extinct but I think this new work demonstrates these extinction events were perhaps not as abrupt as previously thought.

Readers on here can be heartened the work was an international collaboration with a big input from Irish scientists including UCD's Patrick Orr and especially when you consider Yale's Derek Briggs is a TCD graduate. Briggs is famous for documenting the Burgess shale with Simon Conway Morris and others including Orr which are bizarre critters and take for example, Hallucigenia cf. http://en.wikipedia.org/wiki/Hallucigenia

A post-doc, Peter Van Roy appears to have championed the site and is to be congratulated as it is a precious window back in time to the dawn of animal life on this planet and will be invaluable in studying early animal evolution and it's subsequent radiation.

From :http://www.ucd.ie/news/2010/06JUN10/010610_fossil_discovery.html

Fossils discovery fills 30-million-year gap in evolution of early life
According to new findings published on the cover of the leading journal Nature, UCD scientists working with colleagues in Yale University, England, France and Morocco have shown that various groups of marine animals thought to have died out about 500 million years ago actually lived for another 30 million years or more.

The findings were published as the cover story in the leading journal Nature. The researchers found more than 1500 fossils of marine creatures, such as this cheloniellid arthropod, that lived nearly 500 million years ago.

By discovering fossils of soft bodied organisms like worms, sponges, and various types of soft-shelled arthropods, including the oldest horse shoe crabs, in the Fezouata Formations in the Draa Valley north of Zagora in southeastern Morocco, the team has provided the first examples of these ancient animals outside of classic older localities such as the Burgess Shale in Canada, which dates back 505 million years.
Until now, no other match for the fossils such as in the Burgess Shale had been found. Some scientists had speculated that the various groups may have gone extinct during that period due to a mass extinction event. While others believed that the exceptional preservation required to preserve them was so infrequent that it would be difficult to duplicate. With this latest discovery, the scientists have shown that these marine floor animals lived for at least another 30 million years.
The lead author of the scientific article Dr Peter Van Roy, a postdoctoral researcher at Yale University, recently completed a two-year IRCSET EMPOWER Postdoctoral Fellowship at UCD School of Geological Sciences. He first recognised the significance of the fossils almost a decade ago. Since then, he has worked with local Moroccan geologists and a team of researchers from Ireland, the UK, France and the USA to document the incredible diversity of the fossil discoveries.
“We know that the fossil record is an important record of life, but it is an incomplete record,” says Dr Patrick Orr from the UCD School of Geological Sciences, University College Dublin one of the scientists involved in the findings published in Nature. “It makes interpretation of the progress of early evolution very difficult, akin to trying to assemble the plot of a film using only intermittent still images.”
According to Orr, there was an explosion of new life forms during the Cambrian period – about 540 million years to 490 million years ago – with the shales revealing soft-bodied animals, and then the record went blank.
With these new Moroccan fossils the evolutionary story continues. It shows many of the animals from the Cambrian survived and multiplied into the next period, the Ordovician.
“This discovery is a landmark in evolutionary research, and provides a new window on the history of life,” says Orr.

Journal Reference:
Peter Van Roy, Patrick J. Orr, Joseph P. Botting, Lucy A. Muir, Jakob Vinther, Bertrand Lefebvre, Khadija el Hariri, Derek E. G. Briggs. Ordovician faunas of Burgess Shale type. Nature, 2010; 465 (7295): 215 DOI: 10.1038/nature09038