February 8. The Chengjiang fauna

Chengjiang, in Yunnan, southwest China, is one of the most celebrated and important fossil localities in the world. When well-preserved soft-bodied animals were found there in the 1980s, they were immediately compared to the famous Burgess Shale fossils that we’ll talk about in a few days. And at about 525 million years old, they were found to be about 10 million years older than the Burgess fauna.

Maotianshania cylindrica, a nematode worm.

This was a big deal – because the Burgess shale animals were practically unique in the world. With the discovery of Chengjiang, the record of early Cambrian life forms expanded in time as well as space. Many of the fossils in China are the same types as those in the Burgess Shale, and these critters are critical to our understanding of the Cambrian Explosion.

The life that lived in the Cambrian of China included trilobites, as well as sponges, jellyfish, lots of kinds of worms, and importantly, the oldest probable chordates. Chordates have notochords, a linear arrangement of nerves that in vertebrates like us has evolved into our backbone and spinal chord. This means that the ancestors of modern birds, reptiles, fish, amphibians, and mammals – and us – are pretty ancient, at least 525 million years old.

I would encourage listeners to check the links below to sources for more information and photos of the Chengjiang fauna.

Photo by SNP under GFDL. 

Update (April 2014): New arthropod with cardiovascular system reported
http://en.wikipedia.org/wiki/Maotianshan_Shales
http://www.fossilmuseum.net/Fossil_Sites/Chengjiang.htm