The Cambrian Mystery

[Anomalocaris]

It is no longer believed that there were so many phyla during that time. All forms from Cambrian appeal to fit within modern Phyla.

Thanks for the help, Chuck. This Mayr book from 2001 seems unfamiliar with those discoveries and modifications. I take it they have only developed within the past 15-20 years? Any good resources you could point me to for further investigation?

Actually, It's not entirely accurate to say they only developed within the past 15-20 years. The notion that most or all of known Cambrian fossil belonged within currently existent phyla had in fact been the orthodox interpretation of available fossil evidence amongst paleotonological community all along, and has been since the first major discovery of Cambrian fossils in early 20th century.

The new notion that many of the fossils actually represent previously unknown phyla fundamentally different for currently existent phyla was not based on any new evidence. Instead it is based radical reinterpretation of some of the earliest evidence ever found for Cambrian life. The new view was exciting to younger researchers because it appear to offer the opportunity for a radical change in the direction of the field, and with it many new career opportunities. But it gained relatively little traction with majority of established professional opinion.

Steven Gould, a major champion of the new view, was in addition to being a highly respected paleonotologist, also a world class science writer, science advocate, and polymath. He published beautifully written essays and books to argue his case to the general public. His popular science books made pretty high on New York Times best seller list. He position may thereby have gained visibility and currency with general public somewhat out of proportion to its acceptance amongst mainstream professionals.

The debate amongst professionals became rancorous and very public. An eminent, equally highly respected Cambridge paleotologist whose work Gould cited as a main support for his own position then published a equally well written, but scathing and no holds barred book repudiating Gould's position.

Soon Gould's acolytes and advocates from the rival, orthrodox camp were lobbing flaming books at each other. I have not read Mayr, but i suspect it might have been a shell fired in one of these barrages.

Part of the reason why the debate became so heated was for better part of a century, much of paleotological knowledge of the Cambrian fauna came from a single large haul of fossils discovered in Canada, near Banff national park, in early 20th century, called the Burgess Shale fossils. Burgess Shale, representing one moment in time during Cambrian and one location on earth, was 90% of what was known about Cambrian life. The world inferred from Burgess Shale fossils became known as the burgess fauna.

Since Burgess Shale fossil was all there was, Both sides simply looked at the same Burgess Shale fossils in different ways, and arrived at different conclusions about the burgess fauna, and from these inferred a differnt Cambrian world. Although the orthodox interpretation was never dethroned from its position, neither side could really convince the other.

But in the 1980s and 1990s, additional large hauls of Cambrian fossils were discovered in china and elsewhere. Instead of all from the same place and same moment in time, these new finds allowed pictures of cambrians fauna to be taken at different moments in time, both before and after Burgess Shale, and at widely different types of prehistoric localities. In addition paleotologists also went back to burgess shale and discovered more stuff that had been overlooked nearly a century ago, this allowed even the fossils already discovered at Burgess Shale to be better reinterpreted. These greatly fleshed out what is known about cambrians fauna. Instead of isolated specimens, now it become possible to find relationships between specimens, across time, and across different types of marine environment at different locations on earth. Soon comparison between Burgess Shale fossils and newly discovered fossils from china and elsewhere began to make it increasingly clear that many of Gould camp's interpretation of the structures and the orientations of the creatures found in Burgess Shale fossils were not correct. The interpretation that these fossils represented something radically different from existing fauna was not warranted.

I think Gould camp has clearly lost.