A research group headed by Jennifer A. Dunne of the Santa Fe Institute investigated food webs in the Cambrian era, and discovered that they are remarkably similar to food webs among species today.

The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions among metazoan species.

Only some assemblages of animals from the Chengjiang and Burgess Shale Cambrian era (about 540 to 525 million years ago) were well preserved enough to permit such a study. But among these they found

Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web. Most aspects of Cambrian food-web structure are well-characterized by a simple “niche model,” which was developed for modern food webs and takes into account this scale dependence.

The few differences the researchers observed in these cases may relate to the fact that the number of phyla (basic body plans) is about the same hundreds of millions of years later, but there are many more species within some phyla today. Here are some other stories about the Cambrian era:

Cambrian explosion

The Smithsonian secretary vs. the Cambrian explosion (February 19, 2008)

Cambrian explosion ecosystems closely resemble today's (May 7, 2008) Cambrian explosion. See also big bangs in biology