Until this year, the Bryozoa were missing from the list of Cambrian organisms. Although some had been previously reported, critical scrutiny showed that they were misidentified and that the oldest known bryozoans came from Lower Ordovician strata. This year, however, Upper Cambrian bryozoans were reported from the lower Tinu Formation, southern Mexico. They were said to be about 8 Ma years older than the oldest Ordovician fossils. This means that Cambrian strata can be said to record examples of all the skeletalized metazoan phyla.
"One mineralized group, the phylum Bryozoa, seems to have "missed" the Cambrian radiation. [. . .] As discussed below, Late Cambrian bryozoans are now known, and have features that suggest they lie near the base of the bryozoan lineage."
"Bryozoa", from Ernst Haeckel's Kunstformen der Natur, 1904 (source here)
In view of the ecological perspective this blog has been giving to the appearance of organisms in the fossil record (see here), it is worth highlighting the ecological significance of bryozoans. This is brought out in the following paragraph:
"Bryozoans are an important Paleozoic-Holocene phylum in substrate stabilization, as a food source and major filter-feeding group, as rock formers, and as a component of a new Late Ordovician habitat - animal-constructed reefs. Late Ordovician bryozoan-coral-stromatoporoid reefs were colonized by high-diversity faunas. These reefs replaced earlier, microbially formed, thrombolite reefs. The Tinu Formation shows that Bryozoa, as all other mineralized metazoan phyla, had a Cambrian origin, although Bryozoa formed only small Early Ordovician reefs."
The Cambrian, then was a remarkable period of Earth history. In the Precambrian, we have only soft-bodied organisms. At the end of the Cambrian, we have all the skeletalized metazoan phyla and much more besides. Subsequent periods of Earth history may have had more dramatic radiations at the Order, Class or Family level, but there were no further bauplan innovations affecting skeletalized metazoan organisms.
This phenomenon has long been troubling for the Darwinian paradigm. The branching pattern of speciation endorsed by Darwin and his followers implies that Family, Class, Order and Phylum categories emerge as later stage developments of the evolutionary process. What we see in the fossil record, however, is the opposite of this. We start with discontinuity of body plans, followed by diversification - as variation around a theme. Darwinists have never confronted their theory with the facts - they exhibit all the characteristics of Kuhnian 'normal science' that will force-fit anomalous data to theory. For more on this and the 'inverted cone of diversity', go here.
Cambrian origin of all skeletalized metazoan phyla - Discovery of Earth's oldest bryozoans (Upper Cambrian, southern Mexico)
Ed Landing, Adam English and John D. Keppie
Geology, June 2010, 38(6), 547-550 | doi:10.1130/G30870.1
Abstract: Exquisite Pywackia baileyi Landing n. gen. and sp. specimens from the lower Tinu Formation, southern Mexico, extend the bryozoan record into the Upper Cambrian. They are ~8 m.y. older than the purported oldest bryozoans from South China, and show that all skeletalized metazoan phyla appeared in the Cambrian. The new form differs from similar, twig-like cryptostomes by its shallow autozooecia and an elongate axial zooid, which may be homologous to the stolon in nonmineralized ctenostomes. It may morphologically resemble mineralized stem group bryozoans that retained a stolon-like individual, although an ability to bud was acquired by the feeding individuals (autozooids). The latest Cambrian origin of bryozoans, several mollusk classes (polyplacophorans, cephalopods), and euconodonts was a major evolutionary development and can be considered the onset of the Ordovician radiation of more complex marine communities.
|<< <||> >>|
Evolution has become a favorite topic of the news media recently, but for some reason, they never seem to get the story straight. The staff at Discovery Institute's Center for Science and Culture started this Blog to set the record straight and make sure you knew "the rest of the story".
A blogger from New England offers his intelligent reasoning.
We are a group of individuals, coming from diverse backgrounds and not speaking for any organization, who have found common ground around teleological concepts, including intelligent design. We think these concepts have real potential to generate insights about our reality that are being drowned out by political advocacy from both sides. We hope this blog will provide a small voice that helps rectify this situation.
Website dedicated to comparing scenes from the "Inherit the Wind" movie with factual information from actual Scopes Trial. View 37 clips from the movie and decide for yourself if this movie is more fact or fiction.
Don Cicchetti blogs on: Culture, Music, Faith, Intelligent Design, Guitar, Audio
Australian biologist Stephen E. Jones maintains one of the best origins "quote" databases around. He is meticulous about accuracy and working from original sources.
Most guys going through midlife crisis buy a convertible. Austrialian Stephen E. Jones went back to college to get a biology degree and is now a proponent of ID and common ancestry.
Complete zipped downloadable pdf copy of David Stove's devastating, and yet hard-to-find, critique of neo-Darwinism entitled "Darwinian Fairytales"
Intelligent Design The Future is a multiple contributor weblog whose participants include the nation's leading design scientists and theorists: biochemist Michael Behe, mathematician William Dembski, astronomer Guillermo Gonzalez, philosophers of science Stephen Meyer, and Jay Richards, philosopher of biology Paul Nelson, molecular biologist Jonathan Wells, and science writer Jonathan Witt. Posts will focus primarily on the intellectual issues at stake in the debate over intelligent design, rather than its implications for education or public policy.
A Philosopher's Journey: Political and cultural reflections of John Mark N. Reynolds. Dr. Reynolds is Director of the Torrey Honors Institute at