Some 6 years ago now I visited Mistaken Point, one of the most important Ediacaran localities in the world, which sits right at the bottom of the Avalon Peninsula, a couple of hours drive from St. John's. I was amazed and intrigued by the large and abundant fossils colloquially known as Pizza Disks which do indeed look a little like overloaded 12" deep crust pizzas.
Such structures have long been compared to forms that have been named in the equivalent rocks in the UK (The UK and Eastern Newfoundland once sat on the same terrane known as Avalonia). These obscure and enigmatic fossils have very little internal detail. I first came across such forms in the Charnian of Leicestershire, UK as part of my thesis and had never been convinced of them as body fossils, preferring a microbial interpretation for Ivesheadia Blackbrookia and Shepsheadia )
While Pizza discs are rare in the Charnian, they are very abundant in the Ediacaran of the Mistaken Point sections, and are actually some of the very oldest Ediacaran fossils anywhere in the world. I was bemused as to what they might be. From casual study of the many specimens I was convinced that a continuum existed between sub-radial assemblages of Fractofusus and some of the Pizza Discs. I proposed a model to my colleagues and collaborators from Oxford University.
Martin Brasier (formerly my Ph.D. supervisor- see photo top left) and I set one of our graduate students Alex Liu (now of Cambridge University) on testing the model that the low fidelity of preservation (which is unlike that seen in many Ediacaran fossils) might be due to microbial communities growing on top of dead and decaying Ediacaran organisms smothering and decaying them.
Alex collected much more field data, and I personally think has provided substantial data in support of the model. This work was published in Palaeontology. It took a long time, and is a bit of a departure from the normally ichnological work of the group, but a very worthwhile one.
Liu, A., McIlroy, D. Antcliffe, J. & Brasier, M.D. 2011. Effaced preservation in the Ediacara biota and its implications for the early macrofossil record. Palaeontology, 54, 607-630.
and was also blogged at the Nature Blog