Friday, April 24, 2009

Vindhyan Fossils Show Cambrian Forms...1 *BILLION* Years Earlier

The controversial “Cambrian” fossils of the Vindhyan are real but more than a billion years older

1. Stefan Bengtsona,b,1,
2. Veneta Belivanovaa,
3. Birger Rasmussenc and
4. Martin Whitehouseb,d

-Author Affiliations

1.
aDepartment of Palaeozoology and
2.
dLaboratory for Isotope Geology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden;
3.
bNordic Center for Earth Evolution, SE-104 05 Stockholm, Sweden; and
4.
cDepartment of Applied Geology, Curtin University of Technology, Perth, WA 6845, Australia

1.

Edited by James P. Kennett, University of California, Santa Barbara, CA, and approved March 24, 2009 (received for review December 11, 2008)

Abstract

The age of the Vindhyan sedimentary basin in central India is controversial, because geochronology indicating early Proterozoic ages clashes with reports of Cambrian fossils. We present here an integrated paleontologic–geochronologic investigation to resolve this conundrum. New sampling of Lower Vindhyan phosphoritic stromatolitic dolomites from the northern flank of the Vindhyans confirms the presence of fossils most closely resembling those found elsewhere in Cambrian deposits: annulated tubes, embryo-like globules with polygonal surface pattern, and filamentous and coccoidal microbial fabrics similar to Girvanella and Renalcis. None of the fossils, however, can be ascribed to uniquely Cambrian or Ediacaran taxa. Indeed, the embryo-like globules are not interpreted as fossils at all but as former gas bubbles trapped in mucus-rich cyanobacterial mats. Direct dating of the same fossiliferous phosphorite yielded a Pb–Pb isochron of 1,650 ± 89 (2σ) million years ago, confirming the Paleoproterozoic age of the fossils. New U–Pb geochronology of zircons from tuffaceous mudrocks in the Lower Vindhyan Porcellanite Formation on the southern flank of the Vindhyans give comparable ages. The Vindhyan phosphorites provide a window of 3-dimensionally preserved Paleoproterozoic fossils resembling filamentous and coccoidal cyanobacteria and filamentous eukaryotic algae, as well as problematic forms. Like Neoproterozoic phosphorites a billion years later, the Vindhyan deposits offer important new insights into the nature and diversity of life, and in particular, the early evolution of multicellular eukaryotes.


Not at work so I can't look at the paper pdf...but what they are claiming is true. Or my understanding of it that is...

Whoa.

UPDATE:

There are specific fossils they looked at. None of them are animal life, so no Burgess Shale critters here. There are gas bubbles found from cyanobacterial mats (gas got trapped in a mat and mud covered it) and what look like tubes secreted by specific kinds of algae (filamentous algae such as Spirogyra). There are other fossils as well, but they are not examined in detail. Chambalia (or soemthing like it) also makes an appearance. The age is rock solid though (sorry for the bad pun). This stuff is a billion years older and very similar to Cambrian equivalent taxa, but not necessarily actually Cambrian taxa.

4 comments:

philw1776 said...

Are any of these multicellular eukaryotes what us laypersons would call animals? Is that what the summary hints as as 'problematic' forms? Does this indicate that possibly life was much more advanced at -1.6 GigaYr and then something, say like a deep freeze, put things on hold for a few hundred Million yrs?

Metalraptor said...

If philw1776 comment turns out to be correct, once could consider the Edicaran animals similar to ferns today, opportunists that thrived on disaster and renewed the environment after an extinction, while other less adaptive taxa slowly recovered.

Will Baird said...

I need to see the paper, guys. I'll get it on monday.

Will Baird said...

I am pulling from the update since the comments are being accessed directly:

There are specific fossils they looked at. None of them are animal life, so no Burgess Shale critters here. There are gas bubbles found from cyanobacterial mats (gas got trapped in a mat and mud covered it) and what look like tubes secreted by specific kinds of algae (filamentous algae such as Spirogyra). There are other fossils as well, but they are not examined in detail. Chambalia (or something like it) also makes an appearance. The age is rock solid though (sorry for the bad pun). This stuff is a billion years older and very similar to Cambrian equivalent taxa, but not necessarily actually Cambrian taxa.There are NO variants of Animalia found. No arthropods. No chordata. No Cnidarians. Just to be clear.