NSF Org:	EAR Division Of Earth Sciences
Recipient:	REGENTS OF THE UNIVERSITY OF CALIFORNIA AT RIVERSIDE
Initial Amendment Date:	August 22, 2000
Latest Amendment Date:	August 22, 2000
Award Number:	0074021
Award Instrument:	Standard Grant
Program Manager:	H. Richard Lane EAR  Division Of Earth Sciences GEO  Directorate for Geosciences
Start Date:	August 1, 2000
End Date:	July 31, 2004 (Estimated)
Total Intended Award Amount:	$139,975.00
Total Awarded Amount to Date:	$139,975.00
Funds Obligated to Date:	FY 2000 = $139,975.00
History of Investigator:	Mary Droser (Principal Investigator) mary.droser@ucr.edu
Recipient Sponsored Research Office:	University of California-Riverside 200 UNIVERSTY OFC BUILDING RIVERSIDE CA  US  92521-0001 (951)827-5535
Sponsor Congressional District:	39
Primary Place of Performance:	University of California-Riverside 200 UNIVERSTY OFC BUILDING RIVERSIDE CA  US  92521-0001
Primary Place of Performance Congressional District:	39
Unique Entity Identifier (UEI):	MR5QC5FCAVH5
Parent UEI:
NSF Program(s):	SCEC
Primary Program Source:	app-0100
Program Reference Code(s):	OTHR, 0000
Program Element Code(s):	157100
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

Trace Fossils, Ichnofabrics, and Problematic Sedimentary Structures at the
Proterozoic-Cambrian Transition: Implications for the Early Evolution of
Animals and Their Habitats

Mary Droser
EAR-0074021

The Cambrian radiation was the most significant event in the history of complex animals. Critical to this understanding this event is the record of the burrows, tracks and trails made by soft-bodied animals and preserved in the fossil record; these are known as trace fossils. Additionally, animals mix or churn the sediment and produce a mottled fabric known as ichnofabric. The importance of the ichnological record is exemplified by the fact that the Precambrian-Cambrian boundary is defined on the basis of trace fossils (Narbonne et al., 1987). This research project will be the first detailed systematic field analysis of the correlation of changes in ichnofabrics, discrete trace fossils and mat-related sedimentary structures across the Precambrian-Cambrian boundary. For the proposed project PI has selected four sections located in Newfoundland, Namibia, South Australia and western United States. These sections provide a complete range of
shallow-water siliciclastic facies. Examination of terminal Proterozoic trace fossils has applications to questions of the appearance of bilaterian animals. In addition, the rise in bioturbation (sediment mixing) at the terminal Proterozoic-Cambrian boundary interval profoundly and irreversibly changed the benthic habitat. One consequence was the reduction in microbial binding of siliciclastic sediments, which seem to have occurred in fully marine settings. These microbial mats may have been responsible for the unusual style of preservation of the soft-bodied Ediacara-type faunas. It is also likely that unusual sedimentary structures owe their formation and preservation to these mats. To date there has been no detailed examination of the changes in ichnofabric and discrete trace fossils to constrain the notion of the disappearance of a 'taphonomic window'

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