Skip to Main Content
GEOREF RECORD

The limits of Burgess Shale-type preservation; assessing the evidence for preservation of the blood protein hemocyanin in the Burgess Shale

Robert R. Gaines, Alexander J. Lombardo, Iris O. Holzer and Jean-Bernard Caron
The limits of Burgess Shale-type preservation; assessing the evidence for preservation of the blood protein hemocyanin in the Burgess Shale
Palaios (June 2019) 34 (6): 291-299

Abstract

Cambrian deposits bearing exceptional preservation of soft-bodied fossils offer unique insights into the diversity and paleobiology of the Cambrian biota. In recent years, a growing number of studies have provided evidence that highly labile tissues, such as nervous tissues, may be more common in fossils from Burgess Shale-type deposits than previously appreciated. These discoveries have provided novel insights into the anatomy and phylogeny of Cambrian animals and have also challenged the basic understanding of the limits on the resolution of anatomical information that may be captured by Burgess Shale-type preservation. Evidence used to infer primary blood chemistry was recently reported from the iconic Burgess Shale fossil Marrella splendens, the first such report from a Cambrian Lagerstatte. Diminutive crystals of a copper sulfide mineral found in association with Marrella were interpreted as evidence that the animal's blood contained the Cu-bearing protein hemocyanin. Copper minerals in shales in general, and in the Burgess Shale in particular, however, may have a complex geologic history. Using microscopy and SEM-EDS elemental mapping of material from the Walcott Quarry as well as from the Burgess Shale fossil quarry at Marble Canyon, we assess the timing of emplacement of Cu-sulfides in fossil-bearing mudrocks of the Burgess Shale. These data demonstrate that copper minerals are most conspicuously concentrated within veins that are oriented sub-perpendicular to bedding. These late-stage fluid flow paths allowed Cu-mineralizing fluids to infiltrate bedding plane-parallel cracks, which commonly run through Burgess Shale fossils and extend into the matrix around them. Based upon the relationships of mineral phases associated with fossils, it appears that Cu-mineralization occurred after metamorphic volatilization of a large proportion of the carbonaceous material that originally comprised the fossils. We find that copper minerals in the Burgess Shale are of demonstrably post-Cambrian origin, a secondary overprint that cannot be used to infer original blood chemistry or tissue composition of its fossils.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 34
Serial Issue: 6
Title: The limits of Burgess Shale-type preservation; assessing the evidence for preservation of the blood protein hemocyanin in the Burgess Shale
Affiliation: Pomona College, Geology Department, Claremont, CA, United States
Pages: 291-299
Published: 201906
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 72
Accession Number: 2019-062118
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: NSF Grant EAR-1558497
Illustration Description: illus. incl. 1 table, strat. cols.
N51°25'60" - N51°25'60", W116°28'00" - W116°28'00"
Secondary Affiliation: Royal Ontario Museum, CAN, CanadaUniversity of Toronto, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201915
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal