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Evidence for biogenic copper (hemocyanin) in the Middle Cambrian arthropod Marrella from the Burgess Shale

M. Jake Pushie, Brian R. Pratt, Tracy C. Macdonald, Graham N. George and Ingrid J. Pickering
Evidence for biogenic copper (hemocyanin) in the Middle Cambrian arthropod Marrella from the Burgess Shale
Palaios (October 2014) 29 (10): 512-524


Beginning with the discovery of the middle Cambrian Burgess Shale, the rare examples of exceptional preservation of soft tissues in fine-grained strata have been celebrated as windows into the diversity and complexity of ancient marine animal life. Even so, with the loss of original organic compounds, the physiological attributes of the fossils can be inferred only on the basis of modern descendants or sister groups among extant representatives that can serve as analogs. To test whether soft-bodied fossils from the Burgess Shale and similar Cambrian Lagerstatten could preserve chemical evidence of their original biology, a number of specimens from different groups were analyzed with synchrotron-based X-ray fluorescence imaging to determine the spatial distribution of a range of elements, especially those in exceedingly trace amounts that cannot be detected by more conventional analytical methods. The relative distribution of common elements like Fe, K, Ti, and Ca is related to the composition of the host shale, abundance of pyrite, and presence or absence of preserved exoskeletal calcite. However, the black stain commonly preserved with the arthropod Marrella splendens is preferentially enriched in Cu due to localized residue in the carbon and minute crystals of chalcopyrite. This is interpreted as indicative of the original chemical composition of a primary biotic fluid, likely blood. Since modern-day arthropods generally utilize Cu-containing hemocyanin for oxygen transport, it is hypothesized that hemocyanin was the biogenic source of the observed Cu. This is the first chemical evidence for blood composition in the invertebrate fossil record. These observations reinforce the consensus molecular clock age for the hemocyanin gene family, which traces its origins back to the "Cambrian explosion", thus providing evidence for the early origin of this oxygen carrier among some arthropod groups.

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 29
Serial Issue: 10
Title: Evidence for biogenic copper (hemocyanin) in the Middle Cambrian arthropod Marrella from the Burgess Shale
Affiliation: University of Saskatchewan, Department of Geological Sciences, Saskatoon, SK, Canada
Pages: 512-524
Published: 201410
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 87
Accession Number: 2015-007618
Categories: Invertebrate paleontologyGeneral geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N25°04'00" - N25°04'00", E102°40'60" - E102°40'60"
N51°25'60" - N51°25'60", W116°28'00" - W116°28'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, 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: 201504
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