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Biogeographical and ecological patterns in bryozoans across the Cretaceous-Paleogene boundary; implications for the phytoplankton collapse hypothesis

Caroline E. Sogot, Elizabeth M. Harper and Paul D. Taylor
Biogeographical and ecological patterns in bryozoans across the Cretaceous-Paleogene boundary; implications for the phytoplankton collapse hypothesis
Geology (Boulder) (April 2013) 41 (6): 631-634

Abstract

The hypothesized collapse in primary productivity associated with the Cretaceous-Paleogene (K-Pg) mass extinction would have been particularly severe on suspension feeders dependent on phytoplankton. Previous research on the ecological dynamics of erect bryozoans in the Danish Basin supported the phytoplankton crash hypothesis in showing a major postextinction increase in the skeletal biomass of cyclostome bryozoans relative to the more nutrient-demanding cheilostome bryozoans. New data on the ecological dynamics between these two bryozoan clades across the K-Pg boundary are provided to determine whether the postextinction cyclostome spike is also evident in encrusting bryozoans and over a greater geographical area. Changes across the K-Pg were quantified in encrusting bryozoans using three metrics: (1) abundance of colonies; (2) area of substrate covered; and (3) colony form. Data from the southeastern United States were added to those from Denmark to control for regional factors. Our analyses indicate a globally uniform change among encrusting bryozoans but without the strong postextinction cyclostome spike seen previously in Danish erect bryozoans. An increased proportion of sheet over runner cyclostome colonies was found in the lower Danian of Denmark and the southeastern United States, despite the expectation that runners with widely dispersed zooids should fare better in low nutrient conditions. Furthermore, weighed samples of erect bryozoans from the basal Danian of Maastricht (Netherlands) and the southeastern United States failed to reveal a strong cyclostome spike. These findings question the phytoplankton crash hypothesis, or at least the extent to which this kill mechanism influenced suspension feeders during the K-Pg mass extinction.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 41
Serial Issue: 6
Title: Biogeographical and ecological patterns in bryozoans across the Cretaceous-Paleogene boundary; implications for the phytoplankton collapse hypothesis
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 631-634
Published: 20130404
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 27
Accession Number: 2013-041366
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2013174
Illustration Description: illus.
N30°00'00" - N35°00'00", W88°30'00" - W85°00'00"
N30°15'00" - N35°00'00", W91°40'00" - W88°04'60"
N24°30'00" - N39°28'00", W87°30'00" - W75°30'00"
N54°15'00" - N58°00'00", E08°00'00" - E13°00'00"
Secondary Affiliation: Natural History Museum, GBR, United Kingdom
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 the Geological Society of America, Boulder, CO, United States
Update Code: 201326
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