Latitudinal variation in the planktic foraminifer Contusotruncana contusa in the terminal Cretaceous ocean

Author(s): Kucera, Michal; Malmgren, Bjorn A.
Author Affiliation(s): Primary:
University of Goteborg, Department of Marine Geology, Goteborg, Sweden
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 28(1), p.31-52. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. 65 refs.; illus., incl. 6 tables, 1 plate
Summary: The morphological variability (coiling properties, size and shape) of the planktic foraminifer Contusotruncana contusa (Cushman) in the terminal Cretaceous ocean was examined at eight deep-sea sites and two continental sections from low (16°) to middle (42°) paleolatitudes in both hemispheres. The material used in this study includes samples from the South Atlantic (DSDP Sites 356, 527 and 525A), North Atlantic (Sites 384 and 548A), Indian and Pacific Oceans (DSDP Site 465A and ODP Sites 761C and 762C) and Tethyan Ocean (outcrop sections from El-Kef and Caravaca). On average 45 specimens from two samples per location were analysed, from an interval corresponding approximately to the last 60 kyr of the Cretaceous. No differences in coiling direction (dextral proportions were >90% in all samples), percentage of kummerform specimens (usually >50%) and number of chambers in the last whorl (4-5) were observed between the sites. Both test size (expressed as spiral outline area and test volume) and total number of chambers increase significantly towards lower latitudes. Similarly, test conicity, examined by shape coordinate and eigenshape methods, and angularity of the spiral outline show a rather continuous, slight increase towards lower latitudes. Kummerform specimens of C. contusa were slightly larger and more conical than normalforms and possessed substantially more chambers (both totally and in the last whorl). A principal components analysis of the sample means of five variables describing size and shape clearly distinguished high-latitude sites (525A, 527, 548A, 761C and 762C) from low-latitude sites (384, 465A, Caravaca and El-Kef). Specimens from Site 356 are transitional with respect to those two groups. The results indicate: (1) considerable morphological variation in C. contusa during the terminal Cretaceous comparable to that known in many Recent planktic foraminiferal species and (2) a geographical distribution of this variation corresponding to previously suggested biogeographic schemes based on quantitative analysis of planktic foraminiferal assemblages. Despite the differences in sample means, the overall morphology of C. contusa overlaps among the sites studied, supporting the classification of all C. contusa morphotypes as a single species. Similarly, no discrete morphologic groups could be distinguished within any of the samples.
Year of Publication: 1996
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Adaptation; Africa; Anatomy; Biogeography; Caravaca Spain; Cenozoic; Contusotruncana contusa; Cretaceous; DSDP Site 356; DSDP Site 384; DSDP Site 465; DSDP Site 525; DSDP Site 527; DSDP Site 548; Deep Sea Drilling Project; El Kef Tunisia; Europe; Foraminifera; Global; IPOD; Iberian Peninsula; Invertebrata; K-T boundary; Leg 122; Leg 39; Leg 43; Leg 62; Leg 74; Leg 80; Lower Paleocene; Maestrichtian; Mesozoic; Microfossils; Morphology; Murcia Spain; Murcia region; North Africa; ODP Site 761; ODP Site 762; Ocean Drilling Program; Paleocene; Paleogene; Planktonic taxa; Protista; Quantitative analysis; Senonian; Southern Europe; Spain; Stratigraphic boundary; Tertiary; Tunisia; Upper Cretaceous; Variations; World ocean
Coordinates: S203512 S163357 E1153337 E1121231
N310000 N410000 W0510000 W0680000
N200000 N400000 E1792000 E1735000
S301000 S280000 E0031000 E0014500
N483054 N485457 W0120950 W0133006
Record ID: 1996045399
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands