Motoyama, Isao (1997): Origin and evolution of Cycladophora davisiana (Radiolaria) in DSDP Hole 19-192, Northwest Pacific [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.691060, Supplement to: Motoyama, I (1997): Origin and evolution of Cycladophora davisiana Ehrenberg (Radiolaria) in DSDP Site 192, Northwest Pacific. Marine Micropaleontology, 30(1-3), 45-63, https://doi.org/10.1016/S0377-8398(96)00047-3
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Abstract:
This paper documents the evolutionary history of Cycladophora davisiana Ehrenberg from an uppermost Miocene to Pleistocene sedimentary record in the high-latitude Northwest Pacific. It apparently evolved from C. sakaii Motoyama through a series of intermediates. C. sakaii has a relatively large shell with an external spongy layer. The evolutionary transition is characterized by a relatively rapid decrease in thorax size with a reduction of the spongy appendage. This change occurred during about 0.4 m.y. from 2.8 to 2.4 Ma without cladogenesis. Following this interval, a decrease in thorax size continued gradually up to the Recent, resulting in a very small morphology. Although the population of C. davisiana first appeared at about 2.5 Ma, some morphotypic specimens may occur in earlier periods as indistinguishable very small endmembers in the C. sakaii populations.
Timing of the first appearance events both of morphotypic specimens and of a population of C. davisiana in Site 192 and previously reported cores does not disprove the idea that C. davisiana evolved first in the Northwest Pacific region, and later migrated into other regions of the world ocean.
Biometrics clearly indicate no direct phylogenetic relationships between C. davisiana and C. cornutoides Kling in the studied core. Thus, the latter species, which was originally described as a variation and later elevated to a subspecies of the former species, is separated from the former species and raised to the species rank.
Project(s):
Deep Sea Drilling Project (DSDP)
Coverage:
Latitude: 53.009500 * Longitude: 164.713500
Date/Time Start: 1971-08-30T00:00:00 * Date/Time End: 1971-08-30T00:00:00
Event(s):
19-192 * Latitude: 53.009500 * Longitude: 164.713500 * Date/Time: 1971-08-30T00:00:00 * Elevation: -3014.0 m * Penetration: 942 m * Recovery: 151.5 m * Location: North Pacific/GUYOT * Campaign: Leg19 * Basis: Glomar Challenger * Method/Device: Drilling/drill rig (DRILL) * Comment: 35 cores; 308 m cored; 0 m drilled; 49.3 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
2 datasets
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Datasets listed in this publication series
- Motoyama, I (1997): (Appendix C) Biometric measurements for ten characteristics and developmental degree of the spongy surface layer in the Cycladophora cornutoides lineage of DSDP Hole 19-192. https://doi.org/10.1594/PANGAEA.691059
- Motoyama, I (1997): (Appendix B) Biometric measurements for ten characteristics and developmental degree of the spongy surface layer in the Cycladophora sakaii-davisiana lineage of DSDP Hole 19-192. https://doi.org/10.1594/PANGAEA.691045