How synchronous are neogene marine plankton events?

Abstract

An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer‐Cervato, H. R. Thierstein, D. B. Lazarus, andJ‐P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order. We analyzed the synchrony and diachrony of commonly used Neogene biostratigraphic events from data published in the Initial Reports of the Deep Sea Drilling Project (DSDP) and in the Proceedings of the Ocean Drilling Program (ODP). On the basis of the combined biostratigraphic and magnetostratigraphic evidence, new Neogene age models were constructed for 35 globally distributed DSDP and ODP holes. Biostratigraphic events from the four major plankton groups (calcareous nannofossils, diatoms, planktonic foraminifera, and radiolarians) were compiled from DSDP and ODP reports. After the elimination of possible sources of error such as stratigraphic hiatuses and reworking of specimens, 124 biostratigraphic events that occurred in at least four holes were analyzed in detail: for each event a biochronologic age estimate was derived by projection of the depth of the event onto the line of correlation of each hole, and from these a global mean age for each event was calculated, together with its standard deviation. Average standard deviations for event ages by fossil group are: calcareous nannofossil first appearance datums (FADs): 0.57 m.y. (21 events), calcareous nannofossil last appearance datums (LADs): 0.60 m.y. (25 events), diatom FADs: 0.57 m.y. (7 events), diatom LADs: 0.85 m.y. (14 events), planktonic foraminifera FADs: 0.88 m.y. (22 events), foraminifera LADs: 0.68 m.y. (16 events), radiolarian FADs: 0.30 m.y. (9 events), radiolarian LADs: 0.31 m.y. (10 events). Since the average sample spacing in the sites used for this analysis is only 0.185 m.y., we have examined the data for true patterns of diachrony and for other biases. Diachrony is more frequent among cosmopolitan than among endemic taxa, thus there is a general trade‐off between the obtainable age precision and the geographic extent of a bioevent. Precision of age calibrations also decreases with increasing age. Although some of these features may be due to investigator bias, they appear in part to be real phenomena, and thus could also provide opportunities for further exploration of important paleobiological processes, such as change in environmental gradients through time, evolutionary adaptation of species populations and migration due to water mass changes.

Molecular evidence links cryptic diversification in polar planktonic protists to Quaternary climate dynamics

“…There are two well defined dates that can be used to calibrate the neogloboquadrinid tree. The divergence between N. dutertrei and N. pachyderma is one of the best constrained dates in the foraminiferal fossil record, with the earliest recorded appearance of Neogloboquadrina acostaensis dated at 10.4 million years ago (Ma) (27). The divergence between the N. dutertrei and P. obliquiloculata lineages occurs with the first appearance of Pulleniatina primalis, which is dated at 5.8 Ma (27).…”

The Oligocene time scale and cyclostratigraphy on the Ceara Rise, western equatorial Atlantic

“…Another possibility is that there is an important difference in the ages of the biostratigraphic events observed on the Ceara Rise compared to elsewhere. This could result from miscalibration or diachroneity as demonstrated for Neogene planktonic microfossils (Spencer-Cervato et al, 1994). Berggren et al (1995) preferred to infer undetected hiatuses as a significant factor for inter-site correlations, but it remains possible that diachronism is important at some levels.…”

The deep-sea microfossil record of macroevolutionary change in plankton and its study

“…These sections thus form a globally distributed, if still incomplete, framework for extremely high chronological resolution palaeobiological research. However significant errors can still exist in the age models of many other, often older sections (Lazarus 1994;Spencer-Cervato et al 1994;Lazarus et al 1995a, b;Spencer-Cervato 1999), and these errors can become significant when data is compiled across large numbers of sections in large-scale syntheses. Biostratigraphy using marine microfossils is still the primary method of determining geological age in deep-sea marine sediments, but this method has known limits of precision.…”