2012 Annual Science Report
Massachusetts Institute of Technology Reporting | SEP 2011 – AUG 2012
Paleontological Investigations of the Advent and Maintenance of Multicellular Life
Cohen and Knoll (2012) published a monograph on scale microfossils in the ca. 800 million year old Fifteen Mile group, northwestern Canada. These fossils, document defenses against protistan predation and are the most diverse eukaryotic fossils known from pre-Ediacaran rocks. Justin Strauss discovered a rich new assemblage of testate microfossils in Neoproterozoic strata from northwestern Canada and undergraduate student Ross Anderson completed a senior thesis on testate protists from shales from the Neoproterozoic Dalradian succession in Scotland.
Team member Andrew Knoll and his lab completed several paleontological projects on the early evolution of eukaryotic organisms in general and complex animals in particular, with efforts in three directions. Cohen and Knoll (2012) published a monographic treatment of scale microfossils in the ca. 800 million year old Fifteen Mile group, northwestern Canada. These fossils, which document defenses against protistan predation, constitute the most diverse eukaryotic fossils known from pre-Ediacaran rocks. In related work, graduate student Justin Strauss discovered a rich new assemblage of testate microfossils in Neoproterozoic strata from northwestern Canada (Strauss et al., 2012), and undergraduate student Ross Anderson completed a senior thesis on probable testate protists in metamorphosed shales from the Neoproterozoic Dalradian succession in Scotland (Anderson et al., 2012). And in related work, Knoll (2012a) articulated a hypothesis for the radiation of protist-eating eukaryotes in mid-Neoproterozoic oceans. The predicted consequences of this radiation – increased eukaryotic diversity, direct fossil evidence of eukaryophagic predators, the evolution of mechanical defenses, and altered competitive abilities between eukaryotic and cyanobacterial phytoplankton – are all observed in the geologic record; multicellularity is another predicted consequence, consistent with molecular clock estimates that animals began to diverge 750-800 million years ago.
In a second line of research, graduate student Jessica Creveling completed her Ph.D. thesis on Cambrian phosphorite deposition, providing detailed sedimentological, geochemical and paleobiological analyses of phosphatic limestones in Australia that shed welcome light on the environmental circumstance favoring Ediacaran-Cambrian phosphate deposition and the consequences of these processes for fossil preservation (Creveling, 2012; Creveling et al., 2012). The group expects to complete multiple papers on these projects over the next six months. In other work, Knoll and NAI team member Tanja Bosak completed a forward-looking review of stromatolites that articulates a means of integrating accelerating experimental research with detailed observations of stromatolites in the field. Knoll also completed a paper arguing how physiology can provide a conceptual bridge between the fossil record and the growing geochemical record of environmental history – a review that looks to Mars as well as the deep history of life on Earth (Knoll, 2012b). In education, Knoll is also the editor or author of two new books (Knoll et al., 2012, Morris et al., 2012) and will present the 2012 Howard Hughes Medical Institute Holiday Lectures, aimed to improve science education among high school students.
PROJECT MEMBERS:Douglas Erwin
RELATED OBJECTIVES:Objective 4.2
Production of complex life.