Much
of our knowledge about past life has come from the fossil record, but
how accurately does that record reflect the true history and drivers
of biodiversity on Earth?
Shanan
Peters
Geoscientist
University
of Wisconsin-Madison
 "It's
a question that goes back a long way to the time of Darwin, who
looked at the fossil record and tried to understand what it tells us
about the history of life, In fact, the fossil record can tell us a
great deal, Peters says in results of a new study. We find an
interesting web of connections between these different systems, which
combine to drive what we see in the fossil record. For example,
marine biodiversity is closely related to the sulphur cycle. The
"signal" from sea-level--how much the continents are
covered by shallow seas--is also important in the history of marine
animal diversity, the researchers found. The dramatic changes in
marine biodiversity seen in the fossil record likely arose through
biological responses to changes in the global carbon and sulphur
cycles, and to sea level, through geologic time. Earth systems are
all connected. It's important to realize that when we perturb one
thing, we're not just affecting that one thing. The challenge is
understanding how that perturbation of one thing, for example, the
carbon cycle, will affect the future biodiversity of the planet."
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In
a paper published this week in the journal Science, he and colleague
Bjarte Hannisdal of the University of Bergen in Norway show that the
evolution of marine life over the past 500 million years has been
driven by both ocean chemistry and sea-level changes.
Lisa
Boush
Program
Director
National
Science Foundation
Division
Of Earth Sciences
NSF
 "These
results tell us that the number of species in the oceans through time
has been influenced by the amount and availability of carbon, oxygen
and sulphur, and by sea level. The study allows us to better
understand how modern changes in the environment might affect
biodiversity today--and in the future."
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The
time period studied covers most of the Phanerozoic eon, which extends
to the present and includes the evolution of most plant and animal
life.
Hannisdal
and Peters analyzed fossil data from the Paleobiology Database, along
with paleoenvironmental proxy records and data on the rock record.
These data reflect ancient global climates, tectonic movements,
continental flooding and changes in biogeochemistry, especially in
Earth's oxygen, carbon and sulphur cycles. The scientists used a
method called information transfer, which allowed them to identify
causal relationships, not just general associations, between
biodiversity and environmental proxy records. Despite its
incompleteness, the fossil record is a good representation of marine
biodiversity over the past half-billion years, the scientists
believe. The findings also emphasize the interconnectedness of
Earth's physical, chemical and biological processes.
Source:
National
Science Foundation
Journal
Reference:
B.
Hannisdal, S. E. Peters. Phanerozoic Earth System Evolution and
Marine Biodiversity. Science, 2011; 334 (6059): 1121 DOI:
10.1126/science.1210695
ANCIENT ENVIRONMENT LED TO EARTH'S CURRENT MARINE BIODIVERSITY - WATERWAYS NEWS - 04 DECEMBER 2011
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![Alex Villanueva Mechanical Engineer Virginiatech “Robojelly looks very similar to an actual jellyfish. Its geometry is copied almost exactly from a moon jellyfish [Aurelia aurita]. The robot is built out of silicone and uses shape memory alloy (SMA) actuators to swim. These results clearly demonstrate that the flap plays an important role in the propulsion mechanism of Robojelly and provides an anatomical understanding of natural jellyfish."](../../WATERWAYS%20PEOPLE/021211%20Alex%20Villanueva.jpg "Alex Villanueva Mechanical Engineer Virginiatech “Robojelly looks very similar to an actual jellyfish. Its geometry is copied almost exactly from a moon jellyfish [Aurelia aurita]. The robot is built out of silicone and uses shape memory alloy (SMA) actuators to swim. These results clearly demonstrate that the flap plays an important role in the propulsion mechanism of Robojelly and provides an anatomical understanding of natural jellyfish.\"")
