Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Earliest animals lived in a lake environment

28.07.2009
UC Riverside-led study raises questions about where early animals were living

Evidence for life on Earth stretches back billions of years, with simple single-celled organisms like bacteria dominating the record. When multi-celled animal life appeared on the planet after 3 billion years of single cell organisms, animals diversified rapidly.

Conventional wisdom has it that animal evolution began in the ocean, with animal life adapting much later in Earth history to terrestrial environments.

Now a UC Riverside-led team of researchers studying ancient rock samples in South China has found that the first animal fossils in the paleontological record are preserved in ancient lake deposits, not marine sediments as commonly assumed.

"We know that life in the oceans is very different from life in lakes, and, at least in the modern world, the oceans are far more stable and consistent environments compared to lakes which tend to be short-lived features relative to, say, rates of evolution," said Martin Kennedy, a professor of geology in the Department of Earth Sciences who participated in the research. "Thus it is surprising that the first evidence of animals we find is associated with lakes, a far more variable environment than the ocean."

The study, published in the July 27-31 online edition of the Proceedings of the National Academy of Sciences, raises questions such as what aspects of the Earth's environment changed to enable animal evolution.

In their research, the authors focused on South China's Doushantuo Formation, one of the oldest fossil beds that houses highly preserved fossils dated to about 600 million years ago. These beds have no adult fossils. Instead, many of the fossils appear as bundles of cells interpreted to be animal embryos.

"Our first unusual finding in this region was the abundance of a clay mineral called smectite," said lead author Tom Bristow, who worked in Kennedy's lab. "In rocks of this age, smectite is normally transformed into other types of clay. The smectite in these South China rocks, however, underwent no such transformation and have a special chemistry that, for the smectite to form, requires specific conditions in the water – conditions commonly found in salty, alkaline lakes."

The researchers' work involved collecting hundreds of rock samples from several localities in South China, carrying out mineralogical analysis using X-ray diffraction, and collecting and analyzing other types of geochemical data.

"All our analyses show that the rocks' minerals and geochemistry are not compatible with deposition in seawater," Bristow said. "Moreover, we found smectite in only some locations in South China, and not uniformly as one would expect for marine deposits. This was an important indicator that the rocks hosting the fossils were not marine in origin. Taken together, several lines of evidence indicated to us that these early animals lived in a lake environment."

Bristow noted that the new research gives scientists a glimpse into where some of the early animals lived and what the environmental conditions were like for them – important information for addressing the broader questions of how and why animals appeared when they did.

"It is most unexpected that these first fossils do not come from marine sediments," Kennedy said. "It is possible, too, that similarly aged or older organisms also existed in marine environments and we have not found them. But at the very least our work shows that the range of early animal habitats was far more expansive than presently assumed and raises the exciting possibility that animal evolution first occurred in lakes and is tied to some environmental aspect unique to lake environments. Furthermore, because lakes are of limited size and not connected to each other, there may have been significant parallel evolution of organisms. Now we must wait and see if similar fossils are found in marine sediments."

Kennedy, who directs the Graduate Program in Global Climate and Environmental Change at UCR, and Bristow were joined in the study by Mary Droser and Arkadiusz Derkowski of UCR; Ganqing Jiang of the University of Nevada, Las Vegas; and Robert Creaser of the University of Alberta, Edmonton, Canada.

Kennedy was supported by grants from the National Science Foundation and NASA Exobiology; Bristow, who joined UCR in 2003, was supported by a student research grant from the Geological Society of America. The research was done in its entirety while Bristow was at UCR. In 2008, he graduated with a doctoral degree in geological sciences and joined the California Institute of Technology, where he is a postdoctoral scholar researching Martian clay minerals.

The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 17,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion. To learn more, visit www.ucr.edu or call (951) UCR-NEWS.

Iqbal Pittalwala | EurekAlert!
Further information:
http://www.ucr.edu

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Fraunhofer ISE Pushes World Record for Multicrystalline Silicon Solar Cells to 22.3 Percent

25.09.2017 | Power and Electrical Engineering

Usher syndrome: Gene therapy restores hearing and balance

25.09.2017 | Health and Medicine

An international team of physicists a coherent amplification effect in laser excited dielectrics

25.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>