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Dating Our Ancestors: Study Suggests Macroscopic Bilaterian Animals Did Not Appear Until 555 Million Years Ago

Date:
September 30, 2002
Source:
University Of California - Riverside
Summary:
The traces left behind by ancient animals may hold the key to determining when macroscopic bilaterians -- animals that are symmetric about a central axis, with a body divided into equivalent right and left halves, and with an anterior-posterior polarity (e.g., this includes worms, ants, and ranging up to humans) -- first appeared. A team led by Dr. Mary Droser, professor of geology at the University of California, Riverside, studied "trace" fossils, e.g., burrows, trails and tracks left behind by the earliest bilaterian animals. Results from their study suggest that bilaterian animals did not appear until approximately 555 million years ago.

RIVERSIDE, Calif. -- The traces left behind by ancient animals may hold the key to determining when macroscopic bilaterians -- animals that are symmetric about a central axis, with a body divided into equivalent right and left halves, and with an anterior-posterior polarity (e.g., this includes worms, ants, and ranging up to humans) -- first appeared. A team led by Dr. Mary Droser, professor of geology at the University of California, Riverside, studied "trace" fossils, e.g., burrows, trails and tracks left behind by the earliest bilaterian animals. Results from their study suggest that bilaterian animals did not appear until approximately 555 million years ago.


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The above story is based on materials provided by University Of California - Riverside. Note: Materials may be edited for content and length.


Cite This Page:

University Of California - Riverside. "Dating Our Ancestors: Study Suggests Macroscopic Bilaterian Animals Did Not Appear Until 555 Million Years Ago." ScienceDaily. ScienceDaily, 30 September 2002. <www.sciencedaily.com/releases/2002/09/020927064725.htm>.
University Of California - Riverside. (2002, September 30). Dating Our Ancestors: Study Suggests Macroscopic Bilaterian Animals Did Not Appear Until 555 Million Years Ago. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2002/09/020927064725.htm
University Of California - Riverside. "Dating Our Ancestors: Study Suggests Macroscopic Bilaterian Animals Did Not Appear Until 555 Million Years Ago." ScienceDaily. www.sciencedaily.com/releases/2002/09/020927064725.htm (accessed April 18, 2014).

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