Oldest mass animal stranding revealed in Death Valley fossils

Jul 26, 2017

By Agnese Abrusci

How apt. In Death Valley, a region extraordinarily hostile to animal life today lie fossils of the oldest mass death so far discovered.

On a rocky surface covering about one square metre, and in loose rocks nearby that were once part of the surface, Aaron Sappenfield of the University of California, Riverside, and his colleagues found the remains of 13 jellyfish. The discovery suggests the marine animals behaved in a comparable way to their modern counterparts. But the fossils also hint that environmental conditions at the time were very different from today.

About 540 million years ago, in the Cambrian period, Death Valley lay on the edge of an ancient continent, with sandy beaches along its margin.

The jellyfish in the Cambrian seas seemed to have looked and behaved a lot like they do today. Sappenfield and his colleagues believe that the ancient jellyfish also lived near the shore, until tides or waves pushed them closer to the beach. When the tide receded the animals got stranded, just as modern jellyfish do.

But jellyfish washing up on today’s beaches have a poor chance of becoming fossils. Most are quickly torn to pieces by scavengers or curious children.

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