| Echinoderm plate coquina from the Lower Cambrian Wood Canyon Formation, Inyo County, California; the grayish structures embedded in the reddish-brown matrix are the plates from an undescribed, extinct species of echinoderm, whose original skeleton apparently disassociated, broke apart, very easily after death, thus enabling its myriad individual plates to contribute thick coquinoid developments in a few limestone layers in the Wood Canyon Formation. These locally abundant plates in the Wood Canyon strata are among some of the oldest known echinoderm fossil remains in the world. |