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Joseph Fray, 5, of Brentwood, is dwarfed by a leg bone of an allosaurus dinosaur brought by Andie Lichtman of San Francisco and her "Dino's Rock" program featuring dinosaur bones and fossils at the Pleasant Hill Library Tuesday, Aug. 28, 2012. (Karl Mondon/Staff)

Andie Lichtman, a paleontologist from San Francisco, top, encourages the crowd of youngsters gathered at her "Dinos Rock!" program to roar like a T. rex as she prepares to show off a dinosaur bone and fossil collection at the Pleasant Hill Library on Aug. 28. Up for the request, above, are 5-year-olds Robin Hartz of Concord, Eli Babcock of Twin Falls, Idaho, and John Franco, 4, of Martinez. Joseph Fray, 5, of Brentwood, left, is dwarfed by a leg bone of an allosaurus. Children and families were able to touch dinosaur bones and get an up-close view of dino-eggs, dino-tracks and dinosaur fossils as much as 500 million years old.

Online Extra

To view a slideshow of the dinosaur presentation, visit http://photos.mercurynews.com/2012/08/30/dinos-rock-rolls-through-pleasant-hill-library/.