Plenty of dinosaurs yet to be found.

The dramatic surge in dinosaur discoveries that paleontologists have been enjoying in recent years won't soon abate, a new analysis suggests.

As of 1990, when the first edition of a comprehensive reference book entitled The Dinosauria (David B. Weishampel, Peter Dodson, and Halszka Osmolska, eds., University of California Press: Berkeley) was published, scientists had described dinosaurs representing about 285 genera. Since then, paleontologists have been on a roll, describing at least one species from each of another 222 genera, says Peter Dodson of the University of Pennsylvania in Philadelphia.

Rates of discovery have soared in the past half century, he notes. Before 1969, scientists averaged about 12 new dinosaur genera per decade. Since 1990, they've made finds at more than 10 times that rate, says Dodson. In both 2001 and 2003, paleontologists published journal articles on species from at least 24 new dinosaur genera.

In 1990, dinosaur species from six countries--the United States, China, Mongolia, Canada, England, and Argentina--accounted for three-fourths of all known dinosaur genera. Discoveries in Canada and England since 1990 have boosted those countries' respective tallies of genera only modestly, 10 and 25 percent, respectively. However, new finds from Argentina and China have more than doubled the dinosaur census in those nations. In the past 14 years, for example, China's genera count jumped from 36 to 88, Dodson notes.

A statistical analysis that considers the locations and rates of current dinosaur finds hints that Earth's ancient strata still hold plenty of undiscovered treasures. Worldwide, the analysis suggests, scientists could expect eventually to unearth species that represent 1,889 dinosaur genera. That projection suggests that 73 percent of dinosaur genera remain unknown to science, says Dodson.--S.P.