DINOSAURS Past and Present, Volumes 1 and 2 <i> Sylvia J. Czerkas and Everett C. Olson (editors)</i> (<i> Natural History Museum of Los Angeles County/University of Washington Press: $35 each) </i>

These “terrible lizards” did not lumber awkwardly across prehistoric landscapes as they did across so many horror movie screens, argue the revisionist scholars whose recent work is collected here. They were well-adapted warriors, cruising at the speeds of warm-blooded creatures and displaying great muscle power. And yet consistently, they have been misrepresented pictorially. “It is often assumed that because we cannot observe live dinosaurs we can at best restore them only approximately,” writes Baltimore paleontologist Gregory Paul in a bold essay. “This recalls the assertion of Comte that since astronomers could not directly sample stars they would never be able to know what they are made of.”

Unfortunately, the authors forward their revisionist theories in language that lay readers will find impenetrable. Sample sentence: “The zygapophyses of camarasaurs, unlike those of diplodocids, permitted a wide range of vertical movement, so that the iliocostalis and longissimus muscle groups could elevate the trunk relative to sacrum and tail.” The attractive packaging, profuse in striking illustrations (some of which are more reminiscent of rock album illustrator Roger Dean than of sedate museum dioramas) indicates that the editors are trying to reach a popular audience. And yet to do so, they should have simplified sentences like the above (which argues that certain dinosaurs were bipedal) or provided a glossary. Still, the pictures stand on their own. Despite their attempt at accuracy, they are often exotic and mystical (red reptiles flying over ancient blue vistas) and educational (flying peterosaurs help us understand evolution from reptile to bird).