article_snippet: Experts also believe that sexual dimorphism (pronounced differences in appearance between males and females, such as size) might have played a part too.
article_snippet: A table showing the variation is pictured .
article_snippet: That means we can now start thinking about what regional conditions drove the emergence of this diversity, rather than seeing body size as a fixed and fundamental characteristic of a species.'
article_snippet: The results demonstrate chronological and spatial variation, but no simple temporal or .
highlights_snippet: But this study suggests that there may have been another driving force .
  
highlights_snippet: Experts also claim regional conditions may be to blame for diverse shapes .
  