Differentiated at Birth (image) Brown University Share Print E-Mail Caption Two newborn guppies from Trinidad's Aripo river show clear differences in the maturity of their skeletons: The guppy from upstream (top), which spent longer in gestation, has more mature bone development as indicated by darker staining than the guppy from downstream, which was born earlier in maturity. Images not to scale. Credit Dial et. al. Usage Restrictions with credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.