How Did Dinosaurs Get So Huge?

Part of why we’re so fascinated with extinct dinosaurs it’s just hard for us to believe that animals that huge actually existed. And yet, they existed! From the Jurassic to the Cretaceous Periods, creatures as tall as a five-story building were shaking the Earth.

Produced in collaboration with PBS Digital Studios: http://youtube.com/pbsdigitalstudios

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Female dragonflies fake sudden death to avoid male advances | New Scientist

You could almost say they are drop-dead gorgeous: when certain female dragonflies are pursued by unwanted suitors, they deter them by crashing to the ground

Source: Female dragonflies fake sudden death to avoid male advances | New Scientist

Secrets of the X chromosome – Robin Ball, TED-Ed

The sequence of DNA that we inherit from our parents encodes directions for making our cells and giving us specific traits. Identical twins have the same DNA sequence, so how can one twin end up with a genetic disorder while the other twin does not? Robin Ball explains how the secret lies in X chromosome inactivation.

Lesson by Robin Ball, animation by Anton Trofimov.