The guy named “Florian Kiersch” posted on Google+ a new experimental Google search feature baked into the knowledge graph top carousel bar.
The timeline of knowledge graph means if you search for something, then will show you the facts and the Knowledge graph about it.
you can get more closer look by seeing the screenshot below:
When you mouse over data elements, show like this :
You can also see the resource (Google+ post that has a video from Florian)