Simplify the following text for a Grade 9 native English-speaking person.
Original: While there is only hard proof of such flowers existing about 130 million years ago , there is some circumstantial evidence that they did exist up to 250 million years ago . A chemical used by plants to defend their flowers , oleanane , has been detected in fossil plants that old , including gigantopterids , which evolved at that time and bear many of the traits of modern , flowering plants , though they are not known to be flowering plants themselves , because only their stems and prickles have been found preserved in detail ; one of the earliest examples of petrification .
Simplified: Flowers and flowering plants first appear in the fossil record of 130 million years ago in the Lower Cretaceous .