( ( ( ( ( ( Each ( layer name ) ) ( represents ( ( a ( different period ) ) ( of time ) ) ) ) , ) and ) ( each ( contains ( ( fossilized remains ) ( of ( animals ( that ( lived ( during ( that era ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT Each) (NN layer) (NN name)) (VP (VBZ represents) (NP (NP (DT a) (JJ different) (NN period)) (PP (IN of) (NP (NN time)))))) (, ,) (CC and) (S (NP (DT each)) (VP (VBZ contains) (NP (NP (JJ fossilized) (NNS remains)) (PP (IN of) (NP (NP (NNS animals)) (SBAR (WHNP (WDT that)) (S (VP (VBD lived) (PP (IN during) (NP (DT that) (NN era))))))))))) (. .)))
Each layer name represents a different period of time, and each contains fossilized remains of animals that lived during that era.
(ROOT (S (NP (NP (DT The) (NN presence)) (PP (IN of) (NP (NP (DT an) (NN animal) (NN fossil)) (PP (IN in) (NP (DT a) (NN rock)))))) (VP (VBZ gives) (NP (NP (NN evidence)) (PP (IN of) (NP (DT the) (NN time) (NN period)))) (NP (NP (DT the) (NN animal)) (VP (VBN lived) (PP (IN in))))) (. .)))
The presence of an animal fossil in a rock gives evidence of the time period the animal lived in.