The Fossil RecordLayers of sedimentary rock contain fossils.New layers cover older ones, creating a record over time.When fossils are arrayed in the order of theirage, a progressive series of changes are seen.The younger fossils are more similar toexisting species than older ones.
The Fossil RecordFossils may be used to determineinformation about species:SizeWeightAgeLocationMigrationCause of extinctionDietCommon origins
The Fossil RecordThe Fossil record is incomplete and has many gaps.Reasons: Species with delicate bodies don’t fossilize. Species may not have lived in conditions that allow it to fossilize. Fossils havent been found.
Transitional FossilsA transitional fossil is one that representscharacteristics between groups of organisms.(the missing link)It provides a link between past and presentspecies.
Transitional Fossils: TiktaalikAssumption:Land vertebrates evolved from lobed-finned fishObservations:The first fossils of lobe-finned fish: 390 MYA.The earliest fossils of land vertebrates: 360 MYA.Prediction:The transition to land occurred 390 – 360 MYA.
Transitional FossilsShrubin discovers Fishapod!Four limbs with webbed finsand sturdy wrist bonesNeck and shouldersThick ribsFlattened skull