English: In palaeontology, the evidence for species and evolution comes mainly from the comparative anatomy of fossils. A chronospecies is defined in a single lineage (solid line) whose morphology changes with time. At some point, palaeontologists judge that enough change has occurred that two forms (A and B), separated in time and anatomy, once existed. If only sporadic examples of each survive in the fossil record, then the forms will appear sharply distinct.