Skeletal features such as vertebrae and hips are readily available in the physical fossil evidence of an extinct organism. Soft features such as organs and integument are rarely available. Because certain characteristics are not obvious in the fossil record, scientists formulate hypotheses on whether certain organisms possessed certain characteristics. As with cladograms, parsimony is applied to several hypotheses to help determine which is the preferred hypothesis. By comparing an extinct animal to these two extant groups, hypotheses of varying degrees of confidence can be formulated as to whether or not a particular character was present within the animal.
Parsimony helps choose the preferred hypothesis from the varying hypotheses.
The following examples will use, naturally, non-avian dinosaurs as the extinct animal. Further, these examples use a cladistics viewpoint to simplify the explanation why one hypothesis is more parsimonious than another by comparing the evolutionary steps each hypothesis would require. In real life, the issues are likely far more complex than presented here. Non-avian dinosaurs had hearts. Non-avian dinosaur hearts are not preserved in the fossil record.