Question 6.65

image 30.Archaeopteryx is an extinct animal that had feathers like a bird but teeth and a long bony tail like a reptile. Only six fossil specimens are known. If the specimens belong to the same species and differ in size because some are younger than others, there should be a straight-line relationship between the lengths of a pair of bones from all individuals. An outlier from this relationship would suggest a different species. Here are data on the lengths in centimeters of the femur (a leg bone) and the humerus (a bone in the upper arm) for the five specimens that preserve both bones:

Femur length 38 56 59 64 74
Humerus length 41 63 70 72 84
Table 6.20: Data from M. A. Houck et al., Allometric scaling in the earliest fossil bird, Archaeopteryx lithographica, Science, 247 (1990): 195–198.
  1. Make a scatterplot. Do you think that all five specimens come from the same species?
  2. Find the correlation step by step, as in the procedure box in Section 6.3 (page 257).
  3. Now use one of the methods discussed in Spotlight 6.2 (page 259) to find and check that you get the same result as in part (b).