"These data were generated through analysis of annually-deposited skeletal growth marks in humerus bones obtained from dead, stranded Kemp's ridley sea turtles in the Gulf of Mexico. Each skeletal growth mark is assigned an age estimate and calendar year. The strong relationship between skeletal growth mark diameters and body size (carapace length) allows estimation of carapace length for each measurable skeletal growth mark. Taking the difference between sequential carapace length estimates yields annual growth rates.  Because data are available to determine the timing of growth mark deposition, the size at age relationship pairs age estimates with the carapace length estimated from the skeletal growth mark associated with that age estimate.  Recommendations from the published literature are to analyze growth rates relative to the mean carapace length for the growth increment. As a result, the growth dataset pairs annual growth rate estimates with estimates of mean carapace length for the growth increment."

"The IDs refer to the same turtles in both files. For example, turtle ID 1 has 3 size at age records:
age 0 = estimated size 4.2 cm 
age 0.75 (at the time the first growth mark was deposited) = estimated size 15.8 cm
age 1.5 (the turtle died before it could complete another full year of growth and so no second growth mark was deposited) = measured size at death 23 cm

However, turtle ID 1 only has 1 growth record because it was only possible to calculate growth over 1 yearly interval: 15.8 cm - 4.2 cm = 11.6 cm
According to analytical protocol established for this field of study, that growth rate was attributed to the mean size for turtle ID 1 for that yearly growth interval: 
(4.2 + 15.8) / 2 = 10 cm"
