[Campbell Biology P.811] According to the "Data from the Experiment" table and the informati... | Practice Question

According to the "Data from the Experiment" table and the information about "toothiness" being used by paleoclimatologists, if a 10,000-year-old fossilized red maple leaf from South Carolina had an average of 4.2 teeth per square centimeter of leaf area, what could be inferred about the temperature of South Carolina 10,000 years ago compared with today's temperature?

  • A: It was warmer, because the data suggests a trend where higher toothiness correlates with warmer growing conditions.
  • B: It was cooler, because the data suggests a trend where higher toothiness correlates with cooler growing conditions.
  • C: It was about the same, as 4.2 teeth falls within the range of modern South Carolina leaf toothiness.
  • D: It's impossible to infer, as toothiness is solely determined by genetics and not by environmental factors like temperature.

Explanation

The data shows a general trend where leaves grown in cooler environments or from more northern origins when grown in the same environment tend to have a higher number of teeth per cm². For South Carolina, modern leaves grown in Rhode Island a northern, likely cooler environment have 2.3 teeth/cm², and those grown in Florida a southern, warmer environment have 1.9 teeth/cm². The fossil leaf having 4.2 teeth/cm² is significantly higher than these modern values. This suggests that the environment 10,000 years ago was cooler than today, aligning with the principle that higher toothiness correlates with cooler conditions.