BIO 203 Lecture Notes - Multituberculata, Marsupial
Document Summary
1a) mammals are put into two distinct groups when it comes to gestation and lactation. The two groups are placentals and marsupials (urton, 2022). Unlike them, placentals have a prolonged gestation period (urton, 2022). Again, the lactation periods are the opposite of one another. Marsupials have an extended period of lactation (urton, 2022). Because of these factors, many scientists believed that placentals were the newer way of reproducing when it came to lactation and gestation. This means that marsupials were believed to be closer to their ancestors than placentals (urton, 2022) 1c) in this tree above, the letter c represents a prolonged gestation period, and the letter d represents a smaller lactation period. Since placentals have both prolonged gestation and smaller lactation period, the event that caused these had to happen before getting to the placentals we see today (urton, 2022). Also, marsupials showed neither of these traits (urton, 2022).
