Exam 34: The Origin and Evolution of Vertebrates

Use the following information to answer the question. Brown et al. and Morwood et al. reported in 2004 that they had found skeletal remains of a previously unknown type of hominin, now dubbed Homo floresiensis, on the Indonesian island of Flores. These hominins were small (approximately 1 meter tall) with small braincases (approximately 380 cubic centimeters) as compared with other hominins. The remains of H. floresiensis were found alongside handmade stone tools and the remains of dwarf elephants that also inhabited the island, suggesting that H. floresiensis was able both to make tools and to coordinate the hunting of animals much larger than itself. H. floresiensis is estimated to have lived at the site where the remains were found from at least 38,000 years ago to 18,000 years ago. The table is a comparison of several characteristics of H. floresiensis to those of nine other hominin species (arranged roughly from oldest to most recent). What do these data suggest?

Use the following information to answer the question. While on an intersession course in tropical ecology, Kris pulls a large, snakelike organism from a burrow (the class was granted a collecting permit). The 1-meter-long organism has smooth skin, which appears to be segmented. It has two tiny eyes that are hard to see because they seem to be covered by skin. Kris brings it back to the lab at the field station, where it is a source of puzzlement to the class. Kris says that it is a giant oligochaete worm; Shaun suggests it is a legless amphibian; Kelly proposes it belongs to a snake species that is purely fossorial (lives in a burrow). The organism was found to have two lungs, but the left lung was much smaller than the right lung. Kelly added that the herpetology instructor had said that in most snakes, the same condition exists. If the size difference between the lungs in this organism is not a shared ancestral characteristic with its occurrence in snakes, then its existence in this organism is explained as which of the following?