mass extinctions occurred during Paleozoic, including the largest extinction of all Several at the end of Permian. mass extinctions occurred at the end of Ordovician and Devonian. Other 9 PALEOZOIC LIFE Summary of invertebrate phyla 10 PALEOZOIC LIFE CONT. Summary of invertebrate phyla 11 ADAPTIVE RADIATIONS AND EXTINCTIONS was a time of several adaptive radiations and extinctions. Paleozoic geologic periods began with adaptive radiations (times of rapid evolution). Many periods ended with extinction events of varying severity. Several extinction event at the end of Permian was the most extensive mass extinction in the The history of life. 12 DIVERSITY DURING PALEOZOIC Red arrows mark extinction events. FIGURE 12-94 13 SOFT-BODIED ANIMALS animals evolved during Precambrian. Soft-bodied Ediacaran-type organisms Multicellular ranged into Cambrian. fossils are infrequently preserved. Soft-bodied improved with the origin of hard parts. Preservation 14 first animals with shells are called small shelly fossils. The shelly fossils are found at the base of Cambrian, and during Late Neoproterozoic. Small disappeared during the Early Cambrian. Most SMALL SHELLY FOSSILS FIGURE 12-2 15 SHELLY FOSSILS had phosphatic shells, few mm in size. Many and skeletal remains of primitive molluscs, sponges, and animals of uncertain Shells classification, such as Cloudina, that secreted a calcareous tube. FIGURE 12-1 Tiny fossils from the Late Precambrian and Early Cambrian in Siberia. 16 CAMBRIAN DIVERSIFICATION initial Paleozoic diversification is known as "the Cambrian explosion." Abrupt The appearance of many types of animals about 535 million years ago, followed by rapid evolution.
Several mass extinctions occurred during Paleozoic, including the largest extinction of all at the end of Permian. Other mass extinctions occurred at the end of Ordovician and Devonian. 9 PALEOZOIC LIFE Summary of invertebrate phyla 10 PALEOZOIC LIFE CONT. Summary of invertebrate phyla 11 ADAPTIVE RADIATIONS AND EXTINCTIONS Paleozoic was a time of several adaptive radiations and extinctions. Many geologic periods began with adaptive radiations (times of rapid evolution). Several periods ended with extinction events of varying severity. The extinction event at the end of Permian was the most extensive mass extinction in the history of life. 12 DIVERSITY DURING PALEOZOIC Red arrows mark extinction events. FIGURE 12-94 13 SOFT-BODIED ANIMALS Multicellular animals evolved during Precambrian. Soft-bodied Ediacaran-type organisms ranged into Cambrian. Soft-bodied fossils are infrequently preserved. Preservation improved with the origin of hard parts. 14 The first animals with shells are called small shelly fossils. Small shelly fossils are found at the base of Cambrian, and during Late Neoproterozoic. Most disappeared during the Early Cambrian. SMALL SHELLY FOSSILS FIGURE 12-2 15 SHELLY FOSSILS Many had phosphatic shells, few mm in size. Shells and skeletal remains of primitive molluscs, sponges, and animals of uncertain classification, such as Cloudina, that secreted a calcareous tube. FIGURE 12-1 Tiny fossils from the Late Precambrian and Early Cambrian in Siberia. 16 CAMBRIAN DIVERSIFICATION The initial Paleozoic diversification is known as "the Cambrian explosion." Abrupt appearance of many types of animals about 535 million years ago, followed by rapid evolution.
Ch12%20Life%20of%20the%20Paleozoic%20Notes.docx