1. Figure 13.29: The Gondwana supercontinent of Paleozoic time was made up of South America, Africa, Australia, Antarctica and India.

2. Figure 13.30: Du Toit reconstructed the configuration of the Gondwana supercontinent for late Paleozoic time by matching shorelines, structural features and rock successions (including glacial deposits) from one continent with those of other continents. Du Toit's reconstruction placed a major geosyncline, known as SAMFRAU, along the southern boundary. The SAMFRAU geosyncline is now considered to represent a late Paleozoic collision site between main Gondwanaland and a microcontinent. This mountain-building event is termed the Gondwanan orogeny.

3. There are numberous evidence that the five continents making up Gondwanaland were assembled together throughout the Paleozoic.

(a) Permo-Carboniferous glacial deposits, which indicate the former extent of large ice sheets that existed during the mid- to late-Paleozoic, are found on all five southern continents (see Fig. 13.30).

(b) Paleomagnetic studies, which define the Paleozoic and early Mesozoic paleolatitude positions of all five Gondwana continents, are consistent will these land masses having been assembled during this time.

(c) Figure 13.32: Isotopic dating of igneous and metamorphic rocks allow geologists to extend late Proterozoic and Paleozoic orogenic belts across several continents in a manner consistent with these continents having been assembled during these orogenies.

(d) The distribution of Gondwanian-type rock successions are remarkably similar on all five southern continents (see below).

e) Similar Paleozoic fossils (both plant and animal) are found on several now widely-separated southern continents (see below).

1. Figure 13.34: Late Paleozoic and early Mesozoic strata of the southern cratons display amazingly similar rock sequences that are collectively termed the Gondwana rock succession.

2. The Gondwana succession has prominent glacial tillites in its lower part which are composed of jumbled, unsorted rocks that overlie scratched surfaces apparently abraded by moving ice sheets. Although some of the tillites are associated with marine strata, most are inter-stratified with non-marine rocks that include coal seams.

3. Figure 13.40: The coal seams contain many fossil plants belonging to the assemblage collectively term the Glossopteris flora which refers to a seed fern that bore distinctive tongue-shaped leaves. Fossils of the Glossopteris flora are found today on all five southern continents, including rocks in Antarctica that were collected only 200 miles from the south pole.

4. Plants comprising the Glossopterous assemblage may have grown in temperate climates. The Glossopterous flora flourished during the Late Paleozoic and persisted into Triassic time but was replaced during the Jurassic Period by warmer-climate varieties such as ginkoes, cycads and various new seed ferns. This change in vegetation indicates gradual climatic warming as Gondwanaland moved away from the South Pole during the Late Paleozoic and Early Mesozoic.

5. Figure 13.48: The Gondwana strata also contain similar vertebrate animal fossils such as amphibians, reptiles and fish on now widely-separated continents suggesting that these continents were at one time connected.

6. Figure 13.34: The Gondwana rock succession is capped everywhere by either thick basalt flow or by dikes and sills. These basalts have been isotopically date as Late Triassic or Jurassic in Australia, Jurassic in South America and Antactica, Early Cretaceous in South America and Late Cretaceous to Eocene in India. These basaltic flows, sills and dikes are probably related to rifting events associated with later breakup of Pangea.

7. In addition, ultramafic rocks were emplaced into Gondwanian rocks of South Africa during Early Cretaceous time. These ultramafic intrusions are known as kimberlites and often contain high-pressure minerals such as diamond and garnet that indicate an origin within deeper portions of the upper mantle.

1. Figure 13.46: Early paleogeographic reconstruction of Pangea for Permian time suggested that a single huge polar ice cap spread radially outward from the center of Gondwanaland. Late Paleozoic glacial deposits in Siberia indicate that glaciation also occurred at northern high latitudes during this time.

2. Later investigations, however, found that glaciation of all of Gondwanaland was not simultaneous but actually began during the Late Ordovician in North Africa. Gondwana glaciation then spread to South America during the Silurian and Devonian and later into India, Antarctica and Australia during the late Carboniferous and Permian. Gondwana glaciation reached its maximum during the Carboniferous.

3. Figure 13.47: Scientists now realize that what appeared to be one giant Gondwana ice sheet actually consists of several centers of glaciation that shifted throughout the Paleozoic. The apparantly single huge ice cap actually consists of several ice caps of different ages spread over large areas of Gondwanaland. This shifting in the positions of ice caps over time resulted from movement of the Gondwana supercontinent over the South Polar Region.

4. Some parts of Gondwanaland were warm at the same time that other areas were covered by glaciers. Permian evaporites in northern South America and Permo-Triassic red beds in southern Africa indicate a warming climate in those areas as Gondwanaland drifted north towards lower latitudes.

5. The repetitive sedimentary patterns (cyclothems) observed in Carboniferous strata on several continents, including North America, were deposited during the climax of Gondwana glaciation. This suggests that glacially controlled sea-level fluctuations on a global scale were responsible for the repetitious nature of these cyclothems. Late Paleozoic glaciation on Gondwanaland ultimately spanned almost 100 million years.

1. Figure 13.46: During the late Paleozoic, when both the southern and northern high-latitudes were cold, the equatorial region between Gondwanaland and Laurasia (Laurentia + Asia) was covered by a warm, tropical ocean known as the Tethys Sea.

2. The Tethyan fauna consisted of hundreds of warm-water species of invertebrates that are preserved today as fossils in marine strata along southern portions of Europe and Asia and northern portions of Africa. These Tethyan fauna and their descendants existed throughout the Mesozoic Era and into the Eocene, at which time tectonic activity began to destroy the seaway.

3. Today only relicts of that once vast ocean and its fauna remain. These relicts consist of the Caspian, Black and Mediterranean seas.

The Late Paleozoic was marked by continued expansion of land plants as well as the evolution of the marine communities. It was also a time when the vertebrates evolved into two main lineages, the synapsids and reptiles.

1. Following the Late Devonian extinctions, marine invertebrates soon recovered and again thrived during the Late Paleozoic. The Late Paleozoic marine life included many new groups and species.

2. In addition to abundant crinoids, another type of stalked echinoderm called blastoids thrived in the Late Paleozoic shallow seas. These stalked echinoderms formed vast meadows along the floor of warm shallow seas.

3. The great crinoid and blastoid meadows also featured another group of important filter feeders, the bryozoans. Unlike the earlier lumpy or branching bryozoans of Ordoviian time, the Mississippian bryozoans had lacy, fanlike structures.

4. Figure 13.52: Late Paleozoic brachiopods were dominated by a group of strophomenids known as productids. Productids had one shell that was deeply cupped and sat on the sea floor propped up by long spines. The other shell consisted of a thin, flat lid that would lift during filter feeding. By Permian time, productids had reached the climax of their evolution and took on several bizarre shapes. One Permian species appeared like an ice cream cone on stilts. Another had a leaf-shaped lower shell and a lid shell appearing as a pair of combs that allowed water to flow in even when the lid was closed.

5. Most of the typical Devonian fish groups were extinct by the late Paleozoic, but ray-finned fish continued to thrive. Xenacanth sharks, which had distinctive double pronged teeth and a long spike on their head, dominated the fresh waters as large predators.

6. By late Paleozoic time, graptolites were practically gone and trilobites were extremely scarce, but another group known as foraminiferans became abundant. Foraminiferans are tiny proterozoans (single-celled animals), often microscopic in size, that typically secrete a calcareous protective shell and tend to be free-floating.

7. Figure 13.55: Fusulinids were an important group of Late Paleozoic forams and were among the largest of all protozoans, some reaching over a centemeter in length. Because fusilinids were extremely widespread, they were the best group of index fossils for the Pennsylvanian and Permian. Unfortunately, fusilinids were wiped out at the end of the Permian.

8. Late Paleozoic reef communities were not as well developed as those of the Middle Paleozoic. Permian reefs generally had no wave-resistant framework of corals but instead were formed mainly by calcareous sponges and huge concentrations of bryozoans, productid brachiopods, calcareous algae and fusilinids. The reef communities also included abundant clams and gastropods that typically resided in the muddier parts of the carbonate banks. Crinoids and solitary rugosid corals were much less abundant and trilobites were rare.

1. During the late Paleozoic, life on land diversified into a much more complex range of communities.

2. Plant life became abundant and diverse and formed extensive Carboniferous coal swamps. The growth of floodplains and deltas during the Pennsylvanian Period marked a great expansion of coal swamps and other terrestrial habitats.

3. Figure 13.57: Among spore-bearing plants, lycopsids produced gigantic trees reaching 30 meters (100 feet) in height complete with scaly bark. Lepidodendrons and Sigillaria were two of the most common trees that dwelled in the coal swamps.

4. Figure 13.57: Joint-stemmed sphenopsids, or scouring rushes, also reached gigantic sizes. Calamites was a common Carboniferous sphenopsid whose branches clustered at joints between stems.

5. Figure 13.60: Seed plants also began to flourish during the Late Paleozoic. Seed ferns, the most primitive of the gymnosperms, were important in the Devonian forests. One common gymnosperm was Cordaites, which reached 30 meters (100 feet) in height and had long, strap-like leaves.

6. Another primitive gymnosperm was Glossopteris that was common in the southern Gondwana continent.

7. The great coal swamps began to disappear during the Permian. During middle Permian time, a great drying event occurred that devastated swamp plants and shifted the environments in favor of seed plants.

8. The Middle to Late Permian marked a great expansion of gymnosperms. The drier uplands and floodplains became covered with a variety of seed trees including the first conifers that had needle-like leaves and small cones for seeds.

9. The spore-bearing lycopsids and sphenopsids still persisted during the Permian (and survive today) but had become small, creeping forms restricted to watery environments.

10. True ferns continued to flourish as low growth beneath a canopy of gymnosperms.

By the Late Carboniferous, insects had undergone an explosive radiation and dominated the coal swamps, forests and other vegetated areas. Dragonflies with wingspans that could reach almost a meter (28 inches) in length and mayflies were very abundant. Beetles, cockroaches (some reaching lengths of 8-10 centimeters), grasshoppers and crickets were abundant in the coal swamps by the end of the Carboniferous.

1. Figure 13.61: The first amphibians (Ichthyostega) had crawled out onto land by the end of the Devonian Period. During the Carboniferous, amphibians diversified and inhabited a variety of nitches within the coal swamps.

2. By late Paleozoic time, the original fishlike amphibians had evolved into one branch of large preditors known as temnospondyl amphibians which had long snouts, flattened heads and short sprawling limbs. Many had eyes on top of their head suggesting that they floated in swamps like alligators. The large, flat-bodied temnospondyl amphibians had reached the size of crocodiles by Permian time. Eryops reached 2 meters (7 feet) in length and weighed about 130 kg (285 pounds).

3. Another group of amphibians, known as the nectrideans, included a species that had horns flaring out in the shape of a boomerang.

4. A third group of amphibians, the anthracosaurs, were characterized by deep skulls and reptile-like characteristics. Anthracosaurs continued to thrive in the Permian alongside the newly emerged reptiles.

1. Figure 13.61: A fourth group, the amniotes, evolved from amphibians during the middle Carboniferous.

2. Figure 13.62: The greatest achievement of the early amniotes was development of the amniotic egg. Unlike amphibian eggs that were porous and required a water median to survive, the amniotic egg does not require water. Instead, the amniotic egg encases the embryo in an amniotic membrane that allows oxygen to enter but retains water. The amniotic egg also has a yolk sac to feed the developing embryo as well as a sac to store wastes. The amniotic egg allowed the early amniotes to reproduce on land, far from bodies of water.

3. By the Late Carboniferous, the amniotes had split into two main lineages, the reptiles and synapsids.

4. Figure 13.62: The earliest known reptiles were typically small, lizard-like creatures. The early Pennsylvanian Hylonomus, for instance, was no more than a foot long.

5. Reptiles soon evolved into a number of archaic forms, including beaked lizards that were possibly the ancient relatives of turtles.

1. The other lineage, the synapsids, are often called "mammal-like reptiles" although they are not really true reptiles. The earliest synapsids appeared side by side with the oldest true reptiles during the early Pennsylvanian.

2. Figure 13.63: The primitive synapsids evolved into a variety of forms by early Permian time, including powerful carnivorous creatures such as the finbacked Dimetrodon which reached 2 meters (7 feet) in length and may have weighed 100 kg (220 pounds). Dimetrodons had sharp teeth, including stabbing canines in the front, to quickly kill and devour prey.

3. Another finbacked synapsid was Edaphosaurus, one of the few herbivorous vertebrates in the Early Permian.

4. Figure 13.64: By late Permian time, most of the amphibian groups that dominated the Carboniferous had become extinct and their niches filled with a spectacular radiation of synapsids. Most of the late Permian synapsids were predators and many were beginning to look more and more like mammals. Some of the most advanced Permian synapsids may have even had hair or fur.

5. Figures 13.65: There were also herbivorous synapsids such as the small Lystrosaurus which had beaks for cutting plants. Other plant-eating synapsids included the huge Moschops that were over 2.5 meters long and had heads capped by thick bony skulls.

6. Hiding in the vegetation from the great synapsid predators were small lizard-like reptiles that included the earliest relatives of snakes, crocodiles and dinosaurs.

1. The end of the Permian witnessed the greatest of all marine extinctions when 90-95% of all marine species on earth were wiped out.

2. The list of casualties include graptolites, trilobites, fusulinids, productid brachiopods, reef-building bryozoans and archaic nautiloids. Crinoids and ammonoids had their numbers significantly reduced. Clam and gastropod genera suffered about a 30% reduction.

3. On land, there was a gradual shift from Cordaites and ferns to conifers, cycads and other gymnosperms.

4. The Late Permian witnessed the extinction of 75% of all vertebrate families including archaic amphibians, a variety of primitive reptiles, and many synapsids.

5. The Permian extinctions were not all sudden or catastrophic, but rather many extinctions were gradual over the course of several millions of years. In addition, extinctions were largely focused on tropical, warm-water animals.

1. Figure 13.46: Some paleontologists consider global cooling as a cause for the mass extinctions. The Permian was a time when the great supercontinent Pangea stretched nearly from pole to pole, completely cutting off oceanic circulation in the equatorial belt. However, recent research indicates that the main phase of glaciation occurred during the middle Permian, whereas the latest Permian was actually marked by a rapid global warming.

2. Other scientists argue that the reduced areas of shallow-water habitats resulting from assembly of Pangea may have been responsible for much of the Late Permian marine extinctions.

3. There is evidence of Late Permian climatic instability as evidenced by temperature extremes between high and low latitudes. Evidence in the rock record indicate that during the Late Permian, hot, dry conditions dominated low latitudes while glaciers were characteristic of the high latitudes. This great global temperature contrast between high and low latitudes may have resulted in extreme climatic fluctuations and instability.

4. Marine regressions may have led to exposure and oxidation of organic matter previously stored in deep water, thus seriously reducing the nutrient supply to organisms. This major oxidation event may have also significantly depleted atmospheric oxygen levels.

5. The Late Permian was a time of extensive basaltic lava and explosive eruptions which sent enormous amounts of sulfates and ash clouds into the atmosphere, which in turn blocked sunlight and caused major global cooling.