J. Macroevolution (Midterm II)
Pangaea
(plate tectonics) a hypothetical continent including all the landmass of the earth prior to the Triassic period when it split into Laurasia and Gondwanalan According to geologists, the earth originally had only one "supercontinent" that drifted apart, subsequently into the 7 continents. Name the "supercontinent".
Big 5 mass extinctions
1.) End Ordovician 2.) Late Devonian 3.) End Permian 4.) End Triassic 5.) End Cretaceous Ordovician-silurian (mainly sea creatures killed) Late devonian (reefs and shallow sea life killed) Permian (96% killed) Triassic-Jurassic (by climate change, floods, and asteroids) Cretaceous-Tertiary (killed dinosaurs)
Deep time scales
???
Higher taxonomic levels
???
Major ecological shifts
???
Major morphological changes
???
Chicxulub crater
A prehistoric impact crater buried underneath the Yucutan Peninsula in Mexico. Its center in located near the town of Chicxulub. The age of the rocks marked by the impact shows that this impact structure dates from roughly 66 million years ago, the end of the Cretaceous period, and the start of the Paleogene period. It coincides with the K-Pg boundary, the geological boundary between the Cretaceous and Paleogene. The impact associated with the crater is thus implicated in the Cretaceous-Paleogene extinction event, including the worldwide extinction of non-avian dinosaurs. This conclusion has been the source of controversy. In March 2010, 41 experts from many countries reviewed the available evidence: 20 years' worth of data spanning a variety of fields. They concluded that the impact at Chicxulub triggered the mass extinctions at the K-Pg boundary.
Mesozoic
An era with the Triassic, Jurassic and Cretaceous periods from 251 to 65.5 M years ago, marked by dinosaurs, gymnosperms and angiosperms, as well as the mass extinction at the end of the period. The Mesozoic Era is divided into three time periods: the Triassic (251-199.6 million years ago), the Jurassic (199.6-145.5 million years ago), and the Cretaceous (145.5-65.5 million years ago).* Mesozoic means "middle animals," and is the time during which the world fauna changed drastically from that which had been seen in the Paleozoic. Dinosaurs, which are perhaps the most popular organisms of the Mesozoic, evolved in the Triassic, but were not very diverse until the Jurassic. Except for birds, dinosaurs became extinct at the end of the Cretaceous. Some of the last dinosaurs to have lived are found in the late Cretaceous deposits of Montana in the United States. The Mesozoic was also a time of great change in the terrestrial vegetation. The early Mesozoic was dominated by ferns, cycads, ginkgophytes, bennettitaleans, and other unusual plants. Modern gymnosperms, such as conifers, first appeared in their current recognizable forms in the early Triassic. By the middle of the Cretaceous, the earliest angiosperms had appeared and began to diversify, largely taking over from the other plant groups.
Iridium layer
In the geologic record, the K-Pg event is marked by a thin layer of sediment called the K-Pg boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust but abundant in asteroids.
Large-scale evolution
Macroevolution
Methane belch
Methane burp hypothesis, also called gas hydrate dissociation hypothesis, in oceanography and climatology, an explanation of the sudden onset of the Paleocene-Eocene Thermal Maximum (PETM), an interval of geologic time roughly 55 million years ago characterized by the highest global temperatures of the Cenozoic Era (65 million years ago to the present). According to the hypothesis, the PETM was triggered when large deposits of methane hydrates in ocean sediments were warmed to the point at which methane was released through the ocean and into the atmosphere in large quantities. The methane then oxidized, forming carbon dioxide. The increase in the concentration of carbon dioxide led to atmospheric warming—perhaps not unlike the global warming being observed in the 21st century. Large-scale submarine landslides discovered off the coast of Florida have lent significant support to the hypothesis, although such landslides would have had to occur in many additional locations to provide enough methane to cause the PETM.
Paleozoic
Paleozoic Era, major interval of geologic time that began 542 million years ago with the Cambrian explosion, an extraordinary diversification of marine animals, and ended 251 million years ago with the end-Permian extinction, the greatest extinction event in Earth history. Characterized by the advent of fish, insects, and reptiles. **Most of the diversification of life on Earth occurred during which era?
Broad geographic areas
Terrestrial Biomes Major Land Resource Area (MLRA)
K-Pg (65.5 Ma)
The Cretaceous-Paleogene (K-Pg) extinction event was a mass extinction of some three-quarters of plant and animal species on Earth—including all non-avian dinosaurs—that occurred over a geologically short period of time, 66 million years ago. It marked the end of the Cretaceous period and with it, the entire Mesozoic Era, opening the Cenozoic Era that continues today. In the geologic record, the K-Pg event is marked by a thin layer of sediment called the K-Pg boundary, which can be found throughout the world in marine and terrestrial rocks. The boundary clay shows high levels of the metal iridium, which is rare in the Earth's crust but abundant in asteroids. --- K-T extinction, abbreviation of Cretaceous-Tertiary extinction, also called K-Pg extinction or Cretaceous-Paleogene extinction, a global extinction event responsible for eliminating approximately 80 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods, about 66 million years ago. The K-T extinction was characterized by the elimination of many lines of animals that were important elements of the Mesozoic Era (252.2 million to 66 million years ago), including nearly all of the dinosaurs and many marine invertebrates. The event receives its name from the German word Kreide, meaning "chalk," and the word Tertiary, which was traditionally used to describe the period of time spanning the Paleogene and Neogene periods. The K-T extinction ranks third in severity of the five major extinction episodes that punctuate the span of geologic time. Of the dinosaurs, only the archosaurs, a lineage that gave rise to modern birds and crocodilians, survived the extinction. Of the planktonic marine flora and fauna, only about 13 percent of the coccolithophore and planktonic foraminiferal genera remained alive. Among free-swimming mollusks, the ammonoids and belemnoids became extinct. Among other marine invertebrates, the larger foraminifers (orbitoids) died out, and the hermatypic corals were reduced to about one-fifth of their genera. Rudist bivalves also disappeared, as did bivalves with a reclining life habit, such as Exogyra and Gryphaea. The stratigraphically important inoceramids also died out. The mass extinction was quite different between, and even among, other marine and terrestrial organisms. Land plants appear to have fared better than land animals; however, there is evidence of widespread species extinctions of angiosperms and other dramatic shifts among North American plant communities. It is important to note that some groups of reptiles died out well before the K-T boundary, including flying reptiles (pterosaurs) and sea reptiles (plesiosaurs, mosasaurs, and ichthyosaurs). Among surviving reptile groups, turtles, crocodilians, lizards, and snakes were either not affected or affected only slightly. Effects on amphibians and mammals were also relatively mild. These patterns seem odd, considering how environmentally sensitive and habitat-restricted many of those groups are today. Many hypotheses have been offered over the years to explain dinosaur extinction, but only a few have received serious consideration. The extermination of the dinosaurs has been a puzzle to paleontologists, geologists, and biologists for two centuries. Proposed causes include disease, heat waves and resulting sterility, freezing cold spells, the rise of egg-eating mammals, and X-rays from a nearby exploding supernova. Since the early 1980s, however, much attention has been focused on the so-called "asteroid theory" formulated by American scientists Walter Alvarez and Luis Alvarez. This theory states that a bolide (meteorite or comet) impact may have triggered the extinction event by ejecting a huge quantity of rock debris into the atmosphere, enshrouding Earth in darkness for several months or longer. With no sunlight able to penetrate this global dust cloud, photosynthesis ceased, resulting in the death of green plants and the disruption of the food chain. There is much evidence in the rock record that supports this hypothesis. A huge crater 180 km (112 miles) in diameter dating to the latest Cretaceous was discovered buried beneath sediments of the Yucatán Peninsula near Chicxulub, Mexico. A second, smaller crater, which predates the one at Chicxulub by about 2,000 to 5,000 years, was discovered at Boltysh in Ukraine in 2002. Its existence raises the possibility that the K-T extinction was the result of multiple bolide impacts. In addition, tektites (fractured sand grains characteristic of meteorite impacts) and the rare-earth element iridium, which is common only deep within Earth's mantle and in extraterrestrial rocks, have been found in deposits associated with the extinction. There is also evidence for some spectacular side effects of bolide impact, including an enormous tsunami that washed up on the shores of the Gulf of Mexico and widespread wildfires triggered by a fireball from the impact. The asteroid theory has met with skepticism among paleontologists, with some agitating for terrestrial factors as the cause of the extinction and others claiming that the amount of iridium dispersed by an impact was caused by a smaller object, such as a comet. A huge outpouring of lava, known as the Deccan Traps, occurred in India during the latest Cretaceous. Some paleontologists believe that the carbon dioxide that accompanied these flows created a global greenhouse effect that greatly warmed the planet. Others note that tectonic plate movements caused a major rearrangement of the world's landmasses, particularly during the latter part of the Cretaceous. The climatic changes resulting from such continental drift could have caused a gradual deterioration of habitats favourable to the dinosaurs and other animal groups that suffered extinction. It is, of course, possible that sudden catastrophic phenomena such as an asteroid or comet impact contributed to an environmental deterioration already brought about by terrestrial causes.
Permo-Triassic (250 Ma)
The Permian-Triassic (P-Tr) extinction event, colloquially known as the Great Dying or the Great Permian Extinction, occurred about 252 Ma (million years) ago, forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, possibly up to 10 million years. Marine invertebrates suffered the greatest losses during the P-Tr extinction. There are several proposed mechanisms for the extinctions; the earlier phase was probably due to gradual environmental change, while the latter phase has been argued to be due to a catastrophic event. Suggested mechanisms for the latter include one or more large bolide impact events, massive volcanism, coal or gas fires and explosions from the Siberian Traps, and a runaway greenhouse effect triggered by sudden release of methane from the sea floor due to methane clathrate dissociation or methane-producing microbes known as methanogens; possible contributing gradual changes include sea-level change, increasing anoxia, increasing aridity, and a shift in ocean circulation driven by climate change.
Volcanism
The eruption of magma from the mantle. * two mountain building processes in which magma (molten rock) either breaks through the surface (lava) = volcano or pushes up the earth's crust= doming INCREASE CO2.
Nuclear winter
The expected freeze that would occur in the Earth's climate from the fallout of smoke and dust in the event nuclear weapons were used, blocking out sunlight and destroying the plant and animal life that survived the original blast. Hypothetical climatic effect, most often considered a potential threat following a countervalue, or city-targeted, nuclear war. Climate models suggest that the ignition of a hundred or more firestorms that are comparable in intensity to that observed in Hiroshima in 1945 would produce a small nuclear winter. The burning of these firestorms would result in the injection of soot into the Earth's stratosphere, producing an anti-greenhouse effect. The models conclude that the magnitude of this effect from the cumulative products of 100 firestorms would reach sufficient extent to unmistakably alter the global climate, resulting in agricultural losses from the colder weather, and lasting for a period of years. The scientific speculation that nuclear war could end life on earth be creating atmospheric changes which would block out the sun and result in a general cooling of the planet. The expected freeze that would occur in the Earth's climate from the fallout of smoke and dust in the event nuclear weapons were used, blocking out sunlight and destroying the plant and animal life that survived the original blast.
Plate tectonics
The theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle.
