Today s Topic Evolution: Extinction Learning Goal: SWBAT explain why creatures go extinct from Earth, and why some recently-extinct creatures have gone extinct. Please take out your fill-in notes again, and we will continue learning about extinct creatures.
Homework Complete the Simulating Adaptations Lab (Due Monday, 4/13) Complete the Conditions of Natural Selection homework and History of Evolution Research Assignment. (Five Days Late) Complete cattle, cows, and dogs articles. (Two Days Late)
Upcoming Test Our next test will take place on Wednesday, 4/15. It will cover all of Evolution: Biological Evolution Natural Selection Artificial Selection Adaptations Extinction Succession
Five Extinct Creatures: Pyrenean Ibex Was once numerous across Spain and France. However, by the early 1900s, fewer than 100 remained.
Five Extinct Creatures: Pyrenean Ibex The last was seen on January 6, 2000, when it was found dead under a fallen tree. Their populations dwindled due to interspecific competition and poaching.
Five Extinct Creatures: Pyrenean Ibex In 2009, the ibex was unextinct when scientists cloned an ibex. However, this clone died 7 minutes after being birthed due to lung defects.
Five Extinct Creatures: Spix s Macaw Lived in northern Brazil. 71 exist in captivity, but the last wild macaw disappeared in 2000, and there are no other wild macaws known to remain.
In 1990, a single male was paired with a female in captivity to reproduce in the wild. Seven weeks later after the female s release, she collided with a power line and died.
Five Extinct Creatures: Spix s Macaw Their decline in population is attributed to hunting and trapping, habitat destruction, and introduction of Africanized bees, which compete for nesting sites with macaw.
Today s Fill-In Notes We re next going to work through the five mass-extinction events that took place on Earth. After that, we are going to watch the beginning of an episode of Cosmos regarding one of the extinction events.
The Five Mass-Extinction Events Throughout Earth s history there have been many extinction events. However, there has been five massextinction events that occurred in Earth s history. In a mass-extinction event, over 50% of all plant and animal life go extinct.
The Five Mass-Extinction Events The Five Mass-Extinction Events that occurred are: a. The Ordovician-Silurian (450 440 Mya) b. The Late Devonian (375 360 Mya) c. Permian-Triassic (252 Mya) (Cosmos) d. Triassic-Jurassic (201.3 Mya) e. Cretaceous-Plaeogene (66 Mya)
The Ordovician-Silurian The Ordovician-Silurian mass-extinction occurred approximately 450 440 Mya at the end of the Ordovician Period. Typically large scale events, such as mass-extinctions, mark the end of a geologic time period. During this time, 70% of all species on Earth were killed.
The Ordovician-Silurian During this period of time, all life existed in the oceans.
The Ordovician-Silurian However, two events occurred, an estimated four million years apart, that set off this mass-extinction event.
The Ordovician-Silurian First was the movement of the supercontinent of Gondwana. Gondwana, through tectonic plate movement, shifted towards the south. This in turn led to global cooling.
The Ordovician-Silurian As a result of this global cooling, glaciers began to form all over the planet. This caused a drop in sea levels, which further killed off many creatures.
The Late Devonian The Late Devonian mass-extinction occurred approximately 375 360 Mya at the transition from the Devonian Period to the Carboniferous Period. This extinction event caused 70% of all creatures on Earth to perish.
The Late Devonian It is unclear what caused the massextinction, but evidence suggests that it was not one singular event that triggered the extinction. It is thought that several small events occurred over the span of 20 million years.
The Late Devonian This extinction event only appeared to affected marine life. Some theories as to what caused the extinction event are changed to ocean levels, or depletion of oxygen in oceans. This would have been caused by volcanic activity in the ocean.
The Triassic-Jurassic The Triassic-Jurassic mass-extinction occurred approximately 201.3 Mya at the end of the Triassic Period. This extinction event caused 70% - 75% of all creatures on Earth to go extinct.
The Triassic-Jurassic Land and air-dwelling dinosaurs survived perfectly well through this extinction event.
The Triassic-Jurassic However, non-dinosaur aquatic creatures in the oceans continued to dominate the oceans.
The Triassic-Jurassic There are many theories as to what caused the extinction event: Gradual climate change Sea-level fluctuations Ocean acidification
The Triassic-Jurassic One theory suggests the possibility of an asteroid impact. However, none of these hypotheses have any significant evidence to support them.
The Cretaceous-Paleogene The Cretaceous-Paleogene massextinction occurred approximately 66 Mya at the end of the Cretaceous Period. This extinction event caused 75% of all creatures on Earth to go extinct.
The Cretaceous-Paleogene This extinction event killed all non-avian (non-flying) dinosaurs.
The Cretaceous-Paleogene This extinction event was believed to have been caused by a massive comet/asteroid impact.
The Cretaceous-Paleogene The impact had dire effects on the entire globe s environment.
The Cretaceous-Paleogene The dark line in the rock marks this event
The Cretaceous-Paleogene Sampling shows higher concentrations (30x higher than naturally found on Earth) of iridium in this region, which is prevalent in meteors and comets. It also corresponds to ash and carbon, as the impact triggered many fires (high O 2 levels)
The Cretaceous-Paleogene The impact caused an impact-winter, which is caused by an ejection of dust and dirt into Earth s atmosphere. This dust and dirt blocks sunlight from entering, which prevents photosynthesis from occurring in plants and plankton.
The Permian-Triassic To learn about the Permian-Triassic extinction event, we turn to our friend Neil degrasse Tyson.