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Will Dinosaurs Evolve Again?

Chris Wu

on 6 March 2014

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Transcript of Webquest

By: Chris Wu, Mark Chuang, and Jacky Chen
Works Cited
"Are Birds Really Dinosaurs?" Dinobuzz: Dinosaur-Bird Relationships. N.p., n.d. Web. 06 Feb. 2014.

"Chicken Is T Rex's Closes Living Relative." The Telegraph. Telegraph Media Group, 24 Apr. 2008. Web. 04 Feb. 2014.

"Did the Dinosaurs Really Go Extinct?" About.com Dinosaurs. N.p., n.d. Web. 04 Feb. 2014.

"Feather Evolution." Feather Evolution. N.p., n.d. Web. 04 Feb. 2014.

"Fossils & Evolution - Fossil Evidence Supports Evolution." About.com Agnosticism / Atheism. N.p., n.d. Web. 07 Feb. 2014.

"Geologic Time - EnchantedLearning.com." Geologic Time - EnchantedLearning.com. N.p., n.d. Web. 04 Feb. 2014.

"Global Warming May Take Ocean Sounds Back to Dinosaur Era - Technology & Science - CBC News." CBCnews. CBC/Radio Canada, n.d. Web. 04 Feb. 2014.

"How Did Dinosaurs Evolve?" About.com Dinosaurs. N.p., n.d. Web. 07 Feb. 2014.

"How Many Dinosaurs Were There? -Zoom Dinosaurs." How Many Dinosaurs Were There? -Zoom Dinosaurs. N.p., n.d. Web. 07 Feb. 2014.

"How Did Dinosaurs Evolve?" About.com Dinosaurs. N.p., n.d. Web. 11 Feb. 2014.

"Maniraptora (“Seizing Hands”)." Maniraptoran Dinosaurs. N.p., n.d. Web. 04 Feb. 2014.


Background Information
Role of Genetics in Evolution

Mutation is the changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, deletion, insertion, or rearrangement of larger sections of genes or chromosomes.
Mutations can cause certain preferable traits to arise allowing for those species to have a greater chance of survival thus producing more fertile offspring.
Sexual Reproduction
Sexual reproduction is the production of new living organisms by combining the genetic information of two different types (sexes).

In humans the male would produce gametes which has half the chromosomes of other somatic cells, and those gametes would travel to fuse with a gamete produced by the female.

Sexual Reproduction allows for random recombination of genetic material, allowing for genetic variety, and changes that are well suited for their environment.

Gene Frequency
Gene frequency is the ratio of a particular allele to the total of all other alleles of the same gene in a given population.

Gene frequency connects to evolution because the fluctuation of this frequency is the result of evolution.

As organisms and plants change their genetic compositions over generations and generations, the ones that are relatively more adapted to their environment would produce more offspring. This change in genetic compositions would cause differences in gene frequencies over long periods of time.
What is Evolution?
Evolution is the process by which different kinds of living organisms have developed and diversified from earlier forms during the history of the earth.
Natural Selection
Natural selection is the process where organisms that are better adapted to their environment would most likely survive and produce more fertile offspring.

This theory was first fully explained by Charles Darwin and is now believed to be the main process that brings about evolution.
How did the Dinosaurs Evolve?
Ancestry of all land animals can be traced back over 400 million years ago
Organisms began their transition from water to land at this time
Certain changes and traits are built over time which enabled sea creatures to set foot on land
These changes are due to differences in genetic compositions (ex: genetic changes include limb bones in some fishes, necessary to move around on land)
Limitation on prey and dangerous predators have caused organisms to move onto land, where there's abundances of untouched food
Tetrapods soon roamed the lands
Era of Reptiles - Permian period
End of the Permian period, mass extinction occurs, wiping out 75% of all tetrapod families
(an example of genetic drift, which leads to evolution > dinosaurs)
Lineage of animals which survived lead to the rise of dinosaurs
This would mark the end of the Palaeozoic era, and the start of the Mesozoic era, which the dinosaurs reigned
Extinction of Dinosaurs
There are many theories supported with evidence in how dinosaurs have extincted. This is called the Cretaceous–Paleogene extinction event.
Asteroid Impact
This was a very common theory, in which there has been a extraterrestrial impact. The asteroid, about 10 miles wide, slammed into the gulf of Mexico. The impact would send tons of debris into the air, which would come raining down as fireballs. Forests caught fire, lightning storms raged, and the dust cloud that forms would block all sunlight. With no sunlight, survival of the dinosaurs was impossible. The extinction itself may have taken around 30,000 yrs and even up to 200,000 yrs. Vegetation would gradually die out, along with the herbivores, and then carnivores who ate the herbivores.
Drop in Temperature
Another theory is that the extinction of dinosaurs was due to a sudden drop of temperature at the time. Ice age would bring about the death of plants, which would effect all of dinosaurs.

Some argue that an asteroid is which caused the Ice age, while others insist that an Ice age was the only cause of extinction.

This scenario of extinction could have lasted over a million years as the climate gradually changed, and dinosaur numbers progressively decrease.
Extinction: Evidence that supports Asteroid Impact
Iridium is extremely rare on Earth's crust.
However, a team of researchers have found levels of Iridium to exceed normal levels by a tremendous amount. This suggests that an asteroid had struck Earth, leaving this rare material on Earth's surface.

Discovery of huge tsunami beds along the Gulf of Mexico and a huge crater also suggests an asteroid.

Extinction: Evidence for Ice Age
A team of researchers from Holland and Italy fossilized cold water plankton that dates back 65 million years in an area that has previously been warm (Tunisia)

They discovered Dinoflagellates and Benthic Formanifera plankton were found in the first time-dated fossils that provide clear evidence of climate swings.

These plankton would only live in cold environments and discovering these which strives in this particular place (supposedly warm) and dates back 65 million years ago provides some evidence for an Ice age.
Closest Living Relatives of Dinosaurs
Dinosaurs and Birds
Comparing anatomical features, there are a few similarities for example:
The hipbone of a dinosaur is turned backwards, just like a bird's hipbone
Coelurosaurian dinosaurs are often thought to be the close relative of birds as early birds shared many skeletal characteristics with them.
Similarities they share include:
Elongated arms, forelimbs, and clawed manus (hands)
Hollow, thin-walled bones
S-shaped curved neck
Recently, some possibly feathered dinosaurs were discovered in China, suggesting solid connection to birds
Furthermore, a complex system of air sacs similar to those found in modern birds are also found in large meat-eating dinosaurs.
It was also discovered that the closest living relatives of the Tyrannosaurs rex are chickens (a type of bird). By sequencing proteins from the T-rex, it shows a high amount similarity to those of the chicken.
Dinosaurs and Reptiles
Dinosaurs are genetically connected to reptiles. Dinosaurs and reptiles shared ancestry in the Pennsylvanian period, the first time in history that reptiles walked on Earth. Dinosaurs and reptiles are similar in terms of reproduction. Both lay eggs, impregnates the female, and after hatch, offspring is tended by the female for a while.

They are both reptiles and are vertebrate possessing a spine with several appendages.

They also share bones like the dermal bone (plates and scales), which develop in the skin, and exoskeletal bones, which is found inside the muscles.
Will Dinosaurs Evolve Again?
Our answer is ...No.
The Earth's climate fluctuates over thousands of years, and temperatures would naturally rise at times, and decrease on other occasions.

There is no scientific evidence in how climate (global warming) alone will allow dinosaurs to evolve again. Dinosaurs did not become dinosaurs because the Earth's temperature was a little warmer. Previous organisms evolved into dinosaurs because of countless factors put together at the same time. As of now, no evidence in climate directly suggests how dinosaurs would rise again. Without solid evidence or proof, it would be logical to say climate change does not contribute to the re-evolution of dinosaurs, therefore, dinosaurs will not evolve again.

Humans have altered much of the landscape and the environment on Earth. Infrastructures, roads, etc, have taken over Earth. There is little space for dinosaurs to evolve. Humans are very intelligent in the sense that we can adapt to so much more variations or changes in the environment and still survive well. This means that there aren't many other organisms that are more suited to be on Earth. For as long as man walks on Earth, the chance of dinosaurs evolving again, is pretty much nil. The environment humans live in does not create a place where it is suitable for dinosaurs. When something is not suited to a certain degree for an organism, it will not exist.
Dollo's Law of Irreversibility
Dollo's law of irreversibility states that, "An organism is unable to return, even partially, to a previous stage already realized in the ranks of its ancestors."

According to this theory, predacestors of the dinosaurs like birds today, cannot evolve back into dinosaurs. It may evolve into something similar to dinosaurs, however it will never be the same as dinosaurs.

The species which evolve from dinosaurs will have similar traits as it, with more and more variation as time passes. Organisms that will evolve from birds over the next million year will share attributes similar to dinosaurs and birds, but will not be the exact replica of dinosaurs.

An example could portray a set of branches on a tree. The dinosaur "branch" has died, however a new branch over time has lead to the bird "branch". The dinosaur branch cannot just suddenly revive, after its died off.

Genetic Composition
Genetic compositions today in the successors of dinosaurs such as birds, would have to drastically change, if dinosaurs were to 'come back'. However these mutations or random chances of recombination which make the birds or other organisms more similar to dinosaurs are not favorable genes. The world is ruled by humans today. Dinosaurs are not suited in the environment today.

Habitat is a major factor which supports why dinosaurs cannot evolve again.The genes in dinosaurs which cause them to be so large, does not allow them to fit well in today's environments.

Human Evolution
Example of Law of Independent Assortment
(Notice how different kinds of gametes are created)
* Catastrophic Event Occurs *
Shows how gene frequency can change after catastrophic events, such as earthquakes, particularly in smaller populations.

"How Many Dinosaurs Were There? -Zoom Dinosaurs." How Many Dinosaurs Were There? -Zoom Dinosaurs. N.p., n.d. Web. 07 Feb. 2014.

"How Did Dinosaurs Evolve?" About.com Dinosaurs. N.p., n.d. Web. 11 Feb. 2014.

"Maniraptora (“Seizing Hands”)." Maniraptoran Dinosaurs. N.p., n.d. Web. 04 Feb. 2014.

"TEACHERS." Scholastic Teachers. N.p., n.d. Web. 02 Feb. 2014.

"The 15 Main Dinosaur Types." About.com Dinosaurs. N.p., n.d. Web. 06 Feb. 2014.

Jha, Alok. "Who Are You Calling Chicken? T. Rex's Closest Living Relative Found on the Farm." The Guardian. Guardian News and Media, 13 Apr. 2007. Web. 04 Feb. 2014.

PBS. PBS, n.d. Web. 07 Feb. 2014.

"The Origin of Tetrapods." The Origin of Tetrapods. N.p., n.d. Web. 08 Feb. 2014.

"Tetrapods - The Fish Out of Water." About.com Dinosaurs. N.p., n.d. Web. 11 Feb. 2014.

"Theory of Natural Selection - Genetics and Evolution." Theory of Natural Selection. N.p., n.d. Web. 10 Feb. 2014.

Wade, Michael. "Evolutionary Genetics." Stanford University. Stanford University, 14 Jan. 2005. Web. 09 Feb. 2014.

Impressionist art of an asteroid slamming into Earth. Scary!
Artistic impression of an Ice Age, showing very cold temperatures

Dinosaur? I think not.












Lizard today, with its eggs
Artistic impression of a dinosaur with its eggs
Similar skin tone
The controversy over dinosaurs and birds started back in the 1970s, up till today, and sometimes it is still a problematic matter. It is becoming increasingly difficult to draw the line between "bird" and "non-avian dinosaur".

Some researchers today do not agree that dinosaurs gave rise to birds, and are working to falsify this theory, but so far the evidence for the theory does not go in their favour.

The third possible reason that caused the extinction of dinosaurs is flood basalt, which is the result of a massive volcanic eruption or a series of volcanic eruptions that causes land stretches of the land and the ocean to be covered with basalt lava.

Even though the most probable reason has always been an asteroid impact, a growing number of researchers in the past decades have been supporting the theory of extreme volcanic activity that led to the extinction of the dinosaurs. Strong evidence supporting this theory is the presence of the Deccan Traps, which is a rocky area that covers much of India today. It is formed by volcanic eruptions that spewed lava over an area of the size of France. Additionally, new evidence discovered by geoscientist, Gerta Keller found fossils from the era of the dinosaurs in ancient lava-filled sediments, around the time when the extinction of the dinosaurs were taking place.

To this day, no definite theory have been accepted as correct to explain the extinction of the dinosaurs; further evidence have to be discovered and analyzed in the future to solve this long time mystery.

Flood Basalt Eruptions
Full transcript