Doran Teverovsky
Mr. Mathieu
Period 2
Michelle Lograta
January 15, 2013
http://www.gmanetwork.com/news/story/343973/scitech/science/ancient-legged-fish-provides-missing-link-in-limb-evolution
Summary:
Recently, a new fossil has been found in Canada of a type of fish, about 375 million years old, that had legs, and could possibly walk on land and water. This nine foot long fish also provided challenging to classify because it blurred the line between crocodile and fish. While this fish, named the Tiktaalik roseae, had a similar rib cage and lung structure to a crocodile, it also had gills and scales leading scientists to name it as a fish. This fish has given scientist much more conclusive proof that rear appendages evolved in water then gradually went to land. The massive pelvis of this fish was what gave it away is a walker. The pelvis was open, and was shaped for legs and possibly even a fin as well.
Connection:
This recent fish find relates to evolution, classification, and phylogeny. Before, we were guessing as to where legs evolved, with this fish, we can much more easily place mammals and fish on the same phylogeny because of this ancestor. Also, this connects to classifying organisms, and how difficult it can be for scientists. Because this animal had such crocidillian, and fish like characteristics, people had to pool all of there resources to decide what to call the animal. This animal is a great example of how one thong leads to another in evolution, and how the slightest advantage, by getting on land first, leads to adaptive radiation in the extreme.
Showing posts with label fossil. Show all posts
Showing posts with label fossil. Show all posts
Wednesday, January 15, 2014
Tuesday, January 14, 2014
Iconic Australasian Trees Found as Fossils in South America
Sophie Antonioli
Mr. Mathieu
Period 2
14 January 2014
Author: unknown
Published: January 9, 2014
Summary:
Scientist have recently discovered a tree fossil native to Australian in South America. The tree is known as Dammar in Australia and Kauri in Asia but does not have a name in South America due to the fact that it was not grown there unless planted. This specific tree is 52 million years old and the most intact fossilized one that they have found anywhere. The scientists are predicting that these trees grew in Patagonia when the supercontinent Gondwana was formed. Gondwana was made of Australia, South America, and Antarctica. It is also thought that the Agathis (another name for the tree) must have also grown on Antarctica because it was not all ice when Gondwana was composed. However, the trees much have died because of the extreme temperatures that later undertook Antarctica. So, the Agathis tree moved away from the cold south and towards northern Australia and spread to Asia. In Patagonia, they died out due to the seasonal dryness. The inconsistancy of water availability made it hard for them to survive.
Connection:
In this unit, we learned about continental drift and adaptation. Continental drift plays a huge role in this discovery. We know that the tree was able to be on all three of these continents (South America, Australia and Asia) because the continents were once connected. Without this connection, if Gondwana was never formed, the Agathis tree would not be present in all these places because of geographic isolation. It is also important to notice that as Antarctica began to freeze, the trees were dying and natually migrated north, toward the equator where they could survive in the hot and wet environments.
New Fossils Shed Light On the Origins of Lions, Tigers, and Bears
Jessica Lim
Mr. Mathieu
Period 2
January 14, 2014
No Author given
Published: January 6, 2014
Article: http://www.sciencedaily.com/releases/2014/01/140106160029.htm
Summary:
At the Belgian locality of Dormaal, new fossils of the species Dormaalocyon was discovered and it is said to be very close to the common ancestor of carnivoraformes; modern mammals. Scientists were able to infer that since it had ankle bones it moved around on trees and lived in them. This species was known to have over 250 teeth. Scientists were able to infer that it was "close to the origin of carnivoraforms" because when they inspected the baby teeth of the species, they were able to tell the scientists that it was from a very early time period.
When they recreated the environment 55 million years ago, the environment turned out to be really warm and humid because it was after the Paleocene-Eocene Thermal Maximum, and the evolution of the carnivoraformes and many other species were affected by this. This fossil also shows that there are even more primary species that once lived in an earlier time period.
Connection:
This connects to our unit on evolution. We learned about how when there is a change in the environment, through natural selection, those that inherited the most suitable characteristics to survive and reproduce, evolved and adapted to the new environment. We also learned that through either reproductive isolation or geographical isolation, speciation occurs and therefore one species can diverge into multiple species. Connecting to the article, the common ancestor of carnivoraformes eventually diverged into multiple species that we see today, for example cats, dogs, bears, and seals.
Mr. Mathieu
Period 2
January 14, 2014
No Author given
Published: January 6, 2014
Article: http://www.sciencedaily.com/releases/2014/01/140106160029.htm
Summary:
At the Belgian locality of Dormaal, new fossils of the species Dormaalocyon was discovered and it is said to be very close to the common ancestor of carnivoraformes; modern mammals. Scientists were able to infer that since it had ankle bones it moved around on trees and lived in them. This species was known to have over 250 teeth. Scientists were able to infer that it was "close to the origin of carnivoraforms" because when they inspected the baby teeth of the species, they were able to tell the scientists that it was from a very early time period.
When they recreated the environment 55 million years ago, the environment turned out to be really warm and humid because it was after the Paleocene-Eocene Thermal Maximum, and the evolution of the carnivoraformes and many other species were affected by this. This fossil also shows that there are even more primary species that once lived in an earlier time period.
Connection:
This connects to our unit on evolution. We learned about how when there is a change in the environment, through natural selection, those that inherited the most suitable characteristics to survive and reproduce, evolved and adapted to the new environment. We also learned that through either reproductive isolation or geographical isolation, speciation occurs and therefore one species can diverge into multiple species. Connecting to the article, the common ancestor of carnivoraformes eventually diverged into multiple species that we see today, for example cats, dogs, bears, and seals.
Tiktaalik roseae fossil analysis provides new details on the origin of vertebrate legs
Isabelle Terranova
Author: University of Chicago- Medical Center
Source: http://phys.org/news/2014-01-discovery-tiktaalik-roseae-fossils-reveals.html
Published: January 13, 2014
Summary:
A group of scientists have discovered that the evolution of hind legs actually started as enhanced fins. This contradicts the theory that large, hind limbs were developed after vertebrates made the transition onto land. The scientists discovered that the transitional species discovered a decade ago, Tiktaalik roseae, actually had large hind limbs when they put together the back end of a prehistoric fossil. The fossil had a large hind fin which was previously believed to be a small appendage. Researchers believe that this fin was capable of walking on underwater surfaces, as well as propelling the fish through the water. The fossil showed that the fish had a large pelvic bone the size of it's shoulder. The pelvic bone is used to support the hind limbs, the fact that it was so large shows that the hind limbs were also large. This is a characteristic of early tetrapods; this relationship allows scientist to believe that the development of hind limbs started much earlier than they previously believed. They conclude that the fish were possibly able to walk before they made the transition onto land, and then the hind limbs were simply exaggerated as it made the transition to a tetrapod.
Connection:
In chapters 14 and 15 we discussed evolution. The discovery made was a turning point and changed what scientists believe about evolutionary history. The discovery of a pelvic bone and hind limbs in the Tiktaalik roseae are homologous structures to those of early tetrapods. This is a term that we discussed in class. It means that they are similar structures found in differnet species that came from the same ancestor. The fins on the fish turned into the hind limbs of the tetrapods; this made the tetrapods better adapted to land. We also discussed the how scientists use the fossil records to determine when certain evolutionary changes and adaptations occurred. The scientists who discovered the fossil put it back together and analyzed it. When they found the fin and hind limb, they were able to adjust their theory; the fossils also helped them date the species back to 375 million years ago, right before when tetrapods would have been emerging. This also ties back to the scientific method in a way because they came up with an idea, found evidence and discovered something new. The article is very interesting and provides many ways in which our units tie back to real life discoveries.
Sunday, January 12, 2014
Early Sharks Reared Young in Prehistoric River-Delta Nursery
Megan Zhou
No author given, but is based on materials provided by the University of Michigan.
Published: January 7, 2014
Summary:
310 million years ago, Bandringa sharks had migrated downstream from freshwater swamps to a tropical coastline. This left behind fossil evidence of one of the earliest known shark nurseries. Paleontologists from the University of Michigan concluded that all known species of Bandringa are long-snouted, bottom-feeding predators that lived in an ancient river delta system. This fossil discovery is the earliest known example of shark migration to spawn, and this behavior is still present in species known today. Along with being the earliest example of a shark nursery with egg cases and small sharks preserved in the same sediments, these Bandringa fossils also are the only known example of a freshwater to saltwater shark migration. Today, no shark alive breeds in the open ocean and spends the rest of their lives in freshwater. These Bandringa sharks are most likely one of the earliest close relatives of modern sharks. Bandringa was discovered originally in 1969, and was always thought that the genus contained two species, one that lived in freshwater areas and another that lived in the shallow ocean. With these new fossils and reevaluating 24 different ones, the paleontologists Sallan and Coates concluded that the Bandringa were a single species that lived, at different times of their lives, in both fresh and salt waters. This reclassification as a single species creates a more complete picture of the extinct shark’s anatomy and helps the discovery of some previously unreported features such as downward jaws, spines, and sensory organs. This is the first fossil evidence for a shark nursery is the earliest evidence for segregation of the juveniles and adults.
Connection:
This article relates to our study on evolution, specifically classification and the fossil record. We have learned how fossils are made, and it had initially led the scientists to believe that they were two species. The freshwater sites having these shark fossils tended to preserve the bones and cartilage, while the marine sites was able to preserve the soft tissue. This also lead to the misclassification of the species as two. This also relates to our study on Darwin and how he has mistakenly classified the finches as different species of birds due to the evidence that he had at the time. Similarly, the paleontologists did not make the connection that the Bandringa sharks were one species before they had the fossil evidence from this nursery. These shark fossils shown in the fossil record also displays our study about the age of these fossils. Because these are 310 million year old fossils, they would have been layered upon layered with other fossils on top of them, due to relative dating.
Sunday, October 20, 2013
New Fossil May Trim Branches of Human Evolution
Becky Nitschelm
October 20, 2013
P2
Mr. Mathieu
Science Friday
Host: John Dankosky
Produced by: Alexa Lim, Associate Producer
Guest Speaker: Adam Van Arsdale, Assistant Professor Anthropology Wellesley College
Published: October 18, 2013
Listen to It: http://www.sciencefriday.com/playlist/#play/segment/9250
Summary: Many scientists believe that homo sapiens (humans) come from many different species including homo habilis (from 2.3 million years ago) and homo erectus (from 1.8 million years ago). However, a skull discovered in Dmanisi, Georgia from about 1.8 million years ago,under the site of an old medieval structure from about 1000 years ago, suggests otherwise. Many fossils of homos have been found at this site. One of them, skull 5, is know as the best preserved skull ever found older than 100,000 years old. From the fossils found at the site, scientists get a complete view of what homos were like 1.8 million years ago. The individuals found are both male, female, old, and young and are from the same time period. Each individual has variations between them, similar to the differences that can be seen today in modern chimpanzees or humans. Previous fossils found about human evolution come from sites in East Africa. These fossils show wide ranges of variation over large periods of time (some fossils differ in age up to 400,000 years). From these, scientists concluded that this large amount of differences between homos can only be because they are from different species. However, the fossils at Dmanisi, including the recently discovered skull 5, which rounds out the picture, show that there can be these large differences between homos in the same species. This variation could just be a result of variation due to evolution, or changes that occur over time. This suggests that the homo genus is all from a common ancestor; it is one continuous line of evolution that does not branch out into different species. Adam Van Arsdale, professor at Wellesley College, believes that this conclusion about evolution of homo sapiens is true and that the genus homo developed due to an increasing niche for humans (new tools and places to live). This new niche makes it harder for a new species to branch out, giving more evidence to the conclusion.
Connection: This connects to what we have been learning in many ways. We also spent time on niches of animals and how that effects them. In this article, Van Arsdale believes that the increasing niche of humans due to new tools and new environments created the genus homo. Also, he thinks that this niche causes less of a chance of a new species to arise. This relates to our study of niches and how if two species occupy the same niche, then one may be hurt by the other (competitive exclusion). In addition, we learned about the evolution of species. We learned that species have to adapt to changes around them in order to survive. This is what is known as evolution, or change over time. In this article, it talks about the evolution of the homo genus and the human species. Also, we learned about biodiversity, which is the differences of life on Earth. I think this relates slightly to this article because in this article in shows the diversity between a single species.
Thursday, January 10, 2013
Bus-Size Sea Monster Found
-->
Published January 7, 2013
Summery:
A new type of sea monster was found in Nevada. It was evolved to eat prey it's own size. While this might not seem that special if you think about dragonflies and the like, this Triassic Monster was 28 ft long. That's about the size of a bus! It is called Thalattoarchon It was part of the ichthyosaur family, whose members look a lot like modern dolphins but are fish. The skeleton was found in 1998, but only the body was found. As the digging crew was leaving on the last day, they noticed the monster's teeth. After 10 or so years the crew came back to excavate the rest of the fossil. The skull that was found was massive and it was filled with large teeth. The teeth were found to be capable of tearing apart prey the size of the of itself. Sea predators capable of doing this today include orcas and great white sharks. Also, the discovery of Thalattoarchon shows how the earth is capable of recovering from mass extinctions. Since this creature existed only eight million years after the largest mass extinction in the history of the earth, the Permian extinction, it is possible to tell that the oceanic ecosystem became very stable in a very short time. The appearance of such a large predator can only mean that the ecosystem evolved enough to support four or five tropic levels.
Connection:
This article connects to evolution. The Thalattoarchon must have evolved in such a way that it was able to support it's size. Perhaps it's powerful teeth and jaws let it hunt in the most efficient method as to use as little energy. It also connects to ecosystem stability, in the way that the appearance of Thalattoarchon, shows a stable ecosystem. Perhaps the reasons behind the stabilization of the Triassic ecosystem, if found, could help to rebuild our own damaged ecosystems.
First Fossil Bird With Teeth Specialized for Tough Diet
Benjamin Stern
1/7/13
http://www.sciencedaily.com/releases/2013/01/130107082602.htm
Summary: Darwin's finches showed clear adaptation by beak type, reflecting different food sources. Birds that live in modern times have beaks to chew up their food, but a new fossil has recently been discovered that possesses specialized teeth to manipulate its food, suggesting it had a durophagous diet, which means that the species was capable of eating prey with tough exoskeletons. This is a new type of diversity within birds previously unknown by researchers. The species of birds, called Sulcavis Geeorum lived roughly 125 million years ago near China, meaning it lived in the Cretaceous period among dinosaurs. This species likely evolved from early dinosaurs, but later died out. It is unclear why this relatively advanced species of birds died out, but it likely had to do with changes in food sources. No other birds possessed any dental ornamentations, yet this species had many; preserved ridges, stritations, and serrated edges.
Connection: This clearly connects to evolution, the bird species evolved complex traits to adapt to better survive. Their adaptations, specialized teeth, enabled them to eat animals they wouldn't normally be able to chew. More specifically, this is an example of evolution extremely similar to Darwin's finches. Both involved populations of birds that evolved to be able to eat specific foods.
1/7/13
http://www.sciencedaily.com/releases/2013/01/130107082602.htm
Summary: Darwin's finches showed clear adaptation by beak type, reflecting different food sources. Birds that live in modern times have beaks to chew up their food, but a new fossil has recently been discovered that possesses specialized teeth to manipulate its food, suggesting it had a durophagous diet, which means that the species was capable of eating prey with tough exoskeletons. This is a new type of diversity within birds previously unknown by researchers. The species of birds, called Sulcavis Geeorum lived roughly 125 million years ago near China, meaning it lived in the Cretaceous period among dinosaurs. This species likely evolved from early dinosaurs, but later died out. It is unclear why this relatively advanced species of birds died out, but it likely had to do with changes in food sources. No other birds possessed any dental ornamentations, yet this species had many; preserved ridges, stritations, and serrated edges.
Connection: This clearly connects to evolution, the bird species evolved complex traits to adapt to better survive. Their adaptations, specialized teeth, enabled them to eat animals they wouldn't normally be able to chew. More specifically, this is an example of evolution extremely similar to Darwin's finches. Both involved populations of birds that evolved to be able to eat specific foods.
Subscribe to:
Posts (Atom)