Examples of transitional fossil in the following topics:
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- Because not all animals have bodies which fossilize easily, the fossil record is considered incomplete.
- Because of the specialized and rare conditions required for a biological structure to fossilize, many important species or groups may never leave fossils at all.
- The fossil record is very uneven and is mostly comprised of fossils of organisms with hard body parts, leaving most groups of soft-bodied organisms with little to no fossil record.
- Groups considered to have a good fossil record, including transitional fossils between these groups, are the vertebrates, the echinoderms, the brachiopods, and some groups of arthropods.
- Some scientists have suggested that the geochemistry of the time period caused bad conditions for fossil formation, so few organisms were fossilized.
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- The detailed fossil record of horses has provided insight into their evolutionary progress.
- The fossil record of horses in North America
is especially rich and contains transition fossils: fossils that show intermediate stages between earlier and later forms.
- The
first equid fossil was found in the gypsum quarries in Montmartre,
Paris in the 1820s.
- The sequence of
transitional fossils was assembled by the American Museum of Natural
History into an exhibit that emphasized the gradual, "straight-line"
evolution of the horse.
- Although some transitions were indeed gradual progressions, a number of others
were relatively abrupt in geologic time, taking place over only a few
million years.
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- The fossil record of the mass extinctions was the basis for defining periods of geological history, so they typically occur at the transition point between geological periods.
- The transition in fossils from one period to another reflects the dramatic loss of species and the gradual origin of new species .
- The Cretaceous-Paleogene (K-Pg) boundary marked the disappearance of the dinosaurs in fossils, as well as many other taxa.
- The transitions between the five main mass extinctions can be seen in the rock strata.
- Extinction occurrences, as reflected in the fossil record, have fluctuated throughout earth's history.
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- Fossilized cells, cuticles, and spores of early land plants have been dated as far back as the Ordovician period in the early Paleozoic era.
- This field seeks to find transitional species that bridge gaps in the path to the development of modern organisms.
- Paleobotanists collect fossil specimens in the field and place them in the context of the geological sediments and other fossilized organisms surrounding them.
- Paleobotanists distinguish between extinct species, as fossils, and extant species, which are still living.
- This Rhynie chert contains fossilized material from vascular plants.
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- Fossils believed to represent the oldest animals with hard body parts were recently discovered in South Australia.
- These sponge-like fossils, named Coronacollina acula, date back as far as 560 million years.
- Another recent fossil discovery may represent the earliest animal species ever found.
- These fossils from South Australia date back 650 million years, actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period.
- Fossils of (a) Cyclomedusa and (b) Dickinsonia that evolved during the Ediacaran period.
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- Fossils range in age from 10,000 to 3.48 billion years old.
- These types of fossils are called trace fossils, or ichnofossils, as opposed to body fossils.
- The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata) is known as the fossil record.
- Fossils provide solid evidence that organisms from the past are not the same as those found today; fossils show a progression of evolution.
- Footprints are examples of trace fossils, which contribute to the fossil record.
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- The process of a once living organism becoming a fossil is called fossilization.
- Fossilization is a very rare process, and of all the organisms that have lived on Earth, only a tiny percentage of them ever become fossils.
- Fossilization can occur in many ways.
- Most fossils are preserved in one of five processes:
- Fossilized dinosaur bones, petrified wood, and many marine fossils were formed by permineralization.
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- A substantial hurdle is the difficulty of working out fossil ages.
- There are several different methods for estimating the ages of fossils, including:
- Paleontologists rely on stratigraphy to date fossils.
- If a fossil is found between two layers of rock whose ages are known, the fossil's age is thought to be between those two known ages.
- Misleading results can occur if the index fossils are incorrectly dated.
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- Urban sprawl's segregated land use means that the places where people live, work, shop, and relax are far from one another, which usually makes walking, public transit, or bicycling impractical.
- Urban sprawl is also associated with negative environmental and public health effects, many of which are related to automobile dependence: increases in personal transportation costs, air pollution and reliance on fossil fuel, increases in traffic accidents, delays in emergency medical services response times, and decreases in land and water quantity and quality.
- Smart growth programs often incorporate transit-oriented development goals to encourage effective public transit systems and make bicyclers and pedestrians more comfortable.
- As an approach to urban planning, it encompasses principles such as traditional neighborhood design and transit-oriented development.
- A neighborhood designed along New Urbanist principles would have a discernible center (such as a square or a green) with a transit stop nearby.
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- One of Subversion's goals is for people already accustomed to CVS to find the transition to Subversion relatively smooth.
- Fossil is similar to Veracity in that it is a distributed version control system that versions more than just the code files: it versions the bug tracking database, and a distributed wiki, and a distributed blog.
- Other features include a default "autosync" mode, to do automated merging of non-conflicting changes (i.e., Fossil can operate in a centralized fashion or a decentralized fashion, which is in theory true of other distributed systems as well, but it appears that Fossil makes more of an effort to actually support the centralized workflow).
- Fossil is mainly written by Dr.
- Like Veracity, I have not used Fossil; if you do, let me know how it goes.