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Almost all of the major animal body plans seen today appeared in the fossil record over 500 million years ago at the beginning of the?
Cambrian explosion. This event marked a rapid diversification of life forms and the emergence of many major animal groups. It is considered a key period in the history of life on Earth.
What was a major life from of the Cambrian period?
A major life form from the Cambrian period was the trilobite, a marine arthropod characterized by its segmented body and exoskeleton. Trilobites were among the first organisms to exhibit complex eyes and diverse body forms, making them key indicators of Cambrian biodiversity. They thrived in various marine environments and are considered important for understanding the evolution of early life on Earth. Their widespread presence in fossil records also provides significant insights into the Cambrian explosion, a time of rapid evolutionary development.
What is the Cambrian explosion why is it important to the history of life on earth?
The Cambrian explosion was a period around 541 million years ago characterized by a rapid diversification of multicellular life forms in the fossil record. It marks the emergence of most major animal groups that exist today. This event is significant as it represents a key point in the evolutionary history of life on Earth, leading to the establishment of complex ecosystems and laying the foundation for the diversity of life we see today.
Where do the names of the periods come from on the geologic time scale?
The names of the periods on the geologic time scale are derived from various sources, primarily reflecting geographic locations, significant fossil discoveries, or notable geological events. For instance, the Cambrian period is named after the Latin name for Wales (Cambria), where rocks from this time were first studied. Other periods, like the Jurassic, take their names from specific regions (like the Jura Mountains) where key rock formations were identified. Overall, these names help convey the historical and geological significance of the times they represent.
What period is sometimes called the golden age of trilobites?
The Cambrian and Ordovician periods are often referred to as the golden age of trilobites. Trilobites thrived during these periods, evolving into a diverse array of species and playing key ecological roles in ancient marine ecosystems. Their abundance and diversity make them a prominent feature in the fossil record from this time.
What are the geologic periods named from?
Most geologic periods are named for the location where rock formations were first found that contained fossils from that period, some others (e.g. Carboniferous) were named for materials associated with the fossils.
What is a key Field?
A field in a part or record that holds the value of a key to that record.
What is key field?
A field in a part or record that holds the value of a key to that record.
What came before the Cambrian explosion?
The Precambrian is the informal name for the large expanse of time preceding the current Phanerozoic Eon (and the Cambrian period, hence the name). It began with the Earth's formation about 4.5 billion years ago and lasted until the advent of multicellular life about 542 million years ago. Overall the planetary environment was drastically different. Life appeared sometime late in the Precambrian, but it is not known when. The Precambrian "supereon" is divided into three eons: the Hadean, Archaean, and Proterozoic. Very little is known about the Precambrian, despite the fact that it comprises nearly 90% of the Earth's history. This is simply because Precambrian rocks are so old, and are either heavily metamorphosed, have been destroyed by erosion, or remain buried deep beneath Phanerozoic strata. The fossil record from the time is also very poor, and only some very simple life forms have been found. Some key events that happened during the Precambrian include: -Formation of the Earth -Impact event that tilted the axis at 23.5 degrees and formed the Moon -Formation of the Earth's crust and the beginning of tectonic activity -Comet and asteroid bombardments that brought water to the Earth -Formation of the oceans -First unicellular life forms -Oxygenation of the atmosphere by early photosynthetic bacteria -First multicellular life forms
Is a unique identifier also called a record key?
The normal term would be a primary key, not a record key.
How are eras and periods of the geologic time scale named?
Eras and periods on the geologic time scale are often named based on significant geological events, key fossil groups, or regional stratigraphy that characterize that time interval. For example, the Triassic Period is named after the three distinct rock layers found in Germany. The Cretaceous Period is named after the Latin word "creta," meaning chalk, due to the abundant chalk deposits from this time.
What does 'The present is the key to the past' mean?
This odd-sounding dictum is a summary of Scottish geologist Charles Lyell's idea of uniformatarianism, the idea that geologic processes that are currently occurring are the same processes that occurred in the past. In short, the historical and observable geologic events that are occurring are the 'key' to unlocking the history of the geologic events that have occurred and were recorded in the rock record.
