why are trilobites not found in Triassic rock?
but y did they go extinted
Trilobites are not found in Triassic rock because they went extinct prior to the Triassic period. Trilobites were a diverse group of marine arthropods that dominated the seas for over 270 million years, from the Cambrian period to the end of the Permian period.
The Permian-Triassic extinction event, which occurred approximately 251 million years ago, wiped out 90% of all marine species, including the trilobites. This event was one of the most significant mass extinctions in Earth's history and marked the boundary between the Paleozoic and Mesozoic eras.
The Triassic period, which followed the extinction event, saw the emergence of new groups of organisms, including reptiles and dinosaurs, but trilobites did not recover and become part of the new ecosystems. Therefore, their absence in Triassic rock layers is a result of their extinction rather than any specific geological or environmental reasons during the Triassic period.
Trilobites, which are a group of extinct marine arthropods, are typically not found in Triassic rock because they went extinct before the Triassic period began. To understand why, we need to look at the geological timeline.
Trilobites became abundant during the early Paleozoic era, specifically in the Cambrian period, about 540 million years ago. They thrived for approximately 270 million years and inhabited various marine environments. However, by the end of the Permian period, around 252 million years ago, a major extinction event known as the Permian-Triassic extinction or the "Great Dying" took place.
During this mass extinction event, nearly 90% of marine species and 70% of terrestrial species went extinct. Trilobites were among the casualties, and their decline started before the mass extinction event. Factors such as changes in ocean chemistry, global cooling, volcanic activities, and even asteroid impacts have been suggested as potential causes for their extinction. The exact reason, however, remains a topic of scientific debate.
The Triassic period followed the Permian period and began approximately 252 million years ago. Since trilobites were already extinct by the end of the Permian period, they did not exist during the Triassic period, and therefore, their fossils are not found in Triassic rock.
To find trilobite fossils, one has to search in older rock formations, especially those from the Cambrian to the Permian periods. These fossils provide valuable insights into ancient marine ecosystems and the evolution of life on Earth.
They were extinct by that time.
http://www.absoluteastronomy.com/topics/Trilobite