ナショナルジオグラフィックのインスタグラム(natgeo) - 12月27日 09時38分

@Robert Clark With the recent and huge success of science fiction movies ( #StarWars, #TheMartian) I have always noticed how #Hollywood has long used fossils and insects to help create a scary world that still looks as if it could possible exist. I think that the reason that we react to them the way we do is because the "monsters" are or were real and roamed the planet at one time. Like the common trilobites, which has their own amazing story to tell.
Trilobites are an extinct marine arthropod that occurred abundantly, they first appearance of trilobites in the fossil record defines the base of the Early #Cambrian period (521 million years ago), and they flourished throughout the lower #Paleozoic era before beginning a drawn-out decline to extinction when, during the #Devonian, all trilobite orders except Proetida died out. Trilobites finally disappeared in the mass extinction at the end to the Permian about 250 million years ago, they were among the most successful of all early animals, roaming the oceans for over 270 million years.
For such a long-lasting group of animals, it is no surprise that trilobite evolutionary history is marked by a number of extinction events where some groups perished while surviving groups diversified to fill ecological niches with comparable or novel adaptations. Generally, trilobites maintained high diversity levels throughout the Cambrian and Ordovician periods before entering a drawn-out decline in the Devonian culminating in final extinction of the last few survivors at the end of the #Permian period.
Principal evolutionary trends from primitive morphologies, include the origin of new types of eyes, improvement of mechanisms, increased size and development of extreme spinosity in certain groups.
Effacement is also a common #evolutionary trend resulting in the loss of surface detail. It is believed that effacement is an indication of a burrowing lifestyle.
Because trilobites had wide diversity and an easily fossilized exoskeleton an extensive fossil record was left behind, with some 17,000 known species spanning Paleozoic time. #evolution #evolutionarybiology #Darwin #OnTheOriginOfSpecies

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