Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae.nterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae.
Trilobite fossil from the Cambrian Period. Photo Credit: Archbob. The first period in the Paleozoic Era is known as the Cambrian Period. Many of the ancestors of the species that have evolved into what we know today first came into existence during the Cambrian Explosion in the early Cambrian Period.
The Devonian Period of the Paleozoic Era lasted from 417 million years ago to 354 million years ago. It is named for Devon, England where the old red sandstone of the Devonian was first studied. The Continents of The Devonian. During the Devonian there were important changes in the land masses on the globe.