| Growth ring formation probably evolved late in the Paleozoic Era in response to seasonal changes in water availability. |
|
| During the Middle Devonian Period of the Paleozoic Era, a prehistoric fern adds a new growth ring to its trunk, creating the world's first timeline. |
|
| The first period of activity occurred during the Paleozoic era, with two periods of change. |
|
| In the Paleozoic era, brittle stars had open ambulacral grooves, but in modern forms, these are turned inward. |
|
| They neared extinction at the end of the Paleozoic era, with just six species known from the Permian period. |
|
| Fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. |
|
| The Cambrian spans from 541 million years to 485 million years and is the first period of the Paleozoic era of the Phanerozoic. |
|
| The Permian spanned from 299 to 252 million years ago and was the last period of the Paleozoic Era. |
|
| The Caledonian orogeny was one of several orogenies that would eventually form the supercontinent Pangaea in the Late Paleozoic era. |
|
| This second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. |
|
| The next two periods of the Paleozoic era, the Ordovician and Silurian, were named after ancient Celtic tribes from this area based on Murchison's and Sedgwick's work. |
|
| The eastern slopes are relatively flat, with some hills and rocky outcrops and contain alternating volcanic and sedimentary layers dated to the middle Paleozoic Era. |
|
| His research interests include the magnetic polarity time scale for pre-oceanic periods and changes in magnetic reversal frequency since the Paleozoic Era. |
|
| It received international sanction in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. |
|
| The earliest geological period of the Paleozoic era, the Cambrian, takes its name from the Cambrian Mountains, where geologists first identified Cambrian remnants. |
|
