Search results
Results from the WOW.Com Content Network
"Blastoidea", from Ernst Haeckel's Art Forms of Nature, 1904. Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. [1] They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period.
The extinction's rapidity is a controversial issue because some researchers think the extinction was the result of a sudden event, while others argue that it took place over a long period. The exact length of time is difficult to determine because of the Signor–Lipps effect , where the fossil record is so incomplete that most extinct species ...
The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes. Researchers have identified five other major extinction events in Earth's history, with estimated losses below: [11] End Ordovician: 440 million years ago, 86% of all species lost, including graptolites
Blastozoa is a subphylum of extinct echinoderms characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. [1] It ranged from the Cambrian to the Permian. A significant species has been found at the Zaouïa Formation. [2]
Climate change due to change of ocean circulation patterns. Milankovitch cycles may have also contributed [11] Paleogene: Eocene–Oligocene extinction event: 33.9 Ma: Multiple causes including global cooling, polar glaciation, falling sea levels, and the Popigai impactor [12] Cretaceous: Cretaceous–Paleogene extinction event: 66 Ma
The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian.
A native Great Lakes whitefish thought extinct for nearly 40 years has been rediscovered by ... a place where the cisco long ago thrived but were wiped out. ... "The Great Lakes will never go back ...
The extinction at the end of the Devonian destroyed the sponge reefs where they thrived, and major reef building did not resume until the Mesozoic. Rugose corals are the types of corals that grew as an isolated individual were extremely common in Devonian reefs. They made a horn-shaped skeleton out of calcite, adding a new layer every year.