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The Cenozoic Portal

Introduction

The Cenozoic (/ˌsiːnəˈzoʊ.ɪk, ˌsɛn-/ SEE-nə-ZOH-ik, SEN-ə-; lit. 'new life') is Earth's current geological era, representing the last 66 million years of Earth's history. It is characterised by the dominance of mammals, birds, and angiosperms (flowering plants). It is the latest of three geological eras, preceded by the Mesozoic and Paleozoic. The Cenozoic started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor.

The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammals – the eutherians (placentals) in the northern hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the southern hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large mammals and birds dominated life on Earth. The continents also moved into their current positions during this era.

The climate during the early Cenozoic was warmer than today, particularly during the Paleocene–Eocene Thermal Maximum. However, the Eocene to Oligocene transition and the Quaternary glaciation dried and cooled Earth. (Full article...)

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Selected article on the Cenozoic world and its legacies

Phoronis sp.

Phoronids (scientific name Phoronida, sometimes called horseshoe worms) are a small phylum of marine animals that filter-feed with a lophophore (a "crown" of tentacles), and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long.

The name of the group comes from its type genus: Phoronis. (Full article...)

Selected article on the Cenozoic in human science, culture and economics

A pick axe sitting on a wider, protruding rock. Various sized rock prudences are in the photo; most are a little wider than the pick handle. — Outcrop of Ordovician kukersite oil shale, northern Estonia

Oil shale geology is a branch of geologic sciences which studies the formation and composition of oil shales–fine-grained sedimentary rocks containing significant amounts of kerogen, and belonging to the group of sapropel fuels. Oil shale formation takes place in a number of depositional settings and has considerable compositional variation. Oil shales can be classified by their composition (carbonate minerals such as calcite or detrital minerals such as quartz and clays) or by their depositional environment (large lakes, shallow marine, and lagoon/small lake settings). Much of the organic matter in oil shales is of algal origin, but may also include remains of vascular land plants. Three major type of organic matter (macerals) in oil shale are telalginite, lamalginite, and bituminite. Some oil shale deposits also contain metals which include vanadium, zinc, copper, and uranium.

Most oil shale deposits were formed during Middle Cambrian, Early and Middle Ordovician, Late Devonian, Late Jurassic, and Paleogene times through burial by sedimentary loading on top of the algal swamp deposits, resulting in conversion of the organic matter to kerogen by diagenetic processes. The largest deposits are found in the remains of large lakes such as the deposits of the Green River Formation of Wyoming and Utah, USA. Oil-shale deposits formed in the shallow seas of continental shelves generally are much thinner than large lake basin deposits. (Full article...)

Selected images

Image 1Prolibytherium ("Before Libya's Beast") is an extinct climacoceratid artiodactyl ungulate native to Early Miocene North Africa and Pakistan
Image 2Stegotetrabelodon is an extinct genus of primitive elephant with gomphothere-like anatomical features from the Late Miocene to Early Pliocene of Africa and Eurasia
Image 3Mimoperadectes is an extinct genus of didelphimorph marsupial from the Eocene of North America
Image 4Platybelodon ("flat-spear tusk") was a genus of large herbivorous mammals related to the elephant (order Proboscidea). It lived during the late Miocene Epoch in Asia and the Caucasus.
Image 5Adcrocuta is an extinct genus of terrestrial carnivore in the family Hyaenidae that lived during the Miocene period
Image 6Palaeotragus ("ancient goat") is a genus of very large, primitive, okapi-like giraffid from the Miocene of Africa, Eurasia.
Image 7Morotopithecus bishopi is a species of fossil ape discovered in Miocene-age deposits of Moroto, Uganda.
Image 8Deinotherium was a large prehistoric relative of modern-day elephants that appeared in the Middle Miocene and survived until the Early Pleistocene
Image 9Proconsul is an extinct genus of primates that existed from 23 to 25 million years ago during the Miocene epoch
Image 10Fossil tooth of Hyainailurus, an extinct genus of hyaenodont mammal of the family Hyainailouridae that lived during the Miocene
Image 11Indarctos is a genus of mammals of the bear family, Ursidae, endemic to North America, Europe and Asia during the Miocene
Image 12Victoriapithecus macinnesi was a primate from middle Miocene central Africa