| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Quaternary | Holocene | Meghalayan |  0.0042
| |
| Northgrippian | 0.0082
| |||
| Greenlandian | 0.0117
| |||
| Pleistocene | Upper | 0.129 | ||
| Chibanian | 0.774
| |||
| Calabrian | 1.80
| |||
| Gelasian | 2.58
| |||
| Neogene | Pliocene | Piacenzian | older | |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Gelasian is a lower stage of the Pleistocene series and the whole Quaternary system, corresponding to the Gelasian age of the Pleistocene epoch of the Quaternary period. It lasted from approximately 2.58 Ma to around 1.80 Ma (million years ago). This is the last age that ended more than 1 million years ago. It is preceded by the Piacenzian age of the Pliocene and is followed by the Calabrian age of the Pleistocene. During this age, the Quaternary glaciation began in Northern Hemisphere, and Homo habilis as well as other early human species, appeared in eastern Africa.
Definition[]
The GSSP of the Gelasian stage was ratified in 1998. At that time, this stage was included in the Pliocene series. As the base of the Gelasian stage, the Pleistocene series and the Quaternary system its boundary was accepted in 2009. The lower boundary is fixed in Monte San Nicola, Sicily, Italy, and related to the base of marly layer overlying sapropel MPRS 250, within Marine Isotope Stage 103. The magnetic Matuyama/Gauss boundary lies 1 m below GSSP.[2]
Gelasian life[]
The onset of cooling in the high latitudes of the northern hemisphere had a noticeable effect on the climate. Despite this, some thermophilic species still inhabited relatively high latitudes. Numerous snakes (Heterodon, Coluber, Lampropeltis, Sistrurus, Crotalus) lived at this time in North America. Graptemys, a modern turtle genus, lived in the rivers of Florida. Gopherus, a tortoise, lived on land and fed on plants. Titanochelon, a huge (up to 2 m in shell length) tortoise, still existed in what is now Spain. The rivers were inhabited by the already familiar carp fish, such as Orthodon.
A diverse avian fauna has been found in the terrestrial Gelasian sediments of Florida. In addition to gaviids (Gavia), sandpipers (Scolopax, Gallinago), falcons (Falco), herons (Ardea, Ixobrychus, Botaurus), grebes (Tachybaptus, Podiceps, Podilymbus), woodpeckers (Dryocopus, Melanerpes, Colaptes) and ducks (Anabernicula, Aythya, Anas), most of which still exist today, the huge flightless Titanis also lived in those days.
A variety of mammals lived alongside birds. Herbivores defended themselves from predators in different ways. Glyptodontids (Glyptotherium) and armadillo-like pampatheres (Holmesina) had hard armor, which protected them from the teeth and claws of predators, but reduced their mobility. Ground sloths (Glossotherium, Eremotherium, Paramylodon, Megalonyx) reached enormous sizes and had large sharp claws. Proboscideans, such as the American mastodon and Rhynchotherium defended themselves with tusks, which could kill any attacker. Other ungulates relied mainly on their speed. Artiodactyls of the time include camelids (Hemiauchenia), antilocarpids (Capromeryx), cervids (Odocoileus) and peccaries (Mylohyus, Platygonus). Perissodactyls were already represented by modern genera, for example the horse (Eguus). At the same time, small forms similar to Nannippus were still preserved. Rodents reached large numbers, as in our days. Small species hid in burrows and hollow trees, while others could inflict strong bites with their large teeth. Castoroides, a giant beaver, lived on the banks of rivers, but most likely did not feed on wood, but on softer vegetation. Neochoerus, a relative of the capybara, inhabited open land spaces. Other rodents include gophers (Orthogeomys), squirrels (Sciurus, Glaucomys) and cricetids (Ondatra, Neotoma, Peromyscus, Sigmodon, Reithrodontomys). Related to rodents, rabbits and hares can chew through tougher wood, and their long legs allow them to move faster. Modern Sylvilagus and Lepus already lived in that age.
Miracinonyx, the American cheetah
Two Homotherium are chasing a horse.
Carnivorous mammals specialized in hunting both small and large animals. Shrews (Cryptotis, Blarina) and moles (Scalopus) hunted worms, insects and other invertebrates. Bats, the second largest mammalian group after rodents, also fed on mainly insects. Numerous vespertilionids (Eptesicus, Plecotus, Antrozous, Pipistrellus, Lasiurus) led this way of life. Other bats like Desmodus have adapted to feeding on the blood of large mammals, which is why such bats are called vampires. Carnivorans were able to defeat larger prey. Land carnivorans of the time included small raccoons (Procyon), mustelids (Trigonictis), skunks (Spilogale) and foxes (Urocyo) as well as larger wolves (Borophagus, Canis edwardii), bears (Arctodus pristinus), hyenas (Chasmaporthetes) and cats (Miracinonyx, Lynx, Homotherium, Smilodon gracilis).
A similar fauna (excluding sloths and armadillos) existed in Eurasia. Mammuthus meridionalis, one of the mammoth species, grazed in Europe.
Paracolobus fossil
Homo rudolfensis skull
Homo erectus restoration
The most important evolutionary processes for the Earth took place in East Africa among primates. In addition to monkeys like Paracolobus and Cercopithecoides, first true humans appeared. Homo habilis, the oldest of them, could use primitive tools, which it probably could already make. The volume of its brain remained small and in appearance it still strongly resembled its Australopithecus ancestors that coexisted with it for some time. Quite soon, new human species appeared, such as Homo rudolfensis and Homo erectus, from which Homo sapiens probably descended later. In the Gelasian, people most likely had not yet left Africa and lived in a warm equatorial climate. Before learning to handle fire, early humans were likely frequent prey to predatory mammals such as hyenas and big cats. Paranthropus boisei, a close relative of humans, lived alongside them in Rift Valley, Kenya.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Cenozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=2.