The Oligocene is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present. As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek ὀλίγος and καινός, and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period.
The Proboscidea are a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. From the mid-Miocene onwards, most proboscideans were very large. The largest land mammal of all time may have been a proboscidean; Palaeoloxodon namadicus was up to 5.2 m (17.1 ft) at the shoulder and may have weighed up to 22 t, almost double the weight of some sauropods like Diplodocus carnegii. The largest extant proboscidean is the African bush elephant, with a record of size of 4 m (13.1 ft) at the shoulder and 10.4 t. In addition to their enormous size, later proboscideans are distinguished by tusks and long, muscular trunks, which were less developed or absent in early proboscideans.
Penguins are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found at or north of the Equator. Highly adapted for life in the water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill, fish, squid and other forms of sea life which they catch while swimming underwater. They spend roughly half of their lives on land and the other half in the sea.
The rails, or Rallidae, are a large cosmopolitan family of small- to medium-sized, ground-living birds. The family exhibits considerable diversity and includes the crakes, coots, and gallinules. Many species are associated with wetlands, although the family is found in every terrestrial habitat except dry deserts, polar regions, and alpine areas above the snow line. Members of the Rallidae occur on every continent except Antarctica. Numerous island species are known. The most common rail habitats are marshland and dense forest. They are especially fond of dense vegetation.
The Dalatiidae are the family of kitefin sharks of the order Squaliformes. Members of this family are small, under 2 m (6.6 ft) long, and are found worldwide. They have cigar-shaped bodies with narrow heads and rounded snouts. Several species have specialized bioluminescent organs. Though eight genera are in this family, four of them are monotypic.
The sixgill stingray is a species of stingray and the only extant member of the family Hexatrygonidae. Although several species of sixgill stingrays have been described historically, they may represent variations in a single, widespread species. This flabby, heavy-bodied fish, described only in 1980, is unique among rays in having six pairs of gill slits rather than five. Growing up to 1.7 m (5.6 ft) long, it has a rounded pectoral fin disc and a long, triangular, and flexible snout filled with a gelatinous substance. It is brownish above and white below, and lacks dermal denticles.
Gladioserratus is an extinct genus of cow shark. It contains three species:
Nanocetorhinus is an extinct genus of sharks in the subclass Neoselachii. The type and only described species is N. tuberculatus, which existed in what is now Slovakia during the Miocene epoch, and was described by Charlie J. Underwood and Jan Schlogl in 2011. It was described from 28 fossilized teeth.
Paraetmopterus is an extinct genus of sharks in the family Etmopteridae. It was described by Adnet in 2006, and the type species is P. nolfi, which existed during the middle Eocene of France. A new species, P. horvathi, which existed in what is now Slovakia during the Miocene epoch, was described by Charlie J. Underwood and Jan Schlögl in 2013; however, this species was subsequently transferred to the separate genus Palaeocentroscymnus.
Pristiophorus striatus is an extinct species of sawshark in the genus Pristiophorus. It existed in what is now Slovakia during the Miocene epoch, and was described by Charlie J. Underwood and Jan Schlogl in 2012.
Cretorectolobus is an extinct carpet shark. It was described by G.R. Case in 1978, and the type species is C. olsoni, which existed during the Campanian in Canada and the United States. Another species, C. gracilis, was described by Charlie J. Underwood and Mitchell in 1999, from the Hauterivian to Barremian strata of the Speeton Clay Formation of England. The species epithet refers to the shark's teeth, which Underwood and Mitchell described as gracile and narrow in form. A new species, C. robustus, was described from the Cenomanian of Canada by Underwood and Stephen L. Cumbaa in 2010.
This list of fossil fish species is a list of taxa of fish that have been described during the year 2012. The list only includes taxa at the level of genus or species.
This list of fossil fishes described in 2013 is a list of new taxa of placoderms, fossil cartilaginous fishes and bony fishess of every kind that have been described during the year 2013. The list only includes taxa at the level of genus or species.
Rolfodon bracheri is an extinct species from the family Chlamydoselachidae. It lived during the Miocene.
Rolfodon goliath is a species of large frilled shark that lived during the Late Campanian stage of the Late Cretaceous in Angola's southern Benguela Basin. It was described by Miguel Telles Antunes and Henri Cappetta in 2002 during the beginning stages of the PaleoAngola project. Originally it was described as a species belonging to the genus Chlamydoselachus; Cappetta, Morrison & Adnet (2019) transferred it to the chlamydoselachid genus Rolfodon.
Xiphodolamia is a rare extinct genus of mackerel shark which lived during the Eocene epoch. It is only known from isolated teeth, but has been found in Europe, Africa, and Asia. It is assumed to be pelagic, occurring more frequently in deeper water deposits, most notably the London Clay and Eocene deposits in Denmark. It is distinguished by its rectangular root and twisted blade, unique among Mackerel sharks. It is unclear what niche this specialized dentition helped exploit.
Adnetoscyllium is an extinct genus of bamboo shark from the Cretaceous period. It is currently monotypic, containing only the species A. angloparisensis. The genus is named for prominent paleoichthyologist, Dr. Sylvain Adnet. The specific epithet refers to the range which is thus far restricted to the Anglo-Paris Basin of France and the United Kingdom.
Amamriabatis is an extinct genus of devil ray from the Eocene epoch. It in honor of Amamria, Tunisia, a hamlet near the type locality whose people were hospitable to researchers. It contains a single species, A. heni. It was named for Mr. Kamel Hen, who provided help during the field season in which this species was first collected. It is known from the Bartonian-aged Souar-Fortuna formations of Tunisia and possibly the late Eocene of Egypt. It is similar to many early devil rays.
Ctenacanthiformes is an extinct order of chondrichthyan fish. They possessed ornamented fin spines and cladodont dentition. Members of the family Ctenacanthidae may have survived into the Cretaceous based on teeth found in deep water deposits of Valanginian age in France and Austria.
Propristis is an extinct genus of sawfish that lived from the Eocene to the Miocene. It contains two valid species, P. schweinfurthi and P. mayumbensis. It has been found in Egypt, Cabinda, Morocco, Qatar, Spain, the United Kingdom, and the United States. Isolated rostral denticles are the most common remains, but rostra have also been found.
