Neontology is a part of biology that, in contrast to paleontology, deals with living (or, more generally, recent) organisms. It is the study of extant taxa (singular: extant taxon): taxa (such as species, genera and families) with members still alive, as opposed to (all) being extinct. For example:
A taxon can be classified as extinct if it is broadly agreed or certified that no members of the group are still alive. Conversely, an extinct taxon can be reclassified as extant if there are new discoveries of extant species ("Lazarus species"), or if previously-known extant species are reclassified as members of the taxon.
Most biologists, zoologists, and botanists are in practice neontologists, and the term neontologist is used largely by paleontologists referring to non-paleontologists. Stephen Jay Gould said of neontology:
All professions maintain their parochialisms, and I trust that nonpaleontological readers will forgive our major manifestation. We are paleontologists, so we need a name to contrast ourselves with all you folks who study modern organisms in human or ecological time. You therefore become neontologists. We do recognize the unbalanced and parochial nature of this dichotomous division.
Neontological evolutionary biology has a temporal perspective between 100 to 1000 years. Neontology's fundamental basis relies on models of natural selection as well as speciation. Neontology's methods, when compared to evolutionary paleontology, has a greater emphasis on experiments. There are more frequent discontinuities present in paleontology than in neontology, because paleontology involves extinct taxa. Neontology has organisms actually present and available to sample and perform research on. Neontology's research method uses cladistics to examine morphologies and genetics. Neontology data has more emphasis on genetic data and the population structure than paleontology does.
When the scientific community accepted the synthetic theory of evolution, taxonomies became phylogenetic. As a result, information gaps arose within the fossil record of species- especially in Homo sapiens. The anthropologists who accepted the synthetic theory, reject the idea of an "ape man" because the concept had mistaken paleontology with neontology. An ape man, in actuality, would be a primate with traits that would represent anything in between Homo sapiens and the great apes. If the concept of an ape man was based on neontology, then our phenotype would resemble Bigfoot. Since the concept was based on paleontology, the idea of an ape man could possibly be represented by the fossil hominids.
Neontology studies extant (living) taxa and also recently extinct taxa, but declaring a taxon to be definitively extinct is difficult. Taxa that have previously been declared extinct may reappear over time. Species that were once considered extinct and then reappear unscathed are characterized by the term "the Lazarus effect", or are also called a Lazarus species. For example, a study determined that 36% of supposed mammalian extinction had been resolved, while the other 64% had insufficient evidence to be declared extinct or had been rediscovered. Currently, the International Union for Conservation of Nature considers a taxon to be recently extinct if the extinction occurred after 1500 C.R. The most recently considered extinct mammal was the Bouvier's red colobus monkey, who was considered extinct up until 2015 when it was rediscovered after no recorded sightings for 40 years.
Neontology's fundamental theories relies on biological models of natural selection and speciation that connects genes, the unit of heredity with the mechanism of evolution, natural selection. For example, researchers utilized neontological and paleontological datasets to study mouse dentitions compared with human dentitions. In order to understand the underlying genetic mechanisms that influences this variation between nonhuman primates and humans, neontological methods are applied to the research method. By incorporating neontology with different biological research methods, it can become clear how genetic mechanisms underlie major events in things such as primate evolution.
Angaroceras is a conical Cambrian fossil originally classified as a cephalopod, but which is too poorly preserved for a classification to be upheld.Barrandeocerina
The Barrandeocerina comprise a suborder of Early Paleozoic nautiloid cephalopods, primitively coiled but later forms may be cyroconic, gyroconic, torticonic, and even breviconic, all having empty siphuncles with thin connecting rings. The Barrandeocerina were originally defined as a separate order by Rousseau Flower (Flower and Kummel, 1950), but since then have been united within the Tarphycerida as a suborder (Teichert 1988). Derivation is from the Tarphyceratidae.
In early forms the siphuncle is central or subcentral, orthochoanitic (septal necks short and straight), and thin, with tubular segments. Later forms include those with cyrochoanitic septal necks (curved outward) and segments that may be slightly to strongly expanded into the chambers.Bing Zhi
Bing Zhi (Chinese: 秉志; pinyin: Bǐng Zhì; Wade–Giles: Ping Chih; 9 April 1886 - 21 February 1965), was a Chinese zoologist of Manchu ancestry, considered the founder of China's neontology. He was an academician of the Chinese Academy of Sciences and Academia Sinica. He was a delegate to the 1st, 2nd and 3rd National People's Congress.Cephalopod
A cephalopod () is any member of the molluscan class Cephalopoda (Greek plural κεφαλόποδα, kephalópoda; "head-feet") such as a squid, octopus or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles (muscular hydrostats) modified from the primitive molluscan foot. Fishermen sometimes call them inkfish, referring to their common ability to squirt ink. The study of cephalopods is a branch of malacology known as teuthology.
Cephalopods became dominant during the Ordovician period, represented by primitive nautiloids. The class now contains two, only distantly related, extant subclasses: Coleoidea, which includes octopuses, squid, and cuttlefish; and Nautiloidea, represented by Nautilus and Allonautilus. In the Coleoidea, the molluscan shell has been internalized or is absent, whereas in the Nautiloidea, the external shell remains. About 800 living species of cephalopods have been identified. Two important extinct taxa are the Ammonoidea (ammonites) and Belemnoidea (belemnites).Cephalopod beak
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. The beak may also be referred to as the mandibles or jaws.Fossilised remains of beaks are known from a number of cephalopod groups, both extant and extinct, including squids, octopuses, belemnites, and vampyromorphs. Aptychi – paired plate-like structures found in ammonites – may also have been jaw elements.Comparative biology
Comparative biology uses natural variation and disparity to understand the patterns of life at all levels—from genes to communities—and the critical role of organisms in ecosystems. Comparative biology is a cross-lineage approach to understanding the phylogenetic history of individuals or higher taxa and the mechanisms and patterns that drives it. Comparative biology encompasses Evolutionary Biology, Systematics, Neontology, Paleontology, Ethology, Anthropology, and Biogeography as well as historical approaches to Developmental biology, Genomics, Physiology, Ecology and many other areas of the biological sciences.The comparative approach also has numerous applications in human health, genetics, biomedicine, and conservation biology. The biological relationships (phylogenies, pedigree) are important for comparative analyses and usually represented by a phylogenetic tree or cladogram to differentiate those features with single origins (Homology) from those with multiple origins (Homoplasy).Eburoceras
Eburoceras is an early nautiloid cephalopod from the Upper Yenchau and Wanwankau, Upper Cambrian Trempealeauan of China, assigned to the Ellesmeroceratidae.
The shell of Eburoceras is long and narrow, curved in a broad arc of near constant curvature, interpreted as endogastric, assuming the small siphuncle on the inner margin to be ventral. Known for sure dorsal siphuncles don't appear until later in the Early Ordovician with the Trocholitidae, which if so would make it (Eburoceras)exogastric. Eburoceras is the most strongly curved of the Cambrian ellesmeroceratids.
Eburoceras is the earliest ellesmeroceratid except for the short lived Hunyuanocers, from the lower part of the Upper Yenchou, that proceeded it. Eburoceras died out at the end of Wanwankau time, along with the other Late Cambrian ellesmeroceratid genera, except for Ectenolites and Clarkoceras, which persisted into the Ordovician.
Late Cambrian Tanycamerocers (Ellesmeroceratidae) is similar in being long and narrow and having a small marginal siphuncle, but is straight. Late Cambrian Huaiheceras (Hauiheceratidae) is also similar in being long with a small marginal siphuncle, but is exogastric and less strongly curved.Ellesmeroceratidae
The Ellesmeroceratidae constitute a family within the cephalopod order Ellesmerocerida. They lived from the Upper Cambrian to the Lower Ordovician. They are characterized by straight and endogastric shells, often laterally compressed, so the dorso-ventral dimension is slightly greater than the lateral, with close spaced sutures having shallow lateral lobes and a generally large tubular ventro-marginal siphuncle with concave segments and irregularly spaced diaphragms. Connecting rings are thick and layered, externally straight but thickening inwardly with the maximum near the middle of the segment so as to leave concave depressions on internal siphuncle molds. Septal necks are typically orthochoanitic but vary in length from almost absent (achoanitic) to reaching halfway to the previous septum (hemichoanitic) and may even slope inwardly (loxochoanitic).Jiagouceras
Jiagouceras is a genus of early primitive cephalopods from the Upper Cambrian of China, assigned to the Plectronoceratidae. The shell is small, nearly straight with a slight endogastric curvature and compressed cross section. The siphuncle is close to the ventral margin, with segments expanded into the chambers.
Jiagouceras is found in the Wanwankou member of the Fengshan formation (Early, Middle and Upper Trempealeauan) in northern Anhui, China. It is similar to Paraplectronoceras except for having more strongly expanded siphuncular segments and less concave septa.Monoplacophora
Monoplacophora, meaning "bearing one plate", is a polyphyletic superclass of molluscs with a cap-like shell now living at the bottom of the deep sea. Extant representatives were not recognized as such until 1952; previously they were known only from the fossil record.
Although the shell of many monoplacophorans is limpet-like in shape, they are not gastropods, nor do they have any close relation to gastropods.Nautilida
The Nautilida constitute a large and diverse order of generally coiled nautiloid cephalopods that began in the mid Paleozoic and continues to the present with a single family, the Nautilidae which includes two genera, Nautilus and Allonautilus, with six species. All told, between 22 and 34 families and 165 to 184 genera have been recognised, making this the largest order of the subclass Nautiloidea.Nautiloid
Nautiloids are a large and diverse group of marine cephalopods (Mollusca) belonging to the subclass Nautiloidea that began in the Late Cambrian and are represented today by the living Nautilus and Allonautilus. Nautiloids flourished during the early Paleozoic era, where they constituted the main predatory animals, and developed an extraordinary diversity of shell shapes and forms. Some 2,500 species of fossil nautiloids are known, but only a handful of species survive to the present day.Olenecoceras
Olenecoceras is a genus of Middle Cambrian fossil that, once believed to be a cephalopod, has since been excluded from that group (although no alternative classification has been offered). The genus was established by Z. G. Balashov in 1966, from the river Olenyok.Orthoceratoidea
Orthoceratoidea is a subclass, formerly considered an infraclass or a superorder (Wade 1988), that comprises Cephalopoda orders that have orthoconic to slightly cyrtoconic shells and central to subcentral siphuncles in which there may be internal deposits. Currently, Orthoceratoidea comprises the orders Dissidocerida, Ascocerida, Pseudorthocerida, Lituitida and Orthocerida.Plectronoceras
Plectronoceras is the earliest known shelly cephalopod, dating to the Late Cambrian. None of the fossils are complete, and none show the tip or opening of the shell. Approximately half of its shell was filled with septa; 7 were recorded in a 2 centimetres (0.79 in) shell. Its shell contains transverse septa separated by about half a millimetre, with a siphuncle on its concave side. Its morphology matches closely to that hypothesised for the last common ancestor of all cephalopods.Plectronoceras is the type genus of the family Plectronoceratidae. Fossils of Plectronoceras have been found in the San Saba Limestone of Texas.Plectronocerida
Plectronocerida is a primitive order from which subsequent cephalopod orders are ultimately derived.Ruthenoceras
Ruthenoceras is a conical Cambrian fossil originally classified as a cephalopod, but which is too poorly preserved for a classification to be upheld.Serra do Mar grass mouse
The Serra do Mar grass mouse or Cerrado grass mouse (Akodon serrensis) is a rodent species from South America. It is found in Brazil.
Pardiñas et al. (2016) transferred this species from the genus Akodon to the separate akodontine genus Castoria. The authors also considered A. serrensis to be likely junior synonym of the species Habrothrix angustidens Winge (1887), described on the basis of fossil (probably late Pleistocene) remains recovered from five cave deposits in the area of Lagoa Santa (Minas Gerais, Brazil), which is the type species of the genus Castoria.Tarphycerida
The Tarphycerida were the first of the coiled cephalopods, found in marine sediments from the Lower Ordovician (middle and upper Canad) to the Middle Devonian. Some, such as Aphetoceras and Estonioceras, are loosely coiled and gyroconic; others, such as Campbelloceras, Tarphyceras, and Trocholites, are tightly coiled, but evolute with all whorls showing. The body chamber of tarphycerids is typically long and tubular, as much as half the length of the containing whorl in most, greater than in the Silurian Ophidioceratidae.
The Tarphycerida evolved from the elongated, compressed, exogastric Bassleroceratidae, probably Bassleroceras, around the end of the Gasconadian through forms like Aphetoceras. Close coiling developed rather quickly, and both gyroconic and evolute forms are found in the early middle Canadian.
Tarphycerids tend to uncoil in the late mature stage of their growth, indicating they settled into a benthic lifestyle as they became older. Younger, wholly coiled forms were probably more active, nektobenthic, certainly more maneuverable.