Anostomidae
Encyclopedia
The Anostomidae are a family
of ray-finned fishes that belong to the order
Characiformes
. Closely related to the Chilodontidae and formerly included with them, the Anostomidae contain over 140 described species
. Commonly known as anostomids, they are found in freshwater
habitat
s from the Río Atrato in northernmost South America
to warm-temperate
central Argentina
; they are of Amazonian origin, with few found west of the Andes
(mainly in Colombia
and Venezuela
). Their scientific name approximately means "mouth on top", from Ancient Greek
áno- (ἄνω) "up" (as an adverb
) + stóma (στόμᾶ) "mouth", in reference to the arrangement of these fishes' mouth opening.
to upturned mouths immediately at or near the snout tip. This family contains many headstander
s, which habitually swim with the head pointing from 45 up to 90 degrees downwards; most feed on plant
s near the ground, while others also eat detritus
and invertebrate
s picked up from river- or lakebeds. Adults will guard the eggs after spawning
. Anostomidae are generally considered edible, and some of the larger species are caught for food on a regular basis, much like large Leuciscinae
(which are superficially similar Cypriniformes
) are in the temperate Northern Hemisphere
.
Their jaw
s are rather short, with the maxilla
r bone small and excluded from the mouth opening, while the ascending process of the premaxilla
is triangular in overall shape and robustly developed. There is one row of 6 or 8 curved teeth in each jaw, arranged by length in a step-like fashion, with the front teeth being the longest; the pharyngeal teeth
are enlarged and have two or more cusps each.
Anostomid gill
openings are small, with the gill membranes firmly joined to the isthmus
; the ligament
between the interopercle and the mouth is elongate and the interopercle is clearly separated from the retroarticular. On the sides of the preopercle, there is a large elongated protrusion, where the powerful jaw adductor muscles attach. The third epibranchial gill arch has a curved anterior process which extends medially over the dorsal
surface of the fourth infrapharyngobranchial arch. The circumorbital bone series is complete and includes a supraorbital
bone, and at least four, often more of the forward rib
s are united by two or more intercostal
ligaments.
The lateral line
is complete, contains 33-44 perforated scale
s and runs along the midline of the body. The dentary bears a short lateral-line canal ending at or shortly behind mid-length, and altogether the lateral-line canals of the head are divided into at least two ossified tubes. All anostomids have an adipose fin; their dorsal fin
contains 1 and 11, the anal fin 1 and 9, and the pelvic fins 1 and 8-9 hard and soft rays, respectively.
This family is in all probability monotypic
as traditionally defined. Several attempts to delimit subfamilies have taken place, and several of the proposed groupings indeed correspond to clade
s within this family. Leporellus
has been recognized as the basal most living anostomid genus since long, due to its many plesiomorphies shared with the Chilodontidae and its peculiar apomorphies, and separated as a monotypic
subfamily by some. A large clade of "modern" genera was treated as Anostominae by some authors; others considered that subfamily more inclusive.
But the latter view is incorrect, as it includes a large number of lineages that are really basal members of the family and should not be treated as a subfamily (except monotypic ones, but these is generally avoided). Also, the huge assemblage usually treated under Leporinus
is not monophyletic and in need of thorough study, to see how it is best divided up. Depending on the exact relationships of Anostomoides
, a Leporinus sensu lato clade could warrant recognition as another subfamily. Finally, Rhytiodus
and Schizodon
would almost certainly qualify as another subfamily, even if only the Anostominae warrant recognition otherwise.
Anostominae is also used to denote the entire family in outdated treatments, where the name "Anostomidae" is applied to the entire Anostomoidea (and sometimes even more distant relatives). In that respect, there is widespread agreement today that the closest living relatives of the Anostomidae sensu stricto are the Chilodontidae headstander
s, the toothless characins (Curimatidae) and the flannel-mouthed characins (Prochilodontidae).
The origin of the Anostomidae can be quite confidently placed in the Paleogene
, and somewhat less securely in late Paleogene, based on various evidence. For one thing, the biogeography
of the family, with some very basal taxa found west of the Andes, indicates that it was already well distinct when the northern part of that mountain range uplift
ed at the end of the Middle Miocene
about 12 million years ago (mya). Then, there is some scant but highly informative fossil
evidence assigned to this family: a premaxilla
ry tooth was found in the Colombia
n Villavieja Formation and dated to the Laventan
age about 13.5-11.5 mya, while some pharyngeal teeth
and other jaw
parts found near Cuenca, Ecuador
in the Cuenca basin (a structural basin) are about 19 million years old. The fossil remains resemble Leporinus
and were assigned to the living genus, but given its paraphyly and rather basal position, until more fossils are found the known remains can only be considered fairly basal Anostomidae, incertae sedis
but probably close to the Leporinus assemblage.
Cyphocharax mosesi, a fossil toothless characin found in Brazil
, lived at the Oligocene-Miocene
boundary about 23 mya. Thus, at that time the Anostomoidea families must have already been well distinct. Given that the Characiformes
originated slightly more than 115 mya, the Anostomoidea probably diverged from their characiform relatives the Late Cretaceous
and diversified thereafter; a Paleogene origin of the Anostomidae is thus most likely, with present-day subfamiilies (whatever eventually will be accepted) having diverged by the start of the Neogene
. Whether the family originated in Oligocene or already in the Eocene
(or perhaps even in the Paleocene
) cannot be said until more fossil material is recovered, either to answer this question directly or to provide calibration
for molecular phylogenetic studies.
Basal lineages
Schizodon clade
(4 species) Schizodon
(16 species)
Anostominae sensu stricto
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of ray-finned fishes that belong to the order
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
Characiformes
Characiformes
The Characiformes are an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, there are a few thousand different species, including the well-known piranha and tetras.-Taxonomy:...
. Closely related to the Chilodontidae and formerly included with them, the Anostomidae contain over 140 described species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Commonly known as anostomids, they are found in freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s from the Río Atrato in northernmost South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
to warm-temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
central Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
; they are of Amazonian origin, with few found west of the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
(mainly in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
). Their scientific name approximately means "mouth on top", from Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
áno- (ἄνω) "up" (as an adverb
Adverb
An adverb is a part of speech that modifies verbs or any part of speech other than a noun . Adverbs can modify verbs, adjectives , clauses, sentences, and other adverbs....
) + stóma (στόμᾶ) "mouth", in reference to the arrangement of these fishes' mouth opening.
Description
Anostomids have elongated bodies ranging from 15 centimetres (5.9 in) to around 60 centimetres (23.6 in) in length; their shape varies between fusiform and deeper-bodied, but even the latter are only moderately laterally. They have elongated tapering heads with rather long straight snouts, and small apicalApical
Apical, from the Latin apex meaning to be at the apex or tip, may refer to:*Apical , an anatomical term of location for features associated with the base of an organism or structure...
to upturned mouths immediately at or near the snout tip. This family contains many headstander
Headstander
A headstander is any of several species of South American fish, including Anostomus ternetzi, Anostomus anostomus and members of genus Chilodus from the family Chilodontidae. The name derives from their habit of swimming at a 45° angle, head pointed downwards. The fish could "stand up" with its...
s, which habitually swim with the head pointing from 45 up to 90 degrees downwards; most feed on plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s near the ground, while others also eat detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
and invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s picked up from river- or lakebeds. Adults will guard the eggs after spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
. Anostomidae are generally considered edible, and some of the larger species are caught for food on a regular basis, much like large Leuciscinae
Leuciscinae
Leuciscinae, commonly known as true minnows, are a subfamily of small fish belonging to the family Cyprinidae.However, the term minnow is also used as an unspecific term for tiny freshwater and saltwater fish, especially those used as fishing bait....
(which are superficially similar Cypriniformes
Cypriniformes
The Cypriniformes are an order of ray-finned fish, including the carps, minnows, loaches and relatives. This order contains 5-6 families, over 320 genera, and more than 3,250 species, with new species being described every few months or so, and new genera being recognized regularly...
) are in the temperate Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
.
Their jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
s are rather short, with the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
r bone small and excluded from the mouth opening, while the ascending process of the premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
is triangular in overall shape and robustly developed. There is one row of 6 or 8 curved teeth in each jaw, arranged by length in a step-like fashion, with the front teeth being the longest; the pharyngeal teeth
Pharyngeal teeth
Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species lacking teeth.Popular aquarium fish such as goldfish and loaches have these structures. Members of the Botia genus such as clown loaches are known to make distinctive clicking...
are enlarged and have two or more cusps each.
Anostomid gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
openings are small, with the gill membranes firmly joined to the isthmus
Isthmus
An isthmus is a narrow strip of land connecting two larger land areas usually with waterforms on either side.Canals are often built through isthmuses where they may be particularly advantageous to create a shortcut for marine transportation...
; the ligament
Ligament
In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...
between the interopercle and the mouth is elongate and the interopercle is clearly separated from the retroarticular. On the sides of the preopercle, there is a large elongated protrusion, where the powerful jaw adductor muscles attach. The third epibranchial gill arch has a curved anterior process which extends medially over the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
surface of the fourth infrapharyngobranchial arch. The circumorbital bone series is complete and includes a supraorbital
Supraorbital
Supraorbital refers to the region immediately above the eye sockets, where in humans the eyebrows are located. It denotes several anatomical features, such as:*Supraorbital artery*Supraorbital foramen*Supraorbital gland*Supraorbital nerve...
bone, and at least four, often more of the forward rib
Rib
In vertebrate anatomy, ribs are the long curved bones which form the rib cage. In most vertebrates, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax...
s are united by two or more intercostal
Intercostal
Intercostal means "between the ribs". It can refer to:* Intercostal muscle* Highest intercostal vein* Intercostal arteries* Intercostal space...
ligaments.
The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
is complete, contains 33-44 perforated scale
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
s and runs along the midline of the body. The dentary bears a short lateral-line canal ending at or shortly behind mid-length, and altogether the lateral-line canals of the head are divided into at least two ossified tubes. All anostomids have an adipose fin; their dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
contains 1 and 11, the anal fin 1 and 9, and the pelvic fins 1 and 8-9 hard and soft rays, respectively.
Systematics and evolution
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
as traditionally defined. Several attempts to delimit subfamilies have taken place, and several of the proposed groupings indeed correspond to clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s within this family. Leporellus
Leporellus
Leporellus is a genus of headstanders found in South America. There are currently four described species in this genus.-Species:* Leporellus cartledgei Fowler, 1941* Leporellus pictus...
has been recognized as the basal most living anostomid genus since long, due to its many plesiomorphies shared with the Chilodontidae and its peculiar apomorphies, and separated as a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
subfamily by some. A large clade of "modern" genera was treated as Anostominae by some authors; others considered that subfamily more inclusive.
But the latter view is incorrect, as it includes a large number of lineages that are really basal members of the family and should not be treated as a subfamily (except monotypic ones, but these is generally avoided). Also, the huge assemblage usually treated under Leporinus
Leporinus
Leporinus is a genus of Anostomid fish. Seven species have been recently separated in Hypomasticus, but Leporinus is still paraphyletic and needs to be split up further.-Species list:...
is not monophyletic and in need of thorough study, to see how it is best divided up. Depending on the exact relationships of Anostomoides
Anostomoides
Anostomoides is a small genus of fish in the family Anostomidae that are found in South America.-Species:* Anostomoides atrianalis, Pellegrin, 1909* Anostomoides laticeps,...
, a Leporinus sensu lato clade could warrant recognition as another subfamily. Finally, Rhytiodus
Rhytiodus
Rhytiodus is a genus of headstander from South America. There are currently four described species.-Species:* Rhytiodus argenteofuscus Kner, 1858* Rhytiodus elongatus * Rhytiodus lauzannei Géry, 1987...
and Schizodon
Schizodon
Schizodon is a genus of headstander from South America. There are currently 16 described species in this genus-Species:* Schizodon altoparanae Garavello & Britski, 1990* Schizodon australis Garavello, 1994...
would almost certainly qualify as another subfamily, even if only the Anostominae warrant recognition otherwise.
Evolution and fossil record
The taxonTaxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
Anostominae is also used to denote the entire family in outdated treatments, where the name "Anostomidae" is applied to the entire Anostomoidea (and sometimes even more distant relatives). In that respect, there is widespread agreement today that the closest living relatives of the Anostomidae sensu stricto are the Chilodontidae headstander
Headstander
A headstander is any of several species of South American fish, including Anostomus ternetzi, Anostomus anostomus and members of genus Chilodus from the family Chilodontidae. The name derives from their habit of swimming at a 45° angle, head pointed downwards. The fish could "stand up" with its...
s, the toothless characins (Curimatidae) and the flannel-mouthed characins (Prochilodontidae).
The origin of the Anostomidae can be quite confidently placed in the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
, and somewhat less securely in late Paleogene, based on various evidence. For one thing, the biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
of the family, with some very basal taxa found west of the Andes, indicates that it was already well distinct when the northern part of that mountain range uplift
Tectonic uplift
Tectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.-Orogenic uplift:...
ed at the end of the Middle Miocene
Middle Miocene
The Middle Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Langhian and Serravallian stages. The Middle Miocene is preceded by the Early Miocene....
about 12 million years ago (mya). Then, there is some scant but highly informative fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
evidence assigned to this family: a premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry tooth was found in the Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
n Villavieja Formation and dated to the Laventan
Laventan
The Laventan age is a period of geologic time within the Miocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Colloncuran and precedes the Mayoan age....
age about 13.5-11.5 mya, while some pharyngeal teeth
Pharyngeal teeth
Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species lacking teeth.Popular aquarium fish such as goldfish and loaches have these structures. Members of the Botia genus such as clown loaches are known to make distinctive clicking...
and other jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
parts found near Cuenca, Ecuador
Cuenca, Ecuador
Cuenca is the capital of the Azuay Province. It is located in the highlands of Ecuador at about 2500 m above sea level...
in the Cuenca basin (a structural basin) are about 19 million years old. The fossil remains resemble Leporinus
Leporinus
Leporinus is a genus of Anostomid fish. Seven species have been recently separated in Hypomasticus, but Leporinus is still paraphyletic and needs to be split up further.-Species list:...
and were assigned to the living genus, but given its paraphyly and rather basal position, until more fossils are found the known remains can only be considered fairly basal Anostomidae, incertae sedis
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
but probably close to the Leporinus assemblage.
Cyphocharax mosesi, a fossil toothless characin found in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, lived at the Oligocene-Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
boundary about 23 mya. Thus, at that time the Anostomoidea families must have already been well distinct. Given that the Characiformes
Characiformes
The Characiformes are an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, there are a few thousand different species, including the well-known piranha and tetras.-Taxonomy:...
originated slightly more than 115 mya, the Anostomoidea probably diverged from their characiform relatives the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
and diversified thereafter; a Paleogene origin of the Anostomidae is thus most likely, with present-day subfamiilies (whatever eventually will be accepted) having diverged by the start of the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
. Whether the family originated in Oligocene or already in the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
(or perhaps even in the Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
) cannot be said until more fossil material is recovered, either to answer this question directly or to provide calibration
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....
for molecular phylogenetic studies.
Genera
The genera of Anostomidae are:Basal lineages
- AbramitesAbramitesAbramites is a genus of headstanders that occurs in South America. Both species swim in a head down position, due to their feeding habits in the wild.- Species :* Abramites eques...
(2 species) - AnostomoidesAnostomoidesAnostomoides is a small genus of fish in the family Anostomidae that are found in South America.-Species:* Anostomoides atrianalis, Pellegrin, 1909* Anostomoides laticeps,...
(3 species) - HypomasticusHypomasticusHypomasticus is a genus of headstander found in tropical South America. There are currently seven described species.-Species:* Hypomasticus despaxi * Hypomasticus garmani...
(7 species) - LeporellusLeporellusLeporellus is a genus of headstanders found in South America. There are currently four described species in this genus.-Species:* Leporellus cartledgei Fowler, 1941* Leporellus pictus...
(4 species) - LeporinusLeporinusLeporinus is a genus of Anostomid fish. Seven species have been recently separated in Hypomasticus, but Leporinus is still paraphyletic and needs to be split up further.-Species list:...
(87 species; paraphyletic)
Schizodon clade
Rhytiodus
Rhytiodus is a genus of headstander from South America. There are currently four described species.-Species:* Rhytiodus argenteofuscus Kner, 1858* Rhytiodus elongatus * Rhytiodus lauzannei Géry, 1987...
(4 species)
Schizodon
Schizodon is a genus of headstander from South America. There are currently 16 described species in this genus-Species:* Schizodon altoparanae Garavello & Britski, 1990* Schizodon australis Garavello, 1994...
(16 species)
Anostominae sensu stricto
- AnostomusAnostomusAnostomus is a small genus of fish in the family Anostomidae found in northern South America. It currently contains five described species...
(5 species) - Gnathodolus (1 species)
- LaemolytaLaemolytaLaemolyta is a genus of headstander found in tropical South America. There are currently nine described species.-Species:* Laemolyta fasciata N. E...
(9 species) - PetulanosPetulanosPetulanos is a genus of headstander from South America. There are currently three described species.-Species:* Petulanos intermedius * Petulanos plicatus...
(3 species) - PseudanosPseudanosPseudanos is a genus of headstander from South America. There are currently four described species in this genus.-Species:* Pseudanos gracilis * Pseudanos irinae R. Winterbottom, 1980...
(4 species; paraphyletic?) - SartorSartorSartor is a genus of headstander endemic to Brazil. There are currently three described species in this genus.-Species:* Sartor elongatus dos Santos & Jégu, 1987* Sartor respectus Myers & A. L. de Carvalho, 1959...
(3 species) - Synaptolaemus (1 species)