amphibian database, amphibian species, salamander, salamanders, newts, newt, caudata, caudate,
anura, anuran, fire belly newt, fire belly toad, biodiversity, conservation, amphibian,
amphibians, ambystomatidae, ambystoma, amphiumidae, amphiuma, cryptobranchidae, dicamptodontidae,
hynobiidae, proteidae, plethodontidae, rhyacotritonidae, salamandridae, sirenidae, siren, cynops, pachytriton,
Overview of the Caudate Families
Cryptobranchoidea (Fitzinger, 1826): Suborder, primitive or ancient salamanders
The families Cryptobranchidae and Hynobiidae are
closely related, and form the suborder Cryptobranchoidea, the primitive
salamanders (Dunn, 1922). Synapomorphies of Cryptobranchoidea include the fusion
of the first ceratobranchial and first epibranchial, and fusion of the
pubotibialis and puboischiotibialis muscles (Larson, 1996). Other
characteristics include external fertilization, and separated angular and
prearticular bones in the lower jaw (in adults) (Cogger &
Zweifel, 2003). All three species are endangered in the wild due
to over collection, pollution, human encroachment, habitat loss, and the
food industry (Andrias).
(Fitzinger, 1826) Hellbenders & Giant Salamanders
Synonyms: Cryptobranchoidea (Fitzinger, 1826), Cryptobranchi (Wagler,
1828), Menopomatidae (Hogg, 1838), Andriadini (Bonaparte, 1839),
Andriadina (Bonaparte, 1840), Protonopsina (Bonaparte, 1840),
Protonopsidina (Bonaparte, 1840), Megalobatrachidae (Fitzinger, 1843),
Andriadidae (Bonaparte, 1845), Andriantidae (Bonaparte, 1850), Andriantina
(Bonaparte, 1850), Sieboldiidae (Bonaparte, 1850), Sieboldinae (Bonaparte,
1850), Protonopseidae (Bonaparte, 1850), Protonopsidae (Gray, 1850),
Menopomida (Smith, 1877), Menopomidae (Jordan, 1878), Cryptobranchidae
(Cope, 1889), Cryptobranchoidea (Dunn, 1922)
are the largest extant salamanders in the world, with the largest species, Andrias
davidianus, exceeding 5 feet in length. There are two genera, Andrias, with two Asian species, and Cryptobranchus, the only
species. All species are fully aquatic, paedomorphic, and increasingly
rare in the wild. The three species are very similar in appearance, with
minute eyes, paddle-shaped tails, and large folds of highly vascularized skin along the sides of
the body that increase oxygen absorption. Adults lack gills,
but retain gill slits (open in Cryptobranchus, closed in Andrias),
and do not possess eyelids. The limbs are short and powerful,
and help keep the salamanders positioned on the floors of their stream
habitats. Females may produce up to 500 eggs in a season, which are paired in strings. Fertilization is external, and the male guards the eggs until hatching.
Larvae possess short gills to reduce drag in flowing waters, streamlined
bodies, and impressive tails for propulsion.
Andrias japonicus is found in central Japan, Andrias
davidianus in central China, and Cryptobranchus alleganiensis in
eastern United States. Cryptobranchids are found in shallow to medium
depth, cold, flowing waters. They are found under large rocks and other
debris, and blend in nicely to the brown bottoms of rivers and streams.
Cyrptobranchids possess very sensitive skin that help them detect and peruse
prey in the wild. They are capable of detecting light rays when shined on
Cryptobranchids were larger than the modern, reaching more than 2 meters
in length. North American Cryptobranchid fossils are known
as far back as the Paleocene, Asian fossils date as far back as the Middle
and European fossils can be traced to the Pleistocene (Mousetrap, 2003). The latest
discovery is a fossil Cryptobranchid, Chunerpeton tianyiensis,
discovered in volcanic deposits in the Jiulongshan Formation (Bathonian),
Inner Mongolia, China, in 2003 (Gianaro, 2003). This extinct member has been dated to the
Middle Jurassic Period, some 165 million years ago. This is one of the oldest
known fossil representation of salamanders. This fossil serves as evidence that the
Cryptobranchids separated from the Hynobiids in Asia, before the Middle
Jurassic. Recently an even older
caudate fossil has been discovered in Europe; more details on this
find can be found in the Salamandridae section below.
Fossil remains of Andrias scheuchzeri (Scheuchzer, 1726)
were found in Germany, and dated to the Miocene Epoch,
Tertiary Period. A. scheuchzeri was originally thought to be human
remains from Noah's flood, and was given the name Homo diluvii testis,
meaning "head of a flood man". This fossil became known as the
"Diluvian Man", and was thought to be that of a man that may
have witnessed the universal flood described in the biblical tale of
Noah's Ark. In the early 19th century, Georges Cuvier
discovered that the fossil was actually the remains of a giant salamander.
The genus name Andrias was later adopted by Tschudi, meaning
"Man-Image"; a reflection of its initial description.
(Cope, 1859) Hynobiids / Asiatic Salamanders
Synonyms: Molgidae (Gray, 1850), Molgina (Bonaparte, 1850),
Ellipsoglossidae (Hallowell, 1856), Hynobiidae (Cope, 1859), Molgida (Knauer,
1883), Geyeriellinae (Brame, 1959), Protohynobiinae (Fei & Ye, 2000)
to medium sized salamanders found mostly in Asia, with the exception of Salamandrella
keyserlingii (extending into Russia), and Batracuperus persicus
(found in the Middle East). All species have
external fertilization, although Ranodon sibiricus produces
spermatophores. The family Hynobiidae is related to the family
Cryptobranchidae, with which it forms the Suborder Cryptobranchoidea
(primitive salamanders). Keratinization is present on the fingers
and toes in some species, the so-called Clawed Salamanders of the genus Onychodactylus. Some species
have well-developed lungs, while others possess reduced lungs, and the genus Onychodactylus
lack lungs altogether.
species breed in waters after a dormant period spent on land, with the exception
of Hynobius kimurae, who spends the dormant period underwater.
During the aquatic phase, males of many species develop remarkably swollen heads,
and laterally compressed tails. Females deposit crescent-shaped egg sacs in
streams or ponds, where they are fertilized by the male. Larvae are either
stream or pond type, depending on the species, and possess the typical
external gills and caudal fin specialized for their environment.
Previously, the family Hynobiidae was divided
into two subfamilies, Hynobiinae, and Ranodontinae. The genera Pachypalaminus,
Batrachuperus, Hynobius, and Onychodactylus comprised
Hynobiinae, while Ranodontinae consisted only of Ranodon. Today,
the genera Pachypalaminus, Paradactylodon, and Xenobius,
are synonymized with Hynobius,
Batrachuperus, and Pachyhynobius, respectively (Obst, Jacob,
Salamandroidea (Fitzinger, 1826): Suborder, advanced salamanders
The suborder Salamandroidea is comprised of the advanced salamanders. This suborder contains the largest number of species, and
includes the families Salamandridae, Ambystomatidae, Dicamptodontidae,
Amphiumidae, Rhyacotritonidae, Proteidae, and Plethodontidae.
Salamandroidea differs from Cryptobranchoidea in that the angular and
prearticular bones in the lower jaw are fused (in extant species), and all
species are internal fertilizers (Larson, 2004). Members of the suborder Salamandroidea
occur almost everywhere in the world, except Antarctica, Australasia,
Oceania, and Africa south of the Sahara (Cogger & Zweifel, 2003).
(Gray, 1850) Mole Salamanders, Axolotls
Synonyms: Ambystomina (Gray, 1850), Siredontia (Bonaparte, 1850),
Ambystomidae (Hollowell, 1856), Ambystominae (Cope, 1859), Amblystomidae
(Cope, 1863), Amblystomatinae (Boulenger, 1882), Amblystomoidea (Nobel,
1931), Ambystomatoidea (Tihen, 1958)
is comprised of one extant genus, Ambystoma, and approximately 30 species.
Most species complete metamorphosis, and are terrestrial and fossorial, however, some are
permanent neotenes. Ambystoma mexicanum, the Mexican Axolotl, is perhaps the most
recognizable obligate neotene, and is often a specimen of research and
development. A. mexicanum is thought to be extinct in the
wild, with the only remaining populations existing in captivity.
Fortunately, A. mexicanum has been regularly bred for centuries,
and is not on the brink of extinction, despite its absence from the wild.
Ambystomids are restricted to North America,
and can be found from Alaska to Mexico. The terrestrial species are
typically robust salamanders, with thick limbs and tails. Ambystoma
mavortium and Ambystoma tigrinum are considered the longest terrestrial
species in North America, rivaled only by the terrestrial Dicamptodontids, and surpassed
only by the aquatic
Cryptobranchus alleganiensis (Hellbender). A. mavortium, A. tigrinum,
and other Tiger Salamanders also have large larvae, reaching up to 5
inches before metamorphosis. Superficially, these large larvae
resemble adult and young A. mexicanum, but will metamorphose under
normal conditions. Because of their similar appearance, A. mexicanum
and larval tiger salamanders are often confused in captivity. To further
add to the confusion, the name waterdog is often applied to both species,
while a true waterdog is a member of the family Proteidae.
hybrids occur throughout the Great Lakes region to New England and the
Maritime Provinces of Canada (Petranka, 122). Hybrids may be diploid,
triploid, polyploid, or infrequently, tetraploid, or pentaploid. Unisexual
hybrids are female, and can consist of varying
combinations of genetic material from A. laterale, A.
jeffersonianum, A. texanun, and A. tigrinum (Bogart, 1989; Bogard and Licht
1986; Kraus 1985). Some unisexual biotypes have been
given names, A. nothagenes, A. platineum, and A.
tremblayi, although these names are considered incorrect today.
Ambystomids are members of the suborder Salamandroidea, the advanced
salamanders. The families Dicamptodontidae and Rhyacotritonidae have both
been included in Ambystomatidae, but were removed based on genetic
information. Dicamptodontidae is a sister taxa to Ambystomatidae, while Rhyactotritonidae is more distant. Current studies suggest that the
Ambystomatidae-Dicamptodontida clade is sister to Salamandridae. The sharing of a similar spine pattern
also had Ambystoma included in Plethodontidae at one point
The extinct genus Amphitriton is known from the upper Pliocene, and
fossils of the extant genus Ambystoma are known from the lower Oligocene
through the Pleistocene, in North America (Mousetrap, 2003).
(Gray, 1825) Amphiuma / Congo Eels
Synonyms: Amphiumidae (Gray, 1825), Amphiumoidea (Fitzinger, 1828),
Amphiumina (Bonaparte, 1840), Amphiumida (Jan, 1857), Amphiumoideae (Stejneger,
is comprised of one extant genus, Amphiuma, and three species, all of which are
found in the southeastern United States. Amphiuma are large, elongate,
nearly-limbless salamanders, often described as eel-like in appearance,
and sometimes reaching more than a meter in length (except the one-toed
amphiuma, which reaches only around 40cm). The three species can be
differentiated by the number of toes on each limb, one, two, and three,
and by their size as adults.
Like many other caudates, amphiuma are paedomorphic, retaining gill slits
into adulthood. Amphiuma are also the only caudate species that possess
internal gills. The limbs of all three species are reduced, and serve
limited purpose in locomotion in adults. In larvae, however, the limbs are
much larger compared to the body size, and can be used for walking. Amphiuma also possess lungs, and lack eyelids and tongues.
are aquatic, inhabiting densely planted ponds and swamps. They are capable
of exiting the water to forage for foods, and may do so on especially wet
nights. Amphiuma are also capable of enclosing their bodies in a
water-tight mucus, allowing them to survive in a state of suspended
animation for months, sometimes more than a year, if their water source were to dry up. Eggs
are laid on muddy land areas, near water, and are guarded by the females.
Larvae make their way to the water during rainy nights.
Amphiumidae is part of the suborder Salamandroidea, the advanced salamanders,
all of which are internal fertilizers. Amphiumidae was originally placed
in its own suborder Amphiumoidea, but this model has been rejected based
recent clade analyses.
There are three North American fossil species known from the
upper Cretaceous through the upper Miocene. The extinct genus Proamphiuma
is known from the Cretaceous. Those from the Pleistocene were found in the
southeastern United States (Mousetrap, 2003).
(Tihen, 1959) Pacific Giant Salamanders
Synonyms: Dicamptodontinae (Tihen, 1958), Dicamptodontidae (Edwards,
is comprised of four species, in the single genus Dicamptodon. All species
are found in western North America, from California to southern Canada,
and the Rocky Mountains of Montana and Idaho. Dicamptodons are
collectively referred to as Pacific Giant Salamanders, a reflection of
their large, robust physique, and western distribution. In general,
Dicamptodons resemble Ambystomids, with thick limbs and tail, and large
head, but are larger than most Ambystomids. Dicamptodon copei is normally
retaining gills and aquatic behavior into adulthood, however,
metamorphosis is possible.
Dicamptodons inhabit coniferous forests, and cold streams or creeks
during the breeding season (Petranka, 1998). The lifecycle is biphasic and the larval stage can last up to 5 years. Unique to D. ensatus is the ability to vocalize when
Dicamptodons are members of the suborder Salamandroide, the advanced
salamander. The genus Dicamptodon was formerly included in Ambystomatidae,
and removed based on genetic information. The families Dicamptodontidae
and Ambystomatidae are considered sister taxa. Current studies suggest
that the Ambystomatidae-Dicamptodontidae clade is sister to Salamandridae
Fossils of two extinct genera and the extant genera are known from the
Paleocene in North America. Three extinct genera are known from the
Paleocene and Miocene in Europe (Mousetrap, 2003).
(Gray, 1850) Lungless Salamanders
Synonyms: Plethodontidae (Gray, 1850)
is the largest, and most diverse of the ten caudate families. They are
distributed almost exclusively throughout the Americas, with a small group
of Hydromantes populating Southern Europe. Plethodontidae
includes neo-tropical genera that inhabit the Southern
Hemisphere in Central and South America. The family Plethodontidae
consists of two subfamilies, Desmognathinae, and Plethodontinae. The
latter subfamily consists of three tribes, Bolitoglossini, Hemidactyliini,
have adapted to an array of habitats, including arboreal, aquatic,
terrestrial, and fossorial. The typical biphasic lifecycle
is observed in most species of the subfamily Desmognathinae and tribe
Hemidactyliini, with a few that are are strictly terrestrial with no
aquatic larval stage. The tribe Hemidactyliini are also has permanently
aquatic, paedomorphic or perennibranchiate species. Such species are often
troglobitic (cave dwellers), possessing reduced eyes and pigment. The
tribes Bolitoglossini and Plethodontini lack aquatic larvae and hatch as
miniature adults from terrestrial eggs (Larson, 1996). Members of the tribe Bolitoglossini
of the New World tropics are unique in having adapted to the tropical
life. Some species are arboreal or fossorial, and most possess webbed feet.
An arboreal lifestyle is also observed in the genus Aneides, of the
Members of the subfamily Desmognathinae,
collectively called Dusky Salamanders, are found exclusively in North
America, especially the eastern United States. Dusky salamanders are
terrestrial, inhabiting temperate forests and brush areas. Depending on
who is consulted, there are between 10 and 20 recognized species. Most
are biphasic, with the exception of D. aeneus, D.
wrighti, and Phaeognathus hubrichti, which produce terrestrial
eggs that hatch fully formed young. D.
marmoratus and D. quatramaculatus are aquatic and
semi-aquatic, respectively, both with an unusually long larval period of
up to three or four years.
All Plethodontids are lungless and rely
cutaneous and/or branchial respiration. Metamorphosed adults rely solely on oxygen absorption through their most skin, whereas neotenes and some
larvae rely mainly on branchial respiration (gills).
Plethodontidae is included in the suborder
Salamandroidea, the advanced salamanders, all of which are internal
fertilizers. Based on phylogenetic analyses of RNA sequences, it is
concluded that the Plethodontids do not have any close relatives in
North American Plethodontid fossils are known
from the Miocene through the Pleistocene (Mousetrap, 2003).
(Gray, 1825) Mudpuppies, Waterdogs, & the Olm
Synonyms: Proteina (Gray, 1825), Phanerobranchoidea (Fitzinger,
1826), Proteideae (Tschudi, 1838), Hypochthonina (Bonaparte, 1840),
Necturina (Bonaparte, 1845), Hypochthonidae (Bonaparte, 1850), Necturidae
(Bonaparte, 1850), Proteida (Jan, 1857), Menobranchida (Knauer, 1883),
Hylaeobatrachidae (Abel, 1919), Hylaeobatrachoidea (Huene, 1931)
family Proteidae is comprised of six or seven, paedomorphic, fully
aquatic species, often called mudpuppies or waterdogs. All species are
found in North America, except the single species in the genus Proteus,
which occurs in southeastern Europe. The terms Mudpuppy and Waterdog stem
from the belief that these species make barking sounds when disturbed,
however, this is not true, as all species are incapable of vocalizing.
and waterdogs comprise the genus Necturus. They are noted for their bushy,
red gills, and secretive behavior. Adults also retain two gill slits (Petranka,
Necturus species are all similar in appearance, although varying in size,
with dark mottled dorsa that blend into their watery floors. Necturus
are found in ponds, lakes, and streams in eastern North America. Proteus
anguinus is very different in appearance and behavior than the mudpuppies
and waterdogs of North America, possessing a whitish pink, translucent
body, lacking eyes, and inhabiting limestone caves of southeastern
Proteids are members of the suborder Salamandroides, the advanced
salamanders. Two fossil genera are recognized, Mioproteus from the Miocene
into the Caucasus Mountains, and Orthophyia from the Miocene in Germany.
Necturus fossils are known from North America dating to the Paleocene and
the Pleistocene, and fossil Proteus are know from the Pleistocene in
Germany (Mousetrap, 2003).
(Tihen, 1959) Torrent Salamanders
Synonyms: Rhyacotritoninae (Tihen, 1958), Rhyacotritoninae (Hecht
& Edwards, 1977), Rhyacotritonidae (Good & Wake, 1992)
is comprised of four species, in the single genus Rhyacotriton. This genus
was formerly comprised of one species, Rhyacotriton olympicus.
Originally, Rhyacotritonids were placed in
the family Ambystomatidae, later in Dicamptodontidae,
and finally placed into their own family in 1992. Rhyacotritonids are collectively
referred to as Torrent Salamanders, and are found exclusively in the
western United States, specifically northern California, Oregon, and
Washington. Torrent Salamanders are found in coniferous
forests, and well-oxygenated streams during the breeding season. All
species have the typical biphasic lifestyle, with aquatic larvae and
terrestrial adults. Rhyacotritonids can be differentiated from other
northwestern species by their notably square-shaped cloaca (Stebbins,
Rhyacotritonidae is included in the suborder Salamandroidea, the
(Goldfuss, 1820) Newts & Salamanders (true salamanders)
Synonyms: Salamandrae (Godfuss, 1820), Salamandridae (Gray, 1825),
Salamandroidea (Fitzinger, 1826), Tritonidae (Boie, 1828), Cercopi (Wagler,
1828), Salamandrina (Hemprich, 1829), Salamandroidea (Schinz, 1833),
Tritones (Tschudi, 1838), Tritonides (Tschudi, 1838), Pleurodelina
(Bonaparte, 1839), Salamandrina (Bonaparte, 1839), Salamandrinae (Fitzinger,
1843), Tritonines (Bronn, 1849), Salamandridae (Bronn, 1849), Seiranotina
(Gray, 1850), Pleurodelidae (Bonaparte, 1850), Pleurodelina (Bonaparte,
1850), Bradybatina (Bonaparte, 1850), Tritonina (Bonaparte, 1850),
Geotritonidae (Bonaparte, 1850), Geotritonina (Bonaparte, 1850),
Pleurodelini (Massalongo, 1853), Salamandrini (Massalongo, 1853),
Pleurodelidae (Hallowell, 1856), Seiranotidae (Hallowell, 1856),
Tritonidae (Hallowell, 1856), Salamandroidea (Wied-Neuwied, 1865),
Salamandrini (Acloque, 1900), Tritonidi (Acloque, 1900), Salamandroideae (Stejneger,
1907), Salamandroidea (Dunn, 1922), Triturinae (Brame, 1957), Voitiellinae
(Brame, 1958), Triturinae (Kuhn, 1965)
contains perhaps the most recognizable species, the newts and "true
salamanders". There are arguably 65-70 species distributed throughout North
America, Europe, Russia, the Middle East, Asia, and the northern tip of
Africa. Salamandridae includes the newts, which are characterized by their relatively
small size, moderate to highly aquatic behavior, toxicity,
biphasic lifecycle, and their diverse breeding behavior
and sexual dimorphism. Included in the newt group are the genera Cynops,
Neurergus, Notophthalmus, Pachytriton, Paramesotriton, Pleurodeles,
Taricha, Triturus. Depending on the source, the genera Salamandrina, Echinotriton, Euproctus, and
Tylototriton are sometimes included in the newt group because they
produce aquatic larvae that hatch from eggs, and reproduce in water, although they lead more terrestrial
lives than those species that fit the mold of a typical newt.
Although traditionally used to describe species only from the genus Salamandra, particularly Salamandra salamandra, the first
described salamander, the term "true salamander" is often
applied to all species in the family Salamandridae outside of the newt
group. The latter usage of the term would then include the genera Chioglossa, Mertensiella, and Salamandra
in the "true salamander" group. "True salamanders"
are not necessarily "more" salamander than the other species,
rather these species can be thought of as the epitome of a typical
salamander, in the sense that they are used as a model for what a
salamander should look like.
There are many species in other caudate families that fit the image of
salamanders", and so this term is somewhat broad and non-descriptive.
It seems fitting that the newts comprise a rather distinct group in the
family Salamandridae, while the term "true salamander", when
applied to all remaining members outside of the newt group, may be used
simply to exemplify the distinctness of the newts, and when used in its
traditional manner may be applied only to the genus Salamandra. In
summary, all newts are salamanders, but not all salamanders are newts.
word newt has a long history, originating from the Anglo-Saxon word
efete or evete, which later became ewte in Middle
English. Over time, it is presumed the term an ewte was construed
newte (Cogger & Zweifel, 2003).
Newts are characterized by their rough skin (except
Pachytriton), and lack of "slimy" mucus. Newts are also
relatively small, with the largest species reaching around 10 inches in
length, sometimes slightly longer. However, the majority are around 3-6
inches in length, with the smallest only reaching about an inch. Many newt
species are brightly colored, or have bright colored abdomens to warn
of their toxicity. The toxins present in newts was termed Tarichatoxin,
after its isolation in newts of the genus Taricha, and is a diluted form
of Tetrodotoxin, or TTX (for more information on newt toxicity, see
0011 - Toxicity and Defense Methods of Amphibians). Most species are
semi-aquatic, or mostly-aquatic, with some experiencing a terrestrial
are found primarily in Europe and Asia, with a few species in North
America, the Middle East, and northern Africa. Newts display an array of
behaviors, from mostly aquatic to mostly terrestrial, and
everything in between. Many species are terrestrial part of the year, and
return to bodies of water to reproduce during their season, while others
may remain aquatic year round. Taricha in
particular are unique in that they migrate remarkable distances to the
same ponds they emerged from to breed themselves. Other genera also
migrate to breeding ponds, but are less picky, sometimes settling for
puddles or ditches. Triturus in particular are noted for their
extraordinary courtship behavior, and sexual dimorphic characteristics (in
most species), which may include the production of a large dorsal crest,
webbed feet, and a change of colors on certain parts of the body. Triturus
species also partake in elaborate courtship "dances" where the
males go to great lengths to impress the females. Some
species such as those of the genera Pleurodeles, Taricha, and
Notophthalmus may exclude an elaborate courtship display, and opt for
an embrace, called amplexus, that may last for several
hours, up to a day or more. Males of such species may develop cornified
nuptial pads on the toes and inner legs that aid in gripping the female in
amplexus. Other species, such as Tylototriton, Cynops, Pachytriton, and
Paramesotriton, do not amplex, and may develop mild sexual
dimorphic characteristics, usually in the form of laterally compressed
tails, smoother skin, and bluish or whitish sheen on the body and tail.
Courtship from such species usually consists of the mail fanning
pheromones toward the female with the tail (tail-fanning), accompanied
by alert and bold behavior, but may be as mild as circling snout-to-tail
in the water. Tail-fanning is seen in may newt species, often in
combination with other courtship behavior, and is not limited to the fore
mentioned species. Still, others may develop
unique characteristics, such as toe flaps, or a thin thread at the end of
the tail. Euproctus asper is especially unique, in that it is the only species to
reproduce through direct cloacal contact. Euproctus
asper's breeding behavior consists of a complex form of amplexus,
where the male and female look almost knotted together.
Some species and
subspecies of the genera Salamandra and Lyciasalamandra,
not have the typical biphasic lifecycle. These species/subspecies
viviparous, producing fully formed miniature adults, and passing the
aquatic larval phase within the mother. Viviparous salamanders produce few
young, usually between 1-4 each year, compared to the hundreds of eggs
that may be produced by biphasic newts each year.
Fire salamanders are often regarded as typical salamanders, in that they
are of average size (around 8 inches long) and proportion, colorful,
toxic, and possess four normal limbs, and a tail. Chioglossa, on the other
hand, are rather elongate, with the majority of total length contributed
by the tail. Chioglossa are either terrestrial, or semi-aquatic, and
display ventral amplexus during the breeding season. The long, thick tail
of Chioglossa stores food reserves, and can be shed in the presence of
danger (autotomy). The food reserves in the tail serve an important
purpose, and can negatively affect the fertility of females if dropped
off, or missing for other reasons. The true salamanders portray limited
sexual dimorphism, usually in the form of swollen cloaca (in males), and
laterally compressed tail on those that reproduce in the water.
species of the family Salamandridae are internal fertilizers, a characteristic of the suborder
Salamandroidea. The biphasic lifecycle is present in most species, except
the viviparous species. The aquatic larvae of newts
may metamorphose into terrestrial juveniles, sometimes called efts, that
will return to the water several years later to reproduce, or semi-aquatic
young that never enter a terrestrial phase. Facultative neoteny is present
in some species, when induced by their natural habitat, or in
artificial environments. Some dimorphic characteristics, such as
smooth skin, laterally compressed tails, and color change, are sometimes
described as "reverse metamorphosis", as such characteristics
indicate mild reversion to the larval form. The species Salamandrina
terdigitata is regarded as a salamander, but is
probably more similar to the newt group based on morphological
similarities, the biphasic lifecycle, and larval development. There is
also controversy over the monophylic status of the genera Mertensiella and
Triturus. Other suggested models include the monophyly of the true
salamanders, and monophyly of all newts except Salamandrina. Salamandrina
separated from the remaining lineages of the family Salamandridae near the time of separation
from the newt ancestors.
Fossils of the family Salamandridae are widespread in Cenozoic deposits throughout
Europe, from the Eocene through the Pleistocene. There is an extinct genus
known from Miocene in Asia. Fossils of the extant North American species
are known as far back as the Oligocene (Mousetrap, 2003). In 2003 a section of a scull was accidentally
discovered on a beach in North Tynside in 1993, has been determined to
have belonged to a previously unknown, giant newt-like animal. The fossil
was given the name Kyrinion martilli, and dated back to the
Carboniferous (possibly Devonian) era, some 300-350 million years ago.
This is the oldest known fossil caudate, and surpasses the recently
discovered Chunerpeton tianyiensis (Cryptobranchidae)
by more than 150 million years. Kyrinion martilli was a 6-foot
long, newt-like animal, thought to have been one of the earlier ancestors
that gave rise to amphibians in one branch, and reptiles and mammals in
Sirenoidea (Goodrich, 1820): Suborder, sirens
Often times the family Sirenidae is placed in a separate suborder, Sirenoidea.
Sirens do not completely meet the criteria for the suborders
Salamandroidea and Cryptobranchoidea, and in fact possess so many bizarre
characteristics that they are sometimes even placed in a separate order,
Meantes or Trachystomata.
(Gray, 1825) Sirens
Synonyms: Sirenina (Gray, 1825), Sirenea (Hemprich, 1829), Sirenidae
(Hogg, 1838), Sirenina (Bonaparte, 1840), Sirenida (Knauer, 1883)
All species are paedomorphic, retaining their larval gills and 1-3 gill
slits. The forelimbs are reduced, and serve minimal function in adults.
The hind limbs are absent in all species, a feature that distinguished Sirens from any
other caudate species. Sirens are capable of enclosing their bodies in a
mucus that protect them from desiccation during dryer months, when they
may be found aestivating in the mud. The dwarf sirens, Pseudobranchus,
attain lengths up to 6 inches (39cm), whereas the lesser and greater sirens
can reach up to 18 inches (46cm) and 39 inches (100cm),
is the sole family in the suborder Sirenoidea. Sirens are often placed in their
own suborder due to the fact that they are presumed to be external-fertilizers,
but are too morphologically different from members of Cryptobranchoidea
and Salamandroidea to be included in these suborders.
Breeding behavior has not been formally documented for Sirens, and they
are only presumed to be external fertilizers. This conclusion was reached
based on the absence of cloacal
glands used by internal-fertilizers. Sirens differ so much from other
caudates, that they are sometimes placed in their own order, Meantes or
Trachystomata, but recent analyses place them as a sister taxa to all
remaining salamanders (Mousetrap, 2003; Cogger & Zweifel, 2003).
|Table CF.1 - Geological
|Relative Time Span of Eras
||Ice ages; first humans appear
||Ancient human ancestors (Australopithecines,
||Continued radiation of mammals and
||Origins of many primate groups,
||Angiosperm dominance increases;
continued radiation of mammalian orders
||Major radiation of mammals, birds,
and pollinating insects
||Flowering plants (Angiosperms)
appear; many groups of organisms, including dinosaurs, become
extinct at the end of the period
||Gymnosperms continue as dominant
plants, dinosaurs diversify and abound
||Cone-bearing plants (gymnosperms)
dominate; radiation of dinosaurs
||Extinction of many marine and
terrestrial organisms (Permian mass extinction); radiation of
reptiles; origins of mammal-like reptiles and most modern insect
||Extensive forests of vascular
plants; first seed plants; origin of reptiles; amphibians dominant
||Diversification of bony fishes;
first amphibians and insects
||Diversity of jawless fishes; first
jawed fishes; diversification of early vascular plants
||Marine algae abundant;
colonization of land by plants and arthropods
||Radiation of most modern animal
Phyla (Cambrian explosion)
|diverse, soft-bodied invertebrate
animals, diverse algae
Oldest fossils of eukaryotic cells
Oxygen begins accumulating in the atmosphere
Oldest cell fossils (prokaryotes)
Earliest traces of life
Approximate time of origin of
*Mya = Millions of years ago.
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