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Overview of the Anuran Families
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UNDER CONSTRUCTION |
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Ascaphidae - Tailed Frogs
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This family consists of two species, Ascaphus montanus, and
Ascaphus
truei. The family Ascaphidae belongs to the Suborder
Archaeobatrachis, the ancient frogs. Some would place them in the
Superfamily Discoglossoidea, while others would describe them as the
"sister taxa to all other frogs". What distinguishes Ascaphids
from other frogs is the presence of a unique organ, the "tail",
that is actually an extension of the males cloaca. The tail is highly
vascularized, and allows internal fertilization to occur. During amplexus,
which occurs in water, the frogs extend the tail into the females cloaca.
In contrast, all other anurans have external fertilization. Ascaphids also
possess an unusual characteristic, the tail-wagging muscle, shared only by
the family Leiopelmatidae. Although Ascaphids, or any other frog, do not
possess real tails, the muscle seems to be a remnant of it tailed
ancestors. The primitive characteristics of this family include an
abnormally high number of vertebrae (nine in the front sacrum), a characteristic vertebral shape, the
presence of ribs, and a high number of chromosomes. Ascaphids are also thought to be incapable of vocalizing.
Ascaphids are highly aquatic, small frogs found in western North America. The
maximum size is around 25-50mm in length. These tiny frogs typically
inhabit mountainous streams. Larvae are stream type, possessing smaller
tail fins to reduce drag, and a specialized suction device to prevent them
from being swept away in the current. Ascaphus montanus (Mittleman
& Myers, 1949) was only described in 2001, by Nielson et al. The
results of mtDNA data and previous morphological data suggested that the
coastal and inland populations of A. truei were separate species.
Ascaphids were formerly, and sometimes are still, placed in the family
Leioplematidae, for which Ascaphidae shares some similar traits with.
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Bombinatoridae - Fire Belly Toads
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The family Bombinatoridae consists of small to medium sized, semi-aquatic
toads. The family consists of two genera, Bombina and Barbourula. Bombina
are found in Asia and Europe, and Barbourula occur throughout the
Philippine Islands and Borneo. These toads are often referred to as fire
belly toads because of their brightly colored ventral sides that advertise
their toxicity. Bombina are the most noted for the bright bellies, and
often display the unken
reflex when disturbed. Barbourula are slightly more understated in
coloration than Bombina, and possess webbed feet.
Bombinids were initially included in the family Discoglossidae, but
have since been separated based on a phylogenetic analysis that indicated
Discoglossidae was paraphyletic, not monophyletic. Synapomorphies of
Bombinatorids include an expanded flange of the quadratojugal, and the
presence of endochondral ossifications in the hyoid plate. The similar
feature shared between Discoglossidae and Bombinatoridae is a triradiate
sternum. However, this is also present in Leiopelma.
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Discoglossidae - Disc-Tongued Frogs,
Painted Frogs
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There are two genera in the family Discoglossidae, Alytes and Discolossus.
Discoglossids are small frogs found in Europe and northwest Africa. Frogs
of the genus Discoglossus resemble Ranids (Ranidae) in general form,
especially the smooth skin. Alytes, on the other hand, are stocky, and
more toad-like in appearance. Alytes are also more terrestrial, often
found on land, whereas Discoglossus are often found in or near water.
The larvae of both genera are pond-type. Male
Alytes
obstetricans carries egg strings on his back and thighs until they
hatch into water.
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Leiopelmatidae - New Zealand Frogs
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The family Leiopelmatidae is comprised of four species found exclusively
in New Zealand. In fact, they are the only anurans in New Zealand.
Leiopelmatidae is considered closely related to Ascaphidae, the tailed
frogs from North America. Some would consider the genera Leiopelma and
Ascaphus to be synonymous. Like Ascaphus, Leiopelma possess primitive
characteristics such as nine vertebrae in the front sacrum, and
tail-wagging muscles. Unique to Leiopelma are long pieces of cartilage in
the abdomen muscles, called ventral inscriptional ribs.
These tiny frogs, usually around 50mm, are terrestrial, and can be
found under rocks and logs in damp areas. Some species deposit eggs in
damp areas on land, rather than in ponds or pools. The embryos develop
inside the egg casing until the froglet stage (morphs still with tails).
After emerging from the egg, the froglets climb onto the males back and
continue development there. The larvae of L. hochstetteri migrate
to ponds after emerging from eggs. The larvae lack "beaks", and
lack a closed branchial chamber and spiracle.
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Megophryidae
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The family Megophryidae is the most diverse family of Archaeobatrachians
(primitive anurans), and includes 11 genera. Some species are forest
dwellers, and look very similar to the dead leaves littering the ground (see
photo of Megophrys nasuta). Other species are less cryptic in
appearance, and may be found along the rocks of streams or ponds. The
larvae are equally diverse, with some inhabiting ponds, while other are
found in flowing streams. Synapamorphies shared among Megophryids include
intervertebral cartilages with ossified centers, paddle-shaped tongue, and
hyoid plates lacking most of the ceratohyals. The status of Megophryidae
as a monophyletic group has not been disputed.
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Pelobatidae - Spadefoot Toads
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These little toads are stocky and compact, with eyes that seem to protrude
from the head (see
photo of Scaphiopus holbrokii). Spadefoot toads are named because of a
keratinous bone, a metatarsal spade supported by a well-ossified
prehallux, on the hind feet. The spade is used to burrow backward into the
soil. Pelobatidae is comprised of three genera, Pelobates from Europe, and
Scaphioupus and Spea from North America. Although Pelobatidae is
monophyletic, the two North American genera are distinct to emphasize
their morphological differences. Synapomorphies of Pelobatids include a
fused joint between the coccyx and the sacrum, exostosed frontoparietals,
and the presences of the metatarsal spade.
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| Table CF.1 - Geological
Time Scale |
| Relative Time Span of Eras |
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Cenozoic |
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Mesozoic |
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Paleozoic |
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Precambrian |
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| Era |
Period |
Epoch |
Mya* |
Characteristic Events |
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| Cenozoic |
Quaternary |
Recent |
.01 |
Documented history |
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| Pleistocene |
1.8 |
Ice ages; first humans appear |
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| Tertiary |
Pliocene |
5 |
Ancient human ancestors (Australopithecines,
etc.) |
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| Miocene |
23 |
Continued radiation of mammals and
angiosperms |
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| Oligocene |
35 |
Origins of many primate groups,
including apes |
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| Eocene |
57 |
Angiosperm dominance increases;
continued radiation of mammalian orders |
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| Paleocene |
65 |
Major radiation of mammals, birds,
and pollinating insects |
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| Mesozoic |
Cretaceous |
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144 |
Flowering plants (Angiosperms)
appear; many groups of organisms, including dinosaurs, become
extinct at the end of the period |
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| Jurassic |
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206 |
Gymnosperms continue as dominant
plants, dinosaurs diversify and abound |
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| Triassic |
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245 |
Cone-bearing plants (gymnosperms)
dominate; radiation of dinosaurs |
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| Paleozoic |
Permian |
|
290 |
Extinction of many marine and
terrestrial organisms (Permian mass extinction); radiation of
reptiles; origins of mammal-like reptiles and most modern insect
orders |
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| Carboniferous |
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363 |
Extensive forests of vascular
plants; first seed plants; origin of reptiles; amphibians dominant |
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| Devonian |
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409 |
Diversification of bony fishes;
first amphibians and insects |
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| Silurian |
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439 |
Diversity of jawless fishes; first
jawed fishes; diversification of early vascular plants |
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| Ordovician |
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510 |
Marine algae abundant;
colonization of land by plants and arthropods |
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| Cambrian |
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543 |
Radiation of most modern animal
Phyla (Cambrian explosion) |
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| Precambrian |
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600
2,200
2,700
3,500
3,800
4,600
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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
Earth
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*Mya = Millions of years ago.
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References: Papers
Alberch, P. 1981. Convergence and parallelism in foot evolution in the
neotropical salamander genus Bolitoglossa, I. Function. Evolution
35: 84-100.
Good, D. A. and D. B. Wake. 1992. Geographic variation and speciation49 in
the torrent salamanders of the genus Rhyacotriton (Caudata:
Rhyacotritonidae). University of California Publications in Zoology
126: 1-91.
Good, D. A., G. Z. Wurst and D. B. Wake. 1987. Patterns of geographic
variation in allozymes of the olympic salamander, Rhyacotriton
olympicus (Caudata: Dicamptodontidae). Fieldiana Zoology New Series
32: 1-15.
Guttman, S. I., L. A. Weight, P. A. Moler, R. E. Ashton, Jr., B. W.
Mansell and J. Peavy. 1990. An electrophoretic analysis of Necturus from
the southeastern United States. Journal of Herpetology 24: 163-175.
Karlin, A. A. and D. B. Means. 1994. Genetic variation in the aquatic
salamander genus Amphiuma. American Midland Naturalist 132: 1-9.
Kraus, F. 1988. An empirical evaluation of the use of the ontogeny
polarization criterion in phylogenetic inference. Systematic Zoology
37: 106-141.
Kraus, F., P.K Ducey, P. Moler, and M. M. Miyamoto. 1991. Two new
triparental unisexual Ambystoma from Ohio and Michigan. Herpetologica
47: 429-439.
Larson, A. 1984. Neontological inferences of evolutionary pattern and
process in the salamander family Plethodontidae. Evolutionary Biology
17: 119-217.
Larson, A. 1991. A molecular perspective on the evolutionary relationships
of the salamander families. Evolutionary Biology 25: 211-277.
Larson, A. and W. W. Dimmick. 1993. Phylogenetic relationships of the
salamander families: A analysis of congruence among morphological and
molecular characters. Herpetological Monographs 7: 77-93.
Larson, A., D. B. Wake, L. R. Maxson and R. Highton. 1981. A molecular
phylogenetic perspective on the origins of morphological novelties in the
salamanders of the tribe Plethodontini (Amphibia, Plethodontidae). Evolution
35: 405-422.
Morescalchi, A. 1975. Chromosome evolution in the caudate
Amphibia. Evolutionary
Biology 8: 339-387.
Nussbaum, R. A., E. D. Brodie, Jr., and Y. Datong. 1995. A Taxonomic
Review of Tylototriton verrucosus Anderson (Amphibia: Caudata:
Salamandridae). Herpetologica 51(3): 257-268.
Salthe, S. N. and N. O. Kaplan. 1966. Immunology and rates of enzyme
evolution in the Amphibia in relation to the origins of certain taxa. Evolution
20: 603-616.
Wake, D. B. and N. Özeti. 1969. Evolutionary relationships in the family
Salamandridae. Copeia 1969: 124-137.
References: Books
Cogger, H., and Richard Zweifel. Encyclopedia of Reptiles &
Amphibians: A comprehensive illustrated guide by international experts
(third edition).
San Francisco, CA: Fog City Press, 2003.
Duellman, William. Amphibian Species of the World: Additions and
Corrections.
Lawrence, Kansas: University of Kansas Printing Service,
1993.
Duellman, William, and Linda Trueb. Biology of Amphibians.
Johns Hopkins University Pr., 1994.
Frost, D. R. Amphibian Species of the World.
Lawrence, Kansas: Allen Press and the Association of
Systematics Collections, 1995.
Griffiths, Richard A. Newts and Salamanders of Europe.
San Diego, CA: Academic Press Inc., 1996.
Obst, Fritz Jugen, Udo Jacob, and K. Richter. Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium.
Neptune City, NY: T.F.H. Publications, Inc., 1989.
Petranka, James W. Salamanders of the United States and Canada.
Smithsonian Institution Press, 1998.
Stebbins, Robert C. Western Reptiles and Amphibians (third edition).
Houghton Mifflin Company, 2003.
Zhao, E. China Red Data Book of Endangered Animals: Amphibia and
Reptilia.
Beijing, China: Science Press; Endangered Species Scientific
Commission, P.R.C., 1998.
Zhao, E., et al. Studies on Chinese Salamanders.
Society for the Study of Amphibians and Reptiles, 1988.
References: Internet
Encyclopedia Britannica, 9th ed., Amphibia (1878). Clark University
Department of Mathematics and Computer Science.
http://aleph0.clarku.edu/huxley/UnColl/EnBrit/Amphibia.html
(Accessed: 2003).
Gianaro, Catherine. (2003). New Species of Earliest-Known Salamanders
Found in China. The University of Chicago Hospitals.
http://www.uchospitals.edu/news/2003/20030326-salamanders.html
(Accessed: 2003).
Hasumi, Masato Dr. (2003). Study Summary (1983-present). Biglobe.
http://www5d.biglobe.ne.jp/~hasumi/doc1/study_e.html
(Accessed: 2003).
Hasumi, Masato, Dr. (2003). About Hynobiidae. Biglobe.
http://www5d.biglobe.ne.jp/~hasumi/doc1/hyno_e.html
(Accessed: 2003).
Larson, Allan. (1996). Caudata. Tree of Life Web Project.
http://tolweb.org/tree?group=Caudata&contgroup=Living_Amphibians.
(Accessed: 2003).
Evolution and Natural History (2003). Lehigh Earth Observatory.
http://www.leo.lehigh.edu/projects/salamander/history.html
(Accessed: 2003).
Mousetrap, Herp Accounts (2003). Animal Diversity Web.
http://animaldiversity.ummz.umich.edu/mousetrap/herp
(Accessed: 2003).
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