Amphibamidae
Encyclopedia
Amphibamidae is an extinct family
of dissorophoid
euskelia
n temnospondyls. The earliest amphibamids such as Amphibamus
are known from Early Permian strata in the United States
, while the last known amphibamid, Micropholis
, is known from the Early Triassic
Karoo Basin
of South Africa
. According to some phylogenetic studies, modern amphibian
s, including frog
s and salamander
s, may have descended from a common ancestor that was an amphibamid.
from Schoch and Rubidge (2005):
Cladogram from Huttenlocker et al. (2007):
Cladogram from Fröbisch and Reisz (2008):
Gerobatrachus
, which has been interpreted as the sister taxon of Batrachia, the modern amphibians. This would make Amphibamidae a paraphyletic taxon, since it would not contain all descendants of the last common ancestor
of amphibamids. If Gerobatrachus is the sister taxon of Batrachia, then all modern amphibians descend from an amphibamid ancestor. Below is a modified cladogram from Anderson et al. (2008) showing Batrachia nested in Amphibamidae, with Gerobatrachus as the sister taxon of Batrachia:
The cladistic analysis of Anderson et al. (2008) supported the "polyphyly
hypothesis" of modern amphibian ancestry, whereby some extant amphibian groups are descendants of temnospondyls while others are descendants of lepospondyls, another large group of Paleozoic amphibians. Caecilian
s were nested within Lepospondyli, making Lissamphibia
polyphyletic. However, the placement of Batrachia within Amphibamidae has been controversial, and alternate hypotheses of lissamphibian ancestry remain. Some authors of more recent studies have suggested that the findings of Anderson et al. (2008) may be wrong, and that lissamphibians are descendants of lepospondyls. This would make Amphibamidae a monophyletic grouping much more distantly related to lissamphibians.
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 dissorophoid
Dissorophoidea
Dissorophoideans are a clade of medium-sized, temnospondyl amphibians that appeared during the Late Pennsylvanian in Euramerica, and continued through to the Late Permian and even possibly the Early Triassic of Gondwana...
euskelia
Euskelia
Euskelia is a clade of extinct Temnospondyl amphibians.-References:*Yates, A. M. & Warren, A. A. , The phylogeny of the 'higher' temnospondyls and its implications for the monophyly and origins of the Stereospondyli. Zoological Journal of the Linnean Society 128: 77-121....
n temnospondyls. The earliest amphibamids such as Amphibamus
Amphibamus
Amphibamus is a genus of amphibamid temnospondyl amphibian from the Carboniferous of Europe and North America....
are known from Early Permian strata in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, while the last known amphibamid, Micropholis
Micropholis (amphibian)
Micropholis is an extinct genus of dissorophoid temnospondyl. Fossils have been found from the Lystrosaurus Assemblage Zone of the Karoo Basin in South Africa, and date back to the Early Triassic...
, is known from the Early Triassic
Early Triassic
The Early Triassic is the first of three epochs of the Triassic period of the geologic timescale. It spans the time between 251 ± 0.4 Ma and 245 ± 1.5 Ma . Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy...
Karoo Basin
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...
of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
. According to some phylogenetic studies, modern amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s, including frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s and salamander
Salamander
Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant...
s, may have descended from a common ancestor that was an amphibamid.
Classification
CladogramCladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
from Schoch and Rubidge (2005):
Cladogram from Huttenlocker et al. (2007):
Relationship to Batrachia
Amphibamidae contains the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Gerobatrachus
Gerobatrachus
Gerobatrachus, also referred to as a frogamander, is an extinct genus of amphibamid temnospondyl that lived in the Permian period, approximately 290 million years ago, in the area that is now Baylor County, Texas...
, which has been interpreted as the sister taxon of Batrachia, the modern amphibians. This would make Amphibamidae a paraphyletic taxon, since it would not contain all descendants of the last common ancestor
Common descent
In evolutionary biology, a group of organisms share common descent if they have a common ancestor. There is strong quantitative support for the theory that all living organisms on Earth are descended from a common ancestor....
of amphibamids. If Gerobatrachus is the sister taxon of Batrachia, then all modern amphibians descend from an amphibamid ancestor. Below is a modified cladogram from Anderson et al. (2008) showing Batrachia nested in Amphibamidae, with Gerobatrachus as the sister taxon of Batrachia:
The cladistic analysis of Anderson et al. (2008) supported the "polyphyly
Polyphyly
A polyphyletic group is one whose members' last common ancestor is not a member of the group.For example, the group consisting of warm-blooded animals is polyphyletic, because it contains both mammals and birds, but the most recent common ancestor of mammals and birds was cold-blooded...
hypothesis" of modern amphibian ancestry, whereby some extant amphibian groups are descendants of temnospondyls while others are descendants of lepospondyls, another large group of Paleozoic amphibians. Caecilian
Caecilian
The caecilians are an order of amphibians that superficially resemble earthworms or snakes. They mostly live hidden in the ground, making them the least familiar order of amphibians. All extant caecilians and their closest fossil relatives are grouped as the clade Apoda. They are mostly...
s were nested within Lepospondyli, making Lissamphibia
Lissamphibia
The subclass Lissamphibia includes all recent amphibians and means smooth amphibia.Extant amphibians fall into one of three orders — the Anura , the Caudata or Urodela , and the Gymnophiona or Apoda .Although the ancestry of each group is still unclear, all share certain common characteristics,...
polyphyletic. However, the placement of Batrachia within Amphibamidae has been controversial, and alternate hypotheses of lissamphibian ancestry remain. Some authors of more recent studies have suggested that the findings of Anderson et al. (2008) may be wrong, and that lissamphibians are descendants of lepospondyls. This would make Amphibamidae a monophyletic grouping much more distantly related to lissamphibians.
External links
- Amphibamidae in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...