Brachyopomorpha
Encyclopedia
Brachyopomorpha is a clade
of stereospondyl temnospondyls within the infraorder Trematosauria
. It was constructed in 2000 to include Bothriceps australis
and the superfamily Brachyopoidea
. It is phylogenetically
defined as a stem-based
taxon including Pelorocephalus
and all taxa closer to it than to Rhytidosteus. In contrast, Brachyopoidea is defined as a node-based
taxon including Brachyops and Pelorocephalus and all descendants of their most recent common ancestor. Because Bothriceps is not thought to be a descendant of that recent common ancestor and would be more basal
than it, the genus is placed just outside Brachyopoidea and is considered to be a sister taxon to the clade.
Damiani and Kitching, 2003
Bothriceps was once considered to be a brachyopid
within Brachyopoidea, but is now placed on the brachyopoid stem closer to Brachyopoidea than to Rhytidosteidae
due to the presence of several plesiomorphies (ancestral characters). The probable presence of a tabular horn in Bothriceps also suggests that it is a basal brachyopomorph rather than a brachyopid.
Keratobrachyops
, once assigned to Chigutisauridae
, is now thought to be a basal brachyopomorph closely related to Bothriceps.
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...
of stereospondyl temnospondyls within the infraorder Trematosauria
Trematosauria
Trematosauria is one of two major groups of temnospondyl amphibians that survived the Permian-Triassic extinction event, the other being the Capitosauria. The trematosaurs were a diverse and important group that included many medium-sized to large forms that were semi-aquatic to totally aquatic...
. It was constructed in 2000 to include Bothriceps australis
Bothriceps
Bothriceps is an extinct genus of stereospondyl temnospondyl. It is a member of the infraorder Trematosauria and is the most basal brachyopomorph known. It is one of the only brachyopomorph that lies outside the superfamily Brachyopoidea, which includes the families Brachyopidae and Chigutisauridae...
and the superfamily Brachyopoidea
Brachyopoidea
Brachyopoidea is a superfamily of temnospondyls that lived during the Mesozoic. It contains the families Brachyopidae and Chigutisauridae. The earliest records of brachyopids are from the Lower Triassic in Australia...
. It is phylogenetically
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
defined as a stem-based
PhyloCode
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a developing draft for a formal set of rules governing phylogenetic nomenclature...
taxon including Pelorocephalus
Pelorocephalus
Pelorocephalus is an extinct genus of chigutisaurid temnospondyl from Late Triassic of Argentina....
and all taxa closer to it than to Rhytidosteus. In contrast, Brachyopoidea is defined as a node-based
PhyloCode
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a developing draft for a formal set of rules governing phylogenetic nomenclature...
taxon including Brachyops and Pelorocephalus and all descendants of their most recent common ancestor. Because Bothriceps is not thought to be a descendant of that recent common ancestor and would be more basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
than it, the genus is placed just outside Brachyopoidea and is considered to be a sister taxon to the clade.
Bothriceps was once considered to be a brachyopid
Brachyopidae
Brachyopidae is an extinct family of Temnospondyl labyrintodonts. They evolved in the early Mesozoic and were mostly aquatic. A fragmentary find from Lesotho, Africa is estimated to have been 7 meter long, the largest amphibian ever known to have lived besides Prionosuchus.-External links:*...
within Brachyopoidea, but is now placed on the brachyopoid stem closer to Brachyopoidea than to Rhytidosteidae
Rhytidosteidae
Rhytidosteidae is a family of Temnospondyli that lived in the Permian and Triassic.-References:*Yates, AM , A new tiny rhytidosteid from the Early Triassic of Australia and the possibility of hidden temnospondyl diversity. J. Vert Paleontol. 20:484-489.-External links:*...
due to the presence of several plesiomorphies (ancestral characters). The probable presence of a tabular horn in Bothriceps also suggests that it is a basal brachyopomorph rather than a brachyopid.
Keratobrachyops
Keratobrachyops
Keratobrachyops is an extinct genus of trematosaurian temnospondyl. It was previously thought to be a basal chigutisaurid but is now thought to be a basal brachyopomorph closely related to the genus Bothriceps, and may even be a synonym of it....
, once assigned to Chigutisauridae
Chigutisauridae
Chigutisauridae is an extinct family of large temnospondyl amphibians. The only genera recognized as belonging to Chigutisauridae at the current time are all from Gondwana and include Koolasuchus and Siderops.-References:*Sengupta, D.P. 1995. Palaeontology 38: 19-59.*Sengupta, D.P. 2003...
, is now thought to be a basal brachyopomorph closely related to Bothriceps.
External links
- Cladogram of Brachyopomorpha at Mikko's Phylogeny ArchiveMikko's Phylogeny ArchiveMikko's Phylogeny Archive is an amateur paleontology website maintained by Mikko Haaramo, a student at the University of Helsinki's Department of Geology, Division of Geology and Palaeontology....