Heliocanthus
Encyclopedia
Heliocanthus is the name of a problematic genus
of aetosaur
that has undergone many taxonomic
revisions in recent years, and may prove to be synonymous
with Rioarribasuchus. Fossil
s have been found from the Chinle Formation
in Arizona
and New Mexico
that date back to the upper Late Carnian
stage of the Late Triassic
.
" chamaensis, named in 2003 and found from the Petrified Forest Member
of the Chinle Formation in New Mexico. It was suggested to be more closely related to Paratypothorax
. However, this new generic name was first proposed in an unpublished thesis, and thus did not meet ICZN
regulations for the naming of a new taxon. Later published papers reasserted the genetic separation of "D". chamaensis from Desmatosuchus, but the name Heliocanthus remained a nomen nudum
until 2007, where it was thoroughly rediscribed in a paper published by the Journal of Systematic Palaeontology
. However, a paper previously published in late 2006 assigned "D". chamaensis to the new genus Rioarribasuchus. As a result, Heliocanthus can be considered a junior synonym of Rioarribasuchus because the genus has seniority over Heliocanthus. However, the name Rioarribasuchus has been viewed as a violation of the code of ethics laid out in Appendix A of the International Code of Zoological Nomenclature and the papers that made use of the name have even been described as practicing "intellectual theft". An article published later in 2007 in the popular science blog Tetropod Zoology brought these events to the attention of a wider range of readers. This sparked continued debate regarding these issues among vertebrate paleontologists, which eventually led to an investigation by the Society of Vertebrate Paleontology
into these issues and a response given in mid 2008 regarding the unethical conduct of the authors who described Rioarribasuchus.
Genus
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...
of aetosaur
Aetosaur
Aetosaurs are an extinct order of heavily armoured, medium- to large-sized Late Triassic herbivorous archosaurs. They have small heads, upturned snouts, erect limbs, and a body covered by plate-like scutes. All aetosaurs belong to the family Stagonolepididae...
that has undergone many taxonomic
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
revisions in recent years, and may prove to be synonymous
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Rioarribasuchus. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been found from the Chinle Formation
Chinle Formation
The Chinle is a geologic formation that is spread across the U.S. states of northern Arizona, Nevada, Utah, western New Mexico, and western Colorado. The Chinle is controversially considered to be synonymous to the Dockum Group in eastern Colorado, eastern New Mexico, southwestern Kansas, the...
in Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
and New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
that date back to the upper Late Carnian
Carnian
The Carnian is the lowermost stage of the Upper Triassic series . It lasted from about 228.7 till 216.5 million years ago . The Carnian is preceded by the Ladinian and is followed by the Norian...
stage of the Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
.
History
The name Heliocanthus was first used as a generic replacement name for the aetosaur "DesmatosuchusDesmatosuchus
Desmatosuchus is an extinct genus of archosaur belonging to the Order Aetosauria. It was one of the largest aetosaurs, being long and about 1.50 m high. It lived during the Late Triassic in Texas....
" chamaensis, named in 2003 and found from the Petrified Forest Member
Petrified Forest National Park
Petrified Forest National Park is a United States national park in Navajo and Apache counties in northeastern Arizona. The park's headquarters are about east of Holbrook along Interstate 40 , which parallels a railroad line, the Puerco River, and historic U.S. Route 66, all crossing the park...
of the Chinle Formation in New Mexico. It was suggested to be more closely related to Paratypothorax
Paratypothorax
Paratypothorax is an extinct genus of aetosaur. It was first named in 1985 from specimens collected from the Lower Stubensandstein in Germany and was also noted to be present in the Chinle Group of the southwestern United States in both the Dockum and Chinle Formations, which are latest Carnian and...
. However, this new generic name was first proposed in an unpublished thesis, and thus did not meet ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
regulations for the naming of a new taxon. Later published papers reasserted the genetic separation of "D". chamaensis from Desmatosuchus, but the name Heliocanthus remained a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
until 2007, where it was thoroughly rediscribed in a paper published by the Journal of Systematic Palaeontology
Journal of Systematic Palaeontology
The Journal of Systematic Palaeontology is a peer-reviewed quarterly scientific journal of paleontology published by Taylor & Francis on behalf of the British Natural History Museum. , the editor-in-chief is Paul D. Taylor....
. However, a paper previously published in late 2006 assigned "D". chamaensis to the new genus Rioarribasuchus. As a result, Heliocanthus can be considered a junior synonym of Rioarribasuchus because the genus has seniority over Heliocanthus. However, the name Rioarribasuchus has been viewed as a violation of the code of ethics laid out in Appendix A of the International Code of Zoological Nomenclature and the papers that made use of the name have even been described as practicing "intellectual theft". An article published later in 2007 in the popular science blog Tetropod Zoology brought these events to the attention of a wider range of readers. This sparked continued debate regarding these issues among vertebrate paleontologists, which eventually led to an investigation by the Society of Vertebrate Paleontology
Society of Vertebrate Paleontology
The Society of Vertebrate Paleontology was founded in 1940 for individuals with an interest in vertebrate paleontology. SVP now has almost 2,000 members. The society's website states that SVP "is organized exclusively for educational and scientific purposes...
into these issues and a response given in mid 2008 regarding the unethical conduct of the authors who described Rioarribasuchus.