Redondasuchus
Encyclopedia
Redondasuchus is an extinct genus
of aetosaur
. It may a junior synonym of Typothorax coccinarum
, another aetosaur. Redondasuchus is a member of the clade
Typothoracisinae
within the subfamily Aetosaurinae
, and lived during the middle Norian
stage of the Late Triassic
. Material belonging to the genus has been found from the Redonda Formation in east-central New Mexico
. The type species
, R. reseri, was named in 1991 after having been referred to as a species of Typothorax since 1985. A second species, R. rineharti, was described in 2006.
. R. rineharti was described in 2006 from several scutes and part of a right femur
found from Apache Canyon.
While other aetosaurs have scute
s covered in pits and grooves that often form radial patterns, the scutes of Redondasuchus are densely covered in pits and lack any patterning. The dorsal paramedian scutes (those that line the back) are unique in that they are angled approximately 45°. In other aetosaurs, the scutes arc smoothly around the back from the midline to the lateral scutes that lie below them and run along the side of the animal.
The dorsal paramedians of R. reseri are smaller than those of R. rineharti. In both species, each paramedian possesses a keel on the underside that extends from the medial edge (the edge near the vertebrae) to the flexed area of the scute.
of R. reseri was identified as a left paramedian based on the position of a bar that was known to lie on the anterior edge of the scute in other aetosaurs. However, a more recent study by Spielmann et al. (2006) has argued that the holotype scute is actually a right paramedian, claiming that the source of confusion was a mislabeling of the scute in the diagrams of previous papers. The orientation of one diagram, with the anterior margin being placed near the bottom of the page and the posterior margin near the top, may have contributed to its misidentification. This is because in most papers on aetosaurs, the anterior margin of a scute is positioned toward the top of the page and the posterior margin is positioned toward the bottom. If the scute is a right paramedian, the medial and lateral edges would be reversed, and the angled section would be one third the way down from the medial edge.
Four years before Spielmann et al. published their study of Redondasuchus, an unpublished thesis
by Jeffrey Martz at Texas Tech University
claimed that the holotype of R. reseri was actually a right paramedian (Martz also suggested that R. reseri was synonymous
with Typothorax coccinarum). Martz, along with paleontologists Darren Naish
, Mike Taylor, and Matt Wedel, later accused Spielmann et al. of committing plagiarism, claiming that the authors could not have come up with the same interpretation as Martz independently. This controversy became part of what was called Aetogate, involving several issues surrounding possible plagiarism by paleontologists at the New Mexico Museum of Natural History and Science
.
, Longosuchus
, Desmatosuchus
, Paratypothorax
, and Typothorax
.
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...
. It may a junior synonym of Typothorax coccinarum
Typothorax
Typothorax is an extinct genus of aetosaur that lived in the Late Triassic. Its remains have been found in North America. Two species are known: T. coccinarum, the type species, and T. antiquum.-Description:...
, another aetosaur. Redondasuchus is a member of the clade
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...
Typothoracisinae
Typothoracisinae
Typothoracisinae is a clade of aetosaurs within the subfamily Aetosaurinae. It is a stem-based taxon defined as all aetosaurs closer to Typothorax than to Stagonolepis or Desmatosuchus. As with many aetosaur taxa, most of the synapomorphies that diagnose the clade are found in the osteoderms...
within the subfamily Aetosaurinae
Aetosaurinae
Aetosaurinae is one of the two subfamilies of aetosaurs, the other being Desmatosuchinae. It is a stem-based taxon defined as all aetosaurs more closely related to Aetosaurus than to the last common ancestor of Aetosaurus and Desmatosuchus. The only synapomorphy that diagnoses the clade...
, and lived during the middle Norian
Norian
The Norian is a division of the Triassic geological period. It has the rank of an age or stage . The Norian lasted from 216.5 ± 2.0 to 203.6 ± 1.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.-Stratigraphic definitions:The Norian was named after the Noric Alps in...
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...
. Material belonging to the genus has been found from the Redonda Formation in east-central 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...
. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, R. reseri, was named in 1991 after having been referred to as a species of Typothorax since 1985. A second species, R. rineharti, was described in 2006.
Description and species
Redondasuchus was first named with the description of the type species, R. reseri, in 1991. R. reseri was named on the basis of isolated scutes found at Apache Canyon and Shark Tooth Hill in Quay County, New MexicoQuay County, New Mexico
-2010:Whereas according to the 2010 U.S. Census Bureau:*86.1% White*1.1% Black*1.2% Native American*1.0% Asian*0.0% Native Hawaiian or Pacific Islander*3.4% Two or more races*7.2% Other races*42.4% Hispanic or Latino -2000:...
. R. rineharti was described in 2006 from several scutes and part of a right femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
found from Apache Canyon.
While other aetosaurs have scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s covered in pits and grooves that often form radial patterns, the scutes of Redondasuchus are densely covered in pits and lack any patterning. The dorsal paramedian scutes (those that line the back) are unique in that they are angled approximately 45°. In other aetosaurs, the scutes arc smoothly around the back from the midline to the lateral scutes that lie below them and run along the side of the animal.
The dorsal paramedians of R. reseri are smaller than those of R. rineharti. In both species, each paramedian possesses a keel on the underside that extends from the medial edge (the edge near the vertebrae) to the flexed area of the scute.
Orientation of scutes and plagiarism allegations
The orientation of the dorsal paramedian scutes of Redondasuchus has been disputed. Originally, it was thought that the angled part of the scute was two thirds the way down from the medial edge. The holotypeHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
of R. reseri was identified as a left paramedian based on the position of a bar that was known to lie on the anterior edge of the scute in other aetosaurs. However, a more recent study by Spielmann et al. (2006) has argued that the holotype scute is actually a right paramedian, claiming that the source of confusion was a mislabeling of the scute in the diagrams of previous papers. The orientation of one diagram, with the anterior margin being placed near the bottom of the page and the posterior margin near the top, may have contributed to its misidentification. This is because in most papers on aetosaurs, the anterior margin of a scute is positioned toward the top of the page and the posterior margin is positioned toward the bottom. If the scute is a right paramedian, the medial and lateral edges would be reversed, and the angled section would be one third the way down from the medial edge.
Four years before Spielmann et al. published their study of Redondasuchus, an unpublished thesis
Thesis
A dissertation or thesis is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings...
by Jeffrey Martz at Texas Tech University
Texas Tech University
Texas Tech University, often referred to as Texas Tech or TTU, is a public research university in Lubbock, Texas, United States. Established on February 10, 1923, and originally known as Texas Technological College, it is the leading institution of the Texas Tech University System and has the...
claimed that the holotype of R. reseri was actually a right paramedian (Martz also suggested that R. reseri was 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 Typothorax coccinarum). Martz, along with paleontologists Darren Naish
Darren Naish
Darren Naish is a vertebrate palaeontologist and science writer. He obtained a geology degree at the University of Southampton and later studied vertebrate palaeontology under British palaeontologist David Martill at the University of Portsmouth, where he obtained both an M. Phil...
, Mike Taylor, and Matt Wedel, later accused Spielmann et al. of committing plagiarism, claiming that the authors could not have come up with the same interpretation as Martz independently. This controversy became part of what was called Aetogate, involving several issues surrounding possible plagiarism by paleontologists at the New Mexico Museum of Natural History and Science
New Mexico Museum of Natural History and Science
The New Mexico Museum of Natural History and Science is a natural history and science museum in Albuquerque, New Mexico near Old Town Albuquerque. The Museum was founded in 1986....
.
Phylogeny
Heckert et al. (1996) considered Redondasuchus to be part of an advanced grade of aetosaurs that also included NeoaetosauroidesNeoaetosauroides
Neoaetosauroides is an extinct genus of primitive aetosaur. Its type and only species is N. engaeus. Fossils have been found from the Los Colorados Formation outcropping along the Sierra Morada River in La Rioja, Argentina, and date back to the Norian age of the Late Triassic...
, Longosuchus
Longosuchus
Longosuchus is an extinct genus of aetosaur from the Late Triassic of North America. It measured about 3 metre in length....
, Desmatosuchus
Desmatosuchus
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....
, 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...
, and Typothorax
Typothorax
Typothorax is an extinct genus of aetosaur that lived in the Late Triassic. Its remains have been found in North America. Two species are known: T. coccinarum, the type species, and T. antiquum.-Description:...
.