Guaibasaurus
Encyclopedia
Guaibasaurus is an extinct genus
of basal
dinosaur
known from the Triassic
of Rio Grande do Sul
, southern Brazil.
, MCN PV2355, a well-preserved partial postcrania
l skeleton
and the paratype
, MCN PV2356, an articulated and nearly complete left hindlimb, which were discovered in the "Sesmaria do Pinhal 2" locality near Candelária
, Rio Grande do Sul
, in Brazil
, in the geopark
of Paleorrota
. Later, two additional specimens were referred to G. candelariensis: UFRGS PV0725T is an articulated and nearly complete postcranial skeleton missing one forelimb
, both feet and the neck, and MCN PV 10112 is still being unprepared block containing articulated parts and some isolated elements of which, including a partial hand. The referred materials were collected from the "Linha São Luiz" locality near the town of Faxinal do Soturno
, Rio Grande do Sul, also in the geopark of Paleorrota. All specimen were collected in these two localities from the lower portion of the Caturrita Formation
(Rosário do Sul Group, Paraná Basin) or alternatively the uppermost Santa Maria 2 Sequence, dating to the early Norian
faunal stage
of the Late Triassic
, about 216.5-212 million years ago.
, Jorge Ferigolo and Ana Maria Ribeiro in 1999
and the type species
is Guaibasaurus candelariensis. The generic name is named after the "Rio Guaíba Hydrographic Basin" where the holotype was found as a part of the "Prό-Guaíba Project", a scientific program supporting research on fossils from the Triassic period. The specific name is named after Candelária
, a city near the fossil locality in which the holotype was found.
and colleagues, in their 1999 description of the genus, found it to be possible basal theropod and placed it in its own family
, Guaibasauridae
. Bonaparte and colleagues (2007) found another early Brazilian dinosaur Saturnalia
to be very similar to it, and placed the two in the Guaibasauridae
which was found to be a primitive saurischian group. Bonaparte found that these forms may have been primitive sauropodomorphs, or an assemblage of forms close to the common ancestor of the sauropodomorphs and theropods. Overall, Bonaparte found that both Saturnalia and Guaibasaurus were more theropod-like than prosauropod-like. However, all more recent cladistic analyses found the members of Guaibasauridae to be very basal
sauropodomorphs, except Guaibasaurus itself which was found to be a basal theropod or alternatively a basal sauropodomorph.
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 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:...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
known from the Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
of Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
, southern Brazil.
Discovery
Guaibasaurus was originally named on the basis of 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...
, MCN PV2355, a well-preserved partial postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
and the paratype
Paratype
Paratype is a technical term used in the scientific naming of species and other taxa of organisms. The exact meaning of the term paratype when it is used in zoology is not the same as the meaning when it is used in botany...
, MCN PV2356, an articulated and nearly complete left hindlimb, which were discovered in the "Sesmaria do Pinhal 2" locality near Candelária
Candelaria
-People:*John Candelaria , American baseball pitcher*Candelaria Pérez , sergeant in the Chilean Army, hero of the Battle of Yungay*Nash Candelaria , U.S...
, Rio Grande do Sul
Rio Grande do Sul
Rio Grande do Sul is the southernmost state in Brazil, and the state with the fifth highest Human Development Index in the country. In this state is located the southernmost city in the country, Chuí, on the border with Uruguay. In the region of Bento Gonçalves and Caxias do Sul, the largest wine...
, in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, in the geopark
Geopark
A Geopark is defined by the United Nations Educational, Scientific and Cultural Organization in its UNESCO Geoparks International Network of Geoparks programme as follows:...
of Paleorrota
Paleorrota
Paleorrota , is a geopark located in the center of the Brazilian state of Rio Grande do Sul. The rocks and fossils found along the route date back to the times when there was only one supercontinent Pangaea....
. Later, two additional specimens were referred to G. candelariensis: UFRGS PV0725T is an articulated and nearly complete postcranial skeleton missing one forelimb
Forelimb
A forelimb is an anterior limb on an animal's body. When referring to quadrupeds , the term foreleg is often instead used....
, both feet and the neck, and MCN PV 10112 is still being unprepared block containing articulated parts and some isolated elements of which, including a partial hand. The referred materials were collected from the "Linha São Luiz" locality near the town of Faxinal do Soturno
Faxinal do Soturno
-See also:*List of municipalities in Rio Grande do Sul...
, Rio Grande do Sul, also in the geopark of Paleorrota. All specimen were collected in these two localities from the lower portion of the Caturrita Formation
Caturrita Formation
The Caturrita Formation is a rock formation found in Rio Grande do Sul, Brazil. Its sediments were deposited in the Paraná Basin. The formation has a late Carnian to early Norian age and forms part of the Santa Maria Supersequence in the upper section of the Rosário do Sul Group.-Etymology:The...
(Rosário do Sul Group, Paraná Basin) or alternatively the uppermost Santa Maria 2 Sequence, dating to the early 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...
faunal stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
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...
, about 216.5-212 million years ago.
Etymology
Guaibasaurus was first named by José F. BonaparteJosé Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
, Jorge Ferigolo and Ana Maria Ribeiro in 1999
1999 in paleontology
-Insects:-Newly named taxa:-Newly named dinosaurs:Data courtesy of George Olshevsky's dinosaur genera list and Dr. Jeremy Montague's dinosaur genus database.-New taxa:-New taxa:-Non-mammalian:-References:...
and 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...
is Guaibasaurus candelariensis. The generic name is named after the "Rio Guaíba Hydrographic Basin" where the holotype was found as a part of the "Prό-Guaíba Project", a scientific program supporting research on fossils from the Triassic period. The specific name is named after Candelária
Candelaria
-People:*John Candelaria , American baseball pitcher*Candelaria Pérez , sergeant in the Chilean Army, hero of the Battle of Yungay*Nash Candelaria , U.S...
, a city near the fossil locality in which the holotype was found.
Phylogeny
José BonaparteJosé Bonaparte
José Fernando Bonaparte, Ph.D. , is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria...
and colleagues, in their 1999 description of the genus, found it to be possible basal theropod and placed it in its own family
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...
, Guaibasauridae
Guaibasauridae
Guaibasauridae is a family of primitive saurischian dinosaurs, known from fossil remains of late Triassic period formations in Brazil and Argentina....
. Bonaparte and colleagues (2007) found another early Brazilian dinosaur Saturnalia
Saturnalia (dinosaur)
Saturnalia is an extinct genus of basal sauropodomorph dinosaur known from the Triassic of Rio Grande do Sul, southern Brazil.-Discovery:Saturnalia was originally named on the basis of three partial skeletons...
to be very similar to it, and placed the two in the Guaibasauridae
Guaibasauridae
Guaibasauridae is a family of primitive saurischian dinosaurs, known from fossil remains of late Triassic period formations in Brazil and Argentina....
which was found to be a primitive saurischian group. Bonaparte found that these forms may have been primitive sauropodomorphs, or an assemblage of forms close to the common ancestor of the sauropodomorphs and theropods. Overall, Bonaparte found that both Saturnalia and Guaibasaurus were more theropod-like than prosauropod-like. However, all more recent cladistic analyses found the members of Guaibasauridae to be very 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:...
sauropodomorphs, except Guaibasaurus itself which was found to be a basal theropod or alternatively a basal sauropodomorph.