Decuriasuchus
Encyclopedia
Decuriasuchus is an extinct genus
of prestosuchid
rauisuchian from the Middle Triassic
period (Ladinian
stage). It is a carnivorous archosaur
that lived in what is now southern Brazil
. It was first named by Marco Aurélio G. França, Jorge Ferigolo and Max C. Langer in 2011
and the type species
is Decuriasuchus quartacolonia. The generic name means "legion of ten crocodile" in Greek in reference to the ten known specimens and the animal's possible group behavior. The specific name refers to the Quarta Colonia region where the fossils were collected.
s, three of which have nearly complete skulls. The holotype
MCN PV10105a consists of an articulated partial skeleton, lacking scapular girdle and limbs. Eight specimens associated with the holotype, MCN PV10105b-i, and the tenth specimen (MCN PV10004), consists of cranial remains from a different spot in the same locality. The specimens were found in the Alemoa Member of the Santa Maria Formation
, Rosário do Sul Group. The discovery locality is Rio Grande do Sul
, Brazil.
Like other rauisuchids, Decuriasuchus was a quadrupedal carnivore that was one of the top predators of its environment. It grew to a length of around 2.5 metres (8.2 ft).
and Batrachotomus
. A phylogenetic study of the genus placed it in the family Prestosuchidae, but found the Rauisuchia group to be paraphyletic. The study was based on an earlier 2010 analysis of archosaurs. As a rauisuchian, Decuriasuchus is a distant relative of modern crocodilians.
of the site (the conditions under which the skeletons became fossilized) indicates that the assemblage represents the single burial of multiple individuals rather than the collection of unrelated remains in one spot over a longer period of time. The congregation of nine individuals in one area suggests that they may have been traveling in a group. If this were the case, Decuriasuchus would be the earliest known archosaur to exhibit group behavior.
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 prestosuchid
Prestosuchidae
Prestosuchids were a group of Triassic carnivorous archosaurs. They were large active terrestrial apex predators, ranging from around in length. They succeeded the Erythrosuchidae as the largest archosaurs of their time...
rauisuchian from the Middle 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...
period (Ladinian
Ladinian
The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between 237 ± 2 Ma and 228 ± 2 Ma...
stage). It is a carnivorous archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
that lived in what is now southern 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...
. It was first named by Marco Aurélio G. França, Jorge Ferigolo and Max C. Langer in 2011
2011 in paleontology
-Lobopods:-Arachnids:-Insects:-Newly named jawless vertebrates:-Newly named acanthodian:-Newly named cartilaginous fishes:-Newly named bony fishes:-Newly named lepospondyls:-Newly named temnospondyls:-Newly named lissamphibians:...
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 Decuriasuchus quartacolonia. The generic name means "legion of ten crocodile" in Greek in reference to the ten known specimens and the animal's possible group behavior. The specific name refers to the Quarta Colonia region where the fossils were collected.
Description
Decuriasuchus is known from ten specimens, including nine articulated and associated skeletonSkeleton
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...
s, three of which have nearly complete skulls. The holotype
Holotype
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 PV10105a consists of an articulated partial skeleton, lacking scapular girdle and limbs. Eight specimens associated with the holotype, MCN PV10105b-i, and the tenth specimen (MCN PV10004), consists of cranial remains from a different spot in the same locality. The specimens were found in the Alemoa Member of the Santa Maria Formation
Santa Maria Formation
The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It has a late Ladinian – early Carnian age , and is notable for its fossils of early dinosaurs, including the herrerasaur Staurikosaurus, the basal saurischian Teyuwasu, and the basal sauropodomorph...
, Rosário do Sul Group. The discovery locality is 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...
, Brazil.
Like other rauisuchids, Decuriasuchus was a quadrupedal carnivore that was one of the top predators of its environment. It grew to a length of around 2.5 metres (8.2 ft).
Classification
Decuriasuchus is closely related to the genera PrestosuchusPrestosuchus
Prestosuchus is an extinct genus of a group of rauisuchians called prestosuchids. Friedrich von Huene named the genus in honor of Vicentino Prestes de Almeida....
and Batrachotomus
Batrachotomus
Batrachotomus is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of Middle Triassic period, around 228 to 231 million years ago. Batrachotomus was described by palaeontologist David J...
. A phylogenetic study of the genus placed it in the family Prestosuchidae, but found the Rauisuchia group to be paraphyletic. The study was based on an earlier 2010 analysis of archosaurs. As a rauisuchian, Decuriasuchus is a distant relative of modern crocodilians.
Paleobiology
Nine specimens of Decuriasuchus were found in close proximity to each other. A study of the taphonomyTaphonomy
Taphonomy is the study of decaying organisms over time and how they become fossilized . The term taphonomy was introduced to paleontology in 1940 by Russian scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms, from the biosphere, to the...
of the site (the conditions under which the skeletons became fossilized) indicates that the assemblage represents the single burial of multiple individuals rather than the collection of unrelated remains in one spot over a longer period of time. The congregation of nine individuals in one area suggests that they may have been traveling in a group. If this were the case, Decuriasuchus would be the earliest known archosaur to exhibit group behavior.