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First 'Rauisuchian' archosaur (Pseudosuchia, Loricata) for the Middle Triassic Santacruzodon assemblage zone (Santa Maria Supersequence), Rio Grande do Sul State, Brazil.

Lacerda MB, Schultz CL, Bertoni-Machado C - PLoS ONE (2015)

Bottom Line: In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes).Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei.Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Geociências, Laboratório de Paleovertebrados, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.

ABSTRACT
The 'Rauisuchia' are a group of Triassic pseudosuchian archosaurs that displayed a near worldwide distribution. In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes). Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei. Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis.

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Comparative chart with the biostratigraphical framework of the Santa Maria Supersequence along with the ones from South Africa, Madagascar and Argentina.From [23].
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pone.0118563.g001: Comparative chart with the biostratigraphical framework of the Santa Maria Supersequence along with the ones from South Africa, Madagascar and Argentina.From [23].

Mentions: ‘Rauisuchians’ displayed a near worldwide distribution, with the exception of Oceania and Antarctica [3, 5, 20]. In Brazil, their fossils are found only in the Santa Maria Supersequence [21, 22], Paraná Basin, Rio Grande do Sul State, in the southern part of the country. This Supersequence encompasses two biostratigraphic units bearing ‘rauisuchians’; the Middle Triassic Dinodontosaurus Assemblage Zone (AZ) with the species Prestosuchus chiniquensis, ‘Prestosuchus loricatus’ and Decuriasuchus quartacolonia, and the Late Triassic Hyperodapedon AZ, with the record of Rauisuchus tiradentes [5, 14, 23, 24]. Placed between these two biozones, occurs the Santacruzodon AZ, for which no ‘rauisuchians’ had been found until now. The faunal association of this biozone includes mainly traversodontid (Santacruzodon hopsoni [25]; Menadon sp. [26] and probainognathid (cf. Probainognathus [23]) cynodonts, the proterochampsian Chanaresuchus bonapartei Romer 1971 [27] and cranial fragments of dicynodonts [26, 27]. The presence of Menadon and the close taxonomic relationships between Santacruzodon hopsoni and Dadadon isaloi [28] indicates a temporal correlation between the Santacruzodon AZ and the Ladinian “Isalo II” fauna of Madagascar [28, 29] (Fig. 1).


First 'Rauisuchian' archosaur (Pseudosuchia, Loricata) for the Middle Triassic Santacruzodon assemblage zone (Santa Maria Supersequence), Rio Grande do Sul State, Brazil.

Lacerda MB, Schultz CL, Bertoni-Machado C - PLoS ONE (2015)

Comparative chart with the biostratigraphical framework of the Santa Maria Supersequence along with the ones from South Africa, Madagascar and Argentina.From [23].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340915&req=5

pone.0118563.g001: Comparative chart with the biostratigraphical framework of the Santa Maria Supersequence along with the ones from South Africa, Madagascar and Argentina.From [23].
Mentions: ‘Rauisuchians’ displayed a near worldwide distribution, with the exception of Oceania and Antarctica [3, 5, 20]. In Brazil, their fossils are found only in the Santa Maria Supersequence [21, 22], Paraná Basin, Rio Grande do Sul State, in the southern part of the country. This Supersequence encompasses two biostratigraphic units bearing ‘rauisuchians’; the Middle Triassic Dinodontosaurus Assemblage Zone (AZ) with the species Prestosuchus chiniquensis, ‘Prestosuchus loricatus’ and Decuriasuchus quartacolonia, and the Late Triassic Hyperodapedon AZ, with the record of Rauisuchus tiradentes [5, 14, 23, 24]. Placed between these two biozones, occurs the Santacruzodon AZ, for which no ‘rauisuchians’ had been found until now. The faunal association of this biozone includes mainly traversodontid (Santacruzodon hopsoni [25]; Menadon sp. [26] and probainognathid (cf. Probainognathus [23]) cynodonts, the proterochampsian Chanaresuchus bonapartei Romer 1971 [27] and cranial fragments of dicynodonts [26, 27]. The presence of Menadon and the close taxonomic relationships between Santacruzodon hopsoni and Dadadon isaloi [28] indicates a temporal correlation between the Santacruzodon AZ and the Ladinian “Isalo II” fauna of Madagascar [28, 29] (Fig. 1).

Bottom Line: In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes).Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei.Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Geociências, Laboratório de Paleovertebrados, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.

ABSTRACT
The 'Rauisuchia' are a group of Triassic pseudosuchian archosaurs that displayed a near worldwide distribution. In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes). Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei. Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis.

Show MeSH