iBet uBet web content aggregator. Adding the entire web to your favor.
iBet uBet web content aggregator. Adding the entire web to your favor.



Link to original content: https://pubmed.ncbi.nlm.nih.gov/27706191
Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians - PubMed Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2016 Oct 5;11(10):e0162945.
doi: 10.1371/journal.pone.0162945. eCollection 2016.

Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians

Agustín G Martinelli  1 , Marina Bento Soares  1 , Cibele Schwanke  2
Affiliations

Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians

Agustín G Martinelli et al. PLoS One. .

Abstract

We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.

PubMed Disclaimer

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Chrono- and biostratigraphy of Triassic units with vertebrate assemblages zones (AZ) from southern Brazil.
Modified from [29, 48, 49]. The ages of the column follow Gradstein et al., [50]. The radiometric dating of 236.1, 231.4 and 225.9 Ma correspond to the first half of the Chañares Formation [51], the base of the Ischigualasto Formation, and the base of Los Colorados Formation [6], respectively. Abbreviations: Ind., Induan; Ole., Olenekian; Se., sequence.
Fig 2
Fig 2. Localities and Catalog cards.
(A) Map showing the Middle to Upper Triassic outcrops (in light red colour) in Candelária and Santa Cruz do Sul municipalities, state of Rio Grande do Sul (RS), southern Brazil (based partially on [80]). The two specimens (MCT-1716-R and MCT-1717-R) of Bonacynodon come from the Pinheiros region, about 12 km south of Candelária city, and the arrow indicates the site where the specimen (UFRGS-PV-1121-T) of Santacruzgnathus was discovered from the Santacruzodon AZ. Catalog cards of MCT-1716-R (holotype) from “Sanga do Janguta” (B) and MCT-1717-R (referred specimen) from “Sanga do Forno” (C) of Bonacynodon schultzi.
Fig 3
Fig 3. Bonacynodon schultzi, holotype MCT-1716-R.
Partial skull and lower jaws, with the snout and right lower jaw positioned in lateral view. Dark grey indicates broken areas and soft grey indicates matrix.
Fig 4
Fig 4. Bonacynodon schultzi, holotype MCT-1716-R.
Partial skull and lower jaws, with the secondary palate horizontally positioned, in ventral view. Dark grey indicates broken areas and soft grey indicates matrix.
Fig 5
Fig 5. Bonacynodon schultzi, holotype MCT-1716-R.
Detail of the basicranial region in ventral view with interpretative line drawing.
Fig 6
Fig 6. Bonacynodon schultzi, holotype MCT-1716-R.
Detail of the left postdentary bones in medial view with interpretative line drawing.
Fig 7
Fig 7. Bonacynodon schultzi, holotype MCT-1716-R.
Detail of the right upper dentition in lateral view. Dark grey indicates broken areas and soft grey indicates matrix.
Fig 8
Fig 8. Bonacynodon schultzi, holotype MCT-1716-R.
Detail of right upper canine in lateral labial view (A). Detail of incisors in anterolateral view (B). Detail of the only lower postcanines of the holotype, two anterior-middle left teeth in labial view (C).
Fig 9
Fig 9. Bonacynodon schultzi, referred specimen MCT-1717-R.
Partial skull and lower jaws in right laterodorsal view (A) and detail of the right upper canine (B).
Fig 10
Fig 10. Bonacynodon schultzi, referred specimen MCT-1717-R.
Partial skull and lower jaws in left lateral view. Dark grey indicates broken areas and soft gray indicates matrix.
Fig 11
Fig 11. Bonacynodon schultzi, referred specimen MCT-1717-R.
Detail of upper canine and postcanine dentition in labial view. Dark grey indicates broken areas and soft grey indicates matrix.
Fig 12
Fig 12. Skull reconstruction and upper canines morphologies.
(A) Reconstruction of the skull of Bonacynodon schultzi, in lateral view, based on both known specimens and its close relative Probainognathus jenseni [41, 63]. Comparisons of upper canines in labial view. (B) right canine of Bonacynodon (MCT-1716-R), (C) left canine of Bonacynodon (MCT-1717-R), (D) left canine of Probainognathus (PVL 4673), (E) apical half of right canine of Trucidocynodon (UFRGS-PV-1051-T), and (F) right canine of Chiniquodon (PVL 4167). Not to scale.
Fig 13
Fig 13. Details of the postcanine dentition of Probainognathus jenseni from Chañares Formation, Ischigualasto-Villa Unión Basin, western Argentina.
Upper and lower postcanines (A) and detail of the lingual aspect of the upper postcanines (B) (picture taken in ventrolingual view) of PVL 4673. Right lower jaw in labial view (C) and detail of pc5 and pc6 in labial (D) and lingual (E) views of PVL 4445. Left lower pc1and pc2 in lingual view (F) of PVL 4446.
Fig 14
Fig 14. Selected postcanines of probainognathians used for comparisons.
A, B, Chiniquodon theotonicus, anterior right upper (A) and posterior left lower (B) postcanines in labial view (PVL 4444). C, D, Trucidocynodon riograndensis, posterior right upper (C) and left lower postcanines in labial view (UFRGS-PV-1051-T). E, F, Prozostrodon brasiliensis, posterior left upper (E) and lower (F) postcanines in labial view (UFRGS-PV-0248-T). G, H, Irajatherium hernandezi, left upper (G, UFRGS-PV-1175-T) and posterior right lower (H, UFRGS-PV-1029-T) in labial view. I, Riograndia guaibensis, left lower postcanines in lingual view (UFRGS-PV-0833T). J, K, Botucaraitherium belarminoi, left upper postcanine in labial view (J) and posterior left postcanine in lingual view (K) (MMACR-PV-003-T). L, Brasilodon quadrangularis, right upper postcanines in labial view (UFRGS-PV-0611T). M, Brasilitherium riograndensis, left lower postcanines in labial view (UFRGS-PV-0603T). The arrows indicate mesial side. Scale bar equals 2 mm.
Fig 15
Fig 15. Restoration of Bonacynodon schultzi in life by Jorge Blanco.
Fig 16
Fig 16. Santacruzgnathus abdalai, holotype UFRGS-PV-1121-T.
Partial right lower jaw with complete crown of last postcanine in lateral (A) and medial (B) views. Gray indicates broken areas.
Fig 17
Fig 17. Santacruzgnathus abdalai, holotype UFRGS-PV-1121-T.
Detail of last lower postcanine in labial (A), lingual (B) and occlusal (C) views. Gray indicates broken areas.
Fig 18
Fig 18. Phylogenetic analysis.
Strict consensus tree (L = 450, Ci = 47, Ri = 77) of four most parsimonious trees depicting the phylogenetic position of Bonacynodon schultzi. Bremer support is indicated at each node.
Fig 19
Fig 19. Protheriodon estudianti (Holotype UFRGS-PV-0962-T).
Skull in right lateral (A), left lateral (B), dorsal (C), ventral (D) views. Dark grey indicates most broken areas and soft grey indicates matrix.
Fig 20
Fig 20. Protheriodon estudianti (Holotype UFRGS-PV-0962-T).
Details of canines and incisors in right lateral (A) and anteroventral (B) views, middle left upper postcanine (C) and left posterior lower postcanines (D) in labial view. Dark grey indicates broken areas and soft grey indicates matrix. Arrow indicates mesial direction.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Bonaparte JF. Annotated list of the South American Triassic tetrapods In: Haughton SH, editors. Second Gondwana Symposium, Proceedings and Papers (South Africa 1970). Pretoria: CSIR; 1970. pp. 665–682.
    1. Kokogian D, Spalletti LA, Morel EM, Artabe AE, Martínez RN, Alcober OA, et al. Estratigrafía del Triásico argentino In: Artabe AE, Morel EM, Zamuner AB, editors. El Sistema Triásico en la Argentina. La Plata: Fundación Museo de La Plata Francisco Pascasio Moreno; 2001. pp. 23–54.
    1. Marsicano C, Gallego O, Arcucci A. Faunas del Triásico: relaciones, patrones de distribucion y sucesión temporal In: Artabe AE, Morel EM, Zamuner AB, editors. El Sistema Triásico en la Argentina. La Plata: Fundación Museo de La Plata “Francisco Pascasio Moreno”; 2001. pp. 131–141.
    1. Langer MC, Ribeiro AM, Schultz CL, Ferigolo J. The continental tetrapod bearing Triassic of south Brazil. Bulletin of the New Mexico Museum of Natural History and Science. 2007; 41:201–218.
    1. Abdala F, Ribeiro MA. Distribution and diversity patterns of Triassic cynodonts (Therapsida, Cynodontia) in Gondwana. Palaeogeogr Palaeoclimatol Palaeoecol. 2010; 286:202–217.

Grants and funding

Funds were provided by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; 304143/2012-0) and the Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS).

LinkOut - more resources