A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil
A primitive ‘ictidosaur’ from lower Norian beds of southern Brazil, Riograndia guaibensis gen. et sp. nov., represented by a fragmentary skull and a lower jaw bearing a complete dentition, shows a more generalized morphology than Chaliminia from the Upper Triassic of Argentina and Pachygenelus Diart...
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crwiley:10.1111/1475-4983.00194 2024-09-15T18:09:49+00:00 A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil Bonaparte, José F. Ferigolo, Jorge Ribeiro, Ana maria 2001 http://dx.doi.org/10.1111/1475-4983.00194 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1475-4983.00194 https://onlinelibrary.wiley.com/doi/pdf/10.1111/1475-4983.00194 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Palaeontology volume 44, issue 4, page 623-635 ISSN 0031-0239 1475-4983 journal-article 2001 crwiley https://doi.org/10.1111/1475-4983.00194 2024-07-25T04:21:18Z A primitive ‘ictidosaur’ from lower Norian beds of southern Brazil, Riograndia guaibensis gen. et sp. nov., represented by a fragmentary skull and a lower jaw bearing a complete dentition, shows a more generalized morphology than Chaliminia from the Upper Triassic of Argentina and Pachygenelus Diarthrognathus from the Lower Jurassic of South Africa, Canada and Greenland. The frontal bone borders the orbit, and ventrally contacts the dorsal process of the palatine. The secondary bony palate extends back to the last postcanine. I1 and i2 are reduced, whereas I2‐3 and i1 are hypertrophied. Both PC 1–7 and pc 1–7 have blade‐like crowns without cingula and with 5–9 small sharp cuspules. The upper postcanine crowns are semicircular in labial view with the cuspules around their margins. The lower postcanine crowns are asymmetrical with most of the cuspules dorsodistally distributed. The possible origin of this peculiar dentition is interpreted as the retention of the juvenile dentition of ancestors. The hypothesis that Riograndia guaibensis and the so‐called ‘ictidosaurs’ might have been derived from gomphodont cynodonts is presented. Article in Journal/Newspaper Greenland Wiley Online Library Palaeontology 44 4 623 635 |
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language |
English |
description |
A primitive ‘ictidosaur’ from lower Norian beds of southern Brazil, Riograndia guaibensis gen. et sp. nov., represented by a fragmentary skull and a lower jaw bearing a complete dentition, shows a more generalized morphology than Chaliminia from the Upper Triassic of Argentina and Pachygenelus Diarthrognathus from the Lower Jurassic of South Africa, Canada and Greenland. The frontal bone borders the orbit, and ventrally contacts the dorsal process of the palatine. The secondary bony palate extends back to the last postcanine. I1 and i2 are reduced, whereas I2‐3 and i1 are hypertrophied. Both PC 1–7 and pc 1–7 have blade‐like crowns without cingula and with 5–9 small sharp cuspules. The upper postcanine crowns are semicircular in labial view with the cuspules around their margins. The lower postcanine crowns are asymmetrical with most of the cuspules dorsodistally distributed. The possible origin of this peculiar dentition is interpreted as the retention of the juvenile dentition of ancestors. The hypothesis that Riograndia guaibensis and the so‐called ‘ictidosaurs’ might have been derived from gomphodont cynodonts is presented. |
format |
Article in Journal/Newspaper |
author |
Bonaparte, José F. Ferigolo, Jorge Ribeiro, Ana maria |
spellingShingle |
Bonaparte, José F. Ferigolo, Jorge Ribeiro, Ana maria A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
author_facet |
Bonaparte, José F. Ferigolo, Jorge Ribeiro, Ana maria |
author_sort |
Bonaparte, José F. |
title |
A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
title_short |
A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
title_full |
A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
title_fullStr |
A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
title_full_unstemmed |
A Primitive Late Triassic ‘ictidosaur’ from Rio Grande Do Sul, Brazil |
title_sort |
primitive late triassic ‘ictidosaur’ from rio grande do sul, brazil |
publisher |
Wiley |
publishDate |
2001 |
url |
http://dx.doi.org/10.1111/1475-4983.00194 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1475-4983.00194 https://onlinelibrary.wiley.com/doi/pdf/10.1111/1475-4983.00194 |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Palaeontology volume 44, issue 4, page 623-635 ISSN 0031-0239 1475-4983 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/1475-4983.00194 |
container_title |
Palaeontology |
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44 |
container_issue |
4 |
container_start_page |
623 |
op_container_end_page |
635 |
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1810447411842121728 |