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Riograndia guaibensis
Taxonomy
Riograndia guaibensis was named by Bonaparte et al. (2001). Its type specimen is MCN-PV 2264, a partial skull (Anterior portion of skull, from the tip of snout to the fronto-parietal contact), and it is a 3D body fossil. Its type locality is 8 km west Candelaria, BR 287, Sesmaria do Pinhal 1, which is in a Norian fluvial sandstone in the Caturrita Formation of Brazil. It is the type species of Riograndia.
Synonymy list
| Year | Name and author |
|---|---|
| 2001 | Riograndia guaibensis Bonaparte et al. p. 624 figs. 2-11 |
| 2011 | Riograndia guaibensis Soares et al. p. 332 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Riograndia guaibensis Bonaparte et al. 2001
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. F. Bonaparte et al. 2001 | Advanced cynodonts with the following associated derived characters: (1) absence of postfrontal; (2) weak anterior portion of the zygomatic arch; (3) dorsoventrally deep lacrimal; (4) secondary bony palate extending posterior to the last postcanine; (5) contact of ventral process of frontal with dorsal process of palatine; (6) reduced upper incisor 1 and hypertrophied lower incisor 1; (7) last upper and lower postcanine crowns imbricated, teeth implanted at an angle to the long axis of the palate; (8) postcanines blade-like with 5 ± 9 subequal small, sharp cuspules regularly distributed on the almost semicircular border of the crown in the upper postcanine crown and in the posterodorsal border of the lower ones. | |
| M. B. Soares et al. 2011 | Emended diagnosis: small tritheledontid (sensu Martinelli et al. 2005) with the combination of the following derived characters: three upper and three lower incisors; reduced upper incisor 1 and hypertrophied lower incisor 1; upper canines larger than the lower ones; postcanines blade-like with 5-9 small, sharp and subequal cuspules evenly distributed on the almost semicircular border of the crown in the upper postcanine crown and in the posterodorsal border of the lower ones; postcanine teeth forming an angle with the long axis of the palate; elongated septomaxilla bordering the posterior margin of the external nares; frontal with an anterolateral projection contacting the nasal medially; absence of prefrontal; postorbital bar absent; dorsoventrally deep lacrimal; contact of the ventral process of frontal with the ascending process of palatine; sphenopalatine foramen bordered by the ascending process of palatine; ossified orbitosphenoid; weak anterior portion of the zygomatic arch; dorsoventrally narrow zygomatic arch; wider amplitude of the zygomatic arch at the half of the arch; quadrate suspended by the squamosal; premaxilla bordering the posterior margin of the incisive foramen; maxilla participating of the anterior margin of the subtemporal fossae in palatal view; maxilla excluded from the ventral margin of the subtemporal fossa by the jugal in lateral view; secondary osseous palate extending posteriorly to the last postcanine; presence of the lesser palatine foramina in the secondary osseous palate; wide primary palate; intermediate pterygopalatine ridges reaching the basisphenoid; broad interpterygoid vacuities; basisphenoid wing excluded from the margin of the fenestra ovalis; jugular foramen separated from the fenestra rotunda; two hypoglossal foramina outside the margin of the jugular foramen; prootic and opisthotic unfused; ascending process of the alisphenoid moderately expanded; open pterygoparoccipital foramen; postdentary bones reduced in a rod-like bar; dentary symphysis unfused; the articular process of the dentary in contact with the squamosal.
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