[D] Pycnonemosaurus nevesi [sG] [T]
Describer
Kellner & Campos 2002
Time
Cretaceous Late
Classification
Saurischia Theropoda Abelisauridae
Diet
Carnivore
Fossilsite
Bauru Basin, Fazenda Roncador (Mato Grosso), Brazil
Info
Genus - Typespecies
A new theropod (Pycnonemosaurus nevesi gen.nov., sp.nov.) is described, based on five incomplete teeth, parts of seven caudal vertebrae, a right pubis (lacking the proximal part), a right tibia, and the distal articulation of the right fibula. The specimen (DGM 859-R) was found in a red conglomeratic sandstone at the locality Fazenda Roncador (Mato Grosso), which is referred to the Upper Cretaceous Bauru Group.
Pycnonemosaurus nevesi is classified in the [Abelisauria] Abelisauridae because of the expanded distal ends of the transverse processes in some (but not all) caudal vertebrae. It differs from all other members of this clade by its small pubic foot and hatchet-shaped cnemial crest of the tibia. This new taxon confirms the presence of abelisaurs in the continental Upper Cretaceous strata of Brazil.
Pycnonemosaurus possesses a prominent cnemial crest on the tibia, whose length is nearly half the total tibial length. It is expanded distally dorsoventrally. Unlike Ceratosaurus, it is not knobby, but flattened mediolaterally. The process length is otherwise approaced only in a tibia of an abelisaur, probably belonging to the new Indian form, previously described by von Huene and Matley, 1933, and may indicate a close affinity between forms with a short tibia, as the side of the femoral emplacement and crest appears to be largely consistent with other \\\\\\\"ceratosaurs.\\\\\\\"
The lateral edge of the distal end is much lower than the medial edge, as in Quilmesaurus, bot not as in other \\\\\\\"ceratosaurs\\\\\\\" save Ceratosaurus itself. The tibia is the most diagnostic material available. Apart from the tibia, there is a distal fibula, distal right pubis lacking a distinct medial lamina (as in Carnotaurus, Masiakasaurus, Elaphrosaurus, and Ligabueino), and partial caudal vertebrae including four proximal caudal centra, two mid- to distal vertebrae from the proximal third of the tail, and a proximal caudal transverse process, which resembles the same in Carnotaurus in having a sigmoid cranial and caudal margin, lacking the distinct awl-like process as in *Aucasaurus.*
The tibiofibular crest of the tibia is not distinct, but there are preservational problems with the tibia, as much of it has been plastered and glued prior to description. Teeth are also considered based on proximity as part of the type, and only one preserves enough enamel to examine the denticulation, though the authers did not figure these nor did they describe them in great detail; the denticles vary in constancy along the crown, so that the basal crown has 2 per mm, and the distal ends has 1.8 /mm.
While Kellner and Campos (2002) were not able to place Pycnonemosaurus more claerly within [Abelisauria] Abelisauridae than generally, or were reluctant to, it is clear than there are several abelisaurid features in the brevity of the tibia and the shape of the distal caudal transverse process. Other features, such as the dorsoventrally ovate caudal centra faces, are autapomorphic; this is circular in Carnotaurus , and dorsoventrally compressed and therefore mediolaterally ovate in Elaphrosaurus, Masiakasaurus. The pubis has bears a large, rhomboid pubic boot that does not contact its opposite by possessing a groove between the paired boots; this boot is larger than that inferred for Carnotaurus by Kellner and Campos, though to be honest, Bonaparte et al. (1990) showed that this material is not well-preserved and the shape of the boot is unknown. The distal fibular is semi-ciurcular in section, and the bredth of the distal tibia suggests it lay, as in Xenotarsosaurus, on the cranial surface of the proximal tarsus.
The holotype (DGM 859-R) come from a conglomerate sandstone, at Paulo Creek on the ranch Fazenda Roncador of Max de Barros Erhart; this conglomerate has been dated based on correlated biostrat to the upper Bauru Group, and would correspond anywhere from the Turonian to the Maastrichtian (in other words, the Senonian). This level is known in the region to occur as the Adamantina Formation and [Merilia Formations], but to which Pycnonemosaurus belongs to is unknown. Material from the Adamantina includes a premaxilla and various teeth, and these were associated by Bertini (1996) as belonging to the same taxon as the [Paulo Creek formation]
Thanks to Jaime A. Headden
Kellner & Campos 2002
Time
Cretaceous Late
Classification
Saurischia Theropoda Abelisauridae
Diet
Carnivore
Fossilsite
Bauru Basin, Fazenda Roncador (Mato Grosso), Brazil
Info
Genus - Typespecies
A new theropod (Pycnonemosaurus nevesi gen.nov., sp.nov.) is described, based on five incomplete teeth, parts of seven caudal vertebrae, a right pubis (lacking the proximal part), a right tibia, and the distal articulation of the right fibula. The specimen (DGM 859-R) was found in a red conglomeratic sandstone at the locality Fazenda Roncador (Mato Grosso), which is referred to the Upper Cretaceous Bauru Group.
Pycnonemosaurus nevesi is classified in the [Abelisauria] Abelisauridae because of the expanded distal ends of the transverse processes in some (but not all) caudal vertebrae. It differs from all other members of this clade by its small pubic foot and hatchet-shaped cnemial crest of the tibia. This new taxon confirms the presence of abelisaurs in the continental Upper Cretaceous strata of Brazil.
Pycnonemosaurus possesses a prominent cnemial crest on the tibia, whose length is nearly half the total tibial length. It is expanded distally dorsoventrally. Unlike Ceratosaurus, it is not knobby, but flattened mediolaterally. The process length is otherwise approaced only in a tibia of an abelisaur, probably belonging to the new Indian form, previously described by von Huene and Matley, 1933, and may indicate a close affinity between forms with a short tibia, as the side of the femoral emplacement and crest appears to be largely consistent with other \\\\\\\"ceratosaurs.\\\\\\\"
The lateral edge of the distal end is much lower than the medial edge, as in Quilmesaurus, bot not as in other \\\\\\\"ceratosaurs\\\\\\\" save Ceratosaurus itself. The tibia is the most diagnostic material available. Apart from the tibia, there is a distal fibula, distal right pubis lacking a distinct medial lamina (as in Carnotaurus, Masiakasaurus, Elaphrosaurus, and Ligabueino), and partial caudal vertebrae including four proximal caudal centra, two mid- to distal vertebrae from the proximal third of the tail, and a proximal caudal transverse process, which resembles the same in Carnotaurus in having a sigmoid cranial and caudal margin, lacking the distinct awl-like process as in *Aucasaurus.*
The tibiofibular crest of the tibia is not distinct, but there are preservational problems with the tibia, as much of it has been plastered and glued prior to description. Teeth are also considered based on proximity as part of the type, and only one preserves enough enamel to examine the denticulation, though the authers did not figure these nor did they describe them in great detail; the denticles vary in constancy along the crown, so that the basal crown has 2 per mm, and the distal ends has 1.8 /mm.
While Kellner and Campos (2002) were not able to place Pycnonemosaurus more claerly within [Abelisauria] Abelisauridae than generally, or were reluctant to, it is clear than there are several abelisaurid features in the brevity of the tibia and the shape of the distal caudal transverse process. Other features, such as the dorsoventrally ovate caudal centra faces, are autapomorphic; this is circular in Carnotaurus , and dorsoventrally compressed and therefore mediolaterally ovate in Elaphrosaurus, Masiakasaurus. The pubis has bears a large, rhomboid pubic boot that does not contact its opposite by possessing a groove between the paired boots; this boot is larger than that inferred for Carnotaurus by Kellner and Campos, though to be honest, Bonaparte et al. (1990) showed that this material is not well-preserved and the shape of the boot is unknown. The distal fibular is semi-ciurcular in section, and the bredth of the distal tibia suggests it lay, as in Xenotarsosaurus, on the cranial surface of the proximal tarsus.
The holotype (DGM 859-R) come from a conglomerate sandstone, at Paulo Creek on the ranch Fazenda Roncador of Max de Barros Erhart; this conglomerate has been dated based on correlated biostrat to the upper Bauru Group, and would correspond anywhere from the Turonian to the Maastrichtian (in other words, the Senonian). This level is known in the region to occur as the Adamantina Formation and [Merilia Formations], but to which Pycnonemosaurus belongs to is unknown. Material from the Adamantina includes a premaxilla and various teeth, and these were associated by Bertini (1996) as belonging to the same taxon as the [Paulo Creek formation]
Thanks to Jaime A. Headden