The anatomy and phylogenetic position of the Triassic dinosaur Staurikosaurus pricei Colbert, 1970

Zootaxa ◽  
2009 ◽  
Vol 2079 (1) ◽  
pp. 1-56 ◽  
Author(s):  
JONATHAS DE SOUZA BITTENCOURT ◽  
ALEXANDER WILHELM ARMIN KELLNER
Keyword(s):  
Morphological Characters ◽  
Late Triassic ◽  
Sister Taxon ◽  
Phylogenetic Position ◽  
Southern Brazil ◽  
Anatomical Features ◽  
Phylogenetic Studies ◽  
Caudal Vertebrae ◽  
Close Relationship ◽  
Santa Maria

We redescribe the holotype of the saurischian dinosaur Staurikosaurus pricei Colbert, 1970 from Late Triassic Santa Maria Formation (southern Brazil), following additional preparation that revealed new anatomical features. A revised diagnosis is proposed and the published synapomorphies for Dinosauria and less inclusive clades (e.g. Saurischia) are evaluated for this species. Some characters previously identified as present in the holotype, including the intramandibular joint, hyposphene-hypantrum articulations in dorsal vertebrae, and a cranial trochanter and trochanteric shelf on the femur, cannot be confirmed due to poor preservation or are absent in the available material. In addition, postcranial characters support a close relationship between S. pricei and Herrerasaurus ischigualastensis Reig, 1963 (Late Triassic, Argentina), forming the clade Herrerasauridae. Several pelvic and vertebral characters support the placement of S. pricei as a saurischian dinosaur. Within Saurischia, characters observed in the holotype, including the anatomy of the dentition and caudal vertebrae, support theropod affinities. However, the absence of some characters observed in the clades Theropoda and Sauropodomorpha suggests that S. pricei is not a member of Eusaurischia. Most morphological characters discussed in previous phylogenetic studies cannot be assessed for S. pricei because of the incompleteness of the holotype and only known specimen. The phylogenetic position of S. pricei is constrained by that of its sister taxon H. ischigualastensis, which is known from much more complete material.

A new aetosaur genus (Archosauria: Pseudosuchia) from the early Late Triassic of southern Brazil

Zootaxa ◽  
2012 ◽  
Vol 3166 (1) ◽  
pp. 1 ◽  
Author(s):  
JULIA B. DESOJO ◽  
MARTÍN D. EZCURRA ◽  
EDIO E. KISCHLAT
Keyword(s):  
Cervical Vertebrae ◽  
Cladistic Analysis ◽  
Axial Skeleton ◽  
Late Triassic ◽  
South American ◽  
Southern Brazil ◽  
Caudal Vertebra ◽  
Caudal Vertebrae ◽  
Santa Maria ◽  
Early Late

We describe the new aetosaur Aetobarbakinoides brasiliensis gen. et sp. nov. from the early Late Triassic (late Carnian-early Norian) Brazilian Santa Maria Formation. The holotype is composed of a partial postcranium including several cer-vical and dorsal vertebrae and ribs, one anterior caudal vertebra, right scapula, right humerus, right tibia, partial right pes,and anterior and mid-dorsal paramedian osteoderms. Aetobarbakinoides is differentiated from other aetosaurs by the pres-ence of cervical vertebrae with widely laterally extended prezygapophyses, mid-cervical vertebrae with anterior articularfacet width more than 1.2 times wider than the posterior one, anterior caudal vertebrae with extremely anteroposteriorlyshort prezygapophyses, elongated humerus and tibia in relation to the axial skeleton, and paramedian osteoderms with aweakly raised anterior bar. A cladistic analysis recovered the new species as more derived than the South American generaAetosauroides (late Carnian-early Norian) and Neoaetosauroides (late Norian-Rhaetian), and it is nested as the sister-tax-on of an unnamed clade, composed of Typothoracisinae and Desmatosuchinae, due to the absence of a ventral keel in thecervical vertebrae. Aetobarbakinoides presents a skeletal anatomy previously unknown among South American aetosaurs,with the combination of presacral vertebrae with hyposphene, anteroposteriorly short and unkeeled cervical vertebrae,gracile limbs, and paramedian osteoderms with a weakly raised anterior bar. Aetobarbakinoides is among the oldest knownaetosaurs together with Aetosauroides from Argentina and Brazil and Stagonolepis robertsoni from Scotland, indicatinga widely distributed early record for the group. In addition, the recognition of a suite of derived features in Aetobarbaki-noides, which is one of the oldest known aetosaurs, is in agreement with an older origin for the group, as it is expected by the extensive ghost lineages at the base of the main pseudosuchian clades.

scholarly journals Anatomy of the dinosaur Pampadromaeus barberenai (Saurischia—Sauropodomorpha) from the Late Triassic Santa Maria Formation of southern Brazil

PLoS ONE ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. e0212543 ◽  
Author(s):  
Max Cardoso Langer ◽  
Blair Wayne McPhee ◽  
Júlio César de Almeida Marsola ◽  
Lúcio Roberto-da-Silva ◽  
Sérgio Furtado Cabreira
Keyword(s):  
Late Triassic ◽  
Southern Brazil ◽  
Santa Maria

Trucidocynodon riograndensis gen. nov. et sp. nov. (Eucynodontia), a new cynodont from the Brazilian Upper Triassic (Santa Maria Formation)

Zootaxa ◽  
2010 ◽  
Vol 2382 (1) ◽  
pp. 1 ◽  
Author(s):  
TÉO VEIGA DE OLIVEIRA ◽  
MARINA BENTO SOARES ◽  
CESAR LEANDRO SCHULTZ
Keyword(s):  
Upper Triassic ◽  
New Taxon ◽  
Southern Brazil ◽  
Morphological Gradient ◽  
Caudal Vertebrae ◽  
Secondary Palate ◽  
Limb Posture ◽  
Posterior Trunk ◽  
Santa Maria

An almost complete skeleton of a new carnivorous cynodont from the Upper Triassic of Southern Brazil, Trucidocynodon riograndensis gen. nov. et sp. nov., is described. The new taxon is very similar to Ecteninion lunensis Martinez et al. 1996 from Upper Triassic of Argentina (Ischigualasto Formation). Both have an elongated skull, large pterygoid flanges, a well developed orbitosphenoid, a relatively short osseous secondary palate, greatly developed canines and sectorial postcanines with posteriorly directed cusps. However, the new taxon shows some differences relative to E. lunensis such as an open pterygoparoccipital foramen, the posterior opening of the post-temporal foramen enclosed by tabular and squamosal, and upper incisors with serrated cutting edges. The more remarkable features of the postcranium of T. riograndensis are the presence of 32 presacral vertebrae, a greater number than in most of non-mammaliaform cynodonts, the accentuated lumbarisation of the posterior trunk vertebrae and a remarkable morphological gradient in the caudal vertebrae; the femur and humerus show some interesting adaptations suggesting a more upright limb posture. The overall morphology of the astragalocalcaneal complex is similar to that of Diademodon and of the therocephalian Bauria.

scholarly journals The phylogenetic relationships of neosuchian crocodiles and their implications for the convergent evolution of the longirostrine condition

2019 ◽  
Author(s):  
Sebastian S Groh ◽  
Paul Upchurch ◽  
Paul M Barrett ◽  
Julia J Day
Keyword(s):  
Bayesian Methods ◽  
Phylogenetic Relationships ◽  
Convergent Evolution ◽  
Morphological Characters ◽  
Late Triassic ◽  
Continuous Data ◽  
Comprehensive Review ◽  
Phylogenetic Studies ◽  
History Of ◽  
First Time

Abstract Since their origin in the Late Triassic, crocodylomorphs have had a long history of evolutionary change. Numerous studies examined their phylogeny, but none have attempted to unify their morphological characters into a single, combined dataset. Following a comprehensive review of published character sets, we present a new dataset for the crocodylomorph clade Neosuchia consisting of 569 morphological characters for 112 taxa. For the first time in crocodylian phylogenetic studies, quantitative variation was treated as continuous data (82 characters). To provide the best estimate of neosuchian relationships, and to investigate the origins of longirostry, these data were analysed using a variety of approaches. Our results show that equally weighted parsimony and Bayesian methods cluster unrelated longirostrine forms together, producing a topology that conflicts strongly with their stratigraphic distributions. By contrast, applying extended implied weighting improves stratigraphic congruence and removes longirostrine clustering. The resulting topologies resolve the major neosuchian clades, confirming several recent hypotheses regarding the phylogenetic placements of particular species (e.g. Baryphracta deponiae as a member of Diplocynodontinae) and groups (e.g. Tethysuchia as non-eusuchian neosuchians). The longirostrine condition arose at least three times independently by modification of the maxilla and premaxilla, accompanied by skull roof changes unique to each longirostrine clade.

scholarly journals Neurocranial anatomy of an enigmatic Early Devonian fish sheds light on early osteichthyan evolution

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Alice M Clement ◽  
Benedict King ◽  
Sam Giles ◽  
Brian Choo ◽  
Per E Ahlberg ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Sister Taxon ◽  
Phylogenetic Position ◽  
Micro Ct ◽  
Bayesian Analyses ◽  
Early Devonian ◽  
Precise Position ◽  
Anatomical Features ◽  
Skull Roof ◽  
Ct Data

The skull of ‘Ligulalepis’ from the Early Devonian of Australia (AM-F101607) has significantly expanded our knowledge of early osteichthyan anatomy, but its phylogenetic position has remained uncertain. We herein describe a second skull of ‘Ligulalepis’ and present micro-CT data on both specimens to reveal novel anatomical features, including cranial endocasts. Several features previously considered to link ‘Ligulalepis’ with actinopterygians are now considered generalized osteichthyan characters or of uncertain polarity. The presence of a lateral cranial canal is shown to be variable in its development between specimens. Other notable new features include the presence of a pineal foramen, the some detail of skull roof sutures, the shape of the nasal capsules, a placoderm-like hypophysial vein, and a chondrichthyan-like labyrinth system. New phylogenetic analyses place ‘Ligulalepis’ as a stem osteichthyan, specifically as the sister taxon to ‘psarolepids’ plus crown osteichthyans. The precise position of ‘psarolepids’ differs between parsimony and Bayesian analyses.

scholarly journals A reassessment of the basal dinosaur Guaibasaurus candelariensis, from the Late Triassic Caturrita Formation of south Brazil

2010 ◽  
Vol 101 (3-4) ◽  
pp. 301-332 ◽  
Author(s):  
Max C. Langer ◽  
Jonathas S. Bittencourt ◽  
Cesar L. Schultz
Keyword(s):  
Rio Grande ◽  
Late Triassic ◽  
Unique Combination ◽  
Rio Grande Do Sul ◽  
Weak Support ◽  
Type Series ◽  
Phylogenetic Studies ◽  
Continuous Radiation ◽  
Santa Maria ◽  
South Brazil

ABSTRACTThe dinosaur record of the Santa Maria beds of Rio Grande do Sul (Mid–Late Triassic; south Brazil) includes the herrerasaur Staurikosaurus pricei, and two basal members of the sauropodomorph lineage: Saturnalia tupiniquim and Unaysaurus tolentinoi. The most enigmatic of the saurischian taxa is, however, Guaibasaurus candelariensis, previously regarded as either a basal theropod or a basal sauropodomorph. This study provides a detailed anatomical revision of all specimens originally referred to G. candelariensis by Bonaparte and co-authors, including its type-series and a more recently excavated partial postcranium. Although coming from different sites, these specimens share a unique combination of traits, and at least one possible autapomorphic feature of the pelvis, which support the inclusivity and uniqueness of the species. G. candelariensis was a medium-sized (nearly 2 m long) biped with an intriguing mix of plesiomorphic and derived (eusaurischian/theropod) features. Phylogenetic studies reveal weak support for the nesting of G. candelariensis within Theropoda, but this affinity is bolstered by various traits it shares with neotheropods. The Norian age of G. candelariensis corroborates previous studies that suggest the continuous radiation of more basal dinosauromorphs until the end of the Triassic, after the appearance of the three main dinosaur clades.

scholarly journals A new genus and species of characid fish from the Amazon basin: the recognition of a relictual lineage of characid fishes (Ostariophysi: Cheirodontinae: Cheirodontini)

2008 ◽  
Vol 6 (4) ◽  
pp. 663-678 ◽  
Author(s):  
Cristina M. Bührnheim ◽  
Tiago P. Carvalho ◽  
Luiz R. Malabarba ◽  
Stanley H. Weitzman
Keyword(s):  
Amazon Basin ◽  
New Genus ◽  
Abdominal Cavity ◽  
Phylogenetic Position ◽  
New Taxon ◽  
New Genus And Species ◽  
Caudal Fin ◽  
Caudal Vertebrae ◽  
Fin Rays ◽  
Close Relationship

Amazonspinther dalmata, a new miniature characid from the streams of rio Purus and rio Madeira, right bank tributaries of the rio Amazonas, is described as a new genus and species of the subfamily Cheirodontinae. The unique characters of the new genus and species are the three remarkable black blotches on the base of the dorsal, anal, and caudal fins, the anteriormost proximal radial of the anal fin with an anteriorly extended lamina entering the abdominal cavity, and the extremely elongate caudal peduncle. The reduced number of ventral procurrent caudal-fin rays (7-9), and the hemal spines of only posterior one, two, or sometimes three caudal vertebrae directly articulating with the ventral procurrent caudal-fin rays further diagnoses the new taxon from remaining genera of the tribe Cheirodontini. The results of a phylogenetic analysis strongly support a close relationship between A. dalmata and Spintherobolus in the tribe Cheirodontini on the basis of fifteen unambiguous synapomorphies. Ten of these characters, previously hypothesized as exclusive synapomorphies for Spintherobolus, were now also identified in Amazonspinther, such as the pattern of exposed neuromasts on the head, the presence of a second pseudotympanum anterior to the first pleural rib, and the nearly discoidal coracoid bone. A discussion about the phylogenetic position of the closely related fossil †Megacheirodon to Spintherobolus and Amazonspinther is also provided. Convergent characters shared between Amazonspinther and the characid Priocharax are discussed in relation to miniaturization. Biogeographical implications of the diversification of Amazonspinther, Spintherobolus, and Megacheirodon lineages are discussed.

Musa ruiliensis (Musaceae, Section Musa), a new species from Yunnan, China

Phytotaxa ◽  
2014 ◽  
Vol 172 (2) ◽  
pp. 109 ◽  
Author(s):  
Wenna Chen ◽  
Markku Häkkinen ◽  
Xuejun Ge
Keyword(s):  
New Species ◽  
Molecular Phylogeny ◽  
Morphological Characters ◽  
Phylogenetic Position ◽  
Close Relationship ◽  
A New Species

A new species Musa ruiliensis, which occurs in Yunnan, China, is described based on morphological characters and molecular phylogeny. It belongs to Musa sect. Musa (former Rhodochlamys) and has close relationship with Musa chunii Häkkinen and Musa rubinea Häkkinen & C.H.Teo. A detailed description, chromosome cytology (2n = 2x = 22) and phylogenetic position are provided.

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