Cranial bones and atlas of titanosaurs (Dinosauria, Sauropoda) from Late Cretaceous (Bauru Group) of Uberaba, Minas Gerais State, Brazil

Martinelli, Agustín G.; Marinho, Thiago da Silva; Filippi, Leonardo; Ribeiro, Luiz Carlos Borges; Ferraz, Mara Lúcia da Fonseca; Cavellani, Camila Lourencini; Teixeira, Vicente de Paula Antunes

doi:10.1016/j.jsames.2015.02.009

Cited by 13 publications

(4 citation statements)

References 36 publications

(52 reference statements)

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“…Near its articulation with the postorbital it bears a relatively short, curved margin that borders the lateral temporal fenestra that is truncated by contact with the descending ramus of the postorbital. This double postorbital contact does not appear to be present in a squamosal recently described from the Upper Cretaceous of Brazil (Martinelli et al ., ). The quadratojugal process of the squamosal ends as a flattened plate of bone that is angled slightly relative to the axis of the process.…”

Section: Descriptionmentioning

confidence: 97%

The skull of the titanosaurTapuiasaurus macedoi(Dinosauria: Sauropoda), a basal titanosaur from the Lower Cretaceous of Brazil

et al. 2016

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Although Titanosauria is the most diverse and late-surviving sauropod lineage, cranial elements are known for just over 24 of its 70+ generathe vast majority of which are fairly fragmentary and restricted to the Late Cretaceous. Only three complete titanosaur skulls have been described to date; two of these are from the latest Cretaceous (Nemegtosaurus, Rapetosaurus), and the third, Tapuiasaurus, is from the Early Cretaceous (Aptian). In this contribution, we build on the initial treatment of the taxon by providing a complete description of the cranial elements that benefits from additional preparation and computed tomography imaging. We identify six additional features diagnosing Tapuiasaurus macedoi, including a jugal with an elongate lacrimal process forming much of the posteroventral border of the antorbital fenestra, a lateral temporal fenestra divided by a second squamosal-postorbital contact, and upper jaw teeth with labial wear facets. We directed the new morphological data in Tapuiasaurus as well as other observations towards a re-analysis of its phylogenetic position within Titanosauria. Our analysis yielded 34 most parsimonious trees, most of which recovered Tapuiasaurus in a basal position adjacent to the Early Cretaceous taxa Malawisaurus and Tangvayosaurus, but two trees recovered it within Late Cretaceous nemegtosaurids. We explored the effects of missing data and missing stratigraphic ranges on our results, concluding that (1) when missing data levels are high, resolution of even small amounts of that missing data can have dramatic effects on topology, (2) taxa that are mostly scored for characters that cannot be scored in other taxa may be topologically unstable and (3) there were several suboptimal trees that had greatly improved stratigraphic fit with relatively little compromise in terms of tree length.

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Section: Descriptionmentioning

confidence: 97%

The skull of the titanosaurTapuiasaurus macedoi(Dinosauria: Sauropoda), a basal titanosaur from the Lower Cretaceous of Brazil

et al. 2016

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“…[ 19 ], Bonatitan [ 20 – 22 ], Bonitasaura [ 23 , 24 ], Brasilotitan [ 25 ], Campylodoniscus [ 9 ], Dreadnoughtus [ 26 ], Isisaurus [ 27 – 30 ], Jainosaurus [ 28 , 30 , 31 ], Karongasaurus [ 32 ], Ligabuesaurus [ 33 ], Lirainosaurus [ 34 , 35 ], Malawisaurus [ 32 ], Maxakalisaurus [ 36 ], Mongolosaurus [ 37 , 38 ], Muyelensaurus [ 39 ], Narambuenatitan [ 40 ], Phuwiangosaurus [ 41 ], Pitekunsaurus [ 42 ], Quaesitosaurus [ 11 , 43 ], Quetecsaurus [ 44 ], Rinconsaurus [ 45 ], Saltasaurus [ 7 , 46 ], Tambatitanis [ 47 ], and Vahiny [ 48 ]. Isolated, generically indeterminate titanosaurian cranial and mandibular elements have also been reported [ 7 , 9 , 21 , 31 , 49 – 64 ]. Nevertheless, complete or even reasonably complete titanosaur skulls remain unknown from the Albian—Santonian (a roughly 30 million year span of the mid- and Late Cretaceous; see Walker et al [ 65 ]), which represents a significant impediment to understanding of titanosaur cranial anatomy and evolution.…”

Section: Introductionmentioning

confidence: 99%

A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria

et al. 2016

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We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian—Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla—lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) ‘tongue-like’ ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with ‘strut-like’ centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a ‘ghost lineage’ with a comparatively plesiomorphic craniodental form, the evolutionary history of which is missing for at least 13 million years of the Cretaceous. The skull anatomy of Sarmientosaurus suggests that multiple titanosaurian species with dissimilar cranial structures coexisted in the early Late Cretaceous of southern South America. Furthermore, the new taxon possesses a number of distinctive morphologies—such as the ossified cervical tendon, extremely pneumatized cervical vertebrae, and a habitually downward-facing snout—that have rarely, if ever, been documented in other titanosaurs, thus broadening our understanding of the anatomical diversity of this remarkable sauropod clade. The latter two features were convergently acquired by at least one penecontemporaneous diplodocoid, and may represent mutual specializations for consuming low-growing vegetation.

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“…These include an isolated caudal vertebra of an indeterminate aeolosaurin (Santucci and Bertini 2001, Martinelli et al 2011, Filippi et al 2013 and other putative aeolosaurin material Buchmann 2008, Martinelli et al 2011), fragmentary cranial bones that appear most similar to derived lithostrotian titanosaurs (Martinelli et al 2015), and several specimens belonging to indeterminate titanosaurs (e.g., Campos and Kellner 1999, Santucci and Bertini 2001, Marinho and Candeiro 2005, Martinelli et al 2015.…”

Section: Latest Cretaceous Dinosaurs From Brazilmentioning

confidence: 99%

The last dinosaurs of Brazil: The Bauru Group and its implications for the end-Cretaceous mass extinction

Brusatte

Candeiro

Simbras

2017

An. Acad. Bras. Ciênc.

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The non-avian dinosaurs died out at the end of the Cretaceous, ~66 million years ago, after an asteroid impact. The prevailing hypothesis is that the effects of the impact suddenly killed the dinosaurs, but the poor fossil record of latest Cretaceous (Campanian-Maastrichtian) dinosaurs from outside Laurasia (and even more particularly, North America) makes it difficult to test specific extinction scenarios. Over the past few decades, a wealth of new discoveries from the Bauru Group of Brazil has revealed a unique window into the evolution of terminal Cretaceous dinosaurs from the southern continents. We review this record and demonstrate that there was a diversity of dinosaurs, of varying body sizes, diets, and ecological roles, that survived to the very end of the Cretaceous (Maastrichtian: 72-66 million years ago) in Brazil, including a core fauna of titanosaurian sauropods and abelisaurid and carcharodontosaurid theropods, along with a variety of small-to-mid-sized theropods. We argue that this pattern best fits the hypothesis that southern dinosaurs, like their northern counterparts, were still diversifying and occupying prominent roles in their ecosystems before the asteroid suddenly caused their extinction. However, this hypothesis remains to be tested with more refined paleontological and geochronological data, and we give suggestions for future work.

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Cranial bones and atlas of titanosaurs (Dinosauria, Sauropoda) from Late Cretaceous (Bauru Group) of Uberaba, Minas Gerais State, Brazil

Cited by 13 publications

References 36 publications

The skull of the titanosaurTapuiasaurus macedoi(Dinosauria: Sauropoda), a basal titanosaur from the Lower Cretaceous of Brazil

The skull of the titanosaurTapuiasaurus macedoi(Dinosauria: Sauropoda), a basal titanosaur from the Lower Cretaceous of Brazil

A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria

The last dinosaurs of Brazil: The Bauru Group and its implications for the end-Cretaceous mass extinction

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