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1.
We report new theropod dinosaur material from the Presidente Prudente Formation (Campanian–Maastrichtian), Bauru Group, in southwestern São Paulo state. The material comprises a fragment of right maxilla of Carcharodontosauridae, an anterior portion of a left ilium of Abelisauroidea and a proximal portion of a right fibula of a coelurosaurian. Previous theropod records from the Bauru Basin comprise Abelisauridae and Tetanurae and in São Paulo state these have been represented by only a right premaxilla of an abelisaurid and isolated abelisaurid and carcharodontosaurid teeth. The new material reported here represents the first theropod remains from the Presidente Prudente Formation, and includes the first abelisauroid and coelurosaurian postcranial remains from the Bauru Basin in São Paulo state and the first latest Cretaceous carcharodontosaurid known from non-dental remains anywhere. 相似文献
2.
A new abelisaurid theropod from the Cenomanian of Candeleros Formation (Neuquén Province, NW Patagonia, Argentina) is described. It includes an isolated frontal, partial pelvis, two fused sacral centra, femoral shaft, rib fragments, partial metatarsal II and shaft of metatarsal III. A paleohistological analysis shows that MMCh-PV 69 was somatically mature at time of death. The prevalence of relatively ordered intrinsic fibers in the primary bone indicates a relatively lower growth rate of MMCh-PV 69 compared with other abelisauroids, such as Aucasaurus garridoi. Phylogenetic analysis found MMCh-PV 69 as a basal abelisaurid, sister group of the node formed by Majungasaurinae and Brachyrostra. We estimated the body mass of MMCh-PV 69 in 240 kg, which makes it one of the smallest abelisaurids recorded. This new form adds to the extensive theropod fauna of the Candeleros Formation, probably the most diverse association of meat-eating dinosaurs recorded in a Cretaceous Formation from South America. 相似文献
3.
The type braincase of Viavenator exxoni (MAU-Pv-LI-530) was recovered complete and isolated from most of the other skull bones. Although the braincase is crossed by numerous fractures, using CT scans allowed the generation of 3D renderings of the endocranial cavity enclosing the brain, cranial nerves, and blood vessels, as well as the labyrinth of the inner ear. Within the abelisaurids, the only taxon with a complete braincase and known endocranial morphology is Majungasaurus crenatissimus, from Madagascar. In turn, in Argentina, partial endocranial morphology is known for another two Cretaceous forms: Abelisaurus comahuensis and Aucasaurus garridoi. Here, we present the most complete reconstruction of the neuroanatomy for a representative of the clade in South America. These findings add knowledge to the field of theropod paleoneuroanatomy in general, and abelisaurid diversity in particular. Comparisons of Viavenator with other abelisaurids indicate greater similarity with Aucasaurus than with Majungasaurus, suggesting that South American forms shared the same neurosensorial capabilities, which include larger flocculus of the cerebellum and larger olfactory ratios than the form from Madagascar. 相似文献
4.
A well preserved skeleton of a new abelisaurid is reported here. The holotype of Viavenator exxoni was found in the outcrops of the Bajo de la Carpa Formation (Santonian, Upper Cretaceous), northwestern Patagonia, Argentina. This new taxon belongs to the South American clade of abelisaurids, the brachyrostrans. The current phylogenetic analysis places it as the basalmost member of a new clade of derived brachyrostrans, named Furileusauria, characterized by distinctive cranial, axial and appendicular anatomical features. The Santonian age of Viavenator allows filling the stratigraphic gap exhibited between the basal brachyrostrans of Cenomanian–Turonian age, and the derived forms from the Campanian-Maastrichtian. The evolution of abelisaurids during the Late Cretaceous, faunal replacements, and the adaptive radiation that occurred during that period of time in South America are discussed. 相似文献
5.
During the latest Cretaceous, distinct dinosaur faunas were found in Laurasia and Gondwana. Tyrannosaurids, hadrosaurids, and ceratopsians dominated in North America and Asia, while abelisaurids and titanosaurians dominated in South America, India, and Madagascar. Little is known about dinosaur faunas from the latest Cretaceous of Africa, however. Here, a new abelisaurid theropod, Chenanisaurus barbaricus, is described from the upper Maastrichtian phosphates of the Ouled Abdoun Basin in Morocco, North Africa on the basis of a partial dentary and isolated teeth. Chenanisaurus is both one of the largest abelisaurids, and one of the youngest known African dinosaurs. Along with previously reported titanosaurian remains, Chenanisaurus documents the persistence of a classic Gondwanan abelisaurid-titanosaurian fauna in mainland Africa until just prior to the end-Cretaceous mass extinction. The animal is unusual both in terms of its large size and the unusually short and robust jaw. Although it resembles South American carnotaurines in having a deep, bowed mandible, phylogenetic analysis suggests that Chenanisaurus may represent a lineage of abelisaurids that is distinct from those previously described from the latest Cretaceous of South America, Indo-Madagascar, and Europe, consistent with the hypothesis that the fragmentation of Gondwana led to the evolution of endemic dinosaur faunas during the Late Cretaceous. 相似文献
6.
The knowledge on the Brazilian theropod fauna is hampered by the limited number of specimens unearthed so far. The most potential deposits for the finding of those dinosaurs are the layers of Bauru Group, which comprises several different formations of Late Cretaceous age. Most of those remains are referred to Abelisauroidea, a clade that is particularly well represented in Gondwana. Here we report two new abelisaurid specimens comprising a left ilium (DGM 927-R) and the distal articulation of a right femur (MCT 1857-R) unearthed from the outcrops of Adamantina Formation (Turonian – Maastrichtian) in the locality known as Santo Anastácio, that comprises an abandoned quarry located in the outskirts of the homonymous city in São Paulo State. The ilium has a preacetabular process horizontally oriented and ventrally deflected, as well as an acute angle between this process and the pubic peduncle. The femur shows a well-developed anteromedial crest, but not to the same degree as in noasaurids, and ossified ridges between condyles and tibiofibular crest. Those features allow us to assign both specimens to Abelisauridae. CT-scans of those specimens shows that the ilium has pneumaticities similar to the camellate pattern previously recorded in neosauropods and reveals the diverticula invasion of abdominal air-sacs. The femur presents a developed anisotropic trabecular system, which suggests that the main muscular strain is located at the distal portion of this bone. These features have not been previously reported in Abelisauridae, indicating that the internal organization of the postcranial skeleton in the group is rather complex and quite variable. 相似文献
7.
《Proceedings of the Geologists' Association. Geologists' Association》2022,133(6):491-500
Pterosaurs are a rare component of the Early Cretaceous (Albian) Gault Formation of southern England. The only named taxon reported, ‘Pterodactylus’ daviesii Owen, 1874, is widely regarded as a nomen dubium or as Pterodactyloidea incertae sedis, while most other material can be referred to Pterodactyloidea indet. Here we describe a fragmentary humerus and elongate mid-series cervical vertebra both from the Gault Formation of Kent, southeast England that can be referred to the edentulous pterodactyloid clade Azhdarchoidea. The cervical vertebra is identified as being from a non-tapejaromorph azhdarchoid on account of its reduced neural spine, a neural arch confluent with the centrum, a neural canal that is subsumed into the centrum and the lack of foramina on the lateral surfaces of the centrum. The humerus is referred to Azhdarchoidea on account of its sub-rectangular distal end. 相似文献
8.
We present a large, fragmentary skull and the humerus of a mosasaur (Squamata, Mosasauroidea) recovered from upper Maastrichtian beds of the López de Bertodano Formation in Marambio (=Seymour) Island, Antarctica. The material belongs to a large, adult individual with marked heterodonty as well as unusual humeral features. Different phylogenetic analyses returned the studied specimen within the Tylosaurinae, while the distinctive features of the skull and humerus allow distinguish it from the unique Antarctic known tylosaurine species, Taniwhasaurus antarcticus (Novas et al., 2002), as well as from other known Late Cretaceous mosasaurids from the Southern Hemisphere, thus, justifying the erection of a new taxon, Kaikaifilu hervei gen. et. sp. nov. The different dental types documented in the specimen studied have been previously recorded through isolated teeth from the same locality and were subsequently referred to several genera. This new find is relevant for assessing the previously known fragmentary records of Antarctic mosasaurids, suggesting that its local diversity could be more reduced than previously interpreted. The new material represents the youngest occurrence of tylosaurines in Antarctica. 相似文献
9.
A new ornithopod dinosaur from the Upper Cretaceous (Maastrichtian) Snow Hill Island Formation, at James Ross Island, Antarctica is here described. This new taxon, named as Morrosaurus antarcticus gen. et sp. nov., is represented by a fragmentary right hind limb belonging to a medium-sized individual. Our phylogenetic analysis nests the new taxon in a monophyletic clade of Southern Hemisphere ornithopods that includes most Patagonian and Antarctic ornithopods. Several members of this group share a slender and bunched foot with narrow metatarsal IV, expanded chevrons, and bowed humerus without deltopectoral crest. Several features indicate that these ornithopods exhibit adaptations for a specialized cursorial mode of life. The recognition of Patagonian and Antarctic Ornithopoda belonging to a monophyletic clade reinforces palaeobiogeographical signals indicating that Patagonia, Antarctica and Australia shared a common Late Cretaceous terrestrial fauna. 相似文献
10.
Multituberculates (Allotheria) are generally regarded as the evolutionarily most successful and longest-lived (Middle Jurassic to late Eocene) clade of Mesozoic and early Paleogene mammals. Despite this “reputation” and the fact that the group is particularly well represented in both taxonomic diversity and relative abundance on Laurasian landmasses during the Cretaceous and Paleocene, multituberculates are exceedingly poorly represented on the southern supercontinent Gondwana. Previous records on Gondwanan landmasses have been based on fragmentary dental remains and all except the three most recently published (each represented by a single isolated tooth or fragment of tooth) have been disputed and allocated to either Haramiyida or Gondwanatheria. Furthermore, several previous records, disputed or not, are based on fragmentary dental remains of a type (plagiaulacoid) that has evolved independently several times in mammalian evolution.Here we place on record a multituberculate femur from the Upper Cretaceous (Maastrichtian) Maevarano Formation of the Mahajanga Basin, Madagascar. This specimen, although fragmentary as well, exhibits a number of features common to all multituberculate femora: neck cylindrical in cross section and set apart from shaft; greater trochanter prominent, extending proximally beyond head, inclined dorsally, and separated from neck by deep incisure; lesser trochanter prominent and protruding ventrally; posttrochanteric fossa present on ventral aspect, lateral to lesser trochanter; subtrochanteric tubercle present on dorsal aspect, distal to incisure between greater trochanter and neck; diaphysis straight, elliptical in cross section (slightly compressed dorsoventrally); and third trochanter absent. Three of these features (prominent, ventrally placed lesser trochanter; presence of posttrochanteric fossa; presence of subtrochanteric tubercle) are regarded as autapomorphies of Multituberculata. This specimen therefore not only independently and conclusively confirms the presence of the clade on Madagascar—previously based on a small molar fragment—but on the entire supercontinent as well. 相似文献
11.
Saltasaurine titanosaurs are characterized by their relatively small size compared to other sauropods, extreme postcranial pneumaticity, and dermal armour covering the body. This group has been reported in the Upper Cretaceous of the Lecho, Allen, and Anacleto formations of Argentina. We describe here a new saltasaurine specimen (MACN-Pv RN 233) from the Campanian of the Angostura Colorada Formation (Río Negro Province) that is represented by eight caudal vertebrae and six osteoderms. This specimen is described in detail and its phylogenetic relationships with the other three known saltasaurines, as well as its implications to the knowledge of caudal vertebra and osteoderm anatomy, are discussed. Our results place MACN-Pv RN 233 more closely related to Saltasaurus loricatus and Rocasaurus muniozi than to Neuquensaurus australis. MACN-Pv RN 233 possesses a combination of features that differ from other saltasaurines, but because of the fragmentary nature of the specimen we decided for the sake of taxonomic stability to not erect a new taxon. This specimen shows the first unambiguous evidence of chevron pneumatisation for a sauropodomorph, implying a broader osteological invasion of the diverticula from the abdominal air sac than previously thought for this group of dinosaurs. MACN-Pv RN 233 preserves two osteoderm morphotypes, one similar to those reported for Neuquensaurus australis and Saltasaurus loricatus. This new specimen expands the distribution of the group to a new geological unit and increases the dinosaur diversity known for the Angostura Colorada Formation. 相似文献
12.
A new dinosaur sauropod from the Golmayo Formation (upper Hauterivian-lower Barremian) in Soria province (Spain) is described as Soriatitan golmayensis gen. et sp. nov. The new material consists of one tooth, three dorsal vertebrae with ribs, a partial sacrum, five caudal centra, two caudal vertebral spines, one chevron, a humerus, an ulna, a radius, two partial ilia, two ischia, a fragment of pubis, and a partial femur. Cladistic analysis identified the material as belonging to Brachiosaruidae within Titanosauriformes. Sauropod material from the Golmayo Formation shares a diagnostic feature with Abydosaurus, Cedarosaurus, Tastavinsaurus and Venenosaurus including anteriorly deflected anterior–middle caudal neural spines and with Cedarosaurus a proximodistally straight lateral margin between the proximal head and the shaft of the humerus. Eight characters are potential autapomorphies in the sauropod from Spain, including the presence of a large rectangular ventral ridge below the preacetabular process of the ilium, the same length of the pubic and ischiadic blades in the ischium, and two lateral ridges in the lateral area of the deltopectoral crest of the humerus. The presence of Early Cretaceous brachiosarids in both, North America and Europe, give support to the hypothesis of a connection between the tectonic plates of these continents at some point during the Early Cretaceous. 相似文献
13.
The complete osteology of the abelisaurid Viavenator exxoni, from the Bajo de la Carpa Formation (Santonian, Upper Cretaceous) is described. Viavenator is characterized by a series of autapomorphies, including: transversely compressed parietal depressions on both sides of the supraoccipital crest; ventral edges of the paraoccipital processes located above the level of the dorsal edge of the occipital condyle; basioccipital-opisthotic complex about two and a half times the width and almost twice the height of the occipital condyle, in posterior view; well-developed crest below the occipital condyle, diverging ventrally and defining the subcondylar recess; deeply excavated and sub-circular basisphenoidal recess, with its major axis transversely oriented; basipterygoid processes horizontally placed with respect to the cranial roof and located slightly dorsally to the basal tubera; mid and posterior cervical centra with slightly convex lateral and ventral surfaces; hyposphene-hypanthrum articular complex present from dorsal 2 onward; presence of an interspinous accessory articular system in middle and posterior dorsal vertebrae; presence of a pair of pneumatic foramina within the prespinal fossa in anterior caudal vertebrae; distal end of the scapular blade posteriorly curved. Particularly, Viavenator shows plesiomorphic cranial characters, i.e. flat frontals lacking domes or horns, combined with derived postcranial characters, e.g. the interspinous accessory joint system of dorsal vertebrae. This combination between plesiomorphic and derived traits suggests that Viavenator is a transitional form, which is an idea supported by its intermediate stratigraphic and phylogenetic placement between the basal and older (e.g. Skorpiovenator, Ilokelesia) and derived and younger members of the clade (e.g. Aucasaurus, Carnotaurus). 相似文献
14.
John P. Green Dean R. Lomax 《Proceedings of the Geologists' Association. Geologists' Association》2014
A fragmentary ichthyosaur specimen collected in situ at Castle Top Quarry in Nettleton, Lincolnshire, UK from exposures of the Lower Cretaceous (Berriasian) Spilsby Sandstone Formation (Subcraspedites ?preplicomphalus Zone) is reported. In general, Early Cretaceous ichthyosaurs from the Berriasian to Barremian are poorly understood. Despite the fragmentary nature of the described specimen, it is the first ichthyosaur reported from this specific zone and adds to the literature another rare ichthyosaur from the Berriasian. 相似文献
15.
Abelisauroid dinosaurs normally reached an average body length (BL) of 5–9 m, but there are controversies due to the incomplete or fragmentary nature of most specimens. For Ekrixinatosaurus, for example, BL was estimated as 10–11 m or 7–8 m; for Pycnonemosaurus it was proposed 7–8 m, however its preserved bones are larger than any other described abelisauroid. The lack of a consistent methodology complicates comparisons of estimated BL, so we reevaluated the estimative for the seven most complete specimens of abelisauroids and compared the values against 40 measurements from the skull, vertebrae and appendicular elements using bivariate equations. It allowed estimating the BL of other 30, less complete, specimens of abelisauroids and to evaluate the allometric scaling of the skeletal parts. Strong correlations (R2 > 0.96) were obtained for all vertebrae and hindlimb measurements, as well as skull height, and length of skull roof, lacrimal–squamosal, scapulocoracoid and humerus; other skull and forelimb measurements present weak correlation due to extreme morphological transformations observed in Abelisauridae and were not adequate for BL estimation. Abelisauroids gradually increased in size during evolution: the mean BL was 3.3 ± 2.5 m for basal abelisauroids and Noasauridae, 5.4 ± 1.8 m for basal Brachyrostra and Majungasauridae, and 7.1 ± 2.1 m for Furileusaura. Despite this variation, diversity of BL on each geographic region and stratigraphic epoch was relatively constant (BL usually varied from 4 to 8 m). The smallest noasaurid and abelisaurid are, respectively, Velocisaurus (1.5 ± 0.1 m) and Genusaurus (3.6 ± 0.0 m). The largest abelisaurids is Pycnonemosaurus nevesi (8.9 ± 0.3 m) followed by Carnotaurus (7.8 ± 0.3 m), Abelisaurus (7.4 ± 0.7 m) and Ekrixinatosaurus (7.4 ± 0.8 m). Skull measurement scale negatively at a similar rate but the height scales almost isometrically and the skull roof length scales more negatively; this probably caused a bending on the skull that may explain the upward orientation of the snout in large taxa. 相似文献
16.
Martín D. Ezcurra 《Cretaceous Research》2009,30(5):1339-1344
Dinosaur remains from Upper Cretaceous outcrops of northern Gondwana are extremely rare, in contrast with the much richer sample of coeval beds from southern Gondwana. Dinosaur remains from the uppermost Cretaceous Ortega locality of the Upper Magdalena Basin (Maastrichtian) of the Department of Tolima, Colombia, provides new information on northern Gondwanan faunas of this time. A revision of dinosaur material from this outcrop, consisting of three theropod shed teeth, reveals the presence of two morphotypes. One of them is referred to Abelisauridae based on the presence of crowns with mesial margin with a strong curvature beginning at about the second-third of the crown height and straight to slightly concave distal margin. The second morphotype exhibits un-serrated mesial and distal margins without carinae and no constriction at the base of the crown, a combination of features only observed in unenlagiine dromaeosaurids within Theropoda. Members of these clades are also present in coeval beds of southern and central South America, Madagascar, northern Africa, and India, indicating a cosmopolitan distribution in western and central Gondwana during the Late Cretaceous. Regarding South America, abelisaurid and probably dromaeosaurid theropods are recorded across a large latitudinal area, from the Palaeo-Equator to considerably high palaeo-latitudes in Patagonia, and probably spanning quite different environmental conditions. 相似文献
17.
Cretornis hlavaci Frič, 1881 from the Upper Cretaceous of Czech Republic (Pterosauria,Azhdarchoidea)
Cretornis hlavaci Frič, 1881 from the Upper Cretaceous (Turonian) of Czech Republic is a valid taxon referred to Azhdarchoidea based on having a saddle-shaped humeral head, pneumatic foramen on proximal humerus present on anterior side and absent on posterior side, elongate deltopectoral crest with subparallel proximal and distal margins, pneumatic foramen absent on distal side of humerus, metacarpals I–III not articulated with carpus and displaced on anterodorsal side of wing metacarpal, and wing metacarpal much longer than humerus. Absence of a pneumatic foramen on posterior side of proximal humerus suggests attribution of Cretornis hlavaci to Neoazhdarchia. It has a unique construction of the distal ulna with a dorsal articulation surface placed distinctly proximal to the tuberculum shared only with the non-azhdarchid azhdarchoid Montanazhdarcho minor from the Campanian of North America. Cretornis hlavaci differs from the latter taxon by the structure of its humerus and distinctly longer wing metacarpal. It is more derived than “Tapejaridae” but shares with Azhdarchidae the deltopectoral crest of the humerus displaced distally from humeral head. Cretornis cannot be assigned to Azhdarchidae because of the oval cross section of the second wing phalanx. A unique rhombic outline of the distal humerus of Cretornis hlavaci is a possible autapomorphy for this taxon. Its wing span estimated as 1.5–1.6 m. This is the first taxon of non-azhdarchid pterosaurs known from the Upper Cretaceous of the Eastern Hemisphere. 相似文献
18.
Here, we describe new theropod materials (several isolated teeth, an axis, two caudal centra and a proximal left tibia) from the type locality of the Bajada Colorada Formation (Lower Cretaceous, Berriasian–Valanginian). Although fragmentary, the recovered material shows a diverse association of meat-eating dinosaurs for this poorly understood period of time. Three techniques were used to assess the phylogenetic position of the isolated teeth: multivariate (PCA), discriminant and phylogenetic analyses. The morphotypes 1, 2 and 3 (small non-recurved isolated crowns) were regarded as Theropoda indet., as our analyses failed to support a more precise classification. Two large almost complete ziphodont crowns, considered morphotype 4, were identified as belonging to megalosaurid tetanurans by phylogenetic, discriminant and multivariate analyses, thus likely representing the first record of this ancient family in South America, and the youngest worldwide. We refer the axis to a small abelisauroid ceratosaurian based on the following suite of characters; long and pointed epipophyses, a pneumatic foramen in the centrum, the invaginated spinopostzygapophyseal lamina, and the anteroposteriorly long, dorsally convex, and dorsally/posteriorly unexpanded neural spine. The caudal centra can be referred to a theropod, and tentatively to Abelisauroidea, suggesting that they may belong to the same taxon than that represented by the axis. The tibia lacks the incisura tibialis, presents a low, sharp and proximally positioned fibular crest, and has a deep lateral fossa, which is limited dorsally by a coarse, rounded in section and anteriorly directed crest. This combination of features allows to refer it to a large abelisaurid. The Bajada Colorada dinosaur record includes so far a small abelisauroid, a large abelisaurid, a probably medium to large megalosaurid tetanuran, diplodocid and dicraeosaurid sauropods. It shows some similarities with Middle and Upper Jurassic units in central Patagonia, Africa and Portugal, suggesting that no significant dinosaur faunal turnover took place through the Jurassic-Cretaceous event in the southern part of South America. 相似文献
19.
《Cretaceous Research》2012,33(6):781-785
The terrestrial lizard fossil record of Gondwana is very scarce. Few lizards, from mostly fragmentary fossils, have been identified in Madagascar, Tanzania, Morocco, South Africa, India and South America. Among the South American specimens there are basal Squamata forms (Olindalacerta and Tijubina) and a possible iguanid (Pristiguana) form Brazil. In Argentina gondwanian terrestrial lizards are represented by a putative iguanid and a small, poorly preserved dentary. This last specimen, recovered from the Anacleto Formation (Neuquén Group, Río Colorado Subgroup) in vicinity of the locality of Cinco Saltos (Río Negro Province), is here described formally. Comparisons with extant lizards indicate more affinity of the fossil with the Scincomorpha (non Scincophidia) than with any other group of lizards. This finding suggests that lizards were probably better represented and more diverse in the Mesozoic of South America than previously thought, although the fossil record is, at the moment, much poorer than in Laurasia. 相似文献
20.
Pipid frogs are fully aquatic frogs that today inhabit freshwater environments of southern continents on both sides of the Atlantic Ocean, with a fairly good fossil record dating back to the Cretaceous. Here I report on fossils from the Allen Formation (upper Campanian–lower Maastrichtian), Río Negro Province, Argentina, that are ascribed to a new genus and species of pipid. In order to assess the evolutionary relationships of the new taxon, which is represented by sphenethmoids, otic capsules, ilia, humeri, and vertebrae, cladistic analyses of a data matrix of 165 osteological characters scored for 36 taxa were performed. The results are congruent with previous hypotheses of pipoid interrelationships and consistently place the new taxon as part of the lineage today represented by the African xenopodines. Temporal calibration of the phylogenetic tree based on the fossil record imply that the origin and early diversification of crown-group Pipidae might have occurred during the Early Cretaceous, prior to the final breakup of western Gondwana. This study highlights the importance of including fossils, even fragmentary ones, directly in phylogenetic analyses in order to disentangling how, when, and where pipid frogs diversified. 相似文献