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History of the terrestrial Cretaceous vertebrates of Gondwana
... Jos e Bonaparte (1986;Bonaparte and Kielan-Jaworowska, 1987) was the first to note the strong faunistic distinctions between Gondwana and Laurasia landmasses. One of the most remarkable differences is the scarcity of ornithischians in the southern continents, particularly in South America. ...
... In this way, the FABI rests mostly on evidence resting from the dinosaur record, and mainly on the hadrosaurid distribution, Bonaparte (1984Bonaparte ( , 1986 indicated that during the Campanian-Maastrichtian time span hadrosaurids reached South America through a migratory event from North America, and then hadrosaurids reached Antarctica (Case et al., 2000). ...
... On the other side, Bonaparte (1986) put forward the idea, based on the particularly apomorphic features exhibited by Minmi, that ankylosaurs were present in Gondwana before the fragmentation of this supercontinent, and their presence in Australia may be the result of vicariance, a hypothesis followed by some authors (Molnar, 1992;Agnolín et al., 2010;Leahey and Salisbury, 2013;Leahey et al., 2015;Francischini et al., 2017; see also Gasparini et al., 1996). As indicated above, this proposal is supported based on the widespread distribution of thyreophorans and specifically ankylosaurs in several Gondwanan landmasses from the Late Jurassic. ...
The fossil record of ornithischians in South America is sparse, and they are clearly underrepresented when compared with sauropod dinosaurs. However, recent discoveries indicate that ornithischians were more diversified than thought. The aim of the present contribution is to describe isolated remains belonging to ankylosaurs, and ornithopods, including basal euiguanodontians and hadrosaurs coming from the Chorrillo Formation (upper Campanian–lower Maastrichtian), Santa Cruz province, southern Argentina. The fossil remains of ankylosaurs reported here are the southernmost recorded for the continent. They show a unique combination of plesiomorphic features, indicating that they may belong to a basal ankylosaur. Ankylosaurs and hadrosaurids are thought to have arrived in South America during the latest Cretaceous through Central America. However, a detailed overview of the fossil record of Gondwana indicates that both clades were present and probably diversified along southern continents. This indicates that their presence in South America may be alternatively interpreted as the result of migration from other landmasses, including Africa and Europe, or may even be the result of Jurassic–Early Cretaceous vicariance from their northern counterparts.
... During most of the Mesozoic the continental masses were principally arranged in two separated continents: Laurasia in the north and Gondwana in the south (BONAPARTE, 1986;FORSTER, 1999;HAY ET AL, 1999;PITMAN ET AL, 1993). By the end of the Mesozoic these masses started to separate into their modern conformation. ...
... The paleogeographical distribution of Abelisauroidea and Carcharodontosauridae remains is the product of the long, isolated evolution of both groups on Gondwanan landmasses (BONAPARTE, 1986). ...
... HAY ET AL. 1999). In addition, South America and North America were sporadically connected through Central America at the end of the Cretaceous(BONAPARTE, 1986;BONAPARTE ET AL. 1984). Thus, these transient geographic connections between West Gondwana and other landmasses during the late Cretaceous permitted faunal interchanges that directly influenced the faunal composition of the terrestrial ecosystems(BONAPARTE, 1991B;SAMPSON ET AL. 1998). ...
... En Patagonia, los hadrosáuridos junto a Aeolosaurus son interpretados como miembros de una asociación faunística para el Cretácico Superior (Campaniano-Maastrichtiano) (Bonaparte, 1984;1986). Son ejemplos de esto las asociaciones dadas por Kritosaurus australis de Bonaparte et al. (1984), posiblemente una sinonimia de Secernosaurus conforme Prieto-Marquez & Salinas (2010), y Aeolosaurus sp. ...
... Finalmente, se considera que los hadrosaurios Secernosaurus koerneri y UNPSJB-Pv 1050, y el dudoso ceratopsio (Tapia, 1919) estarían vinculados al intercambio faunístico ocurrido al menos desde el Campaniano temprano a través de puentes geográfi cos entre América del Norte y América del Sur Bonaparte, 1986, Salgado & Coria, 1996Coria, 1999;Prieto-Marquez & Salinas, 2010;Coria et al., 2012), junto a lagartos Teiidae y mamíferos Eutheria (Bonaparte, 1986). ...
... Finalmente, se considera que los hadrosaurios Secernosaurus koerneri y UNPSJB-Pv 1050, y el dudoso ceratopsio (Tapia, 1919) estarían vinculados al intercambio faunístico ocurrido al menos desde el Campaniano temprano a través de puentes geográfi cos entre América del Norte y América del Sur Bonaparte, 1986, Salgado & Coria, 1996Coria, 1999;Prieto-Marquez & Salinas, 2010;Coria et al., 2012), junto a lagartos Teiidae y mamíferos Eutheria (Bonaparte, 1986). ...
The Chubut Group, central Patagonia, Argentina, is characterized by a lacustrine and fluvial-lacustrine system with variable participation of volcanic ash. This group includes the Bajo Barreal Formation (Cenomanian-Turonian) and a recently nested new lithostratigraphic unit, the Lago Colhue Huapi Formation (Coniacian-Maastrichtian). The Lago Colhue Huapi Formation overlies the Bajo Barreal Formation. These sedimentary units preserve a rich and diverse vertebrate fossil record including, among others, representatives of Crocodylomorpha, Testudines, Pterosauria and abundant Dinosauria. Nevertheless, the stratigraphic position of several of its taxa has been historically controversial. The unclear stratigraphic provenance of these taxa difficults the correct interpretation of the relationships with other Patagonian and South American basins. In this context, we present a detailed stratigraphic study to clarify the position of the vertebrate fossils of both Late Cretaceous formations. We also discuss the implications of this faunistic arrangement in terms of vertebrate evolution and paleobiogeography. Finally, this study broadens our knowledge on the fossil fauna of these units and therefore the vertebrate assemblages of central Patagonia.
... During the Late Cretaceous, highly distinct dinosaur faunas appeared on different land masses (Bonaparte, 1986;Bonaparte and Kielan-Jaworowska, 1987;Csiki-Sava et al., 2015;Longrich et al., 2017;Longrich et al., 2021c). In the northern continents of North America and Asia, dinosaurian faunas were dominated by coelurosaurian theropods and by ornithischians . ...
... It therefore appears that despite broad similarities (Bonaparte, 1986), differential extinction and dispersal led to the evolution of distinct Gondwanan faunas at the end of the Cretaceous (Longrich et al., 2021c). The emergence of geographic barriers between Gondwana and Laurasia saw their faunas evolve in different directions, while the fragmentation of Gondwana during the Cretaceous led the faunas of different Gondwanan landmasses to diverge from one another. ...
The end of the Cretaceous saw the evolution of endemic dinosaur faunas on different landmasses, driven by continental fragmentation. Understanding the evolution of these biogeographic patterns is important for understanding the evolution of Mesozoic ecosystems. However, the faunas of the southern land masses remain understudied relative to the intensively sampled dinosaur faunas of western North America and Asia. In particular, the latest Cretaceous of Africa remains largely unknown, with only a handful of taxa reported so far, including titanosaurian sauropods, the lambeosaurine Ajnabia odysseus, and the large abelisaurid theropod Chenanisaurus barbaricus. We report two new abelisaurid fossils from the upper Maastrichtian phosphates of the Ouled Abdoun Basin, in northern Morocco. The first is the tibia of a medium-sized abelisaurid from Sidi Chennane, with an estimated length of ~5 m. The tibia has a strongly hooked cnemial crest resembling that of the South American Quilmesaurus and Aucasaurus. The highly rugose bone texture suggest the animal was mature, rather than a juvenile of the larger Chenanisaurus. The second is a small right second metatarsal from Sidi Daoui,. The metatarsal measures 190 mm in length, suggesting a small animal, ~2.6 m in length. The metatarsal shows strong mediolateral compression, a feature present in noasaurids and some early abelisaurids, but absent in most Late Cretaceous abelisaurids. It is distinct from other abelisauroids in the strong constriction and bowing of the shaft in lateral view, and the medial curvature of the bone in anterior view. Bone texture suggests it comes from a mature individual. The small size, gracile proportions and unusual shape of the metatarsal suggest it is not closely related to other latest Cretaceous abelisaurids. The new fossils suggest as many as three abelisaurid taxa coexisted in the late Maastrichtian of Morocco, showing dinosaurs were highly diverse in North Africa prior to the end-Cretaceous mass extinction.
... The existence of dinosaur 'bioprovinces', characterised by different faunal compositions, have long been proposed, particularly between northern and southern landmasses. Bonaparte 65 proposed a biogeographic partitioning between the main clades of Mesozoic dinosaurs, which reached a heightened phase in the Cretaceous. A 'Eurogondwanan fauna', characterised by the presence of titanosaurian and rebbachisaurid sauropods, plus abelisaurid and spinosaurid theropods 66 , was proposed to differentiate Gondwana and southern Europe from the remainder of the Northern Hemisphere. ...
... Given the available data, a predominance of sauropods in southern landmasses and in equatorial areas appears to be a genuine characteristic of dinosaur biogeography (e.g. 57,65 ). Africa and South America, in particular, are characterised by a high number of sauropod-rich fossil-bearing assemblages (Figures 1 and 3). ...
Dinosaurs dominated Mesozoic terrestrial ecosystems globally. However, whereas a pole-to-pole geographic distribution characterized ornithischians and theropods, sauropods were restricted to lower latitudes. Here, we evaluate the role of climate in shaping these biogeographic patterns through the Jurassic–Cretaceous (201–66 mya), combining dinosaur fossil occurrences, past climate data from Earth System models, and habitat suitability modeling. Results show that, uniquely among dinosaurs, sauropods occupied climatic niches characterized by high temperatures and strongly bounded by minimum cold temperatures. This constrained the distribution and dispersal pathways of sauropods to tropical areas, excluding them from latitudinal extremes, especially in the Northern Hemisphere. The greater availability of suitable habitat in the southern continents, particularly in the Late Cretaceous, might be key to explaining the high diversity of sauropods there, relative to northern landmasses. Given that ornithischians and theropods show a flattened or bimodal latitudinal biodiversity gradient, with peaks at higher latitudes, the closer correspondence of sauropods to a subtropical concentration could hint at fundamental thermophysiological differences to the other two clades.
... Coloniatherium (Fig. 7A) es un mamífero de relativo gran tamaño, similar en morfología a Mesungulatum housayii, de la Formación Los Alamitos (Bonaparte 1986). Rougier et al. (2009) describieron mandíbulas parciales, elementos dentarios aislados y petrosos aislados. ...
... Comentarios. Ferugliotherium fue descrito para la Formación Los Alamitos por Bonaparte (1986) en forma tentativa como un multituberculado. Posteriormente, basado en materiales adicionales y en colaboración con otros autores (Bonaparte 1990, Krause et al. 1992, Krause 1993, Krause y Bonaparte 1993, Ferugliotherium fue interpretado como un miembro basal de Gondwanatheria, un grupo del Cretácico de Gondwana que incluye taxones con dientes hipsodontes pero aún dentro de Multituberculata. ...
La Formación La Colonia aflora en el borde sureste de la meseta de Somún Curá, en el norte de la provincia de Chubut. Los ambientes de depositación corresponden a fluviales, marino-marginales y marino-someros y se estima una edad entre el Campaniano y el Paleoceno para toda la unidad. Numerosas campañas paleontológicas llevadas a cabo desde principios de la década de 1980 hasta la actualidad han recuperado una diversa fauna de vertebrados continentales y marinos del tramo medio de la Formación La Colonia asignado por relaciones estratigráficas, al Campaniano-Maastrichtiano. Entre los vertebrados continentales se reconocen peces de agua dulce (dipnoos, lepisostéidos, siluriformes y percomorfos), anuros (callyptocephaléllidos, neobatracios indet. y anura indet.), lepidosaurios (escamosos indet., serpientes madtsoiideas y rincocéfalos), dinosaurios ornitisquios (ankylosaurios y hadrosáuridos), dinosaurios saurópodos (titanosaurios indet. y saltasáuridos), dinosaurios terópodos (abelisáuridos), aves enantiornites, tortugas quélidos y meiolaniformes, y mamíferos holoterios (mesungulátidos, reigitéridos) y aloterios (ferugliotéridos). La fauna de tetrápodos continentales de la Formación La Colonia comparte numerosos taxones con la asociación alleniana de tetrápodos basada en la fauna de las formaciones Allen, Los Alamitos, Loncoche y Angostura Colorada. Sin embargo, es llamativa la ausencia, hasta el momento, de anuros pipoideos y aves ornitures en la Formación La Colonia.
... A few studies (e.g., Loewen et al. 2013) have applied quantitative phylogenetic biogeographic analyses to groups such as Tyrannosauroidea, but the majority of coelurosaurian subclades, and the group as a whole, have not been investigated using such approaches. At present, therefore, much of our knowledge of coelurosaurian biogeographic history comes from studies of Dinosauria as a whole (e.g., Bonaparte 1986;Upchurch et al. 2002;O'Donovan et al. 2018). To address these deficits, we perform the first quantitative biogeographic analysis focused on the Coelurosauria as a whole. ...
... This latter view is often based on the observation that vicariancelike repeated area relationships can also be explained by regional extinction events and that many clades were widespread early in their evolutionary history and seem to become more geographically restricted subsequently (Sereno, 1997;1999a;Barrett et al., 2011;Benson et al., 2012;Carrano et al., 2012). Most authors agree that intercontinental dispersal played a key role in creating dinosaurian (coelurosaurian) biogeographic patterns (Bonaparte, 1986;Sereno, 1999b;Brusatte et al., 2013;Dunhill et al., 2016). Such dispersal events are implied from the fossil record and phylogenetic relationships. ...
The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earth’s surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately, few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the Theropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentationinduced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges.
... The most distinctive feature of Dicraeosauridae is a set of long dorsally projected bifid neural spine in most presacral vertebrae (Janensch, 1929;Salgado and Bonaparte, 1991;Rauhut et al., 2005;Coria et al., 2019;Gallina et al., 2019). The Dicraeosauridae biochron extends from the Middle Jurassic to the Early Cretaceous, and its fossil record comes from Argentina, Tanzania, United States and China (Janensch, 1929;Bonaparte, 1986;Salgado and Bonaparte, 1991;Bonaparte, 1996;Harris and Dodson, 2004;Upchurch et al., 2004;Rauhut et al., 2005;Apesteguía, 2007;Xu et al., 2018;Coria et al., 2019;Gallina et al., 2019). ...
... The La Amarga Formation (BarremianeAptian, Lower Cretaceous) assemblage includes a great diversity of tetrapod taxa, collected in field works carried out by Dr. Jos e F. Bonaparte and collaborators (Bonaparte, 1986(Bonaparte, , 1996Chiappe, 1988;Leanza et al., 2004;Otero and Salgado, 2015). Specifically, the sauropod diversity is represented by the dicraeosaurids Amargasaurus cazaui (Salgado and Bonaparte, 1991) and Amargatitanis macni (Apesteguía, 2007) and the rebbachisaurid Zapalasaurus bonapartei (Salgado et al., 2006). ...
Dicraeosauridae is a family of small body-sized sauropod dinosaurs that diversified from the Middle Jurassic to the Lower Cretaceous, whose distinctive feature is a long dorsally projected, bifid neural spines in most of the presacral vertebrae. The dicraeosaurid fossil record is limited to few taxa, therefore each new finding, however fragmentary, allows to improve the knowledge about this group. Here, we report new dicraeosaurid remains, consisting of two associated anterior dorsal vertebrae (MOZ-Pv 6126-1; MOZ-Pv 6126-2) collected from the La Amarga Formation (Barremian–Aptian, Lower Cretaceous). MOZ-Pv 6126-1 is represented by an almost complete anterior dorsal vertebra, while MOZ-Pv 6126-2 is an anterior dorsal vertebral centrum with a portion of the neural arch. The morphological features of these axial elements, as well as the absence of lateral fossae, the orientation of the transverse processes and an elongated bifid neural spine, allow us to refer them to the dicraeosaurid sauropods (Janensch, 1929; Salgado y Bonaparte, 1991; Rauhut et al., 2005; Coria et al., 2019; Gallina et al., 2019). However, due to the lack of more diagnostic features, we prefer to consider MOZ-Pv 6126-1 and MOZ-Pv 6126-2 as Dicraeosauridae indet. The new materials increase the fossil record of dicraeosaurid sauropods from La Amarga Formation and enrich the poor worldwide fossil record of the Dicraeosauridae.
... A few studies (e.g., Loewen et al. 2013) have applied quantitative phylogenetic biogeographic analyses to groups such as Tyrannosauroidea, but the majority of coelurosaurian subclades, and the group as a whole, have not been investigated using such approaches. At present, therefore, much of our knowledge of coelurosaurian biogeographic history comes from studies of Dinosauria as a whole (e.g., Bonaparte 1986;Upchurch et al. 2002;O'Donovan et al. 2018). To address these deficits, we perform the first quantitative biogeographic analysis focused on the Coelurosauria as a whole. ...
... This latter view is often based on the observation that vicariancelike repeated area relationships can also be explained by regional extinction events and that many clades were widespread early in their evolutionary history and seem to become more geographically restricted subsequently (Sereno, 1997;1999a;Barrett et al., 2011;Benson et al., 2012;Carrano et al., 2012). Most authors agree that intercontinental dispersal played a key role in creating dinosaurian (coelurosaurian) biogeographic patterns (Bonaparte, 1986;Sereno, 1999b;Brusatte et al., 2013;Dunhill et al., 2016). Such dispersal events are implied from the fossil record and phylogenetic relationships. ...
The Coelurosauria are a group of mostly feathered theropods that gave rise to birds, the only dinosaurians that survived the Cretaceous-Paleogene extinction event and are still found today. Between their first appearance in the Middle Jurassic up to the end Cretaceous, coelurosaurians were party to dramatic geographic changes on the Earth's surface, including the breakup of the supercontinent Pangaea, and the formation of the Atlantic Ocean. These plate tectonic events are thought to have caused vicariance or dispersal of coelurosaurian faunas, influencing their evolution. Unfortunately , few coelurosaurian biogeographic hypotheses have been supported by quantitative evidence. Here, we report the first, broadly sampled quantitative analysis of coelurosaurian biogeography using the likelihood-based package BioGeoBEARS. Mesozoic geographic configurations and changes are reconstructed and employed as constraints in this analysis, including their associated uncertainties. We use a comprehensive time-calibrated coelurosaurian evolutionary tree produced from the The-ropod Working Group phylogenetic data matrix. Six biogeographic models in the BioGeoBEARS package with different assumptions about the evolution of spatial distributions are tested against geographic constraints. Our results statistically favor the DIVALIKE+J and DEC+J models, which allow vicariance and founder events, supporting continental vicariance as an important factor in coelurosaurian evolution. Ancestral range estimation indicates frequent dispersal events via the Apulian route (connecting Europe and Africa during the Early Cretaceous) and the Bering land bridge (connecting North America and Asia during the Late Cretaceous). These quantitative results are consistent with commonly inferred Mesozoic dinosaurian dispersals and continental-fragmentation-induced vicariance events. In addition, we recognize the importance of Europe as a dispersal center and gateway in the Early Cretaceous, as well as other vicariance events such as those triggered by the disappearance of land bridges.
... The Allen Formation has also yielded remains of several taxa assigned to Titanosauria (Salgado and Coria, 1993;Salgado and Azpilicueta, 2000;Martinelli and Forasiepi, 2004;Garcia and Salgado, 2003). Bonaparte (1986) suggested a faunistic interchange with North America during the Late Cretaceous, in which hadrosaurs and ankylosaurs immigrated to South America, whilst the South American titanosaurs emigrated to North America. Therefore, the Allen Formation reflects a complex community, consisting of a mixed association of local and immigrant taxa. ...
... This assemblage has been named Allenian (Leanza et al., 2004), and includes a mixture of taxa typical from the Northern Hemisphere (such as Ankylosauria and Hadrosauridae) together with Gondwanan groups such as Titanosauria and Abelisauridae (also present in the Late Cretaceous of North America). This is consistent with the biogeographic hypothesis proposed by Bonaparte (1986) who hypothesized that these local fauna were the result of a biotic interchange between both Americas during the Campanian. Gasparini et al. (1996), proposed the alternative hypothesis suggesting that hadrosaurs and ankylosaurs may belong to an endemic fauna in South America. ...
... Posteriormente, Casal et al. (2007) documentaron la presencia del titanosaurio Aeolosaurus colhuehuapensis con relevancia en la información paleoambiental y cronológica. En Argentina, el género Aeolosaurus está registrado únicamente y hasta el momento, a partir del Campaniano (Powell 1987, Salgado y Coria 1993, Salgado et al. 1997, Casal et al. 2007) para ambientes litorales y planicies de inundación vinculadas a ambientes fluviales de alta sinuosidad (Bonaparte 1986(Bonaparte , 1992. Recientemente, Casal et al. (2010) dieron a conocer el hallazgo de un nuevo titanosaurio (MDT-Pv 4) proveniente de la margen sur del río Chico. ...
... La importancia de esta asociación Aeolosaurus-hadrosauridos radica en que la misma fue utilizada para determinar la edad Vertebrado Alamitense como campaniana (Bonaparte 1992), posteriormente confirmada por Salgado et al. (1997). La presencia de estos taxones permitió corroborar la correlación de Bonaparte (1992) entre las Formaciones Los Alamitos, Allen, Angostura Colorada y también con la Formación Loncoche (Candeiro 2010 Asimismo, la fauna de la Formación Bajo Barreal presenta típicos componentes gondwánicos (Lamanna et al. 2002), mientras que los Hadrosauridae en las nacientes del río Chico integran una fauna invasora procedente del hemisferio Norte a partir del Campaniano temprano (Bonaparte et al. 1984, Bonaparte 1986, Salgado y Coria 1996, Coria 1999, Prieto-Marquez y Salinas 2010). ...
... The characteristic of these faunas is the lack of therian mammals with tribosphenic molars (Pascual, 2006). On the contrary, Cenozoic faunas are dominated by therian mammals with tribosphenic molars (Pascual, 2006), probably arrived from North America or Africa (Patterson & Pascual, 1972;Bonaparte, 1986b;Ezcurra & Agnolín, 2012). ...
... If such is correct, the presence of a therian in the Late Cretaceous of central South America have important implications for the evolution of this clade in Gondwanan landmasses, but only detailed studies of this material will shed some light on the evolutionary history of tribosphenic mammals in Gondwanan landmasses. Bonaparte (1986b) proposed a palaeobiogeographical model that was followed by most subsequent authors. They indicate that most vertebrates, including mammals, followed a vicariant distribution pattern. ...
The fossil record of Mesozoic mammals from Argentina is the most complete and diverse among Gondwanan landmasses, thus it became in a reference to understand the evolution and paleogeography of the group. In this contribution we discuss some ideas on the taxonomy of poorly documented mammals from other Gondwanan localities and their paleobiogeographic implications. The resemblances among mammal-bearing Gondwanan localities are more conspicuous clear than previously thought.
... A biota representativa do Cretáceo Superior do Triangulo Mineiro e do estado de São Paulo é caracterizada pela ocorrência de táxons tipicamente gonduânicos (Bonaparte, 1986). Essa fauna típica do Mesozoico é formada por peixes tipicamente de água doce que estavam presentes por todo o Gondwana, e que desapareceram do continente sulamericano no final do Cretáceo ou início do Paleoceno como Lepisosteus e Ceratodus, assim como táxons neotropicais que ainda estão presentes como formas atuais: Osteoglossiformes, Siluriformes e Characiformes (Apendice A e B; Brito; Do Amaral; Machado, 2006 Machado (2006) revelaram que grande parte dos fragmentos de peixes encontrados no Grupo Bauru não pode ser incluída em grupos taxonômicos mais precisos, principalmente em função de dificuldades na identificação de aspectos diagnósticos, dado o estado de preservação dos espécimes. ...
... No obstante, como se ha dicho antes, los carcarodontosáuridos sobrevivieron en la Patagonia solo hasta la depositación de los sedimentos Turonianos-Coniacianos de la Formación Portezuelo y fueron parte de las victimas, junto con los saurópodos rebaquisaurios, de un evento de extinción acaecido en el Turoniano-Coniaciano (SALGADO, 2001;APESTEGUÍA, 2002A;LEANZA et al., 2004). Bonaparte (1986) propuso a los dinosaurios abelisáuridos como buenos indicadores paleobiogegráficos de las faunas gondwánicas. Muchos investigadores continuaron con esta propuesta (e.g., SERENO et al., 2004), inclusive considerándolos en asociación con otras faunas de distribución más amplia. ...
... In addition to obvious differences in size, mobility and routes of dispersion, ceratodontiform dipnoans have a similar regional and stratigraphical distribution to that of titanosauriform sauropods, which have a vast Jurassic and early Cretaceous record in North America through the Cenomanian (Bonaparte 1986). Ceratodontiforms and titanosauriforms were considered extinct at the early late Cretaceous of North America. ...
... Ameghinoce-ratodus). A similar faunal pattern has also been reported for other vertebrate groups (Bonaparte, 1986). Cione (1987), based on Martin (1982), considers Ptychoceratodus wichmanni to be the sister taxon to P. madagascarensis (=Fergana-ceratodus; Martin et al., 1999) based on the presence of only four ridge crests in the tooth plates and the ontogenetic formation of a chewing surface. ...
Annual Meeting of the Society-for-Integrative-and-Comparative-Biology
... The diversity of the dinosaur faunas between Northern and Southern America depends on the probable total biogeographic isolation of South American and, more generally, Gondwanan faunas, from those of boreal continents (Laurasia) during Middle and Late Jurassic and almost all of the Cretaceous, a typical case of endemism (Bonaparte 1986(Bonaparte , 2007. There is, instead, a notable affinity between South American dinosaur faunas and those of the other Gondwanan plates: Africa, Madagascar, 204 G. Leonardi and I. S. Carvalho India, Antarctica, and Australia. ...
The Rio do Peixe basins are the set of four associated basins: Sousa, Uiraúna-Brejo das Freiras (also known as Triunfo), Pombal and Vertentes. They are located in the western Paraíba State and in the Ceará State, northeastern Brazil, in a total area of ~1,280 km². The origin of these basins (Lower Cretaceous, Berriasian to lower Barremian) is related to normal and transcurrent fault movements along preexisting structural trends of the Proterozoic basement during the South and Equatorial Atlantic Ocean opening. Dinosaur footprints are the most abundant fossils in the siliciclastic continental sediments. The main tetrapod ichnofauna comprises, in at least 42 individual tracksites through approximately 96 stratigraphic levels, isolate footprints and trackways of large and small theropods, besides ornithopods, sauropods, and rare ankylosaurs. There are also invertebrate ichnofossils. The body fossils are fish scales and bone fragments, but also rare dinosaur and Crocodylomorpha bones, palynomorphs, plant fragments, ostracods and conchostracans. These basins comprise a lot of dinosaur ichnofaunas, in the same stratigraphic-time-paleogeographical context, and they represent segments of a widespread megatracksite. There are 447 theropod tracks; 90 sauropods (Total of 537 saurischians); 2 quadrupedal ornithischians (one of them an ankylosaurian); 6 small ornithopods; 30 graviportal ornithopods (total of 38 ornithischians); one track of a juvenile biped dinosaur; about 53 unclassifiable dinosaurian tracks (629 dinosaurs, all together); a hand-foot set of batrachopodid prints; traces of a Crocodylomorpha; an isolate lacertoid print; and a large number of small chelonian half-swimming tracks. The environmental setting indicates an endemic biota living nearby ephemeral rivers and shallow lakes under hot climate conditions. These were preserved in alluvial fans, braided, meandering rivers and shallow lake deposits of Berriasian to lower Barremian ages. Dinosaur faunas (both as bone remains and as ichnofaunas) from the Early Cretaceous are quite rare in the world, and the material discovered in these basins is important to the knowledge of the dinosaur diversity during the Cretaceous.
... However, the presence of lizards with polyglyphanodontian affinities de Carvalho and Santucci 2024), would either indicate an ancient and unrecorded history of the group in Gondwana, or the immigration of a Laurasian lineage from northern continents. Supporting the possibility of such a migratory scenario, other groups of terrestrial vertebrates appear to have reached South America from Laurasia, North America in particular, during the Campanian -Maastrichtian interval (Bonaparte 1986). Among those recently advanced as such are the nodosaurine ankylosaur Patagopelta (Riguetti et al. 2022;however, Agnolín, Rozadilla et al. 2023 considered it as a Gondwanan parankylosaurian) and hadrosaurs (Alarcón-Muñoz et al. 2023;Bonaparte 1996;Prieto-Márquez 2010; though this was put into question by Rozadilla et al. 2021). ...
... Paleontological discoveries over the past three decades have substantially improved the fossil record of latest Cretaceous (Campanian-Maastrichtian) non-avian dinosaurs and other terrestrial vertebrates from landmasses that formerly comprised the Gondwanan supercontinent. Phylogenetically and paleobiogeographically informative Campanian and/or Maastrichtian dinosaur finds have come from South America (Bonaparte, 1986(Bonaparte, , 1996Leanza et al., 2004;Novas, 2009;Novas et al., 2013;de Jesus Faria et al., 2015;Ezcurra and Novas, 2016;Rozadilla et al., 2021), Madagascar (Krause et al., 1999(Krause et al., , 2006(Krause et al., , 2019, and even Antarctica (Reguero et al., 2013(Reguero et al., , 2022Lamanna et al., 2019). Nevertheless, the latest Cretaceous dinosaur records of two major Gondwanan land areas-Australasia and mainland Africa (i.e., Africa to the exclusion of Madagascar)-remain woefully incomplete, hindering meaningful insights into the evolutionary and paleobiogeographic relationships of their respective dinosaur faunas during this time (Krause et al., 1999(Krause et al., , 2006(Krause et al., , 2019Wilson et al., 2001;Ali and Krause, 2011;Lamanna, 2013;Sallam et al., 2018). ...
Dinosaur fossils from the latest Cretaceous (Campanian–Maastrichtian) of Africa and the Arabian Peninsula are rare. Most discoveries to date have consisted of limited fossils that have precluded detailed phylogenetic and paleobiogeographic interpretations. Fortunately, recent discoveries such as the informative Egyptian titanosaurian sauropod dinosaur Mansourasaurus shahinae are beginning to address these long-standing issues. Here we describe an associated partial postcranial skeleton of a new titanosaurian taxon from the Upper Cretaceous (Campanian) Quseir Formation of the Kharga Oasis, Western Desert of Egypt. Consisting of five dorsal vertebrae and 12 appendicular elements, Igai semkhu gen. et sp. nov. constitutes one of the most informative dinosaurs yet recovered from the latest Cretaceous of Afro-Arabia. The relatively gracile limb bones and differences in the coracoid and metatarsal I preclude referral of the new specimen to Mansourasaurus. Both model-based Bayesian tip-dating and parsimony-based phylogenetic analyses support the affinities of Igai semkhu with other Late Cretaceous Afro-Eurasian titanosaurs (e.g., Mansourasaurus, Lirainosaurus astibiae, Opisthocoelicaudia skarzynskii), a conclusion supported by posterior dorsal vertebrae that lack a postzygodiapophyseal lamina, for example. Igai semkhu strengthens the hypothesis that northern Africa and Eurasia shared closely related terrestrial tetrapod faunas at the end of the Cretaceous and further differentiates this fauna from penecontemporaneous assemblages elsewhere in Africa, such as the Galula Formation in Tanzania, that exhibit more traditional Gondwanan assemblages. At present, the specific paleobiogeographic signal appears to vary between different dinosaur groups, suggesting that Afro-Arabian Cretaceous biotas may have experienced evolutionary and paleobiogeographic histories that were more complex than previously appreciated.
... A partir de ese momento, Bonaparte sostuvo consistentemente que los continentes australes tuvieron una gran importancia en lo que se refiere al origen y evolución de los diferentes grupos de vertebrados vivientes, y que no fueron simplemente un recipiente al cual iban "cayendo" los distintos linajes que se originaban en el norte. Es así, que a lo largo de la década de 1980 (fundamentalmente en: Bonaparte, 1984Bonaparte, , 1986Bonaparte y Kielan Jaworowska, 1987) da forma al esquema que luego seguirá ampliando y reforzando a lo largo de toda su vida. ...
José Fernando Bonaparte (1927-2020) dedicó su vida entera al estudio de los vertebrados fósiles, en especial reptiles y mamíferos del Mesozoico Sudamericano. Fue llamado el “Amo del Mesozoico” y fue, en su momento, la persona con mayor número de especies de dinosaurios nombrados a nivel mundial. Con un entusiasmo sin fin, Bonaparte abrió las puertas de la mayor parte de los yacimientos mesozoicos de la Argentina y muchos de Brasil y Perú. También dejó discípulos desparramados por todas las latitudes. Principalmente autodidacta y de esforzados orígenes, su elemento primordial, la pasión, lo acompañó en cada momento de su vida. Pero ¿cómo surgió este titán de la ciencia? ¿De dónde salió? ¿Quiénes eran sus padres? ¿Cómo llegó a ser quién fue? En este libro encontrarán las respuestas.
... A partir de sus propios descubrimientos a lo largo de todo el país, y sumado a sus viajes de estudio al exterior y al aporte de otros autores, J. F. Bonaparte se percató de la profunda diferencia entre las faunas del hemisferio sur con las del norte. En el año 1986 publicó un trabajo en el cual planteaba la distinción profunda entre las faunas de vertebrados de Gondwana y Laurasia (Bonaparte, 1986c). Esta idea se transformó en el paradigma que dicta la paleobiogeografía del Mesozoico hoy en día. ...
... quadrupedal stance with small heads, long necks and long tails), sauropods showed a highly morphological variation in the skeleton, particularly in the vertebrae, which exhibit a strong degree of anatomical disparity amongst the different lineages (Salgado & Powell, 2010;Wilson, 1999). Perhaps one of the most extreme examples of vertebral disparity is found in Dicraeosauridae, a clade of diplodocoid sauropods, whose fossil record comes from Argentina, Tanzania, United States and China (Bonaparte, 1986;Bonaparte, 1996;Coria et al., 2019;Gallina, 2016;Gallina et al., 2019;Harris & Dodson, 2004;Janensch, 1929;Rauhut et al., 2005;Salgado & Bonaparte, 1991;Upchurch et al., 2004;Windholz et al., 2021;Xu et al., 2018). Presacral vertebrae of dicraeosaurid sauropods are characterized by the presence of elongate bifid neural spines, which are therefore composed by two hemispinous processes (following Harris [2006] and referring to one half of a bifurcated spine. ...
Dicraeosaurid sauropods are iconically characterized by the presence of elongate hemispinous processes in presacral vertebrae. These hemispinous processes can show an extreme degree of elongation, such as in the Argentinean forms Amargasaurus cazaui, Pilmatueia faundezi and Bajadasaurus pronuspinax. These hyperelongated hemispinous processes have been variably interpreted as a support structure for a padded crest/sail as a display, a bison‐like hump or as the internal osseous cores of cervical horns. With the purpose to test these hypotheses, here we analyze, for the first time, the external morphology, internal microanatomy and bone microstructure of the hemispinous processes from the holotype of Amargasaurus, in addition to a second dicraeosaurid indet. (also from the La Amarga Formatin; Lower Cretaceous, Argentina). Transverse thin‐sections sampled from the proximal, mid and distal portions of both cervical and dorsal hemispinous processes reveal that the cortical bone is formed by highly vascularized fibrolamellar bone interrupted with cyclical growth marks. Obliquely oriented Sharpey's fibres are mostly located in the medial and lateral portions of the cortex. Secondary remodelling is evidenced by the presence of abundant secondary osteons irregularly distributed within the cortex. Both anatomical and histological evidence does not support the presence of a keratinized sheath (i.e. horn) covering the hyperelongated hemispinous processes of Amargasaurus, and either, using a parsimonious criterium, in other dicraeosaurids with similar vertebral morphology. The spatial distribution and relative orientation of the Sharpey's fibres suggest the presence of an important system of interspinous ligaments that possibly connect successive hemispinous processes in Amargasaurus. These ligaments were distributed along the entirety of the hemispinous processes. The differential distribution of secondary osteons indicates that the cervical hemispinous processes of Amargasaurus were subjected to mechanical forces that generated higher compression strain on the anterior side of the elements. Current data support the hypothesis for the presence of a ‘cervical sail’ in Amargasaurus and other dicraeosaurids. Life restoration of Amargasaurus cazaui. Current data support the hypothesis for the presence of a ‘cervical sail’ in Amargasaurus and other dicraeosaurids. Illustration made by Gabriel Lio.
... Later, Suazo-Lara and identified it as Calyptocephalellidae indet. 2) Taxon B- Bonaparte (1986aBonaparte ( , 1986b) mentioned in conference abstracts the record of two specimens (the kind of material was not detailed) assigned as Pipidae indet. The materials were neither described nor illustrated and were mentioned in Sanchiz (1998). ...
Anurans, along with urodeles and caecilians are the extant representatives of the clade Lissamphibia. Nowadays, lissamphibians are widely distributed in all continents, except Antarctica, but are particularly diversified in South America, where almost 3,000 species are found. This huge biodiversity is directly related to the complex geologic history of South America, which includes key events like the Gondwanan breakup, its isolation during parts of Mesozoic and Cenozoic, the Andean uplift, and the formation of the Panamá isthmus. Here, we present the most comprehensive bibliographic review of fossil lissamphibians from South America to date, covering unpublished (e.g. theses and dissertations) and published data (i.e. peer-reviewed scientific papers, book chapters, monographs, and conferences abstracts). We used a mixed approach, both qualitative (with brief comments on each material) and quantitative (including scientometric parameters). Compared to the latest published reviews with similar scope, our results indicate that approximately 85.4% of the records correspond to specimens new to science or older ones that have been revisited. These materials come from 164 different fossil-bearing localities, spread over eight of the twelve South American countries, and range from the Early Jurassic to the Quaternary. In total, we compiled 273 records, mostly anurans (~97.6%), followed by indeterminate caecilians (~1.4%) and urodeles (~1%). Additionally, we discussed issues directly related to those fossil occurrences, such as their temporal and geographic range, as well as the presence of putative biological and taphonomic biases. Finally, we also provided calibration constraints for several anuran taxa.
... Because southern landmasses were closely positioned during Cretaceous times, dinosaurian faunas from Gondwana have usually been regarded as uniform (see details in Bonaparte, 1986). However, several authors identified faunistic differences among the southern landmasses. ...
The fossil record of abelisaurid theropods in South America is mostly limited to Brazil and Argentina. In Argentina, abelisaurids are generally known from Patagonia, where their record is relatively abundant and includes well-known and complete specimens. However, for Northwestern Argentina, abelisaurids are represented by incomplete and isolated bones and teeth that remain largely unpublished. The aim of this contribution is to report a nearly complete abelisaurid braincase from the Late Cretaceous Los Blanquitos Formation (Campanian), Amblayo Valley, Salta province, Argentina. The specimen shows plesiomorphic features for abelisaurids, including a thin skull roof, absence of skull projections like horns or bulges, and low and narrow parietal eminence that lie at the same level as the sagittal crest. Furthermore, the specimen possesses some autapomorphies that support its status as a new taxon and its small size allows it to be assigned as one of the smallest abelisaurids recorded up to date. The finding of this specimen constitutes the first unequivocal occurrence of an abelisaurid in Northwestern Argentina and brings new evidence concerning the geographic distribution of the clade during Late Cretaceous times in South America.
... Huene e Matley (1933) Este terópode foi classificado por Huene (1933) como um "Alossaurídio", mas posteriormente foi reclassificado como um tiranossauro por Chatterjee (1978). Atualmente, Indosuchus raptorius é posicionado dentro de Abelisauridae, possuindo relação de parentesco sustentada por Bonaparte (1986Bonaparte ( , 1991b e Bonaparte et al. (1990). Novas et al. (2004 em análise do lectótipo e outros materiais relacionados a Indosuchus raptorius concluiu que os mesmos pertenceriam a Abelisauridae. ...
Os Abelissaurídeos (Theropoda, Abelisauridae) são di- nossauros carnívoros de médio e grande porte que viveram durante os períodos Jurássico e Cretáceo. Até o momento, os restos destes dinossauros foram encontrados apenas na Amé- rica do Sul, África, Índia, Austrália e Europa.
Muitos trabalhos abordam as relações de parentesco dos Abelisauridae, determinando características diagnósticas do grupo. Um dos mais notáveis caracteres distintivos do grupo é o encurtamento, no sentido anteroposterior de suas pré-maxilas (Bonaparte, 1991b). Outra característica notável das pré-maxi- las de Abelisauridae é a presença do forame neurovascular bem desenvolvido. Esta estrutura está presente em outros terópodes e conduzia ramos do nervo cranial V1 e vasos sanguíneos. No entanto, nos materiais de Majungasaurus crenatissimus este fo- rame pode variar no diâmetro e posição em relação a outros clados de terópodes. Este trabalho se empenha em levantar e relacionar os materiais com ausência ou presença do forame neurovascular em Abelisauridae e discutir as implicações infor- mativas acerca da paleobiologia destes grandes terópodes.
... Late Cretaceous mammal faunas in PAT have been grouped under the Alamitan SALMA. Bonaparte (1986cBonaparte ( , 1990 has greatly improved our knowledge of the land mammal fauna of this interval (see a review in Rougier et al. 2021), but the continued absence of therians has not modified the basic dispersal situation reviewed by Woodburne and Case (1996) and Case et al. (2005). The Alamitan fauna contains numerous dryolestoids, and the less prominent 'triconodonts,' 'symmetrodonts,' and gondwanatheres, which flourished in a variety of ecologies within subtropical to tropical aquatic to woodland settings reflected by a diverse framework of gymnosperms, angiosperms, ferns, monocots, conifers, and grasses (Stiles et al., 2020). ...
The Mesozoic plate tectonic and paleogeographic history of the final break up of West Gondwana had a profound effect on the distribution of terrestrial vertebrates in South America. As the supercontinent fragmented into a series of large landmasses (South America, Antarctica, Australia, New Zealand, the Indian subcontinent, and
Madagascar), particularly during the Late Jurassic and Cretaceous, its terrestrial vertebrates became progressively isolated, evolving into unique faunal assemblages. The episodic nature of South American mammalian Cenozoic faunas became apparent in its modern formulation after George Gaylord Simpson’s seminal works on this topic. Two aspects add complexity to this generally accepted scheme: first, the fact that South America is not (and was not) a biogeographic unit, as the Neotropical Region does not include its southernmost tip (the Andean Region, including Patagonia and the southern Andes). Second, and intimately linked with the first one, that South America was not an island continent during the Late Cretaceous and the beginning of the Cenozoic, being
its southernmost portion closely linked with West Antarctica up to the late Paleocene at least. Here we stress on this second aspect; we summarize a series of recent, detailed paleogeographical analyses of the continental breakup between Patagonia (including the Magallanes Region) and the Antarctic Peninsula crustal block, beginning with the opening of the Atlantic Ocean in the Early Cretaceous and running up to the Early Paleogene
with the expansion of the Scotia Basin. In second place, we comment on the implications of these distinct paleogeographic and paleobiogeographic scenarios (before and after their geographic and faunistic isolation) for the evolution of South American terrestrial mammalian faunas. Summarizing, (1) we recognize a West Weddellian terrestrial biogeographic unit with the assemblage of the southern part of South America (Patagonia and the Magallanes Region) and the Antarctic Peninsula (and probably Thurston Island) crustal block of West Antarctica, spanning from the Late Cretaceous (Campanian) through the Early Paleogene (Paleocene); (2) we suggest that the Antarctic Peninsula acted as a double "Noah’s Ark” regarding, first, the probable migration of some non-therian lineages into southern South America; later, the migration of metatherians to Australasia.
... With the exception of the most recently described taxa, Vintana (Krause et al., 2014) and Adalatherium , gondwanatherians are known only from fragmentary dental and gnathic remains. Based on the very limited morphological information available, the phylogenetic position of Gondwanatheria within Mammaliaformes has historically been controversial and has included a proposed close relationship to (1) the placental clade Xenarthra (Scillato-Yané and Pascual, 1985;Bonaparte, 1986aBonaparte, , 1986bBonaparte, , 1986cBonaparte, , 1987Bonaparte, , 1988Bonaparte, , 2017Bonaparte and Pascual, 1987;Mones, 1987) or (2) members of Allotheria, which have at various times been considered to include Multituberculata, Haramiyida (sensu Butler, 2000), and Euharamiyida (e.g., Krause et al., 1992Krause et al., , 2014Bonaparte et al., 1993;Krause, 1993;Krause and Bonaparte, 1993;Kielan-Jaworowska and Bonaparte, 1996;Gurovich, 2006;Pascual and Ortiz-Jaureguizar, 2007;Gurovich and Beck, 2009;Rougier et al., 2009Rougier et al., , 2011bBi et al., 2014;. Pascual et al. (1999) concluded that Gondwanatheria could not be assigned with certainty to any mammalian clade and simply referred to them as Mammalia incertae sedis, an opinion followed in the compendium on Mesozoic mammals by Kielan-Jaworowska et al. (2004). ...
The phylogenetic position of Gondwanatheria within Mammaliaformes has historically been controversial. The well-preserved skeleton of Adalatherium hui from the Late Cretaceous of Madagascar offers a unique opportunity to address this issue, based on morphological data from the whole skeleton. Gondwanatheria were, until recently, known only from fragmentary dental and mandibular material, as well as a single cranium. The holotype of A. hui provides the first postcranial skeleton for gondwanatherians and substantially increases the amount of character data available to score. We sampled 530 characters and 84 cynodonts (including 34 taxa historically affiliated with Allotheria) to test the phylogenetic relationships of Gondwanatheria and Allotheria using parsimony, undated Bayesian, and tip-dated Bayesian methods. We tested three lower dental formulae for Adalatherium, because its postcanines are distinctly different from those of other mammaliaforms and cannot readily be homologized with any known dental pattern. In all analyses, Adalatherium is recovered within Gondwanatheria, most frequently outside of Sudamericidae or Ferugliotheriidae, which is congruent with establishment of the family Adalatheriidae. The different dental coding schemes do not greatly impact the position of Adalatherium, although there are differences in character optimization. In all analyses, Gondwanatheria are placed within Allotheria, either as sister to Multituberculata, nested within Multituberculata, or as sister to Cifelliodon (and Euharamiyida), or in a polytomy with other allotherians. The composition of Allotheria varies in our analyses. The haramiyidans Haramiyavia and Thomasia are placed outside of Allotheria in the parsimony and tip-dated Bayesian analyses, but in a polytomy with other allotherians in the undated Bayesian analyses.
... Consequently, Late Cretaceous dinosaurs evolved distinct faunas in different regions (Bonaparte, 1986;Bonaparte and Kielan-Jaworowska, 1987;Sampson et al., 1998;Weishampel et al., 2004;Ezcurra and Agnolín, 2012;Longrich et al., 2017). In Asia and North America, ornithischians, including hadrosaurids and ceratopsians, dominated herbivore niches; tyrannosaurids were top predators. ...
The Late Cretaceous saw distinctly endemic dinosaur faunas evolve in the northern and southern hemispheres. The Laurasian continents of North America and Asia were dominated by hadrosaurid and ceratopsian ornithischians, with tyrannosaurs as apex predators. In Gondwanan communities, including Africa, South America, India and Madagascar, titanosaurian sauropods dominated as herbivores and abelisaurids as predators. These patterns are thought to be driven by the breakup of Pangaea and formation of seaways limiting dispersal. Here, we report a new lambeosaurine hadrosaurid, Ajnabia odysseus gen. et sp. nov., from the upper Maastrichtian of Morocco, North Africa, the first Gondwanan representative of a clade formerly thought to be restricted to Laurasia. The new animal shows features unique to Hadrosauridae and specifically Lambeosaurinae. Phylogenetic analysis recovers it within Arenysaurini, a clade of lambeosaurines previously known only in Europe. Biogeographic modelling shows that lambeosaurines dispersed from Asia to Europe, then to Africa. Given the existence of large, persistent seaways isolating Africa and Europe from other continents, and the absence of the extensive, bidirectional interchange characterizing land bridges, these patterns suggest dispersals across marine barriers, similar to those seen in Cenozoic mammals, reptiles, and amphibians. Dispersal across marine barriers also occurs in other hadrosaurid lineages and titanosaurian sauropods, suggesting oceanic dispersal played a key role in structuring Mesozoic terrestrial dinosaur faunas.
... Both ischia are also preserved and incorporated into the mounted skeleton (figure 4d; see table 2 for measurements). They are incomplete proximally and missing some of their margins [60, pl. 1, figs 6,7]. Based on its preserved lower portion, the iliac peduncle is approximately twice as long anteroposteriorly as it is wide, but there is unlikely to have been a large ischial contribution to the acetabulum. ...
Titanosaurs were a globally distributed clade of Cretaceous sauropods. Historically regarded as a primarily Gondwanan radiation, there is a growing number of Eurasian taxa, with several putative titanosaurs contemporaneous with, or even pre-dating, the oldest known Southern Hemisphere remains. The early Late Cretaceous Jinhua Formation, in Zhejiang Province, China, has yielded two putative titanosaurs, Jiangshanosaurus lixianensis and Dongyangosaurus sinensis. Here, we provide a detailed re-description and diagnosis of Jiangshanosaurus, as well as new anatomical information on Dongyangosaurus. Previously, a 'derived' titanosaurian placement for Jiangshanosaurus was primarily based on the presence of procoelous anterior caudal centra. We show that this taxon had amphicoelous anterior-middle caudal centra. Its only titanosaurian synapomorphy is that the dorsal margins of the scapula and coracoid are approximately level with one another. Dongyangosaurus can clearly be differentiated from Jiangshanosaurus, and displays features that indicate a closer relationship to the titanosaur radiation. Revised scores for both taxa are incorporated into an expanded phylogenetic data matrix, comprising 124 taxa scored for 548 characters. Under equal weights parsimony, Jiangshanosaurus is recovered as a member of the non-titanosaurian East Asian somphospondylan clade Euhelopodidae, and Dongyangosaurus lies just outside of Titanosauria. However, when extended implied weighting is applied, both taxa are placed within Titanosauria. Most other 'middle' Cretaceous East Asian sauropods are probably non-titanosaurian somphospondylans, but at least Xianshanosaurus appears to belong to the titanosaur radiation. Our analyses also recover the Early Cretaceous European sauropod Normanniasaurus genceyi as a 'derived' titanosaur, clustering with Gondwanan taxa. These results provide further support for a widespread diversification of titanosaurs by at least the Early Cretaceous.
... In contrast to the ornithischian-dominated faunas of the Northern Hemisphere (Bonaparte & Kielan-Jaworoska 1987), in South America sauropods were the dominant clade of herbivorous dinosaurs during the Jurassic and Cretaceous periods (Bonaparte 1984(Bonaparte , 1986Novas 2009;Novas et al. 2013). However, the records of ornithopods from South America have greatly increased in recent years (e.g. ...
Talenkauen santacrucensis represents one of the most complete South American ornithopods yet discovered. This dinosaur comes from the Mata Amarilla Formation (Turonian) of Santa Cruz Province, Argentina. The aim of this contribution is to present a detailed description of Talenkauen santacrucensis. Features of the cervical series of Talenkauen, which are shared with other elasmarians, indicate that these dinosaurs have a proportionally longer neck than other ornithopods. These traits were convergently acquired by several saurischian clades. Additionally, some features, including an ornamented labial surface of the mandibular teeth and a sigmoidal greater trochanter of femur, are traits shared by most elasmarians, and may prove to be synapomorphies of this clade. A phylogenetic analysis recovers most Cretaceous Gondwanan ornithopods in the clade Elasmaria. This analysis indicates that Elasmaria was distributed more widely geographically and temporally than previously thought.
... Since 1985, the naming of new Gondwanan theropod species showed an exponential increase mainly due to the efforts of the Argentine palaeontologist José Bonaparte (Fig. 2). The discoveries of Bonaparte and his collaborators resulted in the recognition of a different evolutionary history of the southern theropods from that of their northern counterparts (Bonaparte, 1986;Bonaparte and Kielan-Jaworowska, 1987 (Woodward, 1901); 2, isolated tooth crown of an indeterminate theropod (Museo Argentino de Ciencias Naturales, Colección Ameghino 10985) formerly referred to "Loncosaurus argentinus" from the Upper Cretaceous of the Argentinean Patagonia (Ameghino, 1899); 3, right tibia of the averostran Kakuru kujani (South Australia Museum P17926, holotype) from the Lower Cretaceous of Australia (Molnar and Pledge, 1980); 4, postcranial skeleton of the ceratosaurian Elaphrosaurus bambergi (Museum für Naturkunde 4960, holotype) from the Upper Jurassic of Tanzania (Janensch, 1920); 5, right dentary of the abelisaurid Majungasaurus crenatissimus (Muséum National d'Historie Naturelle MAJ 1, holotype) from the Upper Cretaceous of Madagascar (Lavocat, 1955); 6, cast of the partial braincase of the abelisaurid Indosaurus matleyi (cast in the Paläontologische Sammlung der Universität Tübingen) from the Upper Cretaceous of India (Huene and Matley, 1933) ...
... During the latest Cretaceous, distinct dinosaur faunas were found in Gondwana and Laurasia (Bonaparte, 1986;Bonaparte and Kielan-Jaworowska, 1987;Weishampel et al., 2004;Ezcurra and Agnolín, 2012). In North America and Asia, the herbivore community was composed of a diverse assemblage of ornithischians, including hadrosaurids (Horner et al., 2004), ceratopsians You and Dodson, 2004), ankylosaurians (Vickaryous et al., 2004) and pachycephalosaurids , along with herbivorous coelurosaurs (Zanno and Makovicky, 2011), including ornithomimosaurs , oviraptorosaurs (Osmólska et al., 2004), and troodontids . ...
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 titanosaurids 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 titanosaurid remains, Chenanisaurus documents the persistence of a classic Gondwanan abelisaurid-titanosaurid 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.
... The study of geographic distribution of South American Cretaceous ornithopods has only been applied in paleogeographic analysis in regards to hadrosaurs ( Brett-Surman, 1979;Bonaparte and Kielan-Jawarowska, 1987) since, these were the only ornithopods known until now for these latitudes. The presence of this hadrosaur fauna, as well as the recently reported discovery of ankylosaurs from the same levels (Salgado and Coria, 1996) has been explained upon the basis of faunal interchange between both South and North America during Campanian and Maastrichtian ( Bonaparte, 1986). In this time, both South America and North America contacted each other due to the continentalization of Caribbean regions caused by orogenic activity ( Zambrano, 1981;Pitman et al., 1993). ...
The discovery of a new iguanodontian ornithopod in the lower units of the Neuquen Group (Rio Limay Formation, early Upper Cretaceous) increases the South American record of this kind of dinosaurs started few years ago with the report of Gasparinisaura cincosaltensis. Anabisetia saldiviai, gen. et sp. nov. is distinguished from all other ornithopods by several features, as a flattened fifth metacarpal, a scapula with a very strong acromial process, and an ilium with preacetabular process longer than 50% of the total ilium length. Anabisetia is more derived than Tenontosaurus and shares with Euiguanodontia (Gasparinisaura + Dryomorpha) the presence of one primary lateral ridge on each maxillary tooth, a broad brevis-shelf and a reduced first metatarsal. Derived features such as the transversely flattened prepubic process and an anteroventrally oriented ischiadic foot link Anabisetia with Dryomorpha (i.e., Dryosaurus, Camptosaurus and Iguanodon). Anabisetia strengths the hypothesis that basal iguanodontian ornithopods were present in South America before its with North America in the Late Cretaceous.
... Saurischia Seeley, 1887Sauropoda Marsh, 1878Neosauropoda Bonaparte, 1986Titanosauriformes Salgado et al., 1997 Titanosauria Bonaparte andCoria, 1993 Lithostrotia Upchurch et al., 2004 ...
... Sobre la base de esta hipótesis filogenética, Coria (2001) arribó a conclusiones paleobiogeográficas, indicando que Quilmesaurus correspondería a una forma autóctona y no formaría parte de un evento de dispersión faunística proveniente de América del Norte durante el Senoniano Superior sugerido para otros grupos de tetrápodos (p. ej., Bonaparte, 1986a;Powell, 1987;Salgado & Coria, 1996). ...
Resumen
Quilmesaurus curriei Coria, 2001 (Dinosauria, Theropoda). Its taxonomic validity and phylogenetic relationships. A comparative analysis of the Cretaceous theropod Quilmesaurus curriei from the Río Negro province, Patagonia, Argentina was performed in order to elucidate its phylogenetic relationships. Quilmesaurus was considered as basal Tetanurae by Coria (2001), however, Kellner & Campos (2002) suggested that this theropod could be a possible Abelisauria. In our analysis, we observed that the lack of fusion of the tibia with the astragalus- calcaneum is not an exclusive character for Ceratosauria; moreover, the mediodistal crest of femur is commonly well developed in Abelisauroidea. The great development of the distally expanded cnemial crest and the asymmetrical distal end of the tibia are characteristics of Abelisauridae. Finally, other characters like a distally directed process at the end of the cnemial crest and the asymmetry in the origin of the expansion of the malleolii in distal tibia are regarded as synapomorphies of Carnotaurinae. Therefore, Quilmesaurus curriei is considered to belong to Abelisauridae, and it is possibly a member of Carnotaurinae. On the basis of the available evidence, it is not possible to identify autapomorphic characters that allow validating Quilmesaurus curriei, and for this reason we consider it as a nomen vanum.
... The La Amarga Formation (Barremian), outcropping in Neuqu en Province, northwestern Patagonia Argentina, is a remarkable continental unit from this period of time. In addition to saurischian and ornithischian dinosaurs, it contains a diverse vertebrate assemblage including, pterosaurs, crocodyliforms and mammals (Bonaparte, 1986(Bonaparte, , 1996Montanelli, 1987;Chiappe, 1988;Salgado and Bonaparte, 1991;Leanza et al., 2004;Apesteguía, 2007;Pereda-Suberbiola et al., 2013). ...
Saurophaganax maximus is the designation of material attributed to a massive theropod dino-saur recovered from the Kenton 1 Quarry in the Kenton Member of the Upper Jurassic Morrison Formation of Oklahoma. The theropod was originally given the name Saurophagus maximus, but was later revised to Saurophaganax maximus because the former did not conform to the International Commission on Zoological Nomenclature standards. Several autapomorphies were described for S. maximus including the postorbital lacking a postorbital boss, the atlas lacking facets for a proatlas, cervical vertebrae with nearly vertical post-zygapophyses, unique accessory laminae on the holotype neural arch, pneumatized post-pectoral dorsal cen-tra, craniocaudally expanded chevrons, laterally bowed femora, tibiae without an astragalar buttress and more prominent distomedial crest, and less distally divergent fourth metatarsals. However, our re-evaluation shows that some of the elements originally used to distinguish Saurophaganax from Allosaurus are more parsimoni-ously referred to diplodocid sauropods found in the same quarry rather than an allosaurid. Additionally, the holotype neural arch cannot be confidently assigned to a theropod, making Saurophaganax maximus a nomen dubium. The presence of at least one skeletally mature theropod was confirmed through paleohistology of a fourth metatarsal. Despite the similarity of the decisively theropod material to known species of Allosaurus, some elements feature subtle autapomorphies that suggest they pertain to a distinct species, which we de-scribe as Allosaurus anax sp. nov.
ABSTRACT—Small-bodied theropod dinosaurs are rare on southern landmasses but have been known from India for a century. Excavations by Charles Matley and rgansankar Bhattacharji in uppermost Cretaceous sediments at Bara Simla, central India in 1917–1919 recovered small theropod vertebral and limb elements originally interpreted as coelurosaurians and separated into at least three species compsosuchus solus, Laevisuchus indicus, Jubbulpuria tenuis) based on features that can now be attributed to their serial position in the vertebral column. The comparatively recent discoveries of Noasaurus leali and Masiakasaurus knopfleri from similar-aged rocks in South America and Madagascar, respectively, and advances in basal theropod systematics led to a revised interpretation of most small-bodied Indian theropods as noasaurid abelisauroids. Here we review and redescribe Laevisuchus, Jubbulpuria, and Compsosuchus, including several elements that until now were thought lost, and describe a new partial noasaurid dentary from central India. The dentary bears the characteristic procumbent dentition of Masiakasaurus, which apparently is absent in Noasaurus. Likewise, cervical vertebrae of Laevisuchus more closely resemble those of Masiakasaurus than those of Noasaurus. Despite these similarities, phylogenetic analyses indicate that the balance of character data supports the Indian noasaurid species outside the sister-taxon pairing of South American and Malagasy species. Bones of small-bodied theropods have been recovered exclusively from the youngest Mesozoic localities in India (e.g., Pisdura, Bara Simla); to date they have not been reported from the slightly older localities in western and central India, from southern Indian sites in the Cauvery Basin, nor from the Vitakri Formation of Pakistan.
Although the origin of Neosauropoda probably dates back to the Early–Middle Jurassic, it is not until the Late Jurassic that Macronaria become well represented in the fossil record. Unlike the great diversity of South American titanosaurs, basal macronarians are relatively scarce in the fossil record; even so, they provide valuable information for better understanding the first steps at the origin of this clade. The only non-titanosauriform macronarian sauropod from South America is Tehuelchesaurus from the Oxfordian-Tithonian of Argentina, while all other basal macronarians found up to date are titanosauriforms (either Brachiosauridae or Somphospondyli). Brachiosaurids were abundant in the Jurassic, but they apparently became extinct at the Jurassic/Cretaceous boundary all over the world except in North America. Isolated elements from the Late Jurassic of Argentina and Padillasaurus from the Early Cretaceous of Colombia were suggested as brachiosaurids, but these assignments are questionable. Until now, no clear somphospondylans have been recorded in Jurassic levels. In South America, basal, non-titanosaur somphospondylans are represented by three taxa registered in Argentina: Chubutisaurus and Ligabuesaurus from the Early Cretaceous (Aptian–Albian) and Malarguesaurus from the Late Cretaceous (Turonian–Coniacian). Here, we provide a complete revision on the fossil record of non-titanosaur macronarians from South America and the current phylogenetic status of them.
After the extinction of rebbachisaurids during the Cenomanian–Turonian interval, titanosaurs were the only group of sauropods to face the K–Pg event. This same global pattern also holds for the end-Cretaceous (Campanian–Maastrichtian) titanosaur record in South America, where their remains can be found from southern Argentina to Ecuador, with more frequent findings in Argentina and Brazil. In this chapter, we review these fossil findings and the main aspects of the taxonomy, systematics, and paleogeographic implications of this record and briefly discuss the importance of these occurrences for the understanding of titanosaur evolution. The diversity and abundance of end-Cretaceous titanosaur taxa in South America represent about 25% of the known Titanosauria species in the world, which makes them the most common group of large terrestrial herbivores of that time. Cretaceous titanosaurs from South America also vary highly in morphology and size, comprising small to large-sized taxa, for example. Their record mainly consists of appendicular and axial remains, including rare skull material, but also comprises eggs, nests, footprints, and coprolites. In South America, by the end of the Late Cretaceous, titanosaurs were generally represented by more derived titanosaurians that are mainly taxonomically assigned to more derived species within Aeolosaurini and Saltasaurinae.
We describe the first maxillae and additional new specimens of Reigitherium bunodontum, a small meridiolestidan from the Late Cretaceous La Colonia Formation, Patagonia, Argentina. The new material supports a dental formula of I?, C1, P4, M3, resolves postcanine positional uncertainty and corrects previous interpretations. Our phylogeny recovers Reigitherium as a meridiolestidan allied to other bunodont Mesungulatoidea, as the sister group of the Paleocene Peligrotherium. Posterior premolars/molars of Reigitherium, and to a smaller degree Peligrotherium, are dominated by an incomplete transverse ridge running between the protoconid-metaconid in the lowers and the paracone-stylocone in the uppers, semi-symmetrical basins developing mesially and distally from these central ridges. The trigonid-derived single transverse crest results from a mesial shift of the robust metaconid, an enhancement of the basin crest stretching from the protoconid/metaconid, and a shallower trigonid basin. The mesungulatoid condition, with its complete absence of talonid, contrasts sharply with that of therians with lophs, or transverse ridges, which involved at least one talonid-derived loph resulting in two transverse crests per tooth. Mesungulatoid meridiolestidans achieved complex tooth-on-tooth occlusion with a predicted increase in herbivory/omnivory, departing from the traditional sharp-cusp insectivores plesiomorphic for meridiolestidans and Mesozoic mammals in general. Reigitherium’s dramatic remodeling of the primitive meridiolestidan molar morphology, extensive continuous occlusal surface, accessory cuspules, and highly textured crenulated enamel illustrates one of most distinctive adaptations to herbivory among Mesozoic mammals.
The titanosaur sauropod record of Patagonia, mainly recovered from Upper Cretaceous strata, is probably the richest worldwide. Here
we present a new sauropod dinosaur, Ninjatitan zapatai gen. et sp. nov., from the Lower Cretaceous Bajada Colorada Formation (Berriasian–
Valanginian) of north Patagonia (Neuquén Province, Argentina), from which postcranial remains are preserved. The anatomical analysis and com-
parisons performed in this specimen evidence strong affinity with titanosaur sauropods. This assumption is corroborated with the inclusion of
the new taxon in an updated phylogenetic data matrix. The cladistic analyses indicate that Ninjatitan could be considered the earliest known
titanosaur sauropod. The combination of features such as the presence of procoelous anterior caudal centra, the pneumatized neural arch of
anterior caudal vertebrae, and the posterodorsal border of the scapular acromion near the glenoid level supports its titanosaur affinities. The
presence of a basal titanosaurian sauropod in the lowermost Cretaceous of Patagonia supports the hypothesis that the group was established
in the Southern Hemisphere and reinforces the idea of a Gondwanan origin for Titanosauria. The Bajada Colorada sauropod fauna represents
one of the most diverse and unique associations from the lowermost Cretaceous worldwide recorded.
The South American fossil record of Mesozoic mammals and close relatives is one of the best for Gondwana. Early mammals and relatives are found in about a dozen localities in Argentina, Brazil, Bolivia, Chile, and presumably Peru, including a broad sample of non-mammaliaform cynodonts of the Triassic age. Mesozoic mammals span from the latest Early Jurassic to the latest Cretaceous, furthermore some of those archaic lineages unexpectedly survived the end of the Cretaceous period, remaining as minority elements in the Paleocene–Miocene faunal associations. The fossiliferous localities bearing these fossils are presented in this chapter, highlighting the geological setting, age, and their faunal associations.
The sparse record of archaic Mesozoic South American mammals extends from the latest Early Jurassic to the latest Cretaceous, involving about 115 Ma, which can be further extended to about 160 Ma, including the post-K/Pg evidence. We review here the distribution, predicted time of origin, and likely place of origin for the lineages covered in the preceding chapters during that span of time and against the evolving geological backdrop of continental drift and paleogeography. Size, dental diversity, and likely dietary specializations of the Mesozoic South American mammals are discussed in the context of Mesozoic mammals in general. A few of the many surprising advances in comparative genetic and molecular evolution are discussed as part of a holistic view of early mammalian evolution to which fossils can, and should, be integrated. Social, financial, and geographical issues affecting paleontological research in South America, early mammals, in particular, are highlighted. We recognize that we are still in the early stages of development and that much of what we know about Mesozoic South American mammals is likely to be drastically altered by finds in the continent or underrepresented areas from formely Gondwanan landmasses such as Antarctica or Africa. Their scarce mammalian fossil record has hampered their full incorporation into an integrated view of early mammalian evolution. The relatively robust paleontological community present in several South American countries, relatively inexpensive nature of the discipline, and extensive outcrops are likely to ensure continuity of a synergistic research agenda. The potential for novel data, regional strengths in systematics, and the global resurgent importance of time as integral to model-based phylogenies are auspicious signs for the future of Mesozoic mammal research in South America.
Dryolestoids are iconic members of the Mesozoic mammalian associations in South America. They achieved a large taxonomic diversity in this region with disparate dental and cranial morphotypes ranging from the classical role of sharp-toothed insectivores to bunodont, complex dentitions reflecting omnivore/herbivore adaptations. The South American radiation of dryolestoids, the meridiolestidans, are among the most abundant Cretaceous mammals, surviving the K/Pg mass extinction and continuing until the Miocene as minor members of the South American biotas. New specimens have been recently discovered, some of them including associated upper and lower jaws, and exceptionally preserved skulls. These high-quality fossils provide crucial intraspecific dental variation, both along the tooth row and from upper to lower, allowing critical re-interpretation of some taxa originally named on the basis of isolated teeth or very incomplete material. The Cretaceous diversity of meridiolestidans has been grossly overestimated, with taxa based on different dental positions of what was later determinied to be a single taxon. One relatively poorly known Late Cretaceous taxon, Groebertherium, shares many features with the classical Holartic dryolestoids and may represent a Late Jurassic/Early Cretaceous foundational morphology expected for meridiolestidans.
The enigmatic Gondwanatheria includes mammals with a mosaic of plesiomorphic and apomorphic cranial and dental features challenging our attempts to reconstruct their phylogenetic affiliation. They are generally perceived as sharing a closer ancestor with multituberculates than with therians in a variably conceived Allotheria. Two major groups are classically recognized among the South American Gondwanatheria: the brachyodont-toothed Ferugliotheriidae and the hypsodont-toothed Sudamericidae, although not all taxa fall easily in these categories. The affinities of the Ferugliotheriidae are, however, unsettled, with some authors favoring the hypothesis that they are indeed a derived branch of multituberculates. The original foundational Patagonian finds of gondwanatherians have recently been much improved by spectacular Late Cretaceous Malagasy materials, which increase dental diversity of the group, provide detailed cranial/postcranial morphology, and support allotherian affinities for the group.
Non-mammaliaform cynodonts, formerly called “mammal-like reptiles,” illustrate earlier states of the morphological architecture in the mammalian lineage. These mammalian forerunners show unique character combinations without direct counterparts among living vertebrates reflecting adaptations long lost along the millions of years of cynodont history. The fossil record from South America, originating mostly from the Middle to Late Triassic of Argentina and Brazil, is one of the most prolific worldwide. SA non-mammalian cynodonts are systematically diverse, including approximately 40 species that present great morphological disparity in skull shape, tooth morphology, pattern of tooth replacement, masticatory mechanisms, and locomotory architectures. In this chapter, we summarize the record of SA non-mammaliaform cynodonts.
The first fossil remains of vertebrates, invertebrates, plants and palynomorphs of the Chorrillo Formation (Austral Basin), about 30km to the SW of the town of El Calafate (Province of Santa Cruz), are described. Fossils include the elasmarian (basal Iguanodontia) Isasicursor santacrucensis gen. et sp. nov., the large titanosaur Nullotitan glaciaris gen. et sp. nov., both large and small Megaraptoridae indet., and fragments of sauropod and theropod eggshells. The list of vertebrates is also composed by the Neognathae Kookne yeutensis gen. et sp. nov., two isolated caudal vertebrae of Mammalia indet., and isolated teeth of a large mosasaur. Remains of fishes, anurans, turtles, and snakes are represented by fragmentary material of low taxonomical value, with the exception of remains belonging to Calyptocephalellidae. On the other hand, a remarkable diversity of terrestrial and freshwater gastropods has been documented, as well as fossil woods and palinological assemblages. The Chorrillo Formation continues south, in the Las Chinas River valley, southern Chile, where it is called Dorotea Formation. Both units share in their lower two thirds abundant materials of titanosaurs, whose remains cease to appear in the upper third, registering only elasmarians (Chorrillo Formation) and hadrosaurs (Dorotea Formation). Above both units there are levels with remains of invertebrates and marine reptiles. It is striking that the dinosaurs of the lower two thirds of the Chorrillo and Dorotea formations are represented by large basal titanosaurs and Megaraptoridae coelurosaurs, being the Saltasaurinae and Aeolosaurinae sauropods and Abelisauridae theropods totally absent. In contrast, these taxa are dominant components in sedimentary units of central and northern Patagonia (e.g., Allen, Los Alamitos, La Colonia formations). Such differences could reflect, in part, a greater antiquity (i.e., late Campanian-early Maastrichtian) for the Chorrillo fossils, or, more probably, different environmental conditions. Thus, knowledge of the biota of the southern tip of Patagonia is expanded, particularly those temporarily close to the K-Pg boundary.
Extensive and well-preserved tracksites in the coastally exposed Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula provide almost the entire fossil record of dinosaurs from the western half of the Australian continent. Tracks near the town of Broome were described in the late 1960s as Megalosauropus broomensis and attributed to a medium-sized theropod trackmaker. Brief reports in the early 1990s suggested the occurrence of at least another nine types of tracks, referable to theropod, sauropod, ornithopod, and thyreophoran trackmakers, at scattered tracksites spread over more than 80 km of coastline north of Broome, potentially representing one of the world's most diverse dinosaurian ichnofaunas. More recently, it has been proposed that this number could be as high as 16 and that the sites are spread over more than 200 km. However, the only substantial research that has been published on these more recent discoveries is a preliminary study of the sauropod tracks and an account of the ways in which the heavy passage of sauropod trackmakers may have shaped the Dampier Peninsula's Early Cretaceous landscape. With the other types of dinosaurian tracks in the Broome Sandstone remaining undescribed, and the full extent and nature of the Dampier Peninsula's dinosaurian tracksites yet to be adequately addressed, the overall scientific significance of the ichnofauna has remained enigmatic.
At the request of the area's Goolarabooloo Traditional Custodians, 400+ hours of ichnological survey work was undertaken from 2011 to 2016 on the 25 km stretch of coastline in the Yanijarri–Lurujarri section of the Dampier Peninsula, inclusive of the coastline at Walmadany (James Price Point). Forty-eight discrete dinosaurian tracksites were identified in this area, and thousands of tracks were examined and measured in situ and using three-dimensional photogrammetry. Tracksites were concentrated in three main areas along the coast: Yanijarri in the north, Walmadany in the middle, and Kardilakan–Jajal Buru in the south. Lithofacies analysis revealed 16 repeated facies types that occurred in three distinctive lithofacies associations, indicative of an environmental transgression between the distal fluvial to deltaic portions of a large braid plain, with migrating sand bodies and periodic sheet floods. The main dinosaurian track-bearing horizons seem to have been generated between periodic sheet floods that blanketed the preexisting sand bodies within the braid plain portion of a tidally influenced delta, with much of the original, gently undulating topography now preserved over large expanses of the present day intertidal reef system. Of the tracks examined, 150 could be identified and are assignable to a least eleven and possibly as many as 21 different track types: five different types of theropod tracks, at least six types of sauropod tracks, four types of ornithopod tracks, and six types of thyreophoran tracks. Eleven of these track types can formally be assigned or compared to existing or new ichnotaxa, whereas the remaining ten represent morphotypes that, although distinct, are currently too poorly represented to confidently assign to existing or new ichnotaxa. Among the ichnotaxa that we have recognized, only two (Megalosauropus broomensis and Wintonopus latomorum) belong to existing ichnotaxa, and two compare to existing ichnotaxa but display a suite of morphological features suggesting that they may be distinct in their own right and are therefore placed in open nomenclature. Six of the ichnotaxa that we have identified are new: one theropod ichnotaxon, Yangtzepus clarkei, ichnosp. nov.; one sauropod ichnotaxon, Oobardjidama foulkesi, ichnogen. et ichnosp. nov.; two ornithopod ichnotaxa, Wintonopus middletonae, ichnosp. nov., and Walmadanyichnus hunteri, ichnogen. et ichnosp. nov.; and two thyreophoran ichnotaxa, Garbina roeorum, ichnogen. et ichnosp. nov., and Luluichnus mueckei, ichnogen. et ichnosp. nov. The level of diversity of the main track types is comparable across areas where tracksites are concentrated: Kardilakan–Jajal Buru (12), Walmadany (11), and Yanijarri (10).
The overall diversity of the dinosaurian ichnofauna of the Broome Sandstone in the Yanijarri–Lurujarri section of the Dampier Peninsula is unparalleled in Australia, and even globally. In addition to being the primary record of non-avian dinosaurs in the western half of Australia, this ichnofauna provides our only detailed glimpse of Australia's dinosaurian fauna during the first half of the Early Cretaceous. It indicates that the general composition of Australia's mid-Cretaceous dinosaurian fauna was already in place by the Valanginian–Barremian. Both sauropods and ornithopods were diverse and abundant, and thyreophorans were the only type of quadrupedal ornithischians. Important aspects of the fauna that are not seen in the Australian mid-Cretaceous body fossil record are the presence of stegosaurians, an overall higher diversity of thyreophorans and theropods, and the presence of large-bodied hadrosauroid-like ornithopods and very large-bodied sauropods. In many respects, these differences suggest a holdover from the Late Jurassic, when the majority of dinosaurian clades had a more cosmopolitan distribution prior to the fragmentation of Pangea. Although the record for the Lower Cretaceous of Gondwana is sparse, a similar mix of taxa occurs in the Barremian–lower Aptian La Amarga Formation of Argentina and the Berriasian–Hauterivian Kirkwood Formation of South Africa. The persistence of this fauna across the Jurassic-Cretaceous boundary in South America, Africa, and Australia might be characteristic of Gondwanan dinosaurian faunas more broadly. It suggests that the extinction event that affected Laurasian dinosaurian faunas across the Jurassic-Cretaceous boundary may not have been as extreme in Gondwana, and this difference may have foreshadowed the onset of Laurasian-Eurogondwanan provincialism. The disappearance of stegosaurians and the apparent drop in diversity of theropods by the mid-Cretaceous suggests that, similar to South America, Australia passed through a period of faunal turnover between the Valanginian and Aptian. -------- In: Society of Vertebrate Paleontology Memoir (Journal of Vertebrate Paleontology Vol. 36, supplement to 6, November 2016).
In this chapter, we (1) describe and illustrate the anatomy of a complete skull, posterior half of a dentary, and cheektooth dentition of a Miocene ornithorhynchid, Obdurodon dicksoni from Riversleigh, Queensland, Australia; (2) use this new information to reevaluate understanding of the anatomy of the living Ornithorhynchus anatinus; (3) revise previous understanding about the monotreme dentition; and (4) reconsider monotreme relationships.
Alcidedorbignya inopinata Muizon and Marshall is a primitive pantodont from the Early Paleocene of Tiupampa, Department of Cochabamba, in the “Cordillera Oriental” of south-central Bolivia. It is known by almost complete upper and lower dentitions, which are described in detail. The occurrence of abundant juvenile specimens allows a study of tooth replacement. The molars of Alcidedorbignya inopinata are primitive for a pantodont but they show the characteristic synapomorphy of the group, which is the presence of a V-shaped ectoloph of P3-4. However, the paracone and the metacone of A. inopinata are separated at their bases, a feature absent in the Bemalambdidae and Harpyodus , which have connate to semi-connate paracone and metacone. Because of this character, A. inopinata , although the oldest, is not the most primitive pantodont. However, A. inopinata , as in bemalambdids and Harpyodus , does not have a mesostyle on M1-2/ or a strongly V-shaped centrocrista, which are found in all other pantodonts. For this reason, Alcidedorbignya inopinata is removed from the Pantolambdidae (which are too specialized) and referred to the new monotypic family Alcidedorbignyidae. The family Wangliidae Van Valen, 1988, is not accepted here and the genus Wanglia is regarded as a junior synonym of Harpyodus ; the latter includes the two species H. euros and H. decorus. Analysis of pantodont origins leads to the conclusion that didelphodontines constitute the best potential sister-group; however, no synapomorphy could be found to substantiate this hypothesis. Alcidedorbignya inopinata is the first pantodont known from a southern continent and, being the oldest, it raises a discussion on the paleobiogeographic history of the group.
We summarize the configuration of plates, geographical barriers, and possible dispersal events during the Late Cretaceous–Cenozoic between North and South America, the Caribbean, Antarctica, and Australia. The arrival of metatherians in South America was a Late Cretaceous event, and probably a Maastrichtian one. There are few doubts that the first metatherians in this continent arrived from North America. We suggest that not only eutherian mammals but also metatherians may have reached South America from the north in a series of successive dispersal waifs. This FABI (First American Biotic Interchange) may have replicated the successive waif dispersal mood of the late Cenozoic GABI (Great American Biotic Interchange). The initial radiation of basal South American metatherian lineages (“Ameridelphia”) may have already occurred by Late Campanian-Maastrichtian times. We also suggest that a cooling pulse happening by the Latest Cretaceous (Late Maastrichtian, ca. 68–67 Ma) may have been involved in the origin of the Australidelphia, as part of the southern (Austral Kingdom) Nothofagus biota. Four out of six faunal phases were involved in the evolution of South American metatherians: (1) Early South American (Late Cretaceous to the Late Eocene), Late South American (Early Oligocene to late Miocene), Interamerican (Plio–Pleistocene), and Hypoamerican (Holocene). The first of these phases involved the arrival and expansion of many lineages and adaptive types. The global cooling by the Eocene–Oligocene Boundary implied the extinction of many (mostly tropical) lineages, as well as the diversification of several specialized ones. The third of these faunal phases transpired during a time lapse of ecological imbalance and global cooling, while the last phase saw already much impoverished metatherian associations throughout the continent.
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