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Notohypsilophodon comodorensis, un Hypsilophodontidae (Ornithischia: Ornithopoda) del Cretácico Superior de Chubut, Patagonia Central, Argentina
... They are dorsoventrally taller than transversely wide, indicating these centrae correspond to the mid-dorsal series. The ventral surface bears a stout ventral keel, as occurs in most basal ornithopods including elasmarians (i.e., Coria & Salgado, 1996;Martínez, 1998;Coria & Calvo, 2002;Calvo et al., 2007;Coria et al., 2013;Ibiricu et al., 2014;Cruzado-Caballero et al., 2019;Rozadilla et al., 2019). Some vascular foramina are present on the lateral and ventral surfaces of the centra. ...
... The left humerus is represented by isolated and incomplete shaft and distal end. The shaft is laterally bowed, as synapomorphic for Elasmaria (e.g., Anabisetia, Notohypsilophodon, Talenkauen, Trinisaura, Sektensaurus, Mahuidacursor;Martínez, 1998;Coria & Calvo, 2002;Coria et al., 2013;Ibiricu et al., 2014;Cruzado-Caballero, 2019;Rozadilla et al., 2019). The deltopectoral crest is reduced and represented by a low ridge, its lateral surface crossed by longitudinal muscle scars, as diagnostic for Elasmaria (e.g., Anabisetia , Notohypsilophodon, Talenkauen, Trinisaura, Sektensaurus, Mahuidacursor; Martínez, 1998;Coria & Calvo, 2002;Coria et al., 2013;Ibiricu et al., 2014;Cruzado-Caballero, 2019;Rozadilla et al., 2019), in contrast with the well-developed deltopectoral crest present in most ornithopods, including Gasparinisaura (Coria & Salgado, 1996;Rozadilla et al., 2019). ...
... The shaft is laterally bowed, as synapomorphic for Elasmaria (e.g., Anabisetia, Notohypsilophodon, Talenkauen, Trinisaura, Sektensaurus, Mahuidacursor;Martínez, 1998;Coria & Calvo, 2002;Coria et al., 2013;Ibiricu et al., 2014;Cruzado-Caballero, 2019;Rozadilla et al., 2019). The deltopectoral crest is reduced and represented by a low ridge, its lateral surface crossed by longitudinal muscle scars, as diagnostic for Elasmaria (e.g., Anabisetia , Notohypsilophodon, Talenkauen, Trinisaura, Sektensaurus, Mahuidacursor; Martínez, 1998;Coria & Calvo, 2002;Coria et al., 2013;Ibiricu et al., 2014;Cruzado-Caballero, 2019;Rozadilla et al., 2019), in contrast with the well-developed deltopectoral crest present in most ornithopods, including Gasparinisaura (Coria & Salgado, 1996;Rozadilla et al., 2019). The anterior surface of the humeral shaft is concave, while the posterior one is convex. ...
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.
... 6.9. Ornithopoda (Marsh, 1881) Notohypsilophodon comodorensis (Martínez, 1998) Holotype. UNPSJB-PV 942. ...
... Ornithopod fossils in the Bajo Barreal Formation are far rarer than those of sauropods or theropods. This imbues each ornithopod find with much importance, and the first reported was Notohypsilophodon comodorensis by Martínez (1998), represented by a relatively well-preserved partial skeleton (Fig. 10). Notohypsilophodon was originally assigned to the "Hypsilophodontidae" based on morphological features shared with taxa of that clade. ...
... Nevertheless, the presence of this group in pre-Santonian levels has important implications: for example, the probable affinities of these remains with the Australian megaraptoran Australovenator would support some degree of faunal connectivity between the two continents. The only ornithischian from the Bajo Barreal Formation is the possibly elasmarian ornithopod Notohypsilophodon (Martínez, 1998;Ibiricu et al., 2014). ...
In this paper, we present an updated revision of fossil vertebrates from the Chubut Group, Golfo San Jorge Basin, while also describing some new remains. Extensive exposures of both Lower and Upper Cretaceous sedimentary sequences are present in central Patagonia. These outcrops have, over the past several decades, yielded a varied vertebrate fauna, including fishes, turtles, crocodyliforms, pterosaurs, and dinosaurs, currently herein characterized and described. Although vertebrate diversity in the Chubut Group in central Patagonia is remarkable, the most abundant vertebrates recovered are dinosaurs. The Matasiete Formation (Hauterivian?–Albian) is markedly less prolific in terms of fossils discoveries than either the Bajo Barreal Formation (Cenomanian–early Turonian) or the recently recognized Lago Colhué Huapi Formation (Coniacian–Maastrichtian). The Bajo Barreal fauna is, at a high level, typical of coeval Gondwanan faunas. However, interestingly, several taxa occupy a basal position within their respective groups. The Lago Colhué Huapi Formation has produced a more derived vertebrate fauna, again similar to those from other Gondwanan regions. Finally, in a broad context, the new materials described augment our understanding of Cretaceous terrestrial vertebrate assemblage of central Patagonia and add to the generally meager record of vertebrate in the Cretaceous of the Southern Hemisphere.
... However, the fossil record of Thescelosaurinae in North America is absent until the Maastrichtian (Boyd et al. 2009, Eberth et al. 2013. Non-North American, mid-Cretaceous thescelosaurines include two taxa according to Boyd (2015): one from South America, Notohypsilophodon comodorensis from the Cenomanian (Martínez 1998, Ibiricu et al. 2014, and one from Asia, the Aptian to Cenomanian Changchunsaurus parvus from China (Jin et al. 2010, Butler et al. 2011. The fossil record of basal neornithischians is an area identified by other studies as needing more detailed work (i.e., Druckenmiller 2011, Brown et al. 2013 ...
... The intertrochanteric notch in Nevadadromeus schmitti is more developed than in the contemporaneous Chinese thescelosaurine Changchunsaurus parvus (Butler et al. 2011) or in the thescelosaurines, Notohypsilophodon or Thescelosaurus (Gilmore 1915, Ibiricu et al. 2014. Notohypsilophodon differs from Nevadadromeus and Changchunsaurus in that the lesser trochanter sits lower than the greater trochanter (Martínez 1998, Ibiricu et al. 2014). Based upon the preserved elements of Nevadadromeus, Changchunsaurus shares the same morphology of the proximal femur, shape of the unguals, and gross morphology of the vertebrae (Butler et al. 2011). ...
In 2008, and subsequent collecting trips, the remains of a partial basal neornithischian were recovered from the Cenomanian Willow Tank Formation of southern Nevada. Bones identified include the proximal femora, a series of vertebrae missing neural arches, several pedal phalanges, fragments of ossified tendons, and some as yet unidentified elements. Size and shape of the femora are consistent with other known basal neornithischians of both orodromine- and thescelosaurine-grade. The round femoral head exhibits a convex anterior side but a concave posterior surface. The neck beneath the head projects proximodorsally at an obtuse angle (~100°) from the femoral shaft. The greater trochanter sits slightly posterior to and offset from the neck of the femoral head. Anterior and lateral to the greater trochanter is a pointed lesser trochanter. The three-sided lesser trochanter bows slightly posterior toward the greater trochanter. A
prominent and deep notch separates the lesser from the greater trochanter and is characteristic of thescelosaurine-grade ornithischians. This deep intertrochanteric notch is absent in the femora of orodromines. A raised but taphonomically truncated base on the posterior femoral diaphysis likely represents the remnants of a pendant fourth trochanter. The vertebrae of the Nevada basal neornithischian are similar to both thescelosaurine- and orodromine-grade morphology. The laterally biconcave vertebrae are asymmetrical in having a boss on the posteroventral end of the centrum. The centra are nearly twice as long as they are tall with the oval articular surfaces, taller than they are wide. Due to the very fragmentary nature of this specimen, parsimonious phylogenetic analysis yields statistically insignificant results. Nevertheless, a few taxonomically important characters, particularly those of the femur, support the hypothesis that this is a
thescelosaurine, and a new genus and species, herein referred to as Nevadadromeus schmitti gen. et sp. nov. This would represent the earliest occurrence of thescelosaurines in the fossil record of North America as all other thescelosaurines from the continent date to the Maastrichtian. The geographic position of the Willow Tank Formation depocenter, very proximal to the Sevier highlands of the time, likely experienced some biogeographic insularity from other areas represented by contemporaneous units of western North America, e.g., Mussentuchit Member of the Cedar Mountain Formation of Utah, the Wayan Formation of Idaho, and the Blackleaf Formation of Montana.
... It has flat lateral and medial surfaces. The lesser (¼anterior) trochanter is relatively small and not separated from the greater trochanter by a cleft, as in Gasparisaura cincosaltensis (Coria and Salgado, 1996;Salgado et al., 1997) but unlike in Hypsilophodon foxii (Galton, 1974a) Jeholosaurus shangyuanensis (Han et al., 2012), and Notohypsilophodon comodorensis (Martínez, 1998). The shaft of the femur is bowed anteriorly, as in Thescelosaurus neglectus (Galton, 1974b) and T. assiniboiensis although the actual extent of the bowing cannot be determined due to crushing. ...
... Our analysis found these taxa as the only constituent members of the clade Thescelosaurinae, limiting its known temporal and geographic occurrence to the Maastrichtian of North America. This contrast with the result of Madzia et al. (2018), in which Thescelosaurinae also includes the poorly known Notohypsilophodon comodorensis, from the Upper Cretaceous (Cenomanian-Turonian) Bajo Barreal Formation of Chubut Province in Argentina (Martínez, 1998), which would have significantly increased its paleobiogeographic range. These results also contrast the recent results of Dieudonn e et al. (2021) and Yang et al. (2020), which found a sister-taxon relationship between Parksosaurus warreni and Gasparinisaura cincosaltensis. ...
The fossil record of Late Cretaceous non-hadrosaurid neornithischians from the Western Interior of North America is sparse. Parksosaurus warreni is an early Maastrichtian taxon currently known only from a skull and much of the associated postcranial skeleton and a referred isolated tooth from the Horseshoe Canyon Formation of Alberta, Canada. This article presents a detailed anatomical account of the holotype of this dinosaur following extensive additional preparation of the holotype and provides photographs of the postcranial elements for the first time. The premaxilla has a dorsoventrally deep posterolateral process, which overlaps the maxilla. The antorbital fenestra is small and teardrop-shaped. The lingual surfaces of dentary teeth bear nine or 10 vertically extending ridges that terminate in apical denticles. The suprascapula is mineralized or ossified. The dorsal margin of the ischium is posterodorsally concave at mid-length. The greater and lesser trochanters of the femur are not separated by a distinct cleft. The pendent fourth trochanter is placed on the proximal half of the femur. The more distal caudal vertebrae have greatly elongated prezygapophyses, which, together with a basket of ossified tendons ensheathing the caudal vertebrae, indicate that the tail may have functioned as a dynamic stabilizer during locomotion. The substantial new anatomical information from the holotype and only known skeleton of Parksosaurus warreni will allow more detailed comparisons to other closely related taxa and facilitate further discussions of unresolved aspects of the interrelationships of neornithischian dinosaurs.
... El único registro de Ornithischia de los depósitos Cenomaniano temprano-Turoniano tardío de la Formación Bajo Barreal corresponde a Notohypsilophodon comodorensis (UNPSJB-PV 942) (Martínez 1998) (Fig. 14). Se trata de un juvenil (Martínez 1998 representado por numerosos restos post craneales con buena preservación, hallado en areniscas tobáceas de la parte baja del Miembro Inferior de la Formación Bajo Barreal (Fig. 14A). ...
... El único registro de Ornithischia de los depósitos Cenomaniano temprano-Turoniano tardío de la Formación Bajo Barreal corresponde a Notohypsilophodon comodorensis (UNPSJB-PV 942) (Martínez 1998) (Fig. 14). Se trata de un juvenil (Martínez 1998 representado por numerosos restos post craneales con buena preservación, hallado en areniscas tobáceas de la parte baja del Miembro Inferior de la Formación Bajo Barreal (Fig. 14A). Los elementos recuperados incluyen cuatro vértebras cervicales, siete dorsales, cuatro sacras y seis caudales, fragmentos de cuatro costillas, escápula izquierda incompleta, coracoides derecho, húmero derecho, ambas ulnas, extremos proximal y distal del fémur izquierdo, tibia derecha, tibia izquierda incompleta, fíbula izquierda, fíbula derecha incompleta, astrágalo derecho, calcáneo izquierdo y trece falanges del pie, de las cuales tres son ungueales (Fig. 14E). ...
En la cuenca del Golfo San Jorge se encuentran unidades de origen continental reunidas en el Grupo Chubut (Barreamiano-Maastrichtiano) que son portadoras de un alto contenido fosilífero. Este registro paleontológico de vertebrados continentales cretácicos de la cuenca es una de los más diversos de América del Sur. Es relativamente escaso al momento en la Formación Matasiete (Aptiano), pero mucho más abundante en las formaciones Bajo Barreal (Cenomaniano temprano-Turoniano tardío) y Lago Colhué Huapi (Conianciano-Maastrichtiano). Incluye una importante cantidad de grupos de vertebrados, destacándose los dinosaurios saurópodos, terópodos y ornitópodos. También están bien documentados otros taxones como cocodrilos y tortugas, pero son escasos hasta el momento los restos de reptiles voladores, anuros y peces. Muchos de los hallazgos son de gran importancia y han contribuido al conocimiento de diferentes grupos y de sus relaciones filogenéticas y paleobiogeográficas. Se describe en este trabajo, solo el registro paleontológico más relevante y especies válidas conocidas hasta el momento.
... For example, the Bajo Barreal rebbachisaurid sauropod Katepensaurus goicoecheai (Ibiricu et al., , 2017) may pertain to either Limaysaurinae or Nigersaurinae (¼ Rebbachisaurinae according to Wilson and Allain, 2015) (Fanti et al., 2015;Canudo et al., 2018); nevertheless, it is always recovered in a basal position within these rebbachisaurid subclades, in contrast to its relatives from the Candeleros and Huincul formations (e.g., Limaysaurus tessonei, Cathartesaura anaerobica) that are almost invariably postulated as derived limaysaurines. A similar pattern obtains with Ornithopoda, with Notohypsilophodon comodorensis (Martínez, 1998) considered either a basal ornithopod or a basal elasmarian , as well as with Titanosauria, with the Bajo Barreal titanosaurs Epachthosaurus sciuttoi and Sarmientosaurus musacchioi being frequently regarded as plesiomorphic representatives of this clade (Martínez et al., 2004b. Furthermore, the seemingly basal condition of the Bajo Barreal dinosaur fauna is mirrored by other fossil vertebrates from this formation as well (see Lapparent de Broin and de la Fuente, 2001). ...
Xenotarsosaurus bonapartei was the third abelisaurid theropod dinosaur to be named from Argentina. The holotype comprises two partial anterior dorsal vertebrae and a complete right hind limb from the Upper Cretaceous (lower Cenomanian–upper Turonian) Bajo Barreal Formation, central Patagonia, Argentina. The materials display morphological features that undoubtedly position Xenotarsosaurus within Abelisauroidea. Moreover, detailed comparisons with members of that theropod group confirm the close relationship of this taxon to abelisaurids. Here we provide an emended diagnosis of Xenotarsosaurus bonapartei that includes five newly recognized autapomorphies: (1) anterior dorsal vertebrae with large, strongly dorsoventrally developed parapophyses; (2) anterior dorsal vertebrae with well-developed centroprezygapophyseal fossae that are taller dorsoventrally than wide mediolaterally; (3) fibular condyle of femur triangular in shape and projecting posteriorly; (4) well-marked groove on the anterolateral corner of the proximal fibula; and (5) iliofibularis tubercle of fibula distally interrupted by a hook-like shaped concavity. To determine its systematic position within Abelisauroidea, we incorporated Xenotarsosaurus into a phylogenetic analysis, recovering this theropod as a non-carnotaurine abelisaurid more derived than Eoabelisaurus mefi. Xenotarsosaurus displays several plesiomorphic traits when compared with penecontemporaneous abelisaurids from the Neuquén Group. Similarly, other non-avian dinosaur taxa from the Bajo Barreal Formation are frequently postulated as more phylogenetically basal than coeval forms from northern Patagonia. This scenario suggests the potential existence of provincialism in early Late Cretaceous continental vertebrate faunas of southern South America. The present study increases knowledge of abelisaurid systematics, evolution, and paleobiogeography and augments our understanding of the Late Cretaceous dinosaur assemblage of central Patagonia.
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
The deposits of the Chorrillo Formation (Maastrichtian) were accumulated during a ‘continental window’ that occurred during the Late Cretaceous in the Austral-Magallanes foreland basin, southern Patagonia, Argentina. The aim of the present contribution is to describe the depositional conditions as well as new vertebrate and plant fossils from this unit. The analysis of these deposits resulted in the definition of five architectural elements: Complex sandy narrow sheets channels (SS), Complex gravelly narrow sheets channels (GS), Sandstone lobes (SL), Thick fine-grained deposits (GF) and Thin dark fine-grained deposits (DF). These were separated into channelized and non-channelized units and represent the accumulation in a fine-grained dominated, fossil rich fluvial depositional system. Vertebrates fossil records include two species of frogs of the genus Calypteocephalella (representing the southernmost record of Pipoidea), snakes belonging to Madtsoiidae and Anilioidea (the latter ones being the first records for the basin), chelid turtles similar to Yaminuechelys-Hydromedusa, meiolaniiform turtles, titanosaur sauropods, megaraptoran theropods, new remains of the elasmarian Isasicursor santacrucensis (including the first cranial remains available for this species), hadrosaur ornithischians, enantiornithine birds. Sharks and elasmosaurs are also recorded and may possibly derive from the overlying marine Calafate Formation. These new taxa, together with previous findings from the Chorrillo Formation, are included into a stratigraphic column, thus providing valuable information that sheds new light on faunistic composition and paleobiogeography of high-latitude biotas of Gondwana.
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.
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