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Fishes, anurans, and turtles. (A-C), Indeterminate Calyptocephalellidae, MPM 21519, distal end of right humerus with eroded distal margin in anterior (A), posterior (B), and medial (C) views. (D) Indeterminate anuran, MPM 21518, incomplete tibiofibula. (E-G) Indeterminate Teleostei, MPM 21516, tooth crown in lateral (E), occlusal (F), ventral (G) views. (H) cf. Vidalamiinae indet., MPM 21517, isolated tooth in side view. (I-K) Indeterminate Chelidae, carapace fragments. (I) Plastral fragment. (J) Incomplete costal plate. (K) Middle peripheral plate. Abbreviations: ab, articular ball; ue, ulnar epicondyle; vf, ventral fossa. Scale bar: 5 mm.

Fishes, anurans, and turtles. (A-C), Indeterminate Calyptocephalellidae, MPM 21519, distal end of right humerus with eroded distal margin in anterior (A), posterior (B), and medial (C) views. (D) Indeterminate anuran, MPM 21518, incomplete tibiofibula. (E-G) Indeterminate Teleostei, MPM 21516, tooth crown in lateral (E), occlusal (F), ventral (G) views. (H) cf. Vidalamiinae indet., MPM 21517, isolated tooth in side view. (I-K) Indeterminate Chelidae, carapace fragments. (I) Plastral fragment. (J) Incomplete costal plate. (K) Middle peripheral plate. Abbreviations: ab, articular ball; ue, ulnar epicondyle; vf, ventral fossa. Scale bar: 5 mm.

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Article
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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 glaciari...

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... material: MPM 21518, isolated tibiofibula (locality 4) ( Figure 2D). Description: The distal halves of a tibia and a fibula have been collected. ...
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... material: MPM 21519, distal end of right humerus with eroded distal margin (locality 4) (Figure 2A-C). Description: The distal end of the humerus (1.5 mm in maximum transverse width), probably belongs to an adult individual, as suggested by degree ossification and well-finished structures. ...
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... Gray, 1825 Genus and species indeterminate Referred material: Chelid materials include MPM 21520 (consisting in two peripheral and one costal plates; locality 2), MPM 21521 (consisting of an anterior peripheral, one mid-peripheral, three posterior peripherals, fragment of plastral bridge, three incomplete costal plates, and distal end of radius; locality 4) (Figure 2 I-K). Based on locality and size differences, specimens belong to at least two different individuals. ...
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... ventromedial process is observed on the ventral margin of the scapula, as reported in Ligabuesaurus (Bonaparte et al., 2006). Humerus ( Figure 20). A fairly complete right humerus (MPM 21545) is available. ...
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... the femur shaft (immediately proximal to the distal condyles) is highly compressed anteroposteriorly (10cm). Tibia ( Figure 22). The tibia of the holotype (MPM 21542) consists of a right element, broken and slightly distorted. ...
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... the distal end of tibia of Nullotitan is strongly anteroposterior compressed and more trans- versely expanded than in other titanosaurs (e.g., Mendozasaurus; González , suggesting that may constitute an autapomorphic trait of Nullotitan. Fibula ( Figure 23). A nearly complete right fibula is available. ...
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... anterior margin of the bone is straight, whereas the posterior one is strongly sigmoid, much more than in other titanosaurs (for instance, Uberabatitan, Mendozasaurus, Elaltitan; Salgado & Carvalho, 2008;Silva Junior et al., 2019;González Riga et al., 2018;Mannion & Otero, 2012). The fibular shaft is also strongly sigmoidal in posterior view, with the lateral surface markedly convex at level of the biceps tubercle ( Figure 23C). In general terms, the fibula is similar to that of Dreadnoughtus (Ullman & Lacovara, 2016). ...
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... the lateral surface, there is the tubercle for the M. iliofibularis. Astragalus ( Figure 24). As usual among sauropods, the astragalus is conical-shaped, with an excavated lateral surface for articulation with the calcaneum and the fibula, and a pointed end oriented medially, which is partially broken and coincident with the medial expansion of the distal end of tibia. ...
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... material. MPM 21545, fragmentary specimen composed of a posterior dorsal centrum, transverse process of a dorsal vertebra, partial neural arch of a caudal vertebra, fragments of two indeterminate vertebrae, rib fragments and proximal end of pubis (locality 3) ( Figure 25). The specimen was found in a 5x3 m surface area. ...
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... material. MPM 21546, isolated dorsal centrum (locality 4) (Figure 26). Description. ...
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... material. MACN-Pv 19066, isolated shed tooth crown, presumably coming from the lower levels of the Chorrillo Formation (Figure 27). Collected by J. F. Bonaparte in 1981 on the same large area were the holotype of Nullotitan glaciaris was found. ...
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... pedal phalanx IV-2? (locality 4) (Figure 28). Description. ...
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... (Figure 28). Description. ...
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... MPM 21550, incomplete right coracoid lacking sternal end and proximal end damaged (locality 2) (Figure 29). Diagnosis. ...
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... material. MPM 21554, four fragmentary casts (Figure 32 A) (Figure 31, B-C). Description. ...
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... material. MPM 21558, Physa sp., one incomplete cast (Figure 32 E); MPM 215599, Stenophysa sp., two incomplete casts ( Figure 32F). Description. ...
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... material. MPM 21558, Physa sp., one incomplete cast (Figure 32 E); MPM 215599, Stenophysa sp., two incomplete casts ( Figure 32F). Description. ...
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... material. MPM 21562, one fragmentary cast (Figure 32 I). Description. ...
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... material: MPM 21518, isolated tibiofibula (locality 4) ( Figure 2D). Description: The distal halves of a tibia and a fibula have been collected. ...
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... material: MPM 21519, distal end of right humerus with eroded distal margin (locality 4) (Figure 2A-C). Description: The distal end of the humerus (1.5 mm in maximum transverse width), probably belongs to an adult individual, as suggested by degree ossification and well-finished structures. ...
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... Gray, 1825 Genus and species indeterminate Referred material: Chelid materials include MPM 21520 (consisting in two peripheral and one costal plates; locality 2), MPM 21521 (consisting of an anterior peripheral, one mid-peripheral, three posterior peripherals, fragment of plastral bridge, three incomplete costal plates, and distal end of radius; locality 4) (Figure 2 I-K). Based on locality and size differences, specimens belong to at least two different individuals. ...
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... ventromedial process is observed on the ventral margin of the scapula, as reported in Ligabuesaurus (Bonaparte et al., 2006). Humerus ( Figure 20). A fairly complete right humerus (MPM 21545) is available. ...
Context 23
... the femur shaft (immediately proximal to the distal condyles) is highly compressed anteroposteriorly (10cm). Tibia ( Figure 22). The tibia of the holotype (MPM 21542) consists of a right element, broken and slightly distorted. ...
Context 24
... the distal end of tibia of Nullotitan is strongly anteroposterior compressed and more trans- versely expanded than in other titanosaurs (e.g., Mendozasaurus; González , suggesting that may constitute an autapomorphic trait of Nullotitan. Fibula ( Figure 23). A nearly complete right fibula is available. ...
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... anterior margin of the bone is straight, whereas the posterior one is strongly sigmoid, much more than in other titanosaurs (for instance, Uberabatitan, Mendozasaurus, Elaltitan; Salgado & Carvalho, 2008;Silva Junior et al., 2019;González Riga et al., 2018;Mannion & Otero, 2012). The fibular shaft is also strongly sigmoidal in posterior view, with the lateral surface markedly convex at level of the biceps tubercle ( Figure 23C). In general terms, the fibula is similar to that of Dreadnoughtus (Ullman & Lacovara, 2016). ...
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... the lateral surface, there is the tubercle for the M. iliofibularis. Astragalus ( Figure 24). As usual among sauropods, the astragalus is conical-shaped, with an excavated lateral surface for articulation with the calcaneum and the fibula, and a pointed end oriented medially, which is partially broken and coincident with the medial expansion of the distal end of tibia. ...
Context 27
... material. MPM 21545, fragmentary specimen composed of a posterior dorsal centrum, transverse process of a dorsal vertebra, partial neural arch of a caudal vertebra, fragments of two indeterminate vertebrae, rib fragments and proximal end of pubis (locality 3) ( Figure 25). The specimen was found in a 5x3 m surface area. ...
Context 28
... material. MPM 21546, isolated dorsal centrum (locality 4) (Figure 26). Description. ...
Context 29
... material. MACN-Pv 19066, isolated shed tooth crown, presumably coming from the lower levels of the Chorrillo Formation (Figure 27). Collected by J. F. Bonaparte in 1981 on the same large area were the holotype of Nullotitan glaciaris was found. ...
Context 30
... pedal phalanx IV-2? (locality 4) (Figure 28). Description. ...
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... (Figure 28). Description. ...
Context 32
... MPM 21550, incomplete right coracoid lacking sternal end and proximal end damaged (locality 2) (Figure 29). Diagnosis. ...
Context 33
... material. MPM 21554, four fragmentary casts (Figure 32 A) (Figure 31, B-C). Description. ...
Context 34
... material. MPM 21558, Physa sp., one incomplete cast (Figure 32 E); MPM 215599, Stenophysa sp., two incomplete casts ( Figure 32F). Description. ...
Context 35
... material. MPM 21558, Physa sp., one incomplete cast (Figure 32 E); MPM 215599, Stenophysa sp., two incomplete casts ( Figure 32F). Description. ...
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... material. MPM 21562, one fragmentary cast (Figure 32 I). Description. ...

Citations

... MPM-PV-22864 and MPM-PV-22865 are almost identical in morphology differing, as expected, in those traits that vary within the anterior and posterior parts of the jaw (such as the symmetry or not of the tooth crowns). Conversely, one tooth (MACN-Pv 19,066) differs from the rest in having a high density of distal denticles (5 per mm vs 3 per mm in all other megaraptorids 3,39 ). It should be noted that MACN-Pv 19,066 was collected in the area in 1980 but lacks specific stratigraphic and geographic provenances 3 . ...
... Conversely, one tooth (MACN-Pv 19,066) differs from the rest in having a high density of distal denticles (5 per mm vs 3 per mm in all other megaraptorids 3,39 ). It should be noted that MACN-Pv 19,066 was collected in the area in 1980 but lacks specific stratigraphic and geographic provenances 3 . ...
Article
Full-text available
Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.
... In Santa Cruz and Salta Provinces, the microstructural patterns observed in the eggshells from the "titanosaur tibia" and "Puma cave" localities allow the authors to refer them to Fusioolithus oosp. (Novas et al. 2019), and Capurro et al. (2019) assigned the eggs and eggshells from Salta to Fusioolithidae, respectively. Other putative fusioolithid reports come from Argentina and Brazil. ...
Chapter
The South American sauropodomorph egg record is unrivaled in its richness, with Jurassic and Early and Late Cretaceous eggshell occurrences of up to six different oospecies, included in the oofamilies Megaloolithidae, Fusioolithidae and, probably, Faveoloolithidae, and the oldest putative soft-shelled eggs of the fossil record. In addition, numerous clutches, some nests, exquisitely preserved embryos with skin impressions, and delicate embryological structures such as the egg tooth, and perinatal individuals of stem sauropodomorphs have been reported from South America. Thus, it represents one of the most complete oological and developmental records of an extinct clade and provides a unique opportunity to explore its palaeobiology and palaeoecology. In this chapter, the reader will find a detailed revision of the egg-bearing localities of South America, combined with a critical review of all specimens previously referred to as sauropodomorph taxa and parataxa. Detailed account of the impressive sauropodomorph embryo record is provided. Finally, the different Argentinean nesting grounds are discussed in their paleoenvironmental context, to provide an updated picture of the nesting strategies and reproductive traits of South American sauropodomorphs.
... A SantonianeCampanian regression and continental expansion (Egerton, 2011), consisting of deltaic, river and wetlands sandy systems, constitutes a key event in the central depocenter (Fig. 1). The paleogeographic expansion of this continental ecological niche was exploited by theropods and influenced the evolutionary history of dinosaurs (Novas et al., 2004(Novas et al., , 2008(Novas et al., , 2019Ezcurra et al., 2010;Egerton et al., 2013;Lacovara et al., 2014). In this paper, we present new detrital zircon UePb geochronological data in some key localities from the La Anita Formation deltaic system (Figs 2 and 3). ...
... The profile continues with yellowish channel-shaped sandstone bodies with tangential and trough cross-bedding that alternate with mudstones (Fig. 4), corresponding to meandering and braided fluvial deposits of the La Irene Formation (Povilauskas et al., 2008;Moyano Paz et al., 2018;Tettamanti et al., 2018). Meandering fluvial deposits with abundant dinosaur fossil remains of the Chorrillo Formation follow (Leanza, 1972;Nullo et al., 1981;Macellari et al., 1989;Novas et al., 2019). The stratigraphic succession of the Chorrillo Formation is made up by an intercalation of greenish and reddish mudstones beds and lenticular sandstone and conglomeratic bodies (Feruglio 1944;Nullo et al., 2006;Novas et al., 2019). ...
... Meandering fluvial deposits with abundant dinosaur fossil remains of the Chorrillo Formation follow (Leanza, 1972;Nullo et al., 1981;Macellari et al., 1989;Novas et al., 2019). The stratigraphic succession of the Chorrillo Formation is made up by an intercalation of greenish and reddish mudstones beds and lenticular sandstone and conglomeratic bodies (Feruglio 1944;Nullo et al., 2006;Novas et al., 2019). Fossil content of this unit includes large titanosaur bone fragments, theropod remains, medium-sized ornithopods, tiny vertebrate bones, gastropods, and plant remains (Novas et al., 2019). ...
Article
Full-text available
A key event in the paleogeographic evolution of the Austral-Magallanes foreland basin was the Santonian-Maastrichtian continentalization, marked by the appearence of deltaic, fluvial and wetland sequences stacked on top of deep marine deposits. The expanding ecological niche was exploited by theropods and influenced the evolutionary history of dinosaurs. We present new detrital zircon U-Pb geochronological data across this littoral to continetnal depocenter, in order to provide insights of its age, geographical extension, source regions and geodynamic setting. Littoral sandstones from La Anita Formation yield Maximum Depositional Ages (MDA) between ~86-80 Ma (weighted mean ages), and ~79-78 Ma youngest zircons. Our results are in accordance with Santonian-Campanian depositional age. The sequence continues with badlands and fluvial systems (Cerro Fortaleza and La Irene Formations), followed by meandering fluvial and lacustrine deposits (Chorrillo Formation). Transgressive marine facies topping the sequence (Calafate Formation) yield a preferred Maastrichtian 69 ± 2 Ma MDA from the youngest zirzon. The provenance and tectonic analyses indicate that basin shallowing during Santonian-Campanian times was driven by advance of the orogenic front, which produced the shift from foredeep setting to a wedge-top depozone. The unroofing of progressively deeper structural levels is registered in the basin fill, which suggests exhumation in the Basement domain during the Santonian-Maastrichtian.
... Stratigraphic distribution. Cretaceous to Recent (Melchor et al., 2002;Martín & Francesco, 2006;Novas et al., 2019). ...
Article
Full-text available
A taxonomic review of Miocene gastropods from the Solimões Formation, Acre Basin, Brazil, from specimens collected at Cachoeira do Bandeira, Oriente, and an outcrop named Spot 04, is here presented. Three ampullariid species (Pomacea maculata, P.planorbula, Pomacea sp.), one thiarid species (Aylacostoma sp.), and one cochliopid species (Sioliella sp.) are identified for these deposits. These gastropod are known to occur in freshwaters environments, thus consolidating the hypothesis of a non-influence of brackish water on the upper Miocene deposits of the Acre Basin. The previous identification of P. maculata and Aylacostoma sp. is changed here considering biometrical analyses and shell morphological descriptions. The first report of Sioliella in this basin increases the gastropod fauna known for these strata and expands the range of this genus. Keywords: Pomacea, Aylacostoma, Sioliella, Ampullariidae, Thiaridae, Cochliopidae.
... At the Neuqu en Basin gigantic colossosaurians are absent from the record since the Campanian. Whereas colossosaurians appear to be abundant and diversified up to the latest Cretaceous at Austral and Golfo San Jorge basins (see Novas et al., 2019). In spite to that, relatively large sauropods are not totally extinct from Neuqu en basin, with Antarctosaurus wichmannianus (probably belonging to the Aeolosaurini-Saltasaurinae lineage; Novas, 2009) and still innominate taxa (FLA pers. ...
... In the case of Austral Basin, in spite that the record is still not complete, the sauropods appear to be not very diverse (Fig. 13). For example, from Chorrillos beds, the single colossosaurian Nullotitan is known, and represented by several individuals along the stratigraphic column (Novas et al., 2019), whereas for Cerro Fortaleza beds only the gigantic and closely-related forms Puertasaurus and Dreadnougthus were discovered (it should be noted that unpublished remains indicate the presence of an additional smaller titanosaur species) (Novas et al., 2005;Lacovara et al., 2014). Saltasaurines and aeolosaurines are totally absent from the Austral basin, and the former appear to be absent south to 42 S latitude (Salgado and Bonaparte, 2007). ...
... Thus, in spite of the co-occurrence of different titanosaurs (as can be seen in Bajo de Santa Rosa, Salitral Moreno and Salitral Ojo de Agua) their different body plans indicate that they occupied particular niches and that probably competition for resources was (Garrido, 2010;Novas et al., 2005Novas et al., , 2019Casal et al., 2016;Ibiricu et al., 2019). Number of species is based in the case of Austral Basin on Novas et al. (2005Novas et al. ( , 2019, in the San Jorge Basin on Ibiricu et al. (2011), and the Neuqu en Basin on a large number of publications cited in the main text. ...
Article
The record of sauropods in the Upper Cretaceous of Patagonia is rich. However, there are still several blanks on this record. Here it is described a new sauropod assemblage coming from the Salitral Ojo de Agua Area, Río Negro province, northern Patagonia, Argentina (Allen Formation; Maastrichtian). Remains of indeterminate saltasaurines, aeolosaurines, as well as new specimens of the small saltasaurine Rocasaurus muniozi and the new eutitanosaur Menucocelsior arriagadai gen. et sp. nov., are described.. The new eutitanosaur is represented by an incomplete caudal series and some appendicular bones that indicate that it does not belong to any previously recognized eutitanosaur clade (e.g, Colossosauria, Saltasaurinae, Aeolosaurini). The co-occurrence of several roughly coeval titanosaurs in a restricted area (as occur in Bajo de Santa Rosa, Salitral Moreno and Salitral Ojo de Agua sites) with different body plans, indicates that they probably occupied particular ecological niches and that probably competition for resources was limited, allowing the connivance of several taxa in a single locality and age. This pattern is not observed in other sites of the world. Based on these records and on the high diversity of osteoderm morphotypes recovered, it appears to be certain that palaeoecological conditions in the area were able to sustain and promote the flourishing of many species of titanosaurs.
... The sixth Argentinian taxon is Orkoraptor, which is represented by one incomplete specimen (Novas et al. 2008) recovered from Cerro Fortaleza Formation (Campanian-Maastrichtian rocks). Finally, some recently described megaraptorids have come to light, from Upper Cretaceous strata (Bajo Barreal and Chorrillo Formations, respectively;Ibiricu et al. 2019;Novas et al. 2019;Lamanna et al. 2020). These unnamed specimens are fragmentary, but show unequivocal megaraptorid traits. ...
Article
Aerosteon riocoloradensis represents one of the most complete megaraptorans yet discovered. This theropod comes from Anacleto Formation (Campanian) of Mendoza Province, Argentina. The aims of this contribution are: to present a detailed, bone by bone description of this specimen with figures of each bone; provide comparisons to other closely related theropods; revise the original assignation and diagnosis of such taxa. Three bones were re-assigned and almost all the autapomorphies of Aerosteon were modified. Features in the vertebral columns, which are shared with other megaraptorans, show that these theropods shared features with basal coelurosaurs. Anatomical Abbreviations ACDL: Anterior centrodiapophyseal lamina; CDF: Centrodiapophyseal fossa; CPAL: Centroparapophyseal lamina; CPRL: Centroprezygapophyseal lamina; CPRF: Centroprezygapophyseal fossa; CPR-CDF: Centroprezygapophyseal-centrodiapophyseal fossa; Hye: Hyposphene; Hym: Hypantrum; ILT: Intervertebral ligament tuberosity; IPOL: Infrapostzygapophysela lamina; IZL: Intrazygapophyseal lamina; PADL: Paradiapophyseal lamina; PAD-CDF: Paradiapophyseal-centrodiapophsyeal fossa; PCDL: Posterior centrodiapophyseal lamina; POEL: Postzygaepipophysela lamina; PODL: Postzygadiapophyseal lamina; POSF: Postspinal fossa; POCDF: Postzygapophsyeal-centrodiapophyseal fossa; Poz: Postzygapophysis; PRDL: Prezygadiapophyseal lamina; PRPAF: Prezygaparapophyseal fossa; PRPAL: Prezygaparapophyseal lamina; PRSF: Prespinal fossa; PRSL: Prespinal lamina; PRD-CDF: Prezygadiapophyseal-centrodiapophyseal fossa; PRD-PADF: Prezygadiapophyseal-paradiapophyseal fossa; PRD-PODF: Prezygadiapophyseal-postzygadiapophyseal fossa; PRCDF: Prezygapophyseal-centrodiapophyseal fossa; Prz: Prezygapophyses; SDF: Supradiapophsyeal fossa; SDL: Supradiapophyseal lamina; SPOF: Spinopostzygapophyseal fossa; SPOL: Spinopostzygapophyseal lamina; SPRF: Spinoprezygapophyseal fossa; SPRL: Spinoprezygapophyseal lamina; SR(number): Sacral rib; STP(number): Sacral transverse process
... The fossil record of Patagonian gondwanatherians has been geographically extended with the discovery of several isolated cheek teeth and incisors corresponding to the new taxon Magallanodon baikashkenke (Goin et al., 2020) from the CampanianeMaastrichtian Dorotea Formation, outcropping at Magallanes Region, southern Chile. Chimento et al. (2020) described an isolated molariform coming from stratigraphically equivalent beds of southern Argentina (known as the Chorrillo Formation, in Santa Cruz province; Nullo et al., 2006;Novas et al., 2019), which these authors also referred to Magallanodon baikashkenke. 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 Here, we report on additional remains of Magallanodon baikashkenke from the Chorrillo Formation, consisting of a fragmentary dentary bearing the base of one of its lower incisors, which was found in close association with an incomplete upper incisor. ...
... The specimens were discovered in a locality named the "Puma Cave", (S50 30.639 W72 33.617, Fig. 1; Novas et al., 2019). The fossil site belongs to La Anita farm, approximately 30 km SW from El Calafate City, Santa Cruz Province, Argentina. ...
... The fossil site belongs to La Anita farm, approximately 30 km SW from El Calafate City, Santa Cruz Province, Argentina. The gondwanatherian specimens here described were found in close proximity to bones of ankylosaurian and hadrosaurian dinosaurs, as well as remains of the elasmarian Isasicursor (Novas et al., 2019;Rozadilla et al., 2020 Q3 ). This fossil assemblage comes from the level 20 m above the site from which an isolated molariform of Magallanodon baikashkenke (Chimento et al., 2020) was found. ...
Article
The fossil record of gondwanatherian mammaliaforms from Patagonia is represented by several species known on the basis of isolated teeth, with the single exception of a partial dentary with two molariforms of the Paleocene species Sudamerica ameghinoi. The aim of the present contribution is to describe both a fragmentary dentary (with the base of the lower incisive) and a partial upper incisor coming from the Campanian–Maastrichtian Chorrillo Formation, at the La Anita Farm, SW Santa Cruz province, Argentina. The specimens are referred to Magallanodon baikashkenke, a species previously known by isolated teeth from the Dorotea (Chile) and Chorrillo (Argentina) beds. The present discovery expands our knowledge of this mammaliaform clade.
... Podocarpoxylon dusenii was described by Kräusel (1924) from presumptive Cretaceous sediments of southern Patagonia. Recently, it was described from the Upper Cretaceous of the same zone (Novas et al. 2019). The narrower growth rings, absence of biseriate rays (which are rare in the holotype of P. dusenii), and lower rays of the specimen from Corcovado, are all characters that can vary in different organs (e.g., stem, branch, mature wood) or location (e.g., inner/outer rings) of the same organ, or between different trees (intraspecific variability). ...
Article
Eocene paleofloras of Patagonia are diverse and increasingly known. A new assemblage of fossil wood has been recovered from Eocene sediments in Corcovado, western Argentinean Patagonia. The lithological succession (formerly Arroyo Lyn Formation sensu Pesce 1979) is correlated with the Huitrera Formation. The specimens were mostly found embedded in sandstones and conglomerates. One-third of the assemblage are conifers and studied herein. We found four taxonomic types: Agathoxylon cf. antarcticum (Araucariaceae), Phyllocladoxylon antarcticum (Podocarpaceae), Podocarpoxylon dusenii (Podocarpaceae), and Cupressinoxylon hallei (Cupressaceae or Podocarpaceae). The presence of four taxonomic units among only 7 specimens suggests a significant conifer species richness in the assemblage. Araucariaceae and dominant Podocarpaceae are usually found in previously described conifer wood assemblages from the Eocene of Patagonia andAntarctica. The diversity of the conifer assemblage in Corcovado is very similar to that found at Laguna del Hunco (these two localities are 170 km distant), also from the Huitrera Formation. This is consistent with the proposal that the bearing sediments of both localities are from the same stratigraphic unit.
... The gondwanatherian Magallanodon baikashkenke, as well as the meridiolestid Orretherium tzen (Table 1) come from Río de Las Chinas valley, approximately 100 km north of Puerto Natales city, Última Esperanza Province (Magallanes and Chilean Antarctica), in Chilean Patagonia (Goin et al., 2020;Martinelli et al. 2021). The finding of the same species in the Chorrillo Formation in Santa Cruz province (Chimento et al., 2020) reinforces the faunal similarities previously reported for both stratigraphical units, and supports paleontological evidences that suggest both units are probably coeval (Novas et al., 2019) (Table 1). Gondwanatheria is an enigmatic mammaliaform clade distributed in the Cretaceous and Paleogene of South America, Africa, Madagascar, India and Antarctica. ...
Article
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.
... Upper Cretaceous rocks from Argentina have yielded the most complete and diverse record of ornithischian dinosaurs from Gondwana, being currently represented by two main clades: Ornithopoda and Ankylosauria. The first finds are documented by almost complete skeletons, including skull remains, and are represented by Santonian-Campanian basal euiguanodontian Gasparinisaura , the elasmarians Talenkauen, Macrogryphosaurus, Anabisetia, Notohypsilophodon, Isasicursor, Mahuisacursor and Sectensaurus (Martinez, 1998;Coria and Calvo, 2002;Novas et al., 2004Novas et al., , 2019Calvo et al., 2007;Ibiricu et al., 2019;Cruzado-Caballero et al., 2019), and several species of Hadrosauridae (e.g. "Kritosaurus", Secernosaurus, Willinakaqe, Lapampasaurus, and Bonapartesaurus;Brett-Surman, 1979;Bonaparte et al., 1984;Juarez-Valieri et al., 2010;Coria et al., 2013;Cruzado-Caballero and Powell, 2017). ...
... On this basis, Bonaparte and Kielan-Jaworowska (1987) sustained that the dominant herbivores in the southern continents were sauropod dinosaurs, whereas in the north the ornithischians were numerically dominant and highly diversified taxonomically. Although such a basic dichotomy between Gondwana and Laurasia has to be maintained, paleontological discoveries carried on in Patagonia in the last 20 years have considerably improved our knowledge of southern ornithischians, showing that they were present and well-diversified Coria and Calvo, 2002;Novas et al., 2004;Calvo et al., 2007;Rozadilla et al., 2016;Cruzado-Caballero et al., 2019;Ibiricu et al., 2019;Novas et al., 2019). Among them, basal iguanodontians and hadrosaurids are represented by different species, but ankylosaurs remain underrepresented. ...
Article
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.