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Dinosaurs and other vertebrates of the Lake Ezequiel Ramos Mexía Area, Neuquén-Patagonia, Argentina

  • January 1999
Authors:
Jorge Orlando Calvo at National University of Comahue
Jorge Orlando Calvo
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... Sauropodomorpha von Huene 1932 Sauropodomorpha indet. Bianco and Calvo 1999 Locality and Age Los Menucos (40°48 53 S; 68°08 35 W), Río Negro Province (Fig. 1). Vera Formation. ...
... The shape, size, and age of the manus and pes impressions indicate that these tracks were left by a basal sauropodomorph (Manera de Bianco and Calvo 1999). Sauropoda Marsh 1878 Sauropodichnus Calvo 1991Calvo , 1999 Sauropodichnus giganteus Calvo 1991Calvo , 1999 Holotype MUCPv-145-146. ...
... The shape, size, and age of the manus and pes impressions indicate that these tracks were left by a basal sauropodomorph (Manera de Bianco and Calvo 1999). Sauropoda Marsh 1878 Sauropodichnus Calvo 1991Calvo , 1999 Sauropodichnus giganteus Calvo 1991Calvo , 1999 Holotype MUCPv-145-146. ...
Sauropod Ichnology: Overview and New Research Lines from a South American Perspective
Chapter
  • Apr 2022
Forty years ago, L. Branisa and G. Leonardi discovered the first sauropodomorph tracks in South America during expeditions to Toro Toro (Bolivia). Since then, numerous findings, mainly in Argentina, Bolivia, and Brazil, have increased the record. The first research lines mainly covered morphological description, ichnotaxonomic identification, and behavioral analyzes (e.g., gregariousness and speed). Some Cretaceous tracksites allowed the description of three new ichnotaxa: Sauropodichnus giganteus (Calvo in Ameghiniana 28:241–258, 1991), Titanopodus mendozensis (González Riga and Calvo in Palaeontology 52:631–640, 2009), and Calorckosauripus lazari (Meyer et al. in Ann Soc Geol Pol 88:223–241, 2018), the former two corresponding to Argentina, and the latter to Bolivia. A new research line named ‘ichnology and comparative anatomy’ has become relevant in the last years linking the skeletal information to the ichnological record, thus providing an integral interpretation of the set. This kind of approach allowed making more accurate inferences about paleoecological aspects, including limb posture, gauge, gait, speed, and size diversity recorded. In sum, this chapter aims to provide an overview of the South American sauropodomorph ichnotaxonomy, the history of the discoveries, and the results of new research lines in development.
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... Some of the most important discoveries, which are from Argentina, give us information about manus and pes morphology, speed estimation and locomotion of titanosaurs, the largest sauropods from the Cretaceous. In Argentina, sauropod tracks were discovered in Neuqu en (Calvo, 1991(Calvo, , 1999Calvo and Mazzetta, 2004;Canudo et al., 2017;Heredia et al., 2019), Río Negro (Ortiz et al., 2008;Calvo and Ortiz, 2011;Paz et al., 2014;Díaz-Martínez et al., 2018a), Jujuy (C onsole- Gonella et al., 2012Gonella et al., , 2017, Salta (C onsole- Gonella et al., 2015;Díaz-Martínez et al., 2018b), San Juan (Contreras et al., 2010), and Mendoza provinces (Gonz alez Riga and Calvo, 2009;Gonz alez Riga et al., 2015;. However, the preservation of claw impressions is unusual in South America (e.g. ...
... Sauropodichnus presents a poor preservation state and scarce details both in the manus and pes tracks (Lockley et al., 1994). Calvo (1999) subsequently assigned to Sauropodichnus a betterpreserved trackway and emended its diagnosis. The manus tracks of Sauropodichnus (CB-1 trackway, Calvo, 1999: Fig. 19) have a symmetrical kidney-shaped morphology as in Teratopodus although Sauropodichnus manus tracks are markedly wider than long (relation MW/ML ¼ 0.62) while in Teratopodus MW/ML ¼ 0.76 (Fig. 6A, M). ...
New titanosaurian sauropod tracks with exceptional preservation of ungueal phalangeal prints from the Upper Cretaceous of Argentina
Article
  • Aug 2021
  • CRETACEOUS RES
A new titanosaur sauropod ichnotaxon named Teratopodus malarguensis gen. et sp. nov is erected based on a unique association of 10 characters. It is represented by new tracks discovered in the upper section of the Anacleto Formation outcropping in the southern Mendoza Province (middle Campanian, Neuquén Basin). Teratopodus diagnosis includes pes tracks with suboval shaped, with a slightly obtuse ‘V-shaped’ heel and three large claws impressions laterally deflected corresponding to the digits I, II and III; and symmetrical kidney-shaped manus tracks with a slightly concave posterior border. Teratopodus has a medium-gauge trackway and a medium degree of heteropody (∼1/3). In addition, a new characterization of the heels impressions in sauropod tracks is proposed here including the postero-latero-medial angle (PLM°); according to this, Teratopodus pes track can be classified into slightly ‘V-shaped’ heel (PLM° = 95°–100°). The trackmakers are two titanosaurs specimens of relatively small-medium sized of ca. 11 m and 14 m length. These tracks are preserved in a poorly drained floodplain deposits with ephemeral channels controlled by flash flood episodes. In this context, the trackmakers walked from a humid ground to a more flooded one, leaving behind one of the best-preserved pes tracks ever recorded in South America.
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... Calvo (1991) Titanosaurs It is composed of an alternation of sandstones and mudstones interpreted as alluvial plain deposits with wandering courses Cazau and Uliana (1973); Digregorio (1978); Calvo (1991)). Calvo (1991Calvo ( , 1999 Fluvial ...
... Among them there is Punta de Pescadores tracksite, where Calvo (1991) described Sauropodichnus giganteus, the first sauropod ichnotaxon from South America. Based on the wide-gauge of the trackways and the body fossil record found in the same formation, Calvo (1999) proposed Andesaurus delgadoi Calvo and Bonaparte (1991) as the probable trackmaker of S. giganteus. Later, Calvo and Mazzetta (2004) found new sauropod tracks at Isla Cerrito del Bote tracksite and assigned it to cf. ...
Paleoenvironmental contexts of South American Cretaceous sauropod tracks
Article
  • Jun 2021
  • J S AM EARTH SCI
The ichnological Cretaceous sauropod record of South America is analyzed for the first time in relation with skeletal and paleoenvironmental data. The updated database includes 39 tracksites and 71 valid species (53 titanosaurs and 18 non-titanosaurs) from Colombia, Ecuador, Peru, Chile, Brazil and Argentina. The track and bone records analyzed evidence a relationship with continental environments, specifically with fluvial ones. This is observed in all Sauropoda records, indicating an ecological association of the Cretaceous sauropods for these environments. In addition, the paleogeographic reconstruction integrating these records does not evidence any correlation between the distribution of sauropods and the latitudinal range. During the late Campanian–Maastrichtian interval, when the Atlantic transgression event was established, the titanosaur record started to show a singular panorama. The tracksites are preserved not only in continental paleoenvironments but also in marginal-marine ones, being the only last records of titanosaurs associated with that environment in South America. Both the paleoecological aspects based on sauropod Cretaceous record and the paleoenvironmental data collected in this work support the hypothesis that these tracksites were used by titanosaurs as ‘transit areas’ to move among the environments they inhabited.
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... There may be many undescribed fossils in collections around the world that would alter the current data on armor-faced theropods and their respective ecosystems. For example, the presence of only one described large herbivore in some environments is likely the result of incomplete study, based on other penecontemporaneous dinosaur faunas from similar areas ( Table 1) (26)(27)(28). ...
Preliminary investigation of Allosauroidea facial integument and the evolution of theropod facial armor
Article
  • Jan 2022
In amniotes, the growth of specialized facial integument, or external skin tissues, has a close relationship with the texture and morphology of underlying cranial bones. Osteological correlates of facial skin structures have been used before to reconstruct the integument of several extinct dinosaurian lineages but not for theropods from the clade Allosauroidea, whose members exhibit exceptionally rugose and heavily ornamented skulls. This study aims to investigate, in a preliminary sense, the facial integument of Allosauroidea by examining osteological correlates from high-resolution photographs of fossil material. We compared the inferred integument of allosauroids to analogous structures in modern animals in order to discuss potential biological and behavioral implications, with soft-tissue adaptations suggesting headbutting or sparring in some taxa. Allosauroids display an evolutionary trend for increasing cranial cornification throughout their history, and their most derived members exhibit greater development of facial armor than other tetanurans. We developed three hypotheses to explain the selective pressures that may have driven the independent evolution of this dermal armor in several unrelated theropod clades, namely abelisaurids, carcharodontosaurids, and tyrannosaurids. Empirical tests of paleoecological data did not support any of the three hypotheses of intraspecific conflict, competition from other carnivores, or dangerous prey items as the main pressure that drove the evolution of theropod facial armor. We suggest that more sampling of armor-faced theropods and their associated ecosystems, especially those from the Southern Hemisphere, is needed to reveal the reasons behind the convergent evolution of this integument.
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... Pero en 1979 y debido a una bajante histórica del lago Ezequiel Ramos Mexía, fueron halladas una gran cantidad de huellas fósiles por un poblador de la localidad de Picún Leufú, Santiago Astigarraga, quien las reportó como similares a huellas "de un avestruz gigante". Estas huellas fueron estudiadas principalmente por el Dr. Jorge Calvo de la Universidad Nacional del Comahue (UNCo) (Calvo, 1991(Calvo, , 1999Calvo y Rivera, 2018). Desde ese entonces, se ha encontrado una enorme cantidad de hue-llas fósiles de una gran variedad de dinosaurios y pterosaurios en niveles de la Formación Candeleros expuestos en ambas costas del lago Ezequiel Ramos Mexía, desde prácticamente la zona donde se emplaza la represa hasta su cabecera suroccidental (Fig. 4). ...
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Dinosaur tracks with skin impressions in the La Buitrera Paleontological Area (Candeleros Formation, Cenomanian), Río Negro Province, Argentina
Article
  • Jun 2023
  • CRETACEOUS RES
The La Buitrera Paleontological Area, in the north of the Río Negro Province, Argentina, preserves the uppermost section of the Cenomanian Candeleros Formation, as well as a rich vertebrate fauna that inhabited the Kokorkom Desert paleo-erg. Candia Halupczok et al. (2017) reported tracks found on wet and dry interdune. New evidence from 2020 to 2022 fieldtrips enabled the recognition of tracks in cross-section in non-channelized ephemeral fluvial dominated facies within the main aeolian setting located in the vicinity of the wettest recorded area of the La Buitrera Locality: the Cañadón de las Tortugas. The cross-section tracks commonly identified in these facies are from 30 to 75 cm long and 20–30 cm deep. Some of them preserve thin and shallow structures in the filling of the original track wall interpreted here as traces of the trackmaker integument. Specimens preserve two kinds of skin impressions. The first ones are parallel, mostly oblique striations, which sometimes cross each other at a high angle, produced by the pes during penetration and withdrawal from the substrate. The second ones are subrounded to polygonal, here interpreted as scale traces of the sole foot. Two clear, subtriangular to curved, and elongated, claw impressions are recorded in one track that allow us to relate it with a sauropod trackmaker.
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Time for Giants: Titanosaurs from the Berriasian–Santonian Age
Chapter
  • Apr 2022
Titanosaurian sauropods were the most diverse and successful group of large-bodied terrestrial herbivores. Two aspects regarding their evolutionary history stand out, namely their great morphological diversity and their extensive record from various continental masses. In South America, and particularly in Argentina, the group has the richest record worldwide. This is mainly due to the conjunction of two factors: the extensive paleontological investigation carried out by South American researchers since the beginning of the twentieth century and the well-exposed outcrops of Cretaceous continental strata. With the exception of Tapuiasaurus from Brazil, the entire record of South American named titanosaurs discovered in the Berriasian–Santonian interval comes from Argentina, specifically from Patagonia, including the south of Mendoza, Neuquén, Río Negro, and Chubut Provinces. With a number of 22 valid taxa, the Early and ‘Mid’-Cretaceous titanosaur record of South America includes basally branching (‘basal’) forms (e.g., Andesaurus, Ninjatitan), basal and derived lithostrotians (e.g., Sarmientosaurus, Tapuiasaurus, and Epachthosaurus), and most of the colossosaurs (mainly the giant lognkosaurs Mendozasaurus, Futalognkosaurus, Patagotitan, and Notocolossus). After their origin in the Early Cretaceous, titanosaurians experienced a rapid increase in taxonomic diversity, which is maintained toward the Late Cretaceous. However, during the Berriasian–Santonian interval, the size of titanosaurs reached its climax, representing the largest vertebrate animals ever to inhabit the earth. Some South American titanosaurs from this time have been widely used to define new clades (e.g., Colossosauria, Lognkosauria, Rinconsauria) that clarified the main phylogenetic relationships at lower level. Moreover, studies in some key paleobiological aspects related with the estimation of size contributed to better understanding the biology of some species in the context of the process of gigantism.
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Last Titans: Titanosaurs From the Campanian–Maastrichtian Age
Chapter
  • Apr 2022
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.
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A juvenile specimen of the sauropod dinosaur Alamosaurus sanjuanensis from the Upper Cretaceous of Big Bend National Park, Texas
Article
  • Jan 2002
A juvenile specimen of the titanosaurid sauropod Alamosaurus sanjuanensis, recovered from just below the Cretaceous/Tertiary boundary horizon in Big Bend National Park, Texas, is from an individual less than half the size of adult specimens referred to this species. The disarticulated skeleton was preserved in deposits of a shallow flood-plain pond and includes elements not previously described, allowing for an improved diagnosis for this species. The elongate opisthocoelous cervical vertebrae have non-bifid posteriorly deflected neural spines with deep postspinal fossae. The dorsal vertebrae have wide spatulate neural spines with strong prespinal laminae, and lack hyposphene-hypantrum articulations. Alamosaurus sanjuanensis exhibits a unique morphology of the ischium, evident even in this juvenile specimen. Comparison with other titanosaurid species suggests that A. sanjuanensis is most closely related to an unnamed titanosaur from Peiropolis, Brazil and Neuquensaurus australis from Argentina.
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A diverse Late Cretaceous vertebrate tracksite from the Winton Formation of Queensland, Australia
Article
Full-text available
  • Jun 2021
The Upper Cretaceous 'upper' Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the 'upper' Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the 'upper' Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the 'upper' Winton Formation with its heretofore ornithopod-and theropod-dominated ichnofossil record.
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