Ariel Méndez

• Ph.D.
• Investigador Adjunto - CONICET at CENPAT (Centro Nacional Patagónico - CONICET)

Patterns of body size evolution in dinosaurs are relevant for understanding the evolutionary trends that have shaped the disparity of phenotypes observed in the fossil record. In this sense, previous studies have suggested that Abelisau-ridae followed Cope´s rule and Noasauridae exhibited a phylogenetic trend towards decreasing body size. However,...

Marks left by teeth on bones are evidence for inferring trophic interactions. In carnivorous dinosaurs, such evidence is rare in the fossil record. We present here the description of a fragment of sauropod appendicular bone, which exhibits teeth marks consistent with multiple trace makers. The specimen MPM-PV-19111 comes from Cretaceous rocks outcr...

Abelisauridae is a clade of theropods distinguished by short, ornamented skulls and strongly reduced forelimbs. They represented the most abundant predatory dinosaurs in Gondwana during the Cretaceous. Bolstered by biomechanical studies, the morphology of the skull and vertebral column of abelisaurids, have led researchers to hypothesize that Late...

A new specimen, MAU-Pv-PH-453, comprising an isolated femur from the Plottier Formation (Coniacian-Santonian), northern Patagonia, is described here. Its characteristics, i.e., an anteriorly curved diaphysis; fused lesser and greater trochanters forming a trochanteric crest; a prominent medially directed head; and the absence of a fourth trochanter...

We present here a natural cranial endocast assigned to an abelisaurid theropod found in Cretaceous rocks of the outcropping Bajo de la Carpa Formation (Santonian) in Neuquén Province, Northern Patagonia, Argentina. The specimen was found in association with fragmentary braincase remains, which include an otic capsule and part of the skull roof. The...

A new titanosaur sauropod genus including an almost complete skull and axial elements to the hips, reflecting a convergent bauplan with the older rebbachisaurids sauropods.

The Cerro Overo-La Invernada area in north Patagonia has provided a rich record of Cretaceous continental tetrapods in the last two decades, mainly from the Bajo de la Carpa Formation (Upper Cretaceous, Santonian). The dinosaur fauna from this area is diverse, including several new taxa, with abelisaurid theropods particularly abundant. Recently, a...

The diversity of the Upper Cretaceous (Cenomanian to Maastrichtian) crocodyliforms in Argentina is represented by several families of notosuchians (Notosuchidae, Comahuesuchidae, Baurusuchidae, Peirosauridae), and basal mesoeucrocodylian taxa. Most species (such as Neuquensuchus universitas, Notosuchus terrestris, Comahuesuchus brachybuccalis, Cyno...

The Late Cretaceous dinosaur record in southern South America has been improved recently; particularly with findings from Chorrillo and Cerro Fortaleza formations, both bearing ankylosaur remains, a clade that was not previously recorded in the Austral Basin. The dinosaur fauna of the type locality of Cerro Fortaleza Formation is known from -and bi...

Two new specimens of abelisaurid theropods from La Invernada fossil area (Bajo de la Carpa Formation; Santonian) are described. They correspond to an incomplete skull and several postcranial remains. MAU-Pv-LI-582 (skull) shares some morphological traits with other furileusaurs (Viavenator exxoni and Llukalkan aliocranianus) from the same area, as:...

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 relate...

Abelisaurids are among the most abundant and diverse Patagonian Late Cretaceous theropods. Here, we present a new furileusaurian abelisaurid, Llukalkan aliocranianus gen. et sp. nov., represented by cranial remains from the Bajo de la Carpa Formation (Santonian) at La Invernada fossil area, northwestern Patagonia. Features characterizing this taxon...

Teeth with split carina is an uncommon trait recorded in archosaurs with ziphodont dentition (laterally compressed teeth bearing serrated margins). This condition has been reported in few theropod dinosaurs (Allosaurus, tyrannosaurids, dromaeosaurids and carcharodontosaurids) and in one Triassic phytosaur. Here, we report by the first time a split...

The most austral South American ankylosaur record correspond to the preliminary report of an isolate tooth recovered from a microsite (MPM-PV-18805, Museo Padre Molina, Río Gallegos) at Cerro Fortaleza (Cerro Fortaleza Formation, Campanian-Maastrichtian), in Southern Patagonia. Associate materials were recently identified as interstitial armor ossi...

En las últimas décadas se han registrado varios sitios con cáscaras, huevos, y nidos de dinosaurios en los bajos interiores de la provincia de Río Negro. En 2018 fueron hallados dos grupos de huevos en la localidad de Bajo Trapalcó (Río Negro). Los huevos se localizan en el yacimiento Garrido Inferior cerca del Puesto González (equivalente a los ya...

El Área Natural Municipal Protegida Paso Córdoba está ubicada 15 km al sur de la localidad de General Roca. En los últimos años, dicho lugar ha sido motivo de estudios sedimentológicos, taxonómicos, icnológicos y tafonómicos. Allí afloran estratos del Cretácico Superior pertenecientes al Grupo Neuquén (Formaciones Bajo de la Carpa y Anacleto) y al...

Megaraptorids constitute a recently recognized new clade of theropod dinosaurs that have been documented in Africa, Oceania, and Asia, although the most abundant record comes from South America and especially from Argentina. Here we report a new megaraptoran specimen (MCNA-PV 3109 to 3117 and 5119 to 5123) recovered from Cañadón Amarillo in out-cro...

Las marcas de dientes sobre huesos son evidencia para inferir interacciones tróficas. En el caso de dinosaurios carnívoros, dichas evidencias son raras en el registro fósil. Presentamos aquí un fragmento de hueso apendicular de dinosaurio saurópodo de 10,5 cm de longitud, que exhibe marcas de dientes consistentes con depredación por parte de múltip...

El registro fósil de los abelisáuridos es el más abundante entre los terópodos de Gondwana durante el Cretácico Superior. Uno de ellos es Viavenator exxoni, proveniente de la Formación Bajo de la Carpa (Santoniano), al norte de la provincia de Neuquén del cual se conocen en detalle numerosos restos óseos (e.g., neurocráneo y esqueleto axial). A pes...

Abelisauroid theropods constitute the most commonly recorded meat-eating dinosaurs from the Upper Cretaceous of Gondwana. In Argentina, they are known mainly from central and northern Patagonia, especially at the Neuquina basin. However, their record in the southern region of Patagonia is scarce, although the Cretaceous outcrops of the Magallanes b...

Los Phorusrhacoidea o aves del terror, fueron un grupo de aves de hábitos cursoriales, del Cenozoico americano, con registros fragmentarios en Africa y Europa, consideradas como predadores tope. Actualmente no poseen análogos ecológicos, aunque si relaciones filogenéticas cercanas con los Cariamidae. Se estudiaron anatómica y filogenéticamente rest...

Several remains of an abelisaurid theropod including a nearly complete sacral complex articulated with both ilia, the distal boot of the pubes, the furcula, teeth, and fragments of transverse processes of caudal vertebrae was discovered in the La Invernada fossil site, northern Patagonia from the Bajo de la Carpa Formation (Santonian). The sacrum e...

In the last decades, the Argentinian ornithopod record has been increased with new and diverse bone remains found along all the Upper Cretaceous. Most of them are very incomplete and represent taxa of different size. As result, the studies about the palaeobiodiversity of the Ornithopoda clade in South America are complex. In this paper, new postcra...

The complete osteology of the abelisaurid Viavenator exxoni, from the Bajo de la Carpa Formation (Santonian, Upper Cretaceous) is described. Viavenator is characterized by a series of autapomorphies, including: transversely compressed parietal depressions on both sides of the supraoccipital crest; ventral edges of the paraoccipital processes locate...

Ornithopods are the least known dinosaurs within the Upper Cretaceous record of Argentina. For this reason every new record is very important to know their evolution in South America. Here, we describe a new remain of an indeterminate ornithopod recovered in the Petrobrasaurus quarry of the Puesto Hernández area, northeastern Neuquén province (Arge...

El registro de dinosaurios terópodos identificados para la Formación Bajo de la Carpa (Santoniano, Cretácico Superior), corresponden a diversos restos de abelisauroideos (Velocisaurus unicus Bonaparte, una pelvis completa, una vértebra caudal y un nuevo espécimen casi completo recientemente descubierto), una tibia de un terópodo indeterminado, rest...

Isolated bones of abelisauroid theropods from the Baum Group (Upper Cretaceous, Brazil), are described. They correspond to three individuals represented by fused ischia and part of the ilium, a partial axis, and a right fibula, respectively. The fossils come from different sites in the municipalities of Ibira (axis and fibula) and Monte Alto (ilium...

The first bony theropod record from the Campanian Uberaba Formation (Bauru Group) is described. It consists of an isolated caudal centrum (CPPLIP 1324) found in the city of Uberaba, Minas Gerais State, Brazil. The amphicoelous centrum possesses a length to height ratio of 1.74, deep elliptical lateral pneumatic foramen representing 26% of centrum l...

The caudal vertebrae of abelisaurid theropods are compared in detail. Notable trends in vertebral morphology are apparent and illustrated for this group, particularly in the shape of the transverse process. Several differences are also noted among the members of this clade. Such differences in morphology may underlie attributes related to balance a...

The cervical vertebral series of Carnotaurus sastrei from Argentina is described in detail, and compared with Majungasaurus crenatissimus from Madagascar, both Late Cretaceous (Maastrichtian) in age. Notable differences in the morphology of the cervical vertebrae, especially in the shape and development of the epipophysis and the neural spines, are...

An isolated caudal vertebral centrum of a theropod dinosaur was discovered in the Bauru Basin (Late Cretaceous) of Brazil, in the Maastrichtian São José do Rio Preto Formation. The vertebral centrum has pneumatic features that are similar to those in the megaraptoran theropods Aerosteon, Megaraptor, and Orkoraptor. For example, all these taxa share...

The Lameta Formation (Upper Cretaceous, Maastrichtian) of India has yielded abundant fossils of a-belisaurid theropods, including bones from the cranium, vertebral column, pectoral and pelvic girdles, and hind-limb. However, the forelimbs of Indian abelisaurids remain unknown. Here we describe an abelisaurid humerus from exposure of the Lameta Form...

An isolated anterior caudal vertebra of a medium-large sized theropod dinosaur is reported here. It comes from the Bajo de la Carpa Formation (Santonian, Late Cretaceous), Río Colorado Subgroup, Río Negro Province, northern Patagonia, Argentina. The specimen, MACN-PV-RN 1012, exhibits several derived characters that are diagnostic among theropods....

Bones of abelisaurid theropods from the Upper Cretaceous (Maastrichtian) Marília Formation, Bauru Basin, Brazil, are here described. They are a dorsal vertebra, the distal part of a femur, and a pedal phalanx corresponding to three specimens found in different fossil sites of Uberaba County, Minas Gerais State. These specimens are the first abelisa...