Diego Pol

• Ph.D.
• Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Alvarezsauria is a group of morphologically distinctive, medium- to small-sized later-diverging coelurosaurian theropod dinosaurs, whose record ranges from the Late Jurassic to the Late Cretaceous. This clade had a widespread distribution in Laurasia in what is now Europe, Asia, and North America, although there are also several Cretaceous taxa fro...

We describe a protocol for estimating evolutionary rates from phylogenetic trees based on parsimony character optimization. The rate estimation is conducted through a TNT script and the results are analysed in a script for the software environment R. The TNT script allows analysing multiple optimal topologies, considering optimization ambiguity, an...

Since their origin, sauropodomorphs have undergone numerous anatomical changes from small and bipedal early sauropodomorphs towards massive-bodied and quadrupedal sauropods. However, the timing of these changes in the evolution of the group is unclear. Here, we describe the appendicular skeleton of the early diverging eusauropod Bagualia alba from...

Notosuchia were a successful lineage of Crocodyliformes that achieved a remarkable diversity during the Cretaceous of Gondwana, particularly in South America. Although paleohistology has expanded our knowledge of the paleobiology of notosuchians, several clades of this lineage remain poorly understood in this aspect. Here we help to address this ga...

Since the start of the twenty-first century, there has been a notable increase in annual publications focusing on dinosaur reproduction and ontogeny with researchers using these data to address a range of macroevolutionary questions about dinosaurs. Ontogeny, which is closely tied to osteological morphological variation, impacts several key researc...

As the first group of tetrapods to achieve powered flight, pterosaurs first appeared in the Late Triassic. They proliferated globally, and by the Late Jurassic through the Cretaceous, the majority of these taxa belonged to the clade Monofenestrata (which includes the well-known Pterodactyloidea as its major subclade), typified by their single undiv...

Some of the smallest examples of dinosaurian body size are from alvarezsaurians, an enigmatic group of maniraptoran coelurosaurians with a peculiar combination of anatomical features unique among theropods. Despite the large number of alvarezsaurian species described worldwide and the increased understanding this has provided, the body‐size macroev...

En los últimos años, se ha incrementado en gran medida el conocimiento de las faunas de vertebrados de fines del Cretácico en diversas localidades de Patagonia. Este incremento se debe principalmente a la gran cantidad de investigadores abocados al tema, al igual que a la gran cantidad de datos recolectados en los últimos años e ingresados en la Pa...

The Alvarezsauridae comprises a group of enigmatic maniraptoran theropods from the Upper Cretaceous of South America, North America, Europe, and Asia. Among their most distinctive features are their short, robust forelimbs, and manus with an enlarged digit I bearing a massive claw and lateral digits highly reduced or absent. Among the Gondwanan alv...

Terrestrial sediments from the Late Jurassic are abundant in the continents that conformed Laurasia, but few terrestrial Late Jurassic units are known from the Gondwanan continents. The Cañadón Calcáreo Formation of Argentina, together with the Tendaguru Formation of Tanzania, are the only units that have yielded several articulated or closely asso...

Asfaltovenator vialidadi is the most complete tetanuran theropod known from the Cañadón Asfalto Formation (Chubut province, Argentina). This formation represents the most important vertebrate-bearing unit of the latest Early Jurassic in Gondwana and one of the very few units that have yielded terrestrial vertebrate fauna from this critical time per...

Notosuchia is a large and diverse clade of Mesozoic crocodyliforms that thrived in continental environments especially during the Cretaceous of Gondwana. This clade has been the focus of several phylogenetic studies that led to the consensus of two main topological arrangements, mostly differing in the position of the clade Sebecidae: the sebecosuc...

Notosuchia is a group of crocodyliforms with mostly terrestrial habits that lived during the Mesozoic and up to the Miocene. Within this group Uruguaysuchidae is so far represented by eight species, six of them clustered in the genus Araripesuchus. Two species of this genus, A. patagonicus and A. buitreraensis, come from different localities in Pat...

The Portezuelo Formation preserves an outstanding record of the upper Turonian – lower Coniacian. Despite the discovery of a significant quantity of sauropod fossil material from the formation, only two species have been formally described to date: Malarguesaurus florenciae and Futalognkosaurus dukei. Here we present new sauropod material mostly co...

Averostra represents the main clade of theropod dinosaurs, but the interrelationships of its early members and the relationships between the major subclades are still debated. The clade underwent a rapid radiation from the Early to Late Jurassic, with the Pliensbachian-Toarcian extinction event likely being one of the major causes for this explosiv...

Gondwanan dinosaur faunae during the 20 Myr preceding the Cretaceous-Palaeogene (K/Pg) extinction included several line-ages that were absent or poorly represented in Laurasian landmasses. Among these, the South American fossil record contains diverse abelisaurids, arguably the most successful groups of carnivorous dinosaurs from Gondwana in the Cr...

The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroid...

The study of thirty-two shed crowns from the Portezuelo Formation (middle Turonian-late Coniacian) at the Sierra del Portezuelo locality, reveals six distinct tooth morphotypes identified through cladistic, discriminant, and cluster analyses. Two morphotypes were identified as belonging to Megaraptoridae, three to Abelisauridae, one to Abelisauroid...

The Portezuelo Formation preserves an outstanding record of the upper Turonian - lower Coniacian of Gondwana. Despite the discovery of a significant amount of sauropod fossil material from the Formation, only two species have been formally described to date: Malarguesaurus florenciae and Futalognkosaurus dukei . Here we present new sauropod materia...

Studies on pathological fossil bones have allowed improving the knowledge of physiology and ecology, and consequently the life history of extinct organisms. Among extinct vertebrates, non-avian dinosaurs have drawn attention in terms of pathological evidence, since a wide array of fossilized lesions and diseases were noticed in these ancient organi...

The primary function of the forelimbs of non-avian theropod dinosaurs is associated with diverse and often very demanding tasks, such as feeding and social behavior. Among the different clades of non-avian theropods, there are radically different forelimb morphologies that result in a wide variety of functional specializations, as they reflect a ba...

Our understanding on diversity and kinship of Gondwanan armored dinosaurs increased with the description of Stegouros eleganssen, the naming of Parankylosauria reuniting Stegouros with Antarctopelta oliveroi and Kunbarrasaurus ieversi, and the descriptions of the basal thyreophoran Jakapil kaniukura and the nodosaurid Patagopelta cristata. Our stud...

Mientras que los restos terrestres del Jurásico Tardío están bien representados en el hemisferio norte, éstos se encuentran subrepresentados en el hemisferio sur. Juntas, la Formación Tendaguru de Tanzania y la Formación Cañadón Calcáreo de Argentina son las únicas con diversos restos de saurópodos articulados o estrechamente asociados para ese per...

The Supplemental Data includes a brief summary of the general aspects of the dentition of Manidens condorensis, and six different supplemental figures: 1, recognized areas of bone remodeling in the laterally projected jugal boss on MPEF-PV 3211 and captions for the supplemental figures; 2, inferred areas of origin and insertion for musculature in t...

Heterodontosauridae is a clade that appears early in the ornithischian fossil record, and includes small-bodied, highly specialized species characterized by an unusual heterodont dentition. Although known from relatively few taxa, the early representation of the clade and unsolved phylogenetic relationships within heterodontosaurids and among early...

Herein we report the first record of Purussaurus Barbosa-Rodrigues, 1892 for the Neogene of Argentina. This genus is recorded in Miocene beds of different localities in Colombia, Venezuela, Brazil, and Perú, and includes at least three different species with total body lengths ranging from 8 to 13 m. The material reported here is a partially preser...

In amniotes, the predominant developmental strategy underlying body size evolution is thought to be adjustments to the rate of growth rather than its duration. However, most theoretical and experimental studies supporting this axiom focus on pairwise comparisons and/or lack an explicit phylogenetic framework. We present the first large-scale phylog...

Abelisaurids are medium–large-sized theropod dinosaurs that were predominant in the carnivorous fauna during the Late Cretaceous of Gondwana. These predators are abundant in the Cretaceous fossil strata of Patagonia, which yield the best record for this group. In the Late Cretaceous, abelisaurids appear in almost all regions of Gondwana and in all...

We present a detailed histological study of long bones from an ontogenetic series of Mussaurus patagonicus, an early sauropodomorph from the Lower Jurassic of Argentina. Twenty long bones, including humeri, femora and fibulae, obtained from 13 individuals of different body sizes were sampled for histological analysis. In general terms, the cortical...

Sebecidae is a clade of large carnivorous crocodyliforms that thrived in the Cenozoic and is the only lineage of the diverse and terrestrial group Notosuchia that survived the end-Cretaceous mass extinction event. Sebecus icaeorhinus is the best-known taxon from this clade, both in terms of its cranial and postcranial anatomy (known primarily from...

Jaw muscles are key features of the vertebrate feeding apparatus. The jaw musculature is housed in the skull whose morphology reflects a compromise between multiple functions, including feeding, housing sensory structures, and defense, and the skull constrains jaw muscle geometry. Thus, jaw muscle anatomy may be suboptimally oriented for the produc...

Notosuchia represents a highly diverse lineage of Crocodyliformes usually characterized by the presence of a heterodont dentition. Although the dental anatomy has been thoroughly analysed in some taxa, information regarding tooth microstructure and dental attachment tissue are still poorly explored. With the purpose to obtain new data regarding fee...

Myhrvold et al. suggest that our inference of subaqueous foraging among spinosaurids is undermined by selective bone sampling, inadequate statistical procedures, and use of inaccurate ecological categorizations. Myhrvold et al. ignore major details of our analyses and results, and instead choose to portray our inferences as if they were based on qu...

Early sauropodomorphs were diverse in Gondwana, being particularly well represented in South America. Mussaurus patagonicus is one of the best-known non-sauropod sauropodomorphs that inhabited the Southern Hemisphere. Its importance relies on its phylogenetic position close to Sauropoda and also because it is known from a well-represented ontogenet...

Eusauropods are large-bodied and long-necked dinosaurs that dominated the role of large herbivores in terrestrial ecosystems since at least the late Early Jurassic (Pliensbachian–Toarcian). Their early diversification is best recorded in South America where the best-preserved eusauropods and close relatives from this period of time have been found....

Secondary aquatic adaptations evolved independently more than 30 times from terrestrial vertebrate ancestors1,2. For decades, non-avian dinosaurs were believed to be an exception to this pattern. Only a few species have been hypothesized to be partly or predominantly aquatic3–11. However, these hypotheses remain controversial12,13, largely owing to...

The lower jaw of early tetrapods is composed of several intramembranous ossifications. However, a tendency toward the independent reduction of the number of bones has been observed in the mandible of mammals, lepidosaurs, turtles, crocodiles, and birds. Regarding archosaurs, the coronoid and prearticular bones are interpreted to be lost during the...

The extinct herpetofauna of the Chubut Province is one of the most diverse, temporally and spatially extensive, and well-known extinct faunas in Argentina and South America. These fossils help understanding the evolution of the herpetofauna during more than 180 million years, not only in the Patagonian region, but also in a worldwide scale due to t...

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 princip...

Sauropodomorph dinosaurs were the dominant medium to large-sized herbivores of most Mesozoic continental ecosystems, being characterized by their long necks and reaching a size unparalleled by other terrestrial animals (> 60 tonnes). Our study of morphological disparity across the entire skeleton shows that during the Late Triassic the oldest known...

A new crocodyliform, Sebecus ayrampu, sp. nov., is described based on the rostral region of the skull, mandibular rami, and a distal portion of the femur collected in Paleocene rocks of northwestern Argentina. The new taxon is diagnosed (among other characters) by the presence of a sharp sagittal torus on the palatal surface of the premaxilla and m...

Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic–Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood. For instance, knowledge on their behaviour is limited, although herding in sauropodomorphs has been well doc...

In this contribution we introduce a new Late Triassic archosaur, Incertovenator longicollum gen. et sp. nov., with an unusual combination of character states that are present in certain early avemetatarsalian and pseudosuchian archosaur clades. The holotype consists of a partial postcranial skeleton, preserving most of the axial skeleton and displa...

Middle Jurassic sauropod taxa are poorly known, due to a stratigraphic bias of localities yielding body fossils. One such locality is Cerro Cóndor North, Cañadón Asfalto Formation, Patagonia, Argentina, dated to latest Early–Middle Jurassic. From this locality, the holotype of Patagosaurus fariasi Bonaparte 1986 is revised. The material consists of...

All modern crocodyliforms (alligators, crocodiles and the gharial) are semi-aquatic generalist carnivores that are relatively similar in cranial form and function. However, this homogeneity represents just a fraction of the variation that once existed in the clade, which includes extinct herbivorous and marine forms with divergent skull structure a...

Notosuchia is a clade of crocodyliforms that was highly successful and diverse in the Cretaceous of Gondwana. Araripesuchus gomesii is a small notosuchian from the Early Cretaceous of Brazil that belongs to Uruguaysuchidae, one of the subgroups of notosuchians that first radiated, during the Aptian–Albian. Here we present a finite element analysis...

Late Jurassic South American theropod faunas are still extremely poorly known, with large-sized ceratosaurids and megalosaurids having been identified on the basis of isolated teeth, whereas the only named taxa, Chilesaurus and Pandoravenator, are probable tetanurans of uncertain affinities. Here we describe two new specimens of medium-sized to lar...

In this work, we present a comparative analysis between Araripesuchus gomesii, a small notosuchian from the Early Cretaceous of Brazil, and Alligator mississippiensis, a living representative of the crocodyliform lineage considered as a model species for herpetological and functional studies. A finite element analysis (FEA), comparing the skull per...

A stegosaurian humerus from the Oxfordian–Tithonian(?) Cañadón Calcáreo Formation of Chubut, Argentina, extends the fossil record of this clade of thyreophoran ornithischian dinosaurs to the Upper Jurassic of South America. The element shares the derived character of an oblique ridge extending from the deltopectoral crest towards the medial distal...

Here we present the first record of a stem-Coracii outside the Holarctic region, found in the early Eocene of Patagonia at the Laguna del Hunco locality. Ueekenkcoracias tambussiae gen. et sp. nov. consists of an incomplete right hind limb that presents the following combination of characters, characteristic of Coracii: relatively short and stout t...

Sauropodomorpha is the first major dinosaurian group that radiated during the Triassic. During this time the group underwent major changes in body plan, including the acquisition of features related to herbivory, large body size, and quadrupedality. By the end of the Late Triassic, approximately 30 million years after the origin of dinosaurs, sauro...

Notosuchia is a clade of crocodyliforms highly successful and diverse in the Cretaceous of Gondwana. Araripesuchus gomesii is a small early notosuchian from the Lower Cretaceous of Brazil in which a finite element analysis (FEA) was performed in this study. The skull and jaw of A. gomesii was reconstructed from CT scans. The FE analysis was perform...

Sauropods, the giant long-necked dinosaurs, became the dominant group of large herbivores in terrestrial ecosystems after multiple related lineages became extinct towards the end of the Early Jurassic (190-174 Ma). The causes and precise timing of this key faunal change, as well as the origin of eusauropods (true sauropods), have remained ambiguous...

Preprint of In Press manuscript of the Osteological redescription of Patagosaurus fariasi

Abelisaurid theropods dominated the predator role across Gondwana during the Late Cretaceous. They are characterized by highly reduced forelimbs and one of the most specialized cranial morphologies among carnivorous dinosaurs, exemplified by a broad skull, short rostrum, high occipital region, and highly kinetic intramandibular joint, suggestive of...

Supplementary material for this article includes micro-CT scan figures and reconstruction of the skull of Spectrovenator ragei n. gen., n. sp., annotated character list, data matrix in TNT format, strict and reduced consensus trees, support analyses, list of synapomorphies, and selected measurements from the skull of Spectrovenator ragei n. gen., n...

Dental replacement in Heterodontosauridae has been debated over the last five decades primarily on indirect evidence, such as the development of wear facets and the position of erupted teeth. Direct observation of unerupted teeth provides unambiguous data for understanding tooth replacement but this has been done only for Heterodontosaurus and Frui...

Crocodylomorpha is a clade that has its origins during the Late Triassic and attained a global distribution early in their radiation. In this context, although limited to few geological units, the South American record has been relevant in the understanding of the origins of the clade. Additionally analyzing the South American crocodylomorph record...

Calcified eggshells protect developing embryos against environmental stress and contribute to reproductive success¹. As modern crocodilians and birds lay hard-shelled eggs, this eggshell type has been inferred for non-avian dinosaurs. Known dinosaur eggshells are characterized by an innermost membrane, an overlying protein matrix containing calcite...

Araripesuchus (Uruguaysuchidae) is a gondwanan mesoeucrocodylian genus that includes several species, distributed in the Cretaceous of Niger (A. wegeneri and A. rattoides), Madagascar (A. tsangatsangana), Brazil (A. gomesii), and Argentina (A. patagonicus and A. buitreraensis). The two Argentinean species came from different localities of the lower...

Almadasuchus figarii is a basal crocodylomorph recovered from the Upper Jurassic levels of the Cañadón Calcáreo Formation (Oxfordian–Tithonian) of Chubut, Argentina. This taxon is represented by cranial remains, which consist of partial snout and palatal remains; an excellently preserved posterior region of the skull; and isolated postcranial remai...

Previous studies on enamel microstructure in Ornithischia have focused on derived lineages of this clade based on species from the northern hemisphere. Here we describe the enamel microstructure of Manidens condorensis from the late Early Jurassic of Argentina that belongs to Heterodontosauridae (interpreted as the basal-most clade of Ornithischia)...

Tetanurae, the most successful clade of theropod dinosaurs, including modern birds, split into three major clades early in their evolutionary history: Megalosauroidea, Coelurosauria, and Allosauroidea. The oldest tetanurans occur in the earliest Middle Jurassic, but the early fossil record of the clade is still poor. Here we report one of the oldes...

The Cretaceous Cerro Barcino Formation (Chubut Group) of Central Patagonia, Argentina has yielded a remarkable fossil vertebrate fauna, which form important components of the South American “mid-Cretaceous” fauna, including titanosauriform sauropod dinosaurs, theropod dinosaurs, crocodyliforms, turtles, and lepidosauromorphs. However, a lack of rob...

Complex structures, like the vertebrate skull, are composed of numerous elements or traits that must develop and evolve in a coordinated manner to achieve multiple functions. The strength of association among phenotypic traits (i.e., integration), and their organization into highly-correlated, semi-independent subunits termed modules, is a result o...

Ontogenetic information is crucial to understand life histories and represents a true challenge in dinosaurs due to the scarcity of growth series available. Mussaurus patagonicus was a sauropodomorph dinosaur close to the origin of Sauropoda known from hatchling, juvenile and mature specimens, providing a sufficiently complete ontogenetic series to...

Gondwanan Jurassic non-neosauropod eusauropods are key for the understanding of sauropod evolution, although their phylogenetic interrelationships remain poorly understood. However, following the revision of the holotype of a key taxon from the early Middle Jurassic Cañadón Asfalto Formation Patagonia, Argentina, Patagosaurus fariasi, the phylogene...

Crocodylomorpha es un clado de arcosaurios que representa el único linaje de pseudosuquios que sobrevive al límite Triásico-Jurásico e incluye a los cocodrilos vivientes. Uno de los taxones más antiguos de este grupo es Trialestes romeri Reig 1963, proveniente de la Fm. Ischigualasto. En el presente trabajo se describe un nuevo crocodilomorfo no-cr...

El registro actual de los eusaurópodos del Jurásico Temprano y Medio es pobre a nivel mundial. El espécimen MPEF-PV 3301-1 colectado en la localidad de Cañadón Bagual (Formación Cañadón Asfalto, Chubut) confirmaría un origen del clado Eusauropoda mucho antes de lo que se creía (Toarciano), y es destacable que, además de material apendicular, se pre...

The Mkv evolutionary model, based on minor modifications to models of molecular evolution, is being increasingly used to infer phylogenies from discrete morphological data, often producing different results from parsimony. The critical difference between Mkv and parsimony is the assumption of a "common mechanism" in the Mkv model, with branch lengt...

This analysis of the long bone microstructure of Antetonitrus ingenipes fills a crucial gap in our understanding of the growth dynamics of sauropodomorph dinosaurs. The bone histology of basal Sauropodomorpha are often characterized by zonal tissue, and contrasts with that of more derived sauropod taxa which show a shift toward the deposition of un...

New materials of the ornithischian dinosaur Manidens condorensis highlight a strong heterodonty between the upper and lower dentitions and reveal a novel occlusion type previously unreported in herbivorous dinosaurs. The diamond-shaped maxillary teeth have prominent cingular entolophs in a V- to Z-shaped configuration that are absent in dentary tee...