Papers by Raúl Orencio Gómez
Nuestras Aves, 2017
El Cacholote Castaño (Pseudoseisura lophotes) es una especie de la familia Furnariidae típica de ... more El Cacholote Castaño (Pseudoseisura lophotes) es una especie de la familia Furnariidae típica de las ecorregiones del Chaco y el Espinal, distribuyéndose desde el centro de Argentina hasta el sur de Bolivia y oeste de Paraguay. Su relativo gran tamaño (23 cm), su robusto pico y su llamativa cresta lo distinguen entre los representantes de esa familia (Remsen 2003). Al igual que otros furnáridos de la tribu Synallaxini (sensu Derryberry et al. 2011), esta especie construye complejos y voluminosos nidos de palitos (Rodríguez 1918, Narosky et al. 1983, de la Peña 2013). Las parejas de Cacholotes Castaños construyen varios nidos, típicamente de septiembre a febrero, los cuales usan...
Zoologischer Anzeiger - A Journal of Comparative Zoology, 2017
Postembryonic skeletogenesis in anuran amphibians has been widely studied, yet less than one perc... more Postembryonic skeletogenesis in anuran amphibians has been widely studied, yet less than one percent of the extant diversity has been covered and relatively few comparative studies exist. Here we document the sequence and timing of ossification of the Common Toad Rhinella arenarum, a large true toad (Bufonidae) from South America that is a model organism for varied ongoing research. We study histological sections and cleared-and-stained specimens of an ontogenetic series ranging from early larval stages to juveniles, documenting the ossification sequence of the entire skeleton. To diminish potential environmental biases we also study the skeletogenesis of the frog Leptodactylus latinasus (Leptodactylidae) from the same pond and season. We summarize comparative data from numerous anuran species to contextualize our results in a broad phylogenetic context. Histological data shows that skeletal calcification in R. arenarum is temporally dissociated from osteoid matrix formation and occurs later than in most other anurans, which is unexpected given its generalized pond-type larva and heavily ossified adult skeleton. At the onset of metamorphosis, exoccipitals, parasphenoid, and frontoparietals are the only ossified skull elements, whereas most of the postcranium has already started ossification. This pattern is rare among anurans but is shared by other bufonids, in which it has been previously linked to rapid development. Our comparative survey, however, suggests that the delayed bufonid pattern is not related to fast-developing larvae but instead might be a distinctive feature of true toads.
Journal of Vertebrate Paleontology, 2016
The frog genus Odontophrynus comprises 10 species arranged in three species groups that inhabit s... more The frog genus Odontophrynus comprises 10 species arranged in three species groups that inhabit southeastern South America. In Argentina, it is represented by the O. americanus and O. occidentalis species groups and, despite being a fairly common taxon of the extant herpetofauna, it has no known fossil record. Here we report on the first fossil record of the genus, based on an almost complete right ilium from the lower levels of the Buenos Aires Formation (OIS 11, Bonaerian age, middle Pleistocene) in the Bonaerian Pampas of Argentina. The taxonomic allocation is derived from a thorough survey of anuran ilia and is grounded in a set of distinct ilial characters that, in combination, do not occur in any other anuran. These include: ilium not fused to ischium; well-developed dorsal acetabular expansion; broad preacetabular zone with a shallow preacetabular fossa; straight ilial shaft lacking dorsal ridge; and spike-like dorsal prominence bearing a distinct dorsal protuberance. Additionally, after comparing with a large sample of specimens representing most species of Odontophrynus, we propose two main characters (high spike-like dorsal prominence, absence of a lateral knob on the dorsal prominence) that allow referral to Odontophrynus aff. O. americanus or O. cordobae.
Cretaceous Research, 2016
Pipid frogs are fully aquatic frogs that today inhabit freshwater environments of southern contin... more Pipid frogs are fully aquatic frogs that today inhabit freshwater environments of southern continents on both sides of the Atlantic Ocean, with a fairly good fossil record dating back to the Cretaceous. Here I report on fossils from the Allen Formation (upper Campanianelower Maastrichtian), Río Negro Province, Argentina, that are ascribed to a new genus and species of pipid. In order to assess the evolutionary relationships of the new taxon, which is represented by sphenethmoids, otic capsules, ilia, humeri, and vertebrae, cladistic analyses of a data matrix of 165 osteological characters scored for 36 taxa were performed. The results are congruent with previous hypotheses of pipoid interrelationships and consistently place the new taxon as part of the lineage today represented by the African xenopodines. Temporal calibration of the phylogenetic tree based on the fossil record imply that the origin and early diversification of crown-group Pipidae might have occurred during the Early Cretaceous, prior to the final breakup of western Gondwana. This study highlights the importance of including fossils, even fragmentary ones, directly in phylogenetic analyses in order to disentangling how, when, and where pipid frogs diversified.
Palaeobiology, 2016
Understanding the evolution of a Bauplan starts with discriminating phylogenetic signal from adap... more Understanding the evolution of a Bauplan starts with discriminating phylogenetic signal from adaptation and the latter from exaptation in the observed biodiversity. Whether traits have predated, accompanied, or followed evolution of particular functions is the basic inference to establish the type of explanations required to determine morphological evolution. To accomplish this, we focus in a particular group of vertebrates, the anurans. Frogs and toads have a unique Bauplan among vertebrates, with a set of postcranial features that have been considered adaptations to jumping locomotion since their evolutionary origin. This interpretation is frequently stated but rarely tested in scientific literature. We test this assumption reconstructing the locomotor capabilities of the earliest known salientian, Triadobatrachus massinoti. This extinct taxon exhibits a mosaic of features that have traditionally been considered as representing an intermediate stage in the evolution of the anuran Bauplan, some of which were also linked to jumping skills. We considered T. massinoti in an explicit evolutionary framework by means of multivariate analyses and comparative phylogenetic methods. We used length measurements of major limb bones of 188 extant limbed amphibians (frogs and salamanders) and lizards as a morphological proxy of observed locomotor behavior. Our findings show that limb data correlate with locomotion, regardless of phylogenetic relatedness, and indicate that salamander-like lateral undulatory movements were the main mode of locomotion of T. massinoti. These results contrast with recent hypotheses and indicate that derived postcranial features that T. massinoti shared with anurans might have been later co-opted as exaptations in jumping frogs.
Journal of Vertebrate Paleontology, 2016
The ilium has been considered a key element in anuran paleontology, but its terminology is incons... more The ilium has been considered a key element in anuran paleontology, but its terminology is inconsistent across the literature. Therefore, here we review the terminology used so far to describe anuran ilia and provide an annotated glossary of main ilial features. We also survey ilial morphology and comment on variation exhibited by each ilial feature among major anuran lineages. We do so with special consideration for miological correlates, provide muscular maps for a few species and aim to clarify hypotheses of primary homology. We consider previous work that compartmentalizes part of the described variation into cladistic characters, with the intention of providing a starting point for using ilial features in future research on osteology-based phylogenetics of anurans. Finally, we remark on some aspects regarding the dorsal prominence-protuberance complex.
Fossil Imprint, 2016
The holotype of the “archaeobatrachian” (i.e., non-neobatrachian) frog Eodiscoglossus santonjae V... more The holotype of the “archaeobatrachian” (i.e., non-neobatrachian) frog Eodiscoglossus santonjae VILLALTA, 1954 is redescribed herein, with focus on some features that have been misinterpreted. The specimen is articulated and poorly preserved as fragmentary bones and impressions, and is from the Early Barremian La Pedrera de Rúbies Lithographic Limestones Formation at Santa Maria de Meià, Lleida Province. Other specimens from the same fossil site and unit are also examined and their former allocation to the same species critically reconsidered, with the conclusion that more than one taxon might be represented in this sample. Previous viewpoints on the systematic placement of E. santonjae, usually considered a discoglossid, are assessed. However, a full revision of the Jurassic and Cretaceous specimens ascribed to the genus is required in order to resolve its phylogenetic position. Hence, E. santonjae is provisionally considered as Anura incertae sedis.
Nuestras Aves, 2015
El Gavilán Mixto es una de las rapaces más frecuentemente obervada en la ciudad de Buenos Aires, ... more El Gavilán Mixto es una de las rapaces más frecuentemente obervada en la ciudad de Buenos Aires, habiéndose registrado principalmente en espacios verdes. En este trabajo estudiamos la dieta del Gavilán Mixto durante el período reproductivo a partir de restos de presas registrados en la Reserva Ecológica Costanera Norte, Ciudad Autónoma de Buenos Aires, Argentina, identificando las presas a nivel de especie y calculando el aporte de biomasa de cada una. Los resultados que reportamos admitirían catalogar a esta especie como parte del gremio de consumidores de mamíferos, con predilección por presas de tamaño medio. La amplitud y variedad de su dieta en diferentes regiones y diversos ambientes indican cierta flexibilidad en sus hábitos de alimentación y en sus tácticas de caza. Esto se refleja también en el aprovechamiento de presas alternativas temporal o regionalmente abundantes, como el caso de los anfibios que reportamos. Por lo tanto, estas observaciones sugieren que el Gavilán Mixto presenta una dieta generalista y una conducta de caza oportunista, tal como ha sido propuesto para muchas otras rapaces.
Journal of Vertebrate Paleontology, 2011
Eocene caldera-lake deposits from Río Pichileufú have yielded anuran remains in association with ... more Eocene caldera-lake deposits from Río Pichileufú have yielded anuran remains in association with a taxonomically diverse flora. The floral evidence suggests that these anurans lived under climatic conditions similar to those of extant subtropical rainforests. One of the anurans is a helmeted neobatrachian, which is represented by articulated remains and represents a new species that can be assigned to the extant genus Calyptocephalella on the basis of both cranial and postcranial traits. Calyptocephalella pichileufensis, gen. et sp. nov., indicates that, despite the relatively conservative skeletal anatomy of the genus, Calyptocephalella has not always been associated with the temperate austral forests that it inhabits today. The new species also provides evidence of a biotic link with Australia, which has been proposed on the basis of other faunal and floral records, as well as on the paleogeographic history of Patagonia during the mid-Cretaceous–Eocene interval. We also discuss the significance of neobatrachian cranial features that might reflect hyperossification.
The Neotropical frog genus Leptodactylus is one of the most taxonomically diverse of all neobatra... more The Neotropical frog genus Leptodactylus is one of the most taxonomically diverse of all neobatrachian anurans. Despite the genus being highly diversified and widely distributed today, the fossil record is scanty and restricted to the Quaternary of the Neotropics. Here, we report and describe a new record of total group Leptodactylus from the Chapadmalalan (early Pliocene) of the South American Pampas. We evaluate both qualitative and quantitative characters and discuss the taxonomic value of body size in the context of living Leptodactylus. A number of features of the fossil elements suggests an affinity with the living species of the L. latrans species group and, particularly, with L. latrans. However, the lack of resolution of Leptodactylus interrelationships and, thus, the lack of osteological synapomorphies of the species groups and species within the genus conspire to force allocation of the fossils to crown Leptodactylus until they are studied in a rigorous phylogenetic context. In any case, the new material constitutes the oldest record of total group Leptodactylus and extends their stratigraphic range back to the early Pliocene.
Pseudoseisuropsis wintu sp. nov. is described from cranial material that had formerly been design... more Pseudoseisuropsis wintu sp. nov. is described from cranial material that had formerly been designated as a paratype of the extinct Pseudoseisuropsis nehuen. Thorough comparisons were made between the cranial specimens ascribed to Pseudoseisuropsis and many extant furnariid species. This new species is lower Pleistocene in age and increases the known diversity of Pseudoseisuropsis to three species. Cladistic analyses were performed using 43 cranial characters and a backbone constraint based on a well-supported phylogeny from a recent molecular analysis. In the most parsimonious tree, Pseudoseisuropsis was retrieved as a sister group of woodcreepers (Dendrocolaptinae) with low support. However, slightly suboptimal hypotheses, which could not be completely ruled out, suggest that this genus may be more closely related to other clades of Furnariidae. Hence, we agree with previous authors in regarding Pseudoseisuropsis as Furnariidae Incertae sedis. In addition, two fragmentary fossils ascribed to Pseudoseisuropsis were included in taxonomic comparisons: P. cuelloi, in order to assess the possibility that P. wintu sp. nov. belongs to that species, and another paratype of P. nehuen, to reassess its taxonomic identity.
Proceedings. Biological sciences / The Royal Society, Jan 7, 2014
Gondwana Research, 2012
Herein we report on a new anuran genus and species, Uberabatrachus carvalhoi, from exposures of t... more Herein we report on a new anuran genus and species, Uberabatrachus carvalhoi, from exposures of the Marília Formation (Maastrichtian) at the well-known fossil site "Ponto 1 do Price" near Peirópolis, Uberaba, Brazil. The holotype consists of an articulated partial skeleton characterized by a broad, well-ossified skull lacking dermal ornamentation, eight procoelous presacral vertebrae, and posteriorly deflected, cylindrical sacral diapophyses; these features, together with the possible presence of a discrete palatine, are consistent with neobatrachian affinities. It clearly differs from the neobatrachian Baurubatrachus, also from the Marília Formation, in having a skull lacking exostosis and with a different temporal architecture, among other features. It also differs from the still unnamed neobatrachian recovered from the Adamatina Formation in the presence of paired frontoparietals with narrow supraorbital flanges in the anterior orbital region and maxilla-squamosal contact. The new frog is not referable to any of the neobatrachian taxa known from the Aptian-Albian Crato Formation owing to different cranial features (e.g., position of the jaw articulation, relative width of the braincase, and morphology of the frontoparietal). With respect to the extant neobatrachians in the context of recent phylogenetic hypotheses, the cylindrical sacral diapophyses of Uberabatrachus contrast with the dilated diapophyses occurring in australobatrachian hyloids and microhyloid ranoids, whereas the procoelous presacral column is unlike the diplasiocoelous condition of most other ranoids. This evidence together with the combination of features of Uberabatrachus suggests a placement among nobleobatrachian hyloids, although this combination is not shared with any extant or extinct species for which skeletal information is known. From the foregoing we conclude that Uberabatrachus represents a new nobleobatrachian taxon, a record that reinforces the hypothesis of a diversified neobatrachian fauna in South America by the Cretaceous and is consistent with the previous proposal that neobatrachian early diversification is related to the breakup of Gondwana.
Journal of Vertebrate …, Jan 1, 2012
Journal of Vertebrate …, Jan 1, 2011
Journal of Herpetology, Jan 1, 2011
... In nearly all snakes, a tight contact between right and left dentaries is absent, leading to ... more ... In nearly all snakes, a tight contact between right and left dentaries is absent, leading to a ... The only known exceptions might be a single dentary from the Cretaceous of India that has a broad bony symphyseal area and was referred to a “cholophidian” snake, representing a ...
Cretaceous Research, Jan 1, 2009
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Cretaceous Research, Jan 1, 2008
We report the first record of anilioids from southern South America, a region where they do not l... more We report the first record of anilioids from southern South America, a region where they do not live today. The fossils come from the Allen Formation (Late CampanianeEarly Maastrichtian) at Bajo Trapalcó and Bajo de Santa Rosa localities, Río Negro province, Argentina. The remains consist of several vertebrae, most of which belong to the mideposterior precloacal region of the column. Comparisons to other extant and extinct anilioid taxa indicate that these remains represent a new taxon, Australophis anilioides gen. et sp. nov. Australophis is morphologically closer to Palaeocene Hoffstetterella from Brazil and extant South American Anilius than to any other snake. These taxa might be closely related, in which case they would represent a lineage distinct from that including Cylindrophis and uropeltids. The two lineages must have diverged by the Late Cretaceous.
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Papers by Raúl Orencio Gómez