Miocene Of Argentina Research Articles

Tetraodontiformes (Osteichthyes, Actinopterygii) from the Miocene of Argentina: with the southernmost record of fossil Tetraodontidae

Teleostean evolution produced enormous variation in tooth morphology. This variation is related to the exploration and exploitation of very diverse dietary niches. Among extant fishes, several taxa of the order Tetraodontiformes (e.g. pufferfishes, porcupinefishes and ocean sunfishes) have evolved highly specialized beak-like tooth structures. Here we provide the first description of tetraodontiform crushing beaks from Argentina. A single complete premaxillary beak recovered from the early Miocene Gaiman Formation in Chubut Province is assigned to Molidae based on its premaxillaries being completely fused to one another along the midline, general morphology, and size. Moreover, due to the putative presence of rows of teeth fused to the thick and massive bone structure, the specimen might belong to the genus Ranzania Nardo, 1840. Several premaxillary beaks recovered in the late Miocene Paraná Formation of Entre Ríos Province are assigned to Tetraodontidae Bonaparte, 1832 based on the presence of long, slender, rod-like, and parallel dental units; premaxillae not fused in the midline but articulated by interlocking emarginations, and a few small and one large trituration dental units. Argentinian tetraodontiform fishes inhabited the warm-temperate Paranense and Patagoniense Seas (marine transgressions developed in southeastern South America) during the early-late Miocene; these specimens are the southernmost fossil record of the group worldwide. Tetraodontiforms are extremely rare in recent Argentinian marine waters. The new fossil records agree with the higher sea water surface temperatures suggested both locally and worldwide for the Miocene.

First record of a chelonioid sea turtle (Testudines, Pan-Cheloniidae) from the late Miocene of Argentina

The fossil history of Neogene chelonioid sea turtles from South America is very incomplete. To date, only the isolated remains of dermochelyids and stem-cheloniids have been reported from the Miocene Pacific coast, and a single indeterminate dermochelyid is known from the early Miocene of Patagonia. Here, we describe a partial lower jaw of a fossil chelonioid from the late Miocene of Paraná city, in the Entre Ríos Province of Argentina. This new specimen displays a character state combination consistent with attribution to stem-Cheloniidae, and thus represents the first record of a late Miocene chelonioid from the southwestern Atlantic margin of South America.Agustín Falbo [agustinf_25@hotmail.com], Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Av. Ángel Gallardo 470 (C1405DJR), Buenos Aires, Argentina; Federico Agnolin [fedeagnolin@yahoo.com.ar], Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, Av. Ángel Gallardo 470 (C1405DJR), Buenos Aires, Argentina. Fundación de Historia Natural ‘Félix de Azara’, Universidad Maimónides, Hidalgo 775 (C1405BDB), Buenos Aires, Argentina.

Revision of the subfamily Pitarinae Stewart, 1930 (Eucallista Dall, 1902; Austrocallista Erdmann & Morra, 1985; Proteopitar gen. nov.) from Cenozoic southern South America: systematic and phylogenetic analyses

Systematic and phylogenetic analyses of fossil and extant Pitarinae of the South-Western Atlantic Ocean and Chile have been performed. The group is represented by Eucallista Dall, 1902 (early Miocene–Recent), Austrocallista Erdmann & Morra, 1985 (Eocene–Pliocene) and Proteopitar gen. nov. (middle Miocene–Recent). Eucallista and Austrocallista have sculptured nymphs and include species previously assigned to Amiantis Carpenter, 1864. Eucallista is represented by three species: the extant E. purpurata (Lamarck, 1818) (Pleistocene–Recent, South-Western Atlantic Ocean from Golfo San Matías [Argentina] to Espirito Santo [Brazil]) and two fossil taxa, E. laziarina (Ihering, 1907) from the Miocene and Pliocene of Chile, Argentina and Uruguay, and E. domeykoana (Philippi, 1887) from the Miocene and Pliocene of Chile and Peru. Austrocallista has four taxa: Austrocallista sp. from the Eocene of Santa Cruz Province, A. iheringi (Cossmann, 1898) from the late Oligocene–middle Miocene of Patagonia, A. australis (Feruglio, 1935) (lectotype MGGC 607) from the early Miocene of Santa Cruz Province, and A. boliviana (Philippi, 1887) from the Miocene and Pliocene of Chile and Peru. Proteopitar gen. nov. is erected to incorporate two species previously assigned to Pitar Römer, 1857: Proteopitar mutabilis (del Río & Martínez, 1998) from the middle Miocene–late Miocene of Argentina and the Pleistocene–Recent species Proteopitar patagonicus (d’Orbigny, 1835–1847) (from Rio de Janeiro [Brazil] to Bahía Vera [Chubut, Argentina]). These systematic hypotheses are corroborated by the phylogenetic analysis performed, which is the first one of the subfamily that includes fossil and extant taxa based on morphological characters of the shell. In addition, a new site on the coast of Río Negro Province which contains shells of the extant species is dated as 830 Ka BP (MIS21), being the oldest record of both extant species.http://www.zoobank.org/urn:lsid:zoobank.org:pub:16519263-4F9E-41AB-A009-EAC030681826

New skull remains of Phorusrhacos longissimus (Aves, Cariamiformes) from the Miocene of Argentina: implications for the morphology of Phorusrhacidae

AbstractThe giant carnivorous phorusrhacid birdPhorusrhacos longissimus(Aves, Cariamiformes) was first described in 1887 by Florentino Ameghino on the basis of a jaw fragment. The majority of a skull of the species still encased in crumbling rock was preserved only long enough for illustrations to be made by Carlos Ameghino in the field and for a brief description to be written. Skull remains of this species have remained scarce, and few postcranial remains have been figured. Here, we reassess the cranial anatomy of this outstanding ‘terror bird’ species taking into account data from a newly discovered skull. An additional specimen of a well-preserved dorsal vertebra referable to Phorusrhacinae is also described from a separate locality within the Miocene Santa Cruz Formation (late early Miocene) from Santa Cruz Province in Argentina. The skull includes most of the rostrum, skull roof, and mandible and is compared with material from other members of the Phorusrhacinae. The new data from the skull and vertebra provide morphological features of this clade that benefit future taxonomic and phylogenetic analyses of this iconic group of birds.

Phractocephaline catfishes from the late Miocene of Argentina, with the description of a new taxon

ABSTRACTThe fossil record of ‘phractocephaline’ catfishes in South America is relatively rich. The extinct species Phractocephalus ivy Azpelicueta and Cione, 2016, was named on the basis of diverse material coming from late Miocene beds of Paraná City, Argentina. A review of the holotype specimen described by those authors allows us to recognize that the individual may be referred to the extant genus Steindachneridion; thus, we propose the new taxonomic combination Steindachneridion ivy. Furthermore, part of the material described by previous authors may be effectively included within Phractocephalus. In this sense, the finding of new specimens in paleontological collections allows us to refer all these specimens to a new, previously unrecognized Phractocephalus species. The fossil record of ‘phractocephalines’ in the Paraná paleobasin indicates that the area played an important role in the evolution of this clade of basal pimelodids.

First record of a macroraptorial sperm whale (Cetacea, Physeteroidea) from the Miocene of Argentina

Raptorial sperm whales of the genus Livyatan were described from the Miocene of Peru and Chile. Revision of paleontological collections resulted in the finding of isolated teeth belonging to aff. Livyatan sp. coming from Early-Middle Miocene strata from Bajo del Gualicho area, Rio Negro Province, Argentina. These specimens represent the first finding of this genus in the Southwestern Atlantic Ocean and indicate that Livyatan-like forms were more widespread than previously thought. The reasons of the extinction of such predatory whales are still uncertain, but it is not improbable that it may be correlated with competition for food resources with globicephaline delphinids. This hypothesis still rests on weak evidence and should be evaluated through findings of new specimens, as well as detailed analysis of the fossil record.

PLANT-INSECT INTERACTIONS ON DICOTS AND FERNS FROM THE MIOCENE OF ARGENTINA

Fil: Robledo, Juan Manuel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Nordeste. Centro de Ecologia Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecologia Aplicada del Litoral; Argentina

A new teiid lizard of the genus Callopistes Gravenhorst, 1838 (Squamata, Teiidae), from the Lower Miocene of Argentina

Although squamates are commonly found in Cenozoic South American deposits, most findings correspond to fragmentary cranial materials or isolated vertebrae. Among the known South American vertebrate fossil localities, the lower section of the Chichinales Formation (Early Miocene, Colhuehuapian South American Land Mammal Age [SALMA]), in Paso Córdoba Protected Natural Area, Río Negro Province, Argentina, recently yielded an almost complete skull of a previously unknown teiid lizard. Here, we provide a detailed description of this new fossil, based on stereoscopic and high-resolution X-ray computed tomography (CT scan) analyses. Our phylogenetic analysis recovered the new fossil within the monophyletic genus Callopistes, as the sister group of the fossil C. bicuspidatus from upper Miocene–lower Pliocene sediments (Montehermosan SALMA) of the Monte Hermoso Formation. The new species antedates the oldest previously known fossil record of the genus by at least 14 Ma, providing a minimum age of origin for the genus of approximately 20.1 Ma (based on recent revisions of the Cenozoic fossil record of SALMA). The current distribution of the two known extant species of Callopistes and the locality from which the new taxon was recovered indicate that this genus had a much broader distribution in the past that included cis-Andean areas of Patagonia during the Miocene. Our phylogenetic results further suggest that Tupinambis uruguaianensis should be allocated to the genus Dracaena.http://zoobank.org/urn:lsid:zoobank.org:pub:452C7D2A-6819-4488-9C28-1020EBD71F91SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Quadros, A. B., P. Chafrat, and H. Zaher. 2018. A new teiid lizard of the genus Callopistes Gravenhorst, 1838 (Squamata, Teiidae), from the Lower Miocene of Argentina. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1484754.

Neuroanatomy of Gryposuchus neogaeus (Crocodylia, Gavialoidea): a first integral description of the braincase and endocranial morphological variation in extinct and extant gavialoids

ABSTRACTMorphological studies of the braincase and cranial endocast of fossil crocodylians, especially gavialids, are scarce. Here, we present a detailed description of the neuroanatomy of Gryposuchus neogaeus from the Miocene of Argentina, based on CT scans. The cranial endocast is sub-horizontal and the angle formed between the mid-brain and the hind-brain is poorly marked. When compared with Gavialis gangeticus, the mid-brain of G. neogaeus is relatively shorter, although the distribution of cranial nerves is similar. In the floor of the endocranial cavity, posterior to the dorsum sellae, there is a median foramen that leads into a canal that runs anteroventrally through the basisphenoid to penetrate the posterior wall of the pituitary fossa (open foramen for the basilar artery?). The same structure is present in G. gangeticus, but is absent in other living crocodylians, suggesting a potential synapomorphy of Gavialoidea. The pneumaticity of the skull roof and the lateral branches of the pharyngotympanic system in G. neogaeus are markedly reduced when compared with the extant species. Comparisons with the living Gavialis indicate that the pattern of braincase morphology of Gavialidae was present in the Miocene; however, the internal morphology, including brain shape, pneumaticity of the skull roof and basicranium, is different in the two species. This work is the first step to understand the variation of the neuroanatomy in this group of archosaurs and its palaeobiological implication.

Caiman gasparinae sp. nov., a huge alligatorid (Caimaninae) from the late Miocene of Paraná, Argentina

Bona, P. & Paulina Carabajal, A., 2013. Caiman gasparinae sp. nov., a huge alligatorid (Caimaninae) from the late Miocene of Paraná, Argentina. Alcheringa 37, 1–12. ISSN 0311-5518Morphological studies of South American alligatorids are scarce, and the phylogenetic relationships within Caimaninae are poorly understood. In this context, systematic revision and detailed morphological description of the enigmatic Argentinean Miocene caimanines are highly relevant. The current record is characterized by numerous species within the genus Caiman, although morphological disparity remains unclear. Here, we describe Caiman gasparinae sp. nov., which is one of the largest known Caiman species from the late Miocene of Argentina. Similar to other Caiman species and Melanosuchus, the new taxon has orbits larger than the infratemporal fenestrae and small supratemporal fenestrae that are not lost, as in Paleosuchus. Together with the absence of conspicuous rostral crests, the shape of the snout distinguishes C. gasparinae from Melanosuchus. Caiman gasparinae can be further distinguished using other cranial characters, such as a broad and low rostrum with a narial opening oriented dorsally, a relatively long interpremaxillary suture, and the occipital surface of the braincase with a poorly developed crista tuberalis exposing the carotid foramina in lateral view.Paula Bona [paulabona26@gmail.com] CONICET—División Paleontología Vertebrados, Museo de La Plata. Paseo del Bosque s/n, 1900, La Plata, Argentina; Ariana Paulina Carabajal [a.paulinacarabajal@conicet.gov.ar] CONICET—Museo Carmen Funes. Av. Córdoba 55 (8318), Plaza Huincul, Neuquén, Argentina. Received 21.8.2012; revised 29.1.2013; accepted 9.3.2013.

The first fossil species of Salminus, a conspicuous South American freshwater predatory fish (Teleostei, Characiformes), found in the Miocene of Argentina

ABSTRACT The first fossil specimen of the characiform genus Salminus is described here. The material, a three-dimensionally articulated head, is very well preserved and allowed us to identify a new species. We could study both outer and inner bones. The specimen was found in the locality Toma Vieja, northeast of the city of Paraná, central eastern Argentina. The bearing horizon is the so-called ‘Conglomerado osífero,’ which is putatively included in the lowermost beds of the fluvial Ituzaingó Formation. The ‘Conglomerado osífero’ is early Tortonian (early late Miocene) in age. Recent species of Salminus are top-ranking pelagic predatory fishes in temperate to tropical lowland freshwaters of South America. The aquatic vertebrate fauna occurring in the bearing bed shows a similar composition to several northern South American units such as the Urumaco Formation (Venezuela, late Miocene) and La Venta Formation (Colombia, middle Miocene).

Tamaño y Estimación de la Masa Corporal enProcariama simplexRovereto, 1914 (Aves: Phorusrhacidae: Psilopterinae)

SIZE AND BODY MASS IN PROCARIAMA SIMPLEX ROVERETO, 1914 (AVES: PHORUSRHACIDAE: PSILOPTERINAE). Body-mass of fossil birds can be estimated using comparisons with extant birds, taking into account that the measures of hindlimbs are indicators of body weight. Hindlimb bones (femur, tibiotarsus, and tarsometatarsus) would represent a direct relationship with body mass, because they provide, in different degrees, the support of the body. In this contribution, the body-mass of fossil specimens of Procariama simplex Rovereto from the Miocene of Argentina is calculated using two different estimates. The first model assumes that there is geometric similarity between fossil and analogous extant birds, in this case between Procariama simplex and its analogous Cariama cristata Linnaeus. The second model, more used in birds, considers the influence of the size or body-mass on the form and function of the skeleton. It considers the logarithmic relationship between body-mass and the minimum circumference of the shaft of the hindlimb elements involved in the support of a bird. Both models estimate values between 10 and 13 kg for Procariama simplex, higher than previous estimates. These values resemble in size (mass) those of a Patagonian rhea Pterocnemia pennata d'Orbigny. Although this Rheidae is not related phylogenetically to Phorusrhacidae, they share the same morphotype with long hindlimbs, suitable for running.

Megapiranha paranensis, a new genus and species of Serrasalmidae (Characiformes, Teleostei) from the upper Miocene of Argentina

ABSTRACT Megapiranha paranensis from the Upper Miocene of Argentina is described based on a large, partially toothed premaxilla as a new genus and species of serrasalmid fish (pacus and piranhas) and is diagnosed and distinguished from other serrasalmids based on the following unique combination of characters: seven premaxillary teeth with the first four arranged in a shallow, zig-zag row, and third tooth shaped similarly to the fourth and fifth teeth; large, triangular, unicuspid crowns with finely serrated cutting edges. The phylogenetic position of Megapiranha was determined by parsimony analysis of morphological characters. The resulting analysis recovered Megapiranha as sister to the piranha clade (Pygopristis, Pygocentrus, Pristobrycon, Serrasalmus) and is supported by two synapomorphies: (1) teeth triangular in labial view with well-developed cutting edges, and (2) serrations along both sides of tooth cutting edges. The pattern of tooth placement exhibited by the fossil Megapiranha is intermediate between the double-row condition of pacus and the single-row condition of piranhas, and suggests how the double row of teeth may have been rearranged into a single row in the evolution of piranhas.

The aerodynamics of Argentavis , the world's largest flying bird from the Miocene of Argentina

We calculate the flight performance of the gigantic volant bird Argentavis magnificens from the upper Miocene ( approximately 6 million years ago) of Argentina using a computer simulation model. Argentavis was probably too large (mass approximately 70 kg) to be capable of continuous flapping flight or standing takeoff under its own muscle power. Like extant condors and vultures, Argentavis would have extracted energy from the atmosphere for flight, relying on thermals present on the Argentinean pampas to provide power for soaring, and it probably used slope soaring over the windward slopes of the Andes. It was an excellent glider, with a gliding angle close to 3 degrees and a cruising speed of 67 kph. Argentavis could take off by running downhill, or by launching from a perch to pick up flight speed. Other means of takeoff remain problematic.

Ontogeny and diversity of the oldest capybaras (Rodentia: Hydrochoeridae; late Miocene of Argentina)

ABSTRACT According to our previous model for interpreting the fossil record of capybaras the cheek teeth grow in width and length throughout life; flexids (especially h.s.i. and h.t.i.) deepen allometrically resulting in diverse occlusal morphologies during ontogeny; in the more derived species the ‘onset’ of flexid development is pre-displaced, and the relative depth and development rate of the flexids increase. Consequently, we interpreted the different occlusal morphologies found in the fossil record as different ontogenetic stages, leading to a drastic diminution of latest Miocene-Pliocene taxonomic diversity. The analysis of the geologically oldest capybaras, which are from the Arroyo Chasicó Formation (Chasicoan SALMA, late Miocene), is added. This study suggests a single species occurs in this formation that cannot be separated at the genus level from Huayquerian species. In the Arroyo Chasicó species, which is older and theoretically more primitive than that of the Huayquerian, the flexids are shallower as predicted. The analysis supports our model of capybara dental ontogeny and evolution and encourages revision of the whole family according to this model.

New primate genus from the Miocene of Argentina

Killikaike blakei is a new genus and species of anthropoid from the late Early Miocene of southeastern Argentina based on the most pristine fossil platyrrhine skull and dentition known so far. It is part of the New World platyrrhine clade (Family Cebidae; Subfamily Cebinae) including modern squirrel (Saimiri) and capuchin monkeys (Cebus) and their fossil relatives known from Early to Middle Miocene and subrecent periods. Living cebines are relatively large-brained, adroit predatory foragers and live within complex social groups, and wild capuchins exhibit a wide range of behaviors associated with enhanced intelligence. We show that K. blakei lacks diagnostic derived characteristics of the lower face and premolar dentition that are shared by modern cebines, but its strongly vaulted frontal bone and capacious anterior cranial fossa indicate the early evolution of an enlarged forebrain.

Earliest tinamous (Aves: Palaeognathae) from the Miocene of Argentina and their phylogenetic position

Earliest tinamous (Aves: Palaeognathae) from the Miocene of Argentina and their phylogenetic position

Revision of Amydrocarcinus and Palaeograpsus (Decapoda: Brachyura: Xanthoidea) with definition of three new genera

All species referred to Palaeograpsus Bittner, 1875, have been reevaluated, resulting in three new genera, Bittneria, Magyarcarcinus, and Litograpsus. Amydrocarcinus Schweitzer et al., 2002, and Magyarcarcinus new genus are placed within the Goneplacinae MacLeay, 1838, of the Goneplacidae MacLeay, 1838, and constitute some of the earliest occurrences of the family. Bittneria new genus, Carinocarcinus Lőrenthey, 1898, and Palaeograpsus sensu stricto are placed within the Eucratopsinae Stimpson, 1871, of the Panopeidae Ortmann, 1893, and document the first notice of the subfamily in the fossil record. The Pseudorhombilidae Alcock, 1900, and the Eucratopsinae are very difficult to differentiate from one another based upon dorsal carapace characters typically preserved in the fossil record, but the ratios of the frontal width and fronto-orbital width are shown to be useful for this purpose. Litograpsus new genus is placed within the Grapsidae MacLeay, 1838, sensu lato. Palaeograpsus guerini Via, 1959, is placed within Chasmocarcinus Rathbun, 1898. The Panopeidae displayed a Tethyan distribution pattern early in its history, and the Pseudorhombilidae has been largely restricted to the Americas since its first occurrence in the Miocene of Argentina (Glaessner, 1933).

A New Thaumastosaurus (Anura: Familia Incertae Sedis) from the Late Eocene of England, with Remarks on the Taxonomic and Zoogeographic Relationships of the Genus

Anuran maxillary, squamosal, and ilial elements from the Late Eocene of Hampshire and the Isle of Wight in southern coastal England represent a new species, Thaumastosaurus wardi, of this previously monotypic genus. Teeth, represented for the first time in the fossil record of this genus, are of the pedicellate type but appear to have specialized swollen tooth crowns. Based on the unique pit and ridge sculpturing of the cranial bones, the pedicellate teeth, and ilial characters of Thaumastosaurus, the genus resembles the leptodactylid genus Caudiverbera (Telmatobiinae) of the modern fauna of Chile and the Miocene of Argentina. It is suggested, however, that Thaumastosaurus should be considered of uncertain familial relationships (familia incertae sedis) until adequate material becomes available.

A New Thaumastosaurus (Anura: Familia Incertae Sedis) from the Late Eocene of England, with Remarks on the Taxonomic and Zoogeographic Relationships of the Genus

Anuran maxillary, squamosal, and ilial elements from the Late Eocene of Hampshire and the Isle of Wight in southern coastal England represent a new species, Thaumastosaurus wardi, of this previously monotypic genus. Teeth, represented for the first time in the fossil record of this genus, are of the pedicellate type but appear to have specialized swollen tooth crowns. Based on the unique pit and ridge sculpturing of the cranial bones, the pedicellate teeth, and ilial characters of Thaumastosaurus, the genus resembles the leptodactylid genus Caudiverbera (Telmatobiinae) of the modern fauna of Chile and the Miocene of Argentina. It is suggested, however, that Thaumastosaurus should be considered of uncertain familial relationships (familia incertae sedis) until adequate material becomes available.