Locomotor structures in the Middle Triassic archosaurs from Los Chañares (La Rioja,Argentina)

A brief anatomical analysis of the pedial adaptations of the archosaurs from Los Chañares is made based on new available data.

The archosaurs from the Los Chañares local fauna show four different patterns in the structure of their hind limbs: (1) crurotarsal asymmetrical (Chanaresuchus and Tropidosuchus) (2) crurotarsal symmetrical (Gracilisuchus) (3) mesotarsal asymmetrical (Lagerpeton) (4) mesotarsal symmetrical (Lagosuchus). Each group has typical features that define “grades”; or morphological sets that were present at the same time in the local fauna, showing more derived characters than previously expected from the Middle Triassic.     

Lycopodiopsids and equisetopsids from the Triassic of Quebrada de los Fósiles Formation,San Rafael Basin,Argentina

In the late 1960s, rests of a low-diversity flora dominated by the lycopsid Pleuromeia were reported. The specimens were recovered from a creek near San Rafael, Mendoza Province, western Argentina, in the lower section of the Puesto Viejo Group, the Quebrada de los Fósiles Formation, considered as Early Triassic in age. Despite the importance of this flora with respect to the end-Permian mass extinction event, it was not yet described nor illustrated. Since then, the age of the Puesto Viejo Group has been revised and the Quebrada de los Fósiles Formation is now considered to be early Middle Triassic. The fossil plants are here first described and interpreted. The most common element, Pleuromeia cf. sternbergii, a species known worldwide that characterizes the post-extinction flora recovery, is accompanied by sphenopsids such as Neocalamites and Equisetostachys, and an herbaceous lycopsid. This community grew up associated with transient water bodies in flood plain environments that developed under warm temperate, strongly seasonal climatic conditions. The landscape was stressed by volcanism, and the conjunction of these factors probably restricted the colonization and development of a full ecosystem, as happened worldwide after the end-Permian mass extinction.     

Small Celastraceae and Polygonaceae twigs from the Upper Cenozoic (Ituzaingó Formation) of the La Plata Basin,Argentina

Two new wood types from the Late Cenozoic of the Ituzaingó Formation, La Plata Basin, Northeast Argentina add to our knowledge of South American Cenozoic plants. The materials were preserved by siliceous cellular permineralization, and they were prepared for microscopic examination by surface polishing and in thin sections. The anatomy of these new species was described. The relationship and comparison with the nearest living relatives (NLRs) are discussed. Maytenoxylon perforatum Franco gen. and sp. nov. is described as the first fossil wood referable to Celastraceae from South America. This new fossil species is related to extant Maytenus Molina. The other fossil twig, Ruprechtioxylon breae Franco sp. nov., has features of the Polygonaceae family and particularly resembles the extant specie Ruprechtia laxiflora Meisn. The occurrence of these fossil woods in south-eastern South America suggests that a relatively warm and dry to seasonally dry climate prevailed over this region of Gondwana during the Upper Cenozoic. It also provides new evidence for the hypothesis of the more wide distribution of Seasonally Dry Tropical Forest (SDTF) during the Upper Cenozoic.     

Myrtaceae fossil leaves from the Río Turbio Formation (Middle Eocene), Santa Cruz Province,Argentina

Myrtaceae, the gum tree family, is a large angiosperm clade of 5671 species mostly distributed in tropical and subtropical regions of the world. In the southernmost tip of South America (Santa Cruz province) where the fossils analysed in this study come from (Río Turbio Formation), this family is virtually absent and the extant vegetation is largely dominated by deciduous Nothofagus pumilio and Nothofagus antarctica. During the early Paleogene, however, the Myrtaceae were an important element in southern Patagonian floras. Here, we report and describe ten taxa related to the extant genera Eugenia, Myrcia, Psidium, Myrcianthes and possible Eucalyptus and Campomanesia. The presence of a high diversity of Myrtaceae during the Eocene in one of the southernmost regions of the world could be thought as unusual. However, during this period of time (45 Ma), a number of other tropical lineages also reached these high latitudes probably as a consequence a warming climatic trend. In fact, through the Paleocene–Early Eocene interval, climatic conditions were the warmest of the Cenozoic. After this period of time, a progressive decline in temperature forced the migration of megathermal elements towards lower latitudes and, at the same time, led to the expansion of forest dominated by Nothofagus which predominate the region today.     

First multi-proxy record of Jurassic wildfires from Gondwana: Evidence from the Middle Jurassic of the Neuquén Basin,Argentina

Wildfires play a crucial role in recent and ancient ecosystem modeling but their detailed history on the Earth is still not well recorded or understood. The co-occurrence of charcoal and pyrolytic polycyclic aromatic hydrocarbons (PAHs) is used for the recognition of wildfires in geological record that may have implications for the analysis of the terrestrial environment, ecosystems, climate and the level of atmospheric oxygen. Here we present the first multi-proxy evidence of wildfires on the Gondwana continent during the Jurassic, based on the occurrence of charcoal and pyrolytic PAHs in the Middle Jurassic of the Neuquén Basin, Argentina. This is the first evidence of wildfire in the Aalenian, the lowest stage of the Middle Jurassic, and one of the few records of wildfires in the Bathonian. Temperature interpretations, derived from charcoal reflectance data, show that charcoals formed in low temperature surface fires that only sporadically reached the higher temperatures, possibly related to crown fires. The occurrence of charcoals in the Middle Jurassic deposits confirms recent results that the atmospheric oxygen level reached at least 15% during the Middle Jurassic times.     

Description of a new subgenus and a new species of Thamnocephalus (Crustacea: Branchiopoda,Anostraca) from the Salinas Grandes Basin,Córdoba Province,Argentina

At present, the American genus Thamnocephalus has three species, recorded from several states of U.S.A., México and Venezuela: Thamnocephalus platyurus Packard, T. mexicanus Linder and T. venezuelensis Belk & Pereira. The new species Thamnocephalus salinarum, from a turbid saline temporary pond inside the Salinas Grandes of Córdoba, Argentina is described here. The new species differs from all other congeners by the presence in the male, of an unbranched frontal appendage and a pair of soft cordiform parapenial lobes; also, by the sexually dimorphic caudal fin-like lobe. This new species may represent a new genus, however since only five specimens were collected it was not possible to observe if the penial ornamentation conforms to the Thamnocephalus type. Therefore, a conservative position is taken until new material allows proper analysis, by keeping the new species in the genus Thamnocephalus under the new subgenus Simplicephalus.     

The Aragonian and Vallesian high-resolution micromammal succession from the Calatayud-Montalbán Basin (Aragón,Spain)

We present an updated taxonomy and faunal distribution of the micromammal fossil record from the Aragonian and Lower Vallesian of the Calatayud-Montalbán Basin. The analysed record includes the orders Rodentia, Eulipotyphla, and Lagomorpha. The pattern of species turnover shows seven major faunal events, which are correlated with major climate changes based on marine stable oxygen and carbon isotope records. Episodes δ¹⁸O Mi-2 and Mi-3 are significantly correlated with major micromammal turnover at the boundaries between the Lower and Middle Aragonian and the Middle and Upper Aragonian, respectively. Our results support the existence of a selective turnover during the Aragonian and Lower Vallesian.     

First Amphilestid from South America: A Molariform from the Jurassic Ca?adón Asfalto Formation, Patagonia, Argentina

We report here the first amphilestid triconodont from the Jurassic of South America. The specimen, a single isolated molariform, was found at the Queso Rallado locality from where a growing mammalian fauna is known (including a triconodontid, two australosphenidans, and an as yet undescribed allotherian). The specimen, interpreted as a left lower tooth, presents five mesiodistally aligned, fairly symmetrical cusps, and is recognized as the type of a new taxon, Condorodon spanios. The phylogenetic analysis recovers Condorodon as a member of the clade Amphilestheria, closely related to Tendagurodon janenschi, an amphilestid triconodont from the Late Jurassic of Tanzania. Condorodon spanios is only distantly related to Argentoconodon fariasorum, the other triconodont known from Queso Rallado quarry. The phylogenetic position of Condorodon spanios points to the origin and diversification of amphilestherians during the Early Jurassic in a paleogeographical setting that allowed wide dispersion of these forms and argues, at least from the mammalian evidence, against a highly provincialized Pangaea. Some differences are however established between the filial western/eastern Gondwanan masses and their respective faunas.     

The oldest archosauromorph from South America: postcranial remains from the Guadalupian (mid-Permian) Rio do Rasto Formation (Paraná Basin), southern Brazil

In this contribution, we report a distal portion of a left humerus that likely belongs to an indeterminate basal archosauromorph from the Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of southern Brazil. A precise taxonomy of the fragmented and isolated humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level but, likely, this specimen belongs to an Archosauromorpha due to the lack of both the entepicondylar and the ectepicondylar foramina. The narrow distal end of the humerus, the rounded radial and ulnar condyles, and the moderately developed supinator process with a shallow ectepicondylar groove (not notched) are features reminiscent of tanystropheids rather than that of other archosauromorphs. This material likely represents the first and oldest Permian archosauromorph from South America and indicates the presence of this lineage before the P/T boundary.     

Saline paleolake of the Cañadón Asfalto Formation (Middle-Upper Jurassic), Cerro Cóndor, Chubut province (Patagonia), Argentina

The carbonate-evaporitic sequence of the Cañadón Asfalto Formation that crops out in Cañadón Carrizal (Chubut province, Argentina) is characterized by a lacustrine facies association. This sequence includes an extensive biohermal belt, flood facies with high lake-level and low lake-level stages, and desiccation–evaporation facies. The biohermal belt shows three growth-stages of microbial communities. This belt controlled sedimentation in nearby areas, favoring the formation of the pan lake of Cañadón Carrizal. High lake-level flood facies represent sedimentation during periods of great water input to the pan lake. Low lake-level flood facies are characterized by low-energy conditions and by the development of a shallow lake with marginal zones and palustrine subenvironments. Desiccation facies represent a dry mudflat that borders the saline lake. Evaporation facies are related to the shrinkage of the water body and to the migration of the shallower facies towards the center of the ephemeral lake.     

The Crassispora kosankei–Cystoptychus azcuyi palynozone of the Upper Carboniferous Tupambi Formation,Tarija Basin,northern Argentina

Well-preserved and diverse palynomorph assemblages were recovered from surface and core samples from the middle to upper section of the Tupambi Formation. The latter is the basal unit of the Macharetı́ Group (Upper Carboniferous) of the Tarija Basin, northern Argentina. Assemblages are composed of trilete miospores, one hilate species, monosaccate pollen grains (one species striated), one praecolpate species and green algae (Botryococcus). Two key species are Cystoptychus azcuyi sp. nov. and Crassispora kosankei (Potonié and Kremp) Bharadwaj emend. Smith and Butterworth enable definition of the first palynozone for this basin. The age, as well as the biostratigraphic and paleogeographic significance of the palynoflora is discussed.     

Hypowaagenia? bodenbenderi (Behrendsen): A rare aspidoceratid ammonite from the Tithonian of the Neuquén Basin,Argentina

Among the ammonite collection from the Neuquén and Mendoza provinces made by G. Bodenbender, stands Aspidoceras bodenbenderi Behrendsen. This rare aspidoceratid is assigned to the lower Alternans Zone because of the associated Parodontoceras calistoides (Behrendsen), and can be most likely attributed to the recently established genus Hypowaagenia Schweigert & Schlampp.     

Are Spondylosoma and Staurikosaurus (Santa Maria Formation, Middle-Upper Triassic, Brazil) the oldest saurischian dinosaurs?

Spondylosoma absconditum (Ladinian, Middle Triassic) lacks certain Dinosauriformes-Dinosauria characters (sigmoid curve and epipophyses in neck, distally placed deltopectoral crest on humerus) and those present (accessary hyposphene-hypantra vertebral articulations, three sacral vertebrae, elongate pubis) also occur in the Rauisuchia (Crurotarsi, Suchia, Rauisuchiformes).Spondylosoma is tentatively referred to the Rauisuchidae because, as indicated by the ventrolaterally directed sacral ribs, the ilium was held obliquely (and not vertically as in the Poposauridae).Staurikosaurus pricei (Carnian, Upper Triassic), one of the oldest dinosaurs, possesses autapomorphies of Dinosauriformes, Dinosauria, Saurischia, and Herrerasauridae, but it retains certain plesiomorphic characters (subcircular distal end to tibia, ?proximally placed deltopectoral crest, axially unshortened neural spine to sacral 1, ?scapular spine unreduced distally) not present inHerrerasaurus (Carnian, Ischigualasto Formation, Argentina). However, the femur is more derived in the loss of the trochanteric shelf and reduction of the lesser trochanter (as also occurs in some prosauropods). The two vertebrae sacrum ofStaurikosaurus is a plesiomorphic character for Dinosauria (also in other herrerasaurids, German Upper Triassic prosauropodSellosaurus gracilis — ?males), to which was added either a caudosacral (e.g. Santa Maria prosauropodSaturnalia, Sellosaurus gracilis — ?females) or a dorsosacral (e.g. Ischigualasto theropodEoraptor and prosauropodRiojasaurus). Agrosaurus (Upper Triassic, Durdham Down, England — not Australia) is not a herrerasaurid; it is referred to the prosauropod dinosaurThecodontosaurus antiquus (Upper Triassic, Durdham Down).     

A sauropodomorph tooth increases the diversity of dental morphotypes in the Cañadón Asfalto Formation (Early – Middle Jurassic) of Patagonia

This communication aims to describe an isolated sauropodomorph tooth (MPEF-PV 10860) from the Cañadón Asfalto Formation and test its phylogenetic relationships with other sauropodomophs. The novelty of this specimen implies a combination of features present in non-sauropod sauropodomorphs (coarse denticles at 45° with respect to the margin, absent marginal grooves and lingual concavity) and others previously referred to as synapomorphic of Sauropoda and subgroups of this lineage (D-shaped cross section, enamel-wrinkling). A comparison with formerly defined sauropod tooth morphotypes from Cañadón Asfalto highlights major differences in enamel-wrinkling, having a simpler and more homogeneous pattern. The crown proportions, compared with other sauropodomorph teeth, retrieve MPEF-PV 10860 within the morphospace of sauropods in two different age-ratio scatterplots, and the phylogenetic analysis depicts this specimen in multiple positions within Sauropodiforms but outside Eusauropoda, indicating the presence of both eusauropods and non-eusauropods in the Cañadón Asfalto Formation, and of a putative new species.     

The Skeleton of the Manus of Scelidotherium (Xenarthra,Mylodontidae) Specimens from the Pleistocene of the Province of Córdoba,Argentina, and its Systematic Implications

Journal of Mammalian Evolution - Dental and craniomandibular data have been predominantly used to infer relationships among mylodontid ground sloths. Recent studies indicate the osteology of the...     

Large tetrapod burrows from the Middle Triassic of Argentina: a behavioural adaptation to seasonal semi‐arid climate?

Krapovickas, V., Mancuso, A.C., Marsicano, C.A., Domnanovich, N.S. & Schultz, C.L. 2013: Large tetrapod burrows from the Middle Triassic of Argentina: a behavioural adaptation to seasonal semi‐arid climate? Lethaia, Vol. 46, pp. 154–169. We report the discovery of large burrow casts in the early Middle Triassic Tarjados Formation, at Talampaya National Park, north‐western Argentina. Facies analysis indicates the burrows are preserved in sandbars deposited by an ephemeral river under semi‐arid and seasonal climatic conditions. The structures are mostly preserved in longitudinal cross‐section and consist of an opening, an inclined tunnel (ramp), and a terminal chamber. The ramp is 8–14 cm in height, up to 130 cm in length and penetrates 49–63 cm bellow the palaeosurface with an inclination of 22°–30°. We studied burrow cast dimensions, overall architectural morphology, surficial marks, and compared them with other large burrows of both invertebrate and vertebrate origin. A tetrapod origin of the burrow casts was established based on: distinctive architecture, and size, which is more than twice the most common size range for large terrestrial invertebrate burrows. Comparison with other Upper Permian and Triassic tetrapod burrows allows us to identify three general morphological groups: (1) simple inclined burrows; (2) helical burrows; and (3) burrow network complexes, representing different behaviours. A study of tetrapod body fossils preserved within other Upper Permian and Triassic burrows shows that the Tarjados structures were most likely produced by non‐mammalian cynodonts. The environmental and climatic context suggests that aridity and seasonality played a fundamental role selecting burrowing behaviour in therapsids and that by the Early–Middle Triassic their burrowing behaviour attained a complexity comparable to modern mammals. □Argentina, behaviour, palaeoclimate, Permo‐Triassic, Tarjados Formation, Tetrapod burrows.     

New Middle Permian insects from Salagou Formation of the Lodève Basin in southern France (Insecta: Pterygota)

Summary

New insects are described from the Middle Permian (Guadalupian) of Salagou Formation in the Lodève Basin (Languedoc region, France). Palaeopterans are represented by new odonatopterans viz. Huangiopterum lodevense n. gen., n. sp. and Huangiopterum species B, attributed to clade Panodonata (Huangiopteridae n. fam.), already recorded through the family Saxonagrionidae in the same formation, and a diaphanopterodean Martynovia cf. halli Beckemeyer 2004 (Martynoviidae) known from the Lower Permian of Oklahoma. Archaeorthopterans are supplemented by Bethouxia ariegensis n. gen., n. sp., Paralongzhua elongata n. gen., n. sp., Lodevolongzhua incompleta n. gen., n. sp., the caloneurodean Jarmiloptera mouralensis n. gen., n. sp., and a cnemidolestodean cf. Tococladus sp. (Tococladidae). Permophyllum rotundatum n. sp. (?Tettigoniidae) demonstrates the first presence of Orthoptera with wings probably mimicking Peltaspermales reproductive organs in Late Palaeozoic possibly analogous to the known crypsis of roachoid tegmina with pteridosperm pinnules. Frequent occurrence of hardly identifiable grylloblattid wing fragments support their significant role in term of abundance and diversity of the Permian faunas. New taxa based on wing venation pattern as Genera and species undetermined A, B (Liomopteridae), Permobaharellus salagousensis n. gen., n. sp. (family uncertain), Lodevophlebia reticulata n. gen., n. sp. (Sylvaphlebiidae), Oborella lodevensis n. sp. (Euryptilonidae), and Genus and species undetermined C, were described. Paoliida is represented by a paoliid gen. et sp. indet. and three anthracoptilids Strephocladus gandi n. sp., Strephocladus mouralensis n. sp., Lodevocladus subtilis n. gen., n. sp. The first record of miomopteran Palaeomantis sp. (Paleomanteidae) from Salagou Formation is presented. Acercarian insects are represented by the first record of Thripida and diverse new hemipterans, namely Euroscytina lutevanorum n. gen., n. sp. (Cicadomorpha: Scytinopteridae), Prosbole dio n. sp., Prosbole garrici n. sp., Pervestigia cf. veteris Becker-Migdisova 1961 (Prosbolidae), Archescytina species A (Paleorrhyncha: Archescytinidae) and Permopsyllidium lesclansis n. sp. (Sternorrhyncha: Psylloidea: Protopsyllidiidae). Entomofauna from the Salagou Formation demonstrate highly diverse insect communities with some taxa linked to early and late Permian ones known from assemblages in Euramerica and Russia, such as Obora (Czech Republic), Wellington Formation (Kansas and Oklahoma, USA), and Tshekarda (Ural, Russia).     

New Spiriferids (Brachiopoda) from the Middle–Late Permian of Northeastern Mongolian Boreal Basin

Paleontological Journal - Three new spiriferid species are established from the Mongolian key sections of the Middle Permian Tsagaan-Temete horizon and Late Permian Binder horizon, Uldza formation....