Sandy Y. Cui, Nicole S. Mizrahi, Shaily Rahman
et al.
Abstract Modern sponges (Porifera) diverged by the Cryogenian, but their silicious skeletons do not appear in the fossil record until one hundred million years later, a time-span termed the “spicule gap” and thought to be a taphonomic artifact even though sponges convergently evolved siliceous spicules. Due to sponges’ position in animal phylogeny and important role in regulating ocean chemistry, the timing of their biomineralization has major implications for the changing tempo and mode of Earth systems as animals radiate. In a comprehensive dataset of Ediacaran and Cambrian sponges, we find that spicules are readily preserved in Cambrian environments more extreme than those of the Ediacaran. Given the convergent evolution of siliceous spicules, we find that the fossil record accurately represents when spicules first evolved in the different sponge lineages.
The pycnodontiform genera Macromesodon and Apomesodon from the Upper Jurassic and lowermost Cretaceous of Central and Western Europe are described in detail and their union into one genus is rejected. Nomenclature problems are explained and the differences between these two genera are described, supplemented by new specimens and spectacular UV photos that show new characters like sclerites and spines of the skin along with known characteristics in much better detail than what has been previously published. Apomesodon differs from Macromesodon mainly in the dentition, the more prominent dorsal apex, the scale pattern, the shape and ornamentation of the body scales and the articulation of neural arches and spines. Further taxa are assigned to these two genera for the first time, and a comparison of these genera with closely related taxa is made. Additionally, a new phylogeny of the Pycnodontomorpha is presented, in which the families of the basal Pycnodontiformes, Macromesodontidae and Brembodontidae, are redefined.
Seven ruminant taxa have been identified at the Pliocene Jradzor site in Armenia: Bovini indet., Gazellospira sp., Antilopini indet., Caprinae indet. 1 (cf. Eosyncerus), Caprinae ndet. 2, Caprini indet., and Cervinae indet. Jradzor is an exceptionally well-dated site. The ruminant remains derive from two layers dated to the end of the Early Pliocene (ca. 4 Ma) and the late Pliocene (ca. 3.3 Ma). These horizons correspond to a poorly known interval in Southwest Asia – the Late Ruscinian, MN15 and early Villafranchian, MN16a – and provide insights into the faunal composition of the South Caucasus.
Contributions to fossil invertebrates of Argentina began with the collections of d’Orbigny and Darwin and the publications by Forbes and Sowerby. These were continued with the collections of Stelzner and Bodenbender and the studies of Kayser, Gottsche, Behrendsen, Tornquist, and Steuer. Between 1890 and 1930, studies were conducted by foreign expeditions of Nordenskjöld, Skottsberg, and Hatcher to southern Patagonia and of Weaver to west-central Argentina, and those done from the
La Plata Museum by Hauthal and Burckhardt. Studies on Triassic and Tertiary fauna began in the late 1920s. Also during this period, a series of biostratigraphic studies commenced, initially by the División de Minas, Geología e Hidrología, and later from Yacimientos Petrolíferos Fiscales. These studies were done, among others, by Groeber, Keidel, Bonarelli, Wichmann, Windhausen, Feruglio, and Piatnitzky. In 1937, with the studies of Harrington, a national paleontological school was born. Works on Paleozoic faunas by Harrington and Kobayashi, and then by Leanza and Rusconi, duplicated in ca. 10 years all previous production on the subject. In the 30s and 40s, Frenguelli studied insects, Upper Paleozoic continental mollusks, and siliceous microorganisms. Between 1936 and 1947, the number of titles dedicated to invertebrates doubled that of the previous decade. The subsequent period had numerous contributions by Rusconi, mainly on trilobites and graptolites. The diversity of studied invertebrates increased significantly, and studies on foraminifera began. The foundation of the Argentine Paleontological Association in 1955 and the publication of Ameghiniana from 1957 onwards, were instrumental to the continuity of researches on the matter.
Charlène Gaillard, Analía M. Forasiepi, Sergio D. Tarquini
et al.
Abstract In this contribution, we investigate two sparassodonts from the Sarmiento Formation (Colhuehuapian Age; Early Miocene) recovered at the Patagonian locality of Sacanana, Chubut Province, Argentina. The first specimen (MACN-Pv CH1911), identified as Sipalocyon externus, is an almost complete cranium with upper dentition. The second specimen (MACN-Pv CH40), referred to Borhyaena macrodonta, consists of a fragmentary rostral portion of the face with associated m3–m4. The cranium of S. externus was studied through µCT-scanning to investigate its internal anatomy and infer paleoecological aspects of olfaction and hearing. In general, the endocranial anatomy and encephalization quotient are like those of other metatherians. We report the presence of an accessory transverse diploic sinus that has not previously been described in marsupials. Elements of the nasal cavity (e.g., turbinals, ossified nasal septum, cribriform plate) of S. externus exhibit features that are widespread among marsupials. Sense of olfaction, as evaluated from the cribriform plate and the 3D models of the olfactory bulbs, appears to have grossly resembled that of the domestic cat, a well-researched therian proxy. The dimensions of the tympanic membrane, as estimated from the preserved ectotympanic, suggest that the optimal hearing frequency of S. externus would have been similar to that of extant carnivorous marsupials. In sum, our study suggests that S. externus was a typical small-bodied (2–3 kg) hypercarnivorous metatherian that primarily relied on vision to hunt its prey, complemented by other sensory capabilities (olfaction and hearing), in a similar manner to small felids.
High-spired Murchisonia-like slit-band gastropods are an important component of late Paleozoic gastropod faunas. Twenty-seven genera of such gastropods have been reported from the Permian, most of which representing the caenogastropod family Goniasmatidae. Only four genera, Trypanocochlea, Wannerispira, Laschmaspira, and Altadema crossed the Permian/Triassic boundary. Based on the study of newly collected specimens and material from natural history collections, we studied the surviving genera as well as the Triassic recovery of this group. Two new species (Laschmaspira lirata sp. nov. and Altadema hausmannae sp. nov.) and one new subfamily (Cheilotomoninae) are introduced. Murchisonia-like caenogastropods, chiefly Goniasmatidae, were diverse and abundant until the Permian, barely survived the end-Permian extinction, regained a certain generic diversity within the Triassic with the evolution of several new genera but failed by far to regain their Permian generic diversity. This once successful and diverse group shares a similar fate (surviving the end-Permian extinction, a reduced Triassic diversity and extinction during Late Triassic crises) as conodonts, orthoceratids, conulariids, and others. This diversity pattern does not qualify for the “Dead Clade Walking” phenomenon, i.e., the extinction shortly after a major mass extinction event (survival without recovery) because they have survived for ca. 30 Ma (at least until the Norian) and even produced a number of new genera. The exact time of their extinction is unknown but there are no safe Rhaetian occurrences. Their extinction is part of a long-term selective trend against the character “shell-slit”.
Abstract The Mississippian (Tournaisian–Visean) of the Jbel Asdaf area in the Tisdafine Basin (Eastern Anti-Atlas, Morocco) has been, for the first time, the subject of a palynological study. This work aims first to describe the lithological and the paleontological composition of the Aït Yalla and Tinerhir Formations, then to refine the age, reconstruct the paleoenvironment and assess the thermal maturity of the organic matter. The studied section is subdivided, from oldest to youngest, into three intervals, according to their lithological and paleontological compositions. Lithologically, the lower interval (lower part of the Aït Yalla Formation) and middle interval (upper part of the Aït Yalla Formation and basal part of the Tinerhir Formation) consist mostly of clay shales and green shales, respectively, both alternating with limestone or sandstone beds. The upper interval (upper part of the Tinerhir Formation) is dominated by sandstones, also alternating with pelitic-sandstone or limestone beds. The kerogen delivered by the analyzed samples is mostly of continental origin, composed mainly of opaque phytoclasts, while translucent phytoclasts and miospores are less represented. Marine fraction, consisting mainly of granular amorphous organic matter and some phytoplankton, are rare. Biostratigraphically, the late Visean Tripartites vetustus–Rotaspora fracta (VF) miospore Zone of the Western Europe biozonal scheme is recognized with some regards in the Tinerhir Formation, based on the first occurrence of the miospore Rotaspora cf. knoxi. Vallatisporites aff. ciliaris is another biostratigraphic marker taxon of the assemblage, whose the last occurrence marks the end of the VF Biozone at the top of the analyzed section. Qualitative and quantitative parameters of the different palynofacies constituents (e.g., shape, size, % of opaque and translucent phytoclasts) show, from the base to the top of the section, a gradual transition from a distal marine environment generally recognized in the Aït Yalla Formation towards an intermediate marine environment in the Tinerhir Formation, suggesting a sea-level fall. Optical analyses performed on the color of palynomorphs, mainly spores, suggest a thermal maturity, ranging from late mature to early post-mature stage for most of the analysed samples, with a burial depth and a temperature of at least 3300 m and 90 °C, respectively.
We describe a new genus of the chemosymbiotic bivalve family Vesicomyidae, Squiresica, for two Oligocene species,
previously assigned to Archivesica, from western North America. Squiresica is characterized by a small and weakly
inflated shell, a small to nearly absent pallial sinus, an Archivesica-like hinge dentition, with an indistinct to well incised
lunular incision. Two species are assigned to this new genus: the type species, S. knapptonensis from western Washington
State, USA, and S. marincovichi from Oligocene strata of Alaska, USA. Squiresica knapptonensis had previously been
described from the upper Oligocene of the Lincoln Creek Formation; further specimens are here reported from a newly
discovered seep deposit in the lower Oligocene part of the Lincoln Creek Formation.
Los estudios paleoherpetológicos realizados en la ciudad de Mar del Plata se iniciaron a mediados de la década del 90 y se consolidaron y sostuvieron con continuidad desde 1998 hasta la actualidad, a partir de la conformación de un grupo de investigación en paleoherpetología en la Universidad Nacional de Mar del Plata. La mayor actividad de investigación desarrollada en esta institución se concentró sobre los reptiles escamosos (lagartos, serpientes y anfisbenas). La colección de fósiles del Museo de Ciencias Naturales “Lorenzo Scaglia” fue también muy relevante en el desarrollo de la paleoherpetología en la región, por el aporte de importantes materiales de anfibios, pterosaurios, cocodrilos y aves que fueron estudiados por investigadores de otras instituciones del país.
Cuando se piensa en la historia y la trayectoria de la paleontología de vertebrados en Argentina, llegan las imágenes de Florentino Ameghino y de otros tantos paleontólogos de renombre mundial. En este trabajo, se presentan las historias de aquellos técnicos que estuvieron codo a codo, trabajando y apoyando a estos grandes paleontólogos, desde los tiempos de Carlos Ameghino (hermano de F. Ameghino) hasta llegar a las nuevas generaciones, quienes se acercaron a las diferentes instituciones para formarse y trabajar en esta noble profesión.
La Formación San Salvador es uno de los pocos depósitos del Plioceno–Pleistoceno Inferior en el este de la provincia de Entre Ríos, que desde el punto de vista paleontológico ha sido descripta mediante su contenido fitolítico exclusivamente. La presente contribución comprende la síntesis y ampliación de estos conocimientos mediante la incorporación de los resultados del estudio fitolítico del perfil José Etchepare Hijo (Departamento Colón, Entre Ríos) a los ya descriptos. Para ello se ha utilizado una metodología ad-hoc, adaptada para la obtención de fitolitos en depósitos fluviales. Las secuencias sedimentarias se caracterizaron por presentar una sucesión de estratos de conglomerados matriz soportados, facies arenosas finas a gruesas y facies finas (representadas por arcillas y limos). Los resultados permitieron observar mayor abundancia de fitolitos y diversidad en estratos de textura arenosa; y proporcionalmente más escasos y hasta ausentes en los estratos de textura gravosa principalmente. Los fitolitos no diagnósticos de gramíneas fueron comunes en el total de las muestras con microrestos, mientras que entre los de menor tamaño y diagnósticos su presencia se manifestó solo en ciertos sectores de los perfiles. Las asociaciones fitolíticas se conformaron por elementos de las familias Arecaceae, Poaceae (Bambusoideae, Panicoideae, Danthonioideae, Chloridoideae y Pooideae) y Podostemaceae; y han permitido inferir el desarrollo de paleocomunidades de bosques higrófilos estratificados, palmares y bosques en galería, que indican un clima tropical-subtropical húmedo, con gran disponibilidad hídrica.
AbstractBituminous limestone of the Ediacaran Shibantan Member of the Dengying Formation (551–539 Ma) in the Yangtze Gorges area contains a rare carbonate-hosted Ediacara-type macrofossil assemblage. This assemblage is dominated by the tubular fossilWutubusChen et al., 2014 and discoidal fossils, e.g.,HiemaloraFedonkin, 1982 andAspidellaBillings, 1872, but frondose organisms such asCharniaFord, 1958,RangeaGürich, 1929, andArboreaGlaessner and Wade, 1966 are also present. Herein, we report four species ofArboreafrom the Shibantan assemblage, including the type speciesArborea arborea(Glaessner in Glaessner and Daily, 1959) Glaessner and Wade, 1966,Arborea denticulatanew species, and two unnamed species,Arboreasp. A andArboreasp. B.Arborea arboreais the most abundant frond in the Shibantan assemblage.Arborea denticulatan. sp. resemblesArborea arboreain general morphology but differs in its fewer primary branches and lower length/width ratio of primary branches.Arboreasp. A andArboreasp. B are fronds with aHiemalora-type basal attachment. Sealing by microbial mats and authigenic cementation may have played an important role in the preservation ofArboreain the Shibantan assemblage. The Shibantan material ofArboreaextends the stratigraphic, ecological, and taphonomic ranges of this genus.UUID:http://zoobank.org/554f21da-5f09-4891-9deb-cbc00c41e5f1
Víctor Adrián Pérez-Crespo, César A. Laurito, Joaquín Arroyo-Cabrales
et al.
Carbon and oxygen stable isotope values in the dental enamel of fossils were used to infer the diet and habitat of the extinct equids Calippus hondurensis, Dinohippus mexicanus, and Protohippus gidleyi, the gomphothere Gomphotherium hondurensis, and the llama Hemiauchenia vera of the Early–Late Hemphillian (Hh2) from San Gerardo de Limoncito, Puntarenas province, Costa Rica. The results suggest that these mammals fed mainly on C3 plants and lived in clearings of rainforests. This contrasts with previous studies from North America that indicated that the same species lived in forest savannas and fed mainly on C4 plants, but it is similar to the results obtained from the palynological record of the area, as well as with several vegetation models suggesting the presence of humid tropical forest during the Miocene in Central America.
Mathias Harzhauser, Thomas A. Neubauer, İzzet Hoşgör
We describe the first record of a late Oligocene or early Miocene freshwater gastropod fauna from the Susuz Formation of the Oltu-Narman Basin in northeastern Anatolia. The assemblage consists of only six species, indicating the presence of a well-oxygenated lake, pond or anabranch rich in vegetation. Only two of the taxa are related to European Oligo-Miocene species. The fauna might be the first indication of a yet undocumented Eastern Anatolian freshwater biogeographic region, characterized by high endemism and minor influence from the coeval Peri-Paratethyan and Aegean–Anatolian regions in the west. The biostratigraphic value of the assemblage is low but might rather point to a Miocene age of the upper part of the Susuz Formation. Theodoxus susuzianus, Bithynia erzurumensis, and Valvata koehleri are described as new species.
Patterer, Noelia I., Zucol, Alejandro F., Passeggi, Esteban
Los palmares de Butia yatay (Mart.) Becc. en el Parque Nacional El Palmar (Colón, Entre Ríos), son comunidades relictuales que se desarrollan sobre los suelos arenosos que pertenecen al orden de los Entisoles. Estos suelos constituyen las terrazas antiguas del río Uruguay. La serie de suelos Puerto Yeruá son suelos arenosos pardos formados sobre terrazas y poseen un mayor desarrollo pedológico. Se ha estudiado la composición fitolítica de la secuencia pedológica de esta serie de suelos con la finalidad de contribuir al conocimiento de la flora que acompañó el desarrollo de los mismos. Las asociaciones fitolíticas observadas reflejan el cambio de dos ciclos pedológicos, que dividen al perfil analizado en dos zonas demarcadas por la presencia de diferentes paleocomunidades: una de palmares asociados a un estrato herbáceo pobre y una superior de pastizales meso-megatérmicos con escasa presencia de microrestos afines a elementos arbóreos. El registro fitolítico descripto en el presente trabajo es el primer antecedente que muestra el posible punto de cambio en la fisonomía del paisaje y la retracción de los palmares de yatay en el área de estudio.