[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

[dinosaur] Caimains + Eubaena + Pampagyps + more

Ben Creisler

Some recent non-dino papers:

Rafael CÃsar Lima Pedroso de Andrade, Mariana ValÃria AraÃjo Sena, Esaà Victor AraÃjo, Renan Alfredo Machado Bantim, Douglas Riff & Juliana Manso SayÃo (2018)
Osteohistological study on both fossil and living Caimaninae (Crocodyliformes, Crocodylia) from South America and preliminary comments on growth physiology and ecology.
Historical Biology (advance online publication)
ÂDOI: 10.1080/08912963.2018.1493475

Caimaninae is a South American lineage of crocodylians widely distributed in Brazil and composed of six species within three genera. Currently, there is insufficient information regarding growth strategies, growth rates, and ecology extracted from the bone microstructure. Here we present the first osteohistological study of both Caiman yacare and an unidentified fossil Caiman. Long bones of one specimen of C. yacare and of one fossil Caiman found at SolimÃes Formation (Acre Basin), were used to prepare the histological slides. The microstructure of C. yacare shows fibrolamellar complex present in the femur and tibia, while the humerus and radius of both C. yacare and the fossil Caiman revealed a slow-growing bone matrix with gradual decrease and effective stops. According to the results found here, Caimaninae seem to have the capability to adjust their growth rates in response to seasonal changes. The extant Caiman is classified as juvenile, but for the fossilized specimen no ontogenetic stage can be determined. Caiman yacare shows the presence of intraskeletal variability regarding the record of bone growth. We conclude that Caimaninae likely have been experiencing cyclical changes in growth rates in direct correlation to changes in seasons and environmental conditions since the Miocene.


Yann Rollot, Tyler R. Lyson & Walter G. Joyce (2018)
A Description of the Skull of Eubaena Cephalica (Hay, 1904) and New Insights into the Cranial Circulation and Innervation of Baenid Turtles.
Journal of Vertebrate Paleontology 38(3): Article: e1474886
DOI: 10.1080/02724634.2018.1474886.

The internal carotid system has played an important role in the systematics of fossil turtles, including baenids. A new, almost perfectly preserved specimen of Eubaena cephalica provides an opportunity to explore for the first time the cranial circulation and innervation of this taxon using CT (computed tomography) scans. We here document that the skull possesses a well-developed, branching canalis nervus vidianus but lacks a canalis caroticus palatinum, which contradicts the previously reported circulation and innervation pattern for E. cephalica specifically and that of paracryptodires in general. Future investigation using CT scanning technology will be able to clarify if the pattern reported herein is unique to E. cephalica or is representative of paracryptodires in general. The latter conclusion will likely have considerable implications for the systematics of fossil turtles.


Marcos Cenizo, Jorge Noriega, Juan Diederle, Esteban Soibelzon, Leopoldo Soibelzon, Sergio Rodriguez & Elisa Beilinson (2018)
An unexpected large Crested Tinamou (Eudromia, Tinamidae, Aves) near to Last Glacial Maximum (MIS 2, late Pleistocene) of the Argentine Pampas.
Historical Biology: An International Journal of Paleobiology (advance online publication)

A large nearly complete specimen of a Crested Tinamou (Eudromia, Tinamidae, Aves) is described. It was collected at 'NicolÃs Vignogna III' Quarry in Marcos Paz County (Buenos Aires Province, Argentina), coming from near the top of a succession assigned to the Lujanian Stage. Radiocarbon dates constrain the age of the fossil bearing lithosome to the late Pleistocene--early Holocene, including the complete geochronological interval assigned to MIS 2. The new fossil specimen of Eudromia from Marcos Paz exceeds the size range of living species of the genus; but it is osteologically almost indistinguishable from them. Based on the lack of conclusive morphological and metrical differences with modern Eudromia spp., its specific status is not definitely ascertained in this contribution, being considered as a probable large morph of E. elegans. Crested tinamous are inhabitants of open and xeric environments with warm temperate to cold temperate climatic conditions. The fossil location is more than 250 km east of the eastern distributional limit of the nearest extant species. This geographical outlier could be tentatively associated with the expansion of arid or semiarid paleoenvironments typical of the Central or Patagonian domains over the temperate Pampean grasslands during the MIS 2 times.


Free pdf:

Jacqueline M.T. Nguyen, Michael Archer, and Suzanne J. Hand (2018)
Quail-thrush birds from the Miocene of northern Australia.
Acta Palaeontologica Polonica (advance online publication)

Quail-thrushes (Passeriformes: Cinclosomatidae: Cinclosoma) are ground-dwelling corvoid songbirds endemic to Austra lia and New Guinea. Until now, the only known quail-thrush fossils have been from late Quaternary cave deposits in Australia. A new species of quail-thrush, Cinclosoma elachum sp. nov., is described from the early to middle Miocene deposits in the Riversleigh World Heritage Area, Queensland, Australia. A second, larger quail-thrush is identified from the middle Miocene of Riversleigh. The new fossils considerably extend the geographic and temporal ranges of cinclosomatids, and indicate the presence of two species of quail-thrushes in the Miocene of northern Australia, located more than 300 km from the nearest extant member of Cinclosoma. These fossils provide a minimum age of ~18 million years for Cinclosomatidae. They cannot be confidently assigned to the crown group of the genus Cinclosoma, but can be used to calibrate the split between this genus and Ptilorrhoa in molecular dating studies of the Corvides radiation and Passeriformes overall. This material also adds to the growing diversity of songbirds identified from the pre-Pleistocene record of Australia, and reemphasises the global significance of the Riversleigh deposits in developing understanding about the early evolutionary history of passerines.

Not yet officially published but available online:

Pampagyps imperator nov. gen. et sp.Â

Federico L. Agnolin, Federico BrissÃn Egli, Esteban Soibelzon, Sergio G. Rodriguez, Leopoldo H. Soibelzon, Facundo Iacona & David Piazza (2017)
A new large Cathartidae from the quaternary of Argentina, with a review of the fossil record of condors in South America.
PaleontologÃa y EvoluciÃn de las Aves. Contribuciones CientÃficas del Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" 7: 1-16

The fossil record of condors in South America is relatively extensive. However, fossil specimens for the late Pleistocene of Argentina are scarce. Here, we report a new genus and species of a large sized cathartid of the condor lineage. The new taxon, Pampagyps imperator nov. gen. et sp. is based on a right tarsometatarsus from the âCantera NicolÃs Vignogna IIIâ fossiliferous locality, at Marcos Paz County, Buenos Aires Province, Argentina. The fossil was found in the middle levels of the outcrop assigned to the Lujanian Stage/Age (late Pleistocene). Its size is comparable to Geronogyps and Gymnogyps, being smaller than Vultur. Its combination of characters is unique, allowing recognizing a new taxon. An overview of fossil cathartids from Argentine lowlands indicates the existence of several condors that are not closely related to the extant Vultur gryphus. The presence of these large cathartids allows to review the fossil record of V. gryphus. The latter taxon has been recorded in the Pliocene of Buenos Aires Province (Argentina), and the Pleistocene of Estado Plurinacional de Bolivia and Brazil. A review of the Pliocene specimens from Buenos Aires Province suggests that they belong to an unnamed form not closely related to Vultur. Moreover, specimens from Bolivia are different from living V. gryphus, indicating that they belong to the extinct species "Sarcoramphus" patruus. Brazilian records are fragmentary and found near to the locality where the fossil form Pleistovultur nevesi was described. Thus, we restrict the record of V. gryphus to the late Pleistocene of Andean and Patagonian regions.


Free pdf:

FlorÃal SolÃ, Corentin Noiret, Delphine Desmares, Sylvain Adnet, Louis Taverne,Thierry De Putter, Florias Mees, Johan Yans, Thomas Steeman, Stephen Louwye, Annelise Folie, Nancy J. Stevens, Gregg F. Gunnell, Daniel Baudet, Nicole Kitambala Yaya & Thierry Smith (2018)
Reassessment of historical sections from the Paleogene marine margin of the Congo Basin reveals an almost complete absence of Danian deposit.
Geoscience Frontiers (advance online publication)
doi: https://doi.org/10.1016/j.gsf.2018.06.002Â

The early Paleogene is critical for understanding global biodiversity patterns in modern ecosystems. During this interval, Southern Hemisphere continents were largely characterized by isolation and faunal endemism following the breakup of Gondwana. Africa has been proposed as an important source area for the origin of several marine vertebrate groups but its Paleogene record is poorly sampled, especially from sub-Saharan Africa. To document the early Paleogene marine ecosystems of Central Africa, we revised the stratigraphic context of sedimentary deposits from three fossil-rich vertebrate localities: the Landana section in the Cabinda exclave (Angola), and the Manzadi and Bololo localities in western Democratic Republic of Congo. We provide more refined age constraints for these three localities based on invertebrate and vertebrate faunas, foraminiferal and dinoflagellate cyst assemblages, and carbon isotope records. We find an almost complete absence of Danian-aged rocks in the Landana section, contrary to prevailing interpretations over the last half a century (only the layer 1, at the base of the section, seems to be Danian). Refining the age of these Paleocene layers is crucial for analyzing fish evolution in a global framework, with implications for the early appearance of Scombridae (tunas and mackerels) and Tetraodontiformes (puffer fishes). The combination of vertebrate fossil records from Manzadi and Landana sections suggests important environmental changes around the K/Pg transition characterized by an important modification of the ichthyofauna. A small faunal shift may have occurred during the Selandian. More dramatic is the distinct decrease in overall richness that lasts from the Selandian to the Ypresian. The Lutetian of West Central Africa is characterized by the first appearance of numerous cartilaginous and bony fishes. Our analysis of the ichthyofauna moreover indicates two periods of faunal exchanges: one during the Paleocene, where Central Africa appears to have been a source for the European marine fauna, and another during the Eocene when Europe was the source of the Central Africa fauna. These data indicate that Central Africa has had connections with the Tethyian realm.