 Subjects -> PALEONTOLOGY (Total: 43 journals)
|
|
|
- FIRST RECORD OF CRYPTOSPORES FROM THE LATE ORDOVICIAN-EARLY SILURIAN OF
COLOMBIA: NEW CONTRIBUTION TO THE UNDERSTANDING OF PLANT
TERRESTRIALIZATION
Authors: Claudia V. Rubinstein, María C. Vargas, Felipe de la Parra, Victor Caballero, Julián Naranjo, Nelson Sánchez
Pages: 495 - 508
Abstract: The present study involves the palynological analysis of Late Ordovician–early Silurian samples coming from two wells drilled in the Llanos Basin of Colombia. Thirteen core samples of well A yielded a moderately preserved cryptospore assemblage comprising 17 taxa. Although composed mainly of simple forms without stratigraphic value, the marine organic-walled phytoplankton allows us to constrain the age of the palynological assemblage from the Late Ordovician (Katian–Hirnatian) to the early Silurian. A ditch-cutting sample of well B yielded marine organic-walled phytoplankton and one trilete spore species. The marine phytoplankton suggests an age no older than early Silurian for the assemblage of well B. The paleoenvironment of well A, interpreted as a braided fluvial channel system with sporadic and slight tidal influence, is supported by palynological data. The distribution of palynomorphs also suggests an increasing marine influence from the bottom to the top of the studied section. The cryptospore assemblage constitutes the first record of cryptospores of Colombia and northern South America and, therefore, the oldest evidence of land plants in this region. The presence of the trilete spore Ambitisporites avitus in strata of probably early Silurian age would represent the first record of Silurian sediments in the Llanos Basin and the oldest record of trilete spores in Colombia.
PubDate: 2023-09-18
DOI: 10.5710/AMGH.27.07.2023.3560
Issue No: Vol. 60, No. 6 (2023)
- TRITHYRODINIUM VERRUCOSUM (HEISECKE, 1970) COMB. NOV., EMEND: AN EARLY
PALEOGENE (DANIAN) DINOFLAGELLATE CYST SPECIES FROM THE NORTH OF
PATAGONIA, ARGENTINA. REGIONAL STRATIGRAPHIC AND PALEOENVIRONMENTAL
RELEVANCE
Authors: M. Sol González Estebenet, M. Verónica Guler
Pages: 509 - 521
Abstract: Trithyrodinium verrucosum comb. nov., emend. was originally described as Scriniodinium verrucosum in Danian deposits of the Roca Formation (Neuquén Basin, west Argentina) by Heisecke (1970). Well-preserved specimens recovered from the YPF.Ch.PV.es-1 borehole (Valdés Basin, east Argentina) and the re-examination of the original material allowed in this paper the emendation of the species, including recognition of an archeopyle type 3I, one of the diagnostic feature that led us to transfer the species to the genus Trithyrodinium. Based on the dinoflagellate cyst assemblages as well as the calcareous foraminifera and nannofossils content recovered from the stratigraphical interval containing Trithyrodinium verrucosum, we suggest the age of the Highest Common Occurrence (HCO) of this species not younger than middle Danian, and linked to the nannofossil Zone NP3. Hence, Trithyrodinium verrucosum may be a biostratigraphical marker for the Danian in the north of Patagonia, and the HCO is potentially useful for regional (inter-basinal) correlation of early Paleocene chronostratigraphical units from the south Atlantic basins. Also, the peak abundance of Trithyrodinium verrucosum in association with warm-water taxa (e.g., Trithyrodinium evittii) might have occurred during globally warming episodes in the Danian.
PubDate: 2023-09-18
DOI: 10.5710/AMGH.20.07.2023.3558
Issue No: Vol. 60, No. 6 (2023)
- LATE JURASSIC CASSIDULOIDS (ECHINODERMATA, ECHINOIDEA) FROM WEST-CENTRAL
ARGENTINA: TAXONOMIC AND PALEOGEOGRAPHIC IMPLICATIONS
Authors: Patricio E. Caccia, Cecilia S. Cataldo, M. Beatriz Aguirre-Urreta
Pages: 522 - 534
Abstract: Cassiduloids are relatively well-represented in the fossil record, especially in Europe and Northern Africa, ever since their first occurrence in the Lower Jurassic. The group shows an increase in diversity and abundance at the end of the Jurassic. In Argentina, cassiduloids are represented from the Middle Jurassic upwards. This paper describes a Tithonian cassiduloid from the Picún Leufú Formation (Neuquén Basin, Argentina) identified as Mepygurus' andinus new comb. according to the poorly developed bourrelets, straight phyllodes that are continuous up to the margin, and a subpentagonal outline. The species was originally described from the Baños del Flaco Formation on the Chilean slope of the Neuquén-Aconcagua Basin. This record extends the stratigraphical range of the genus to at least the Tithonian and provides further evidence to the interpretation of the spatial continuity of shallow-water platforms during the Late Jurassic in the Andean region.
PubDate: 2023-09-18
DOI: 10.5710/AMGH.28.08.2023.3565
Issue No: Vol. 60, No. 6 (2023)
- REASSESSMENT OF UQUIASAURUS HEPTANODONTA, AN IGUANIAN LIZARD FROM THE LATE
PLIOCENE (UQUÍA FORMATION) OF NORTHWESTERN ARGENTINA
Authors: Carlos Agustin Scanferla, Linda Díaz-Fernández
Pages: 535 - 539
Abstract: Uquiasaurus heptanodonta was originally described as an iguanian lizard from the Uquía Formation (late Pliocene) of NW Argentina, known from numerous skull elements. Reexamination of preserved bones indicates the type series comprises more than one species belonging to the extant iguanian genus Liolaemus. The presence of a premaxilla with seven tooth positions among the bone assemblage suggests that species belonging to Liolaemus nigromaculatus group or Liolaemus montanus section have been present in this region up to the late Pliocene (3.0 to 2.5 Ma), thus expanding the fossil record of the genus Liolaemus in the NW Argentina since these times.
PubDate: 2023-09-18
DOI: 10.5710/AMGH.01.09.2023.3577
Issue No: Vol. 60, No. 6 (2023)
- SYSTEMATIC REVISION OF PRE- AND POST-SANTACRUCIAN SPECIES OF
PROTYPOTHERIUM (INTERATHERIIDAE, NOTOUNGULATA)
Authors: Mercedes Fernández, Juan C. Fernicola, Esperanza Cerdeño
Pages: 540 - 559
Abstract: Within the Order Notoungulata, considered the most diverse and abundant clade of South American native ungulates, Interatheriidae (late Paleocene-Late Miocene) is one of the best-known and most derived families. Most of the interatheriids described during late 19th century was erected from specimens collected from the proliferous Santa Cruz Formation (Santacrucian SALMA; Burdigalian-early Langhian), Santa Cruz Province (Argentina). One of the most important interatheriids is Protypotherium, due to its diversity and wide distribution in Bolivia, Chile, Uruguay, and, especially, Argentina, which was revised more than a century ago and from which most of the species were considered Typotheria incertae sedis. Despite this, several species were erected within this genus by diverse authors in the last years. This contribution provides the taxonomic revision of the pre- and post-Santacrucian species of Protypotherium that were not originally erected by Florentino Ameghino within the genus. We propose P. sinclairi and P. concepcionensis as junior synonyms of P. columnifer and P. colloncurensis, respectively, and conclude that Protypotherium includes P. antiquum, P. australe, P. praerutilum, P. compressidens, P. claudum, P. columnifer, P. minutum, P. distinctum, and P. colloncurensis. Finally, we present the most complete phylogenetic analysis of Interatheriidae, at both genus and species levels. It does not recover Protypotherium as a clade, due to the nesting of Caenophilus within the genus, and shows that this assemblage is the sister taxon of the clade constituted by Deseadan Progaleopithecus and Archaeophylus.
PubDate: 2023-09-18
DOI: 10.5710/AMGH.14.07.2023.3556
Issue No: Vol. 60, No. 6 (2023)
- SERGIO ARCHANGELSKY (1931–2022)
Authors: Eduardo Guillermo Ottone
Pages: 560 - 570
Abstract: N/A
PubDate: 2023-09-18
Issue No: Vol. 60, No. 6 (2023)
|
Open Access journal
