Academic literature on the topic 'Paleontology Oligocene'

The Lower Oligocene Asmari Formation occupies the western and eastern flanks of the Jabal Hafit anticline and the western limb of the Jabal Malaqet-Mundassah anticline in the southeast of the United Arab Emirates near the Oman border. In this area the Asmari Formation unconformably overlies the Upper Eocene Dammam Formation. In this study an Early Oligocene characteristic assemblage of calcareous nannofossils, foraminifera, corals, calcareous algae, bryozoa, mollusks and echinoids is described from the carbonate rocks of the Asmari Formation. The Asmari stratigraphic succession is dated by analysis of the calcareous nannofossil assemblages and planktonic and larger foraminifera. The results of this study indicate that the succession falls within the Early Oligocene Zones NP24 and P20-P21. About seventeen nannofossil species are documented for the first time in this formation, along with three planktonic and larger foraminiferal species. The Oligocene rocks in the study area provide results consistent with a shallow-water inner shelf within the photic zone.

A qualitative and quantitative study was carried out on the benthic foraminiferal assemblages from the upper Eocene to lower Oligocene of a section of the Caltavuturo Formation exposed near Piana degli Albanesi (northwestern Sicily). The recognized taxa are evaluated in terms of their ecology and bathymetric interpretation. Biostratigraphic constraints are defined combining both nannofossils and planktic foraminifers biozonations. The planktic-benthic foraminiferal ratio allowed the reconstruction of water depth variations. Atotal of 48 benthic foraminiferal taxawere extracted from the samples. The benthic assemblages and the P/(P+B) ratio indicate a lower to middle bathyal depositional depth, although an abrupt drop of sea level of about 140 m is recorded across the suspected Eocene-Oligocene transition. Calcium carbonate content decreases upsection, suggesting an increase in terrigenous supply in the lowermost Oligocene.

A systematic study was carried out on the relatively rich and abundant Paleocene to late Oligocene radiolarian fauna from DSDP Site 329 (Leg 36), located on the Falkland Plateau. Among the 78 taxa identified in the studied interval, a new species (Siphocampe ewingensis n. sp.) and a new combination (Eucyrtidium amygdala (Shilov 1995) n. comb. are proprosed. The high-latitude radiolarian interval zones Eucyrtidium antiquum, Lychnocanoma conica and Clinorhabdus robusta, Oligocene in age, were identified in the upper part of the interval. The lowermost studied sample, within core 33, was assigned to an interval of high-latitude radiolarian zones (RP2-RP5; Paleocene in age), mainly due to the co-occurrence of Amphisphaera kina and Protoxiphotractus wilsoni. These biostratigraphic results improve resolution in the early and late Oligocene, whichwas previously undifferentiated asOligocene, based on calcareous nannofossil biostratigraphy.

ABSTRACT The Oligocene (33.9–23.0 Ma) has historically proven to be a difficult interval to examine with respect to planktic foraminifera; the tendency for many of the taxa to be basically globigerine in shape, with 4 or 5 chambers in the final whorl means differences between species are limited. Recently, an international working group has attempted to clarify the Oligocene planktic foraminiferal taxonomy, with the goal of establishing phylogenetically-consistent generic and species concepts. A relatively expanded and continuous Oligocene section recovered at Ocean Drilling Program Site 803 in the western equatorial Pacific was previously studied by Leckie et al. (1993) using fairly conservative species concepts. Since 1993, foraminiferal biostratigraphic datum age calibrations have changed, and so revised sedimentation rates for the 220-m thick Oligocene sequence are actually more constant than previously thought. As a part of the recent taxonomic revision, this site was reevaluated and numerous additional taxa are recorded at this location. Macroevolutionary rates are calculated from the occurrences, and increased extinction is found within the late Oligocene, counter to the expectations laid out in broader-scale macroevolutionary studies. An effort is made here to describe the diagnostic features, which can be used to distinguish all taxa under a standard binocular microscope. Finally, several figures of scanning electron microscope photomicrographs (from Site 803 and tropical Atlantic Ocean ODP Site 628) depict features used to describe and differentiate important, but difficult or homeomorphic taxa, with the hope that these figures can be used by other workers at the microscope attempting to do Oligocene taxonomy-based studies.

Abyssocythere and Dutoitella are extant benthic bathyal ostracod genera that evolved during Coniacian to Santonian/Campanian time from shallow-water progenitors around southeastern Africa. Their Late Cretaceous development was primarily in the South Atlantic, but during the Palaeogene they spread to the Indian and Pacific oceans. The establishment of the psychrosphere (late Eocene-mid-Oligocene) flushed populations of each genus from their central Atlantic cradles into the Pacific, presumably through the Panama Seaway, so that contemporaneous centres of evolution developed disjunct clades: A. trinidadensis and D. praesuhmi. The psychrospheric oceanic event defined temporal thermophyllic and cryophyllic populations of the two genera. Three Neogene ocean events appear to have affected several regionally-confined species, inter alia one of which entailed a counterflow migration of A. atlantica from the eastern Pacific back into the central Atlantic during the mid-Miocene. Modern distributions of Abyssocythere and Dutoitella are disjunct: in the Atlantic both genera occur south of approximately 40 degrees N (Dutoitella), and equatorial areas (Abyssocythere); in the Indian Ocean both are confined to the southern part; and in the Pacific, Abyssocythere is restricted to central and north-eastern areas, and Dutoitella to the west and northwest. Neither genus evolved species that were more than para-cosmopolitan: A. diagrenona (South Atlantic-Indian; Eocene-Oligocene), A. trinidadensis complex (central Atlantic-NW Pacific; Oligocene-Miocene), D. crassinodosa complex (South Atlantic-Indian; Eocene), and D. praesuhmi (north and central Atlantic-central Pacific; Oligocene-Miocene).

A biometric study was carried out on planorbulinids occurring in eight samples from the upper Eocene-Lower Oligocene sediments of the Caltavuturo Formation cropping out at Portella Colla (Sicily, southern Italy). Counts and measurements on internal characters follow the methods currently employed for the similar genera Planorbulinella and Planolinderina such as the length of the initial spiral and the embryo size. The data obtained from the oriented thin sections allow to assign the late Eocene specimens to Planorbulina bronnimanni, whereas Oligocene specimens show larger embryonic apparatus, but the low amount of measured individuals prevents at present the definition of a new chronospecies. The well-known evolutionary trends of embryonic and nepionic accelerations, documented for the fossil Planorbulinella, seem not to be recognizable for Planorbulina.

In 1983 one of us (JGV) in collaboration with J. Van Hinte described the new foraminiferal species Hyperammina rugosa from the Oligocene of DSDP Hole 345 in the Norwegian Sea. It was also reported from the Eocene at Site 346, Lower Miocene at Site 348, and the Oligocene-Miocene at Site 348 (Verdenius and Van Hinte 1983). The species Hyperammina rugosa was subsequently reported throughout the North Sea, Norwegian Sea, and Barents Sea region (Kaminski and Gradstein 2005). The species has been reported more recently from the Miocene of the Fram Strait region and the Central Arctic Ocean by Kaminski et al. (2005, 2009), from the Upper Cretaceous (Santonian–Campanian) of the southern Norwegian Sea by Setoyama and Kaminski (2015), and from the Upper Cretaceous to Paleogene of the Outer Carpathian region by Bindiu et al. (2019) and by Bubik (2019).

The Calama and eastern Pampa del Tamarugal Basins are located between 22°S and 23°S within the forearc of northern Chile. They are filled by sediments deposited in alluvial braidplain, fluvial, playa sandflat, lacustrine and volcaniclastic environments under a semi-arid to hyper-arid climate. The nature of the alluvial braidplain depositional environment is unusual in that it combines elements of both alluvial fan and fluvial depositional systems, in contradiction to recently published models of alluvial fan sedimentation. Detailed sedimentary logging, magnetostratigraphy and dating of 14 volcanic interbeds by the ⁴⁰Ar/³⁹Ar laser fusion method has established a lithostratigraphic and chronostratigraphic framework for the 700 m thick basin-fill. Basin formation was investigated by regional subsidence during the Late Eocene or Early Oligocene, followed by widespread alluvial braidplain deposition during the Oligocene(?). A change to fluvial and playa sandflat deposition during the Early to Mid-Miocene is considered to be coincident with a decrease in active subsidence. Sedimentation ceased and thick (25 m) gypcrete deposits developed along the eastern margin of the basin during the Mid-Miocene as a response to an increasingly arid climate. Phases of minor lacustrine, fluvial and alluvial braidplain deposition during the Late Miocene-Early-Pliocene and the Late Pliocene(?) to Pleistocene were primarily controlled by small-scale fault movements and folding events, although climatic variations may have been important in some cases. A new lithostratigraphic division of the basin-fill is proposed here, which comprises 13 different formations. The previously defined El Loa Formation comprises a number of depositional units which are spatially and temporally discrete formations, and is therefore awarded group status.

Geology
M.S.
Climate change across the terrestrial Eocene-Oligocene boundary of the Great Plains is recorded by shifts in sediments, facies, paleosols, and isotopic records, and is interpreted as a shift to overall cooler and drier conditions. As an independent test of paleoenvironmental shifts caused by climatic change, I compared microwear on M2 molars of Leptomeryx from the White River Group (WR) at Toadstool Park, Nebraska (n = 9) and Flagstaff Rim, Wyoming (n = 11). Comparisons of microwear were made through time at each section. Various measurements of microwear were quantified on original, uncoated specimens using environmental scanning electron microscopy and Microware 4.0 software, and evaluated with ANOVA and Kruskal-Wallis statistical tests. Values of the scratch:pit ratio, scratch number, feature major:minor axis ratio, feature vector length, major axis standard deviation, major:minor axis standard deviation, and feature orientation standard deviation for Leptomeryx M2 molars are significantly different (p<0.05) between Wyoming and Nebraska. Microwear patterns suggest paleoecological differences between the two locations, possibly related to differences in Leptomeryx diet or in amount or character of sediment adhering to ingested vegetation. Little fossil evidence of vegetation type is preserved at either locality, other than clay-filled root traces or occasional rhizoliths or silicified fragments. However, sediments of the WR are a mixture of volcaniclastic enriched mudstone, siltstone, and sandstone, with generally coarser overall particle sizes in Wyoming that reflect proximity to siliciclastic sources. The degree of overall volcaniclastic enrichment and number of airfall tuffs is also higher at Flagstaff Rim. Paleosols suggest a shift from closed canopy forest to progressively open conditions at each locality and, although microwear differences could result from differences in vegetation or particle sizes of adhered sediments on plants, no or very low correlations between microwear features and stratigraphic level were detected at either locality, indicating that any changes in paleoecology over time did not significantly alter the diets of Leptomeryx, although diet may have been geographically different.
Temple University--Theses

Eleven dinoflagellates, acritarchs, and pollen biozones have been identified in Upper Eocene to Pliocene sediments combined from MuS, Tekman, Tercan-ASkale, Pasinler-Horasan basins and the Bayburt-Kars Plateau in this study. FAD&
#8217
s of Compositae (tubuliflorae type), Slowakipollenites hipophä
eoides, Mediocolpopollis compactus, Monoporopollenites gramineoides and Umbelliferae at the base of Rupelian, FAD of Wetzeliella gochtii in the middle Rupelian, LAD of Ascostomocystis potane in the late Rupelian, LAD of Wetzeliella gochtii in the latest Rupelian, LAD of Deflandrea spp. in the latest Chattian, peak occurrences of Chriptoredium spp. in the early and late Aquitanian, FAD of Hystrichosphaeropsis obscura, followed by FAD of Membranilarnacea ?picena in the late Aquitanian should have particular emphasis for palynostratigraphic divisions in regional correlations and indicate that a continuous deposition took place in Eastern Anatolia from Late Eocene to the end of the Early Miocene. A relatively deeper marine deposition prevailed during the Late Eocene, which was followed by a shallowing-upward deposition during the Oligocene in MuS, Tekman, Tercan-ASkale, and Pasinler-Horasan basins. These basins were also characterized by an Early Miocene regional transgression, and terrestrial (lacustrine and fluvial) deposition during the Late Miocene-Pliocene whereas terrestrial conditions have been predominating since Late Eocene in the Bayburt-Kars Plateau. Paleoclimatological reconstructions of Eastern Anatolian Oligocene-Miocene sediments suggest temperate to subtropical climates in which mean annual temperatures vary between 15,6 to 21,3 °
C, mean temperatures of the coldest and the warmest month are 5.0 to 13.3 °
C and 24.7 to 28.1 °
C, respectively, and mean annual precipitation is 1122.0 to 1522.0 mm.

Paleokarst deposits from the Oligo-Miocene of northern Florida preserve undescribed herpetofaunal remains that fill important temporal and geographic gaps in our understanding of Cenozoic lizard evolution. Here I describe and discuss the non-anguimorph lizard diversity of the Brooksville 2 (Ar2) and Miller (He1) local faunas to test for patterns of regional and latitudinal provincialism in the contemporary North American record. Collectively, the sites are significant for documenting 1) extralimital occurrences of the tropical clades Anolis and Corytophaninae, 2) a substantial temporal range extension of the modern southeastern endemic Rhineuridae, 3) the earliest record of eublepharid gekkotans from North America, and 4) the early Miocene arrival of “cnemidophorine” teiids from South America. This work complements recent studies of older, Eocene lizards by others and lends paleontological support to aspects of the tropical conservatism hypothesis: lineages now confined to the tropics were present at higher latitudes when megathermal climates were more extensive.

Aquesta tesi doctoral té com a objectiu principal la caracterització taxonòmica, paleoecològica, paleobiogeogràfica i biostratigràfica dels caròfits de l’Eocè superior-Oligocè inferior de la Conca de l’Ebre. La flora de caròfits de l’Eocè superior-Oligocè inferior del marge est de la Conca de l’Ebre està constituïda per Sphaerochara labellata, Chara aff. antennata, C. artesica n. sp., C. rhenana, C.microcera, Psilochara aff. acuta, Lamprothamnium sp., Gyrogona caelata, Nodosochara jorbae, Lychnothamnus longus, L. stockmansii, L. grambastii, L. vectensis, L. pinguis (=L. major), Nitellopsis (Tectochara) merianii, Harrisichara lineata, H. vasiformis-tuberculata i H. tuberculata. En totes es caracteritza el polimorfisme intraespecífic a parti d’un estudi biomètric dels girogonits. Des d’un punt de vista taxonòmic se sinonimitzen, a partir de les poblacions tipus, dues espècies clau en biostratigrafia del límit Eocè-Oligocè europeu, Lychnothamnus pinguis i L. major. L’anàlisi paleoecològica de les associacions de caròfits de l’Eocè superior al sector NE de la conca de l’Ebre ha permés determinar que espècies clau per la biostratigrafia del límit Eocè-Oligocè presenten clares limitacions paleoecològiques. Així, Harrisichara vasiformis-tuberculata creixeria només en ambients salabrosos i soms pròxims a la costa, Harrisichara lineata es relaciona amb llacs soms d’aigua dolça i Harrisichara tuberculata abunda, però no és exclusiva, de llacs perennes i profunds d’aigua dolça. Altres espècies com Sphaerochara labellata, Lychnothamnus stockmansii, L. pinguis (=L. major) i Chara microcera es troben en llacs permanents. En conclusió, la presència o absència d’aquestes espècies, i per tant, de les biozones homònimes en una determinada conca europea depèn del tipus de fàcies i del paleoambient associat mes que no d’esdeveniments evolutius. Altres espècies com Lychnothamnus vectensis, Nodosochara jorbae, Lychnothamnus longus o Chara artesica n. sp., en canvi, no presenten cap limitació ecològica important dins el context dels sistemes aquàtics continentals. L’anàlisi paleobiogeogràfica de la caroflora de l’Eocè superior-Oligocè inferior d’Europa permet identificar una polaritat latitudinal en la distribució i abundància de les espècies. No obstant, partint de les espècies comunes a totes les conques europees es defineix una bioprovíncia europea per l’Eocè superior-Oligocè inferior la qual es pot caracteritzar a partir dels llinatges Harrisichara vasiformis-H. tuberculata i Lychnothamnus stockmansii-L. major així com de les espècies Nitellopsis (T.) merianii i Chara microcera. Les variacions regionals d’aquesta flora responen a factors climàtics locals i a factors ecològics lligats a la dinàmica de cada conca. La distribució biogeogràfica de determinades espècies, com Sphaerochara labellata o L. pinguis ha mostrat que l’us d’aquestes especies en biostratigrafia està condicionada per factors paleogeogràfics. L’anàlisi de la biogeografia històrica del llinatges evolutius Lychnothamnus stockmansii-L. major i Nitellopsis(Tectochara)merianii-N. obtusa suggereix que les espècies de caràcies fòssils seguien diferents patrons de dispersió en funció de la disposició dels seus gametangis (dioica vs. monoica). És clar que les espècies monoiques com Lychnothamnus stockmansii-L. major, amb velocitats d’expansió geològicament instantànies, són idònies alhora de correlacionar biostratigraficament conques allunyades. Des d’un punt de vista biostratigràfic, les associacions de caròfits han permès precisar l’atribució biostratigràfica de les unitats litostratigràfiques estudiades. S’ha proposat una biozonació de carofits per la conca de l’Ebre a partir d’espècies ecològicament euritípiques. Aquesta biozonació s’ha correlacionat amb la biozonació local de vertebrats i s’ha calibrat amb la magnetostratigrafia definida a l’est de la conca per Barberà et al. (2001) i Costa et al. (2010, 2011). La nova proposta permet caracteritzar el límit Eocè-Oligocè dins la biozona de Lychnothamnus vectensis. A més, s’ha revisat la biozonació europea avui dia en us. La calibració dels límits de les biozones europees amb l’escala del temps absolut mitjançant la magnetostratigrafia ha permès, per primera vegada, precisar la durada temporal de les biozones de caròfits del límit Eocè-Oligocè.

As pesquisas apresentadas nesta dissertação integram o projeto CNPq - PROANTAR 550352/02-3 \"Mudanças paleoclimáticas na Antártica durante o Cenozóico: o registro geológico terrestre\", que estuda os depósitos cenozóicos da ilha Rei George em busca elucidação do histórico ambiental e climático desta região antártica. A evolução dos padrões de circulação marinha e atmosférica no Hemisfério Sul ocorreu em resposta ao isolamento geográfico e térmico da Antártica, resultado de sua separação da Austrália, no limite Eoceno/Oligoceno, e da América do Sul, no final do Oligoceno. Sob este aspecto, o estudo de organismos fósseis registrados nos depósitos cenozóicos da Antártica contribui para o entendimento das evoluções biológicas e ambientais ocorridas concomitantemente às mudanças paleogeográficas, oceanográficas e climáticas na região ao longo do Cenozóico. Frente à dificuldade de acesso, demanda logística e extensa cobertura de gelo, apenas uma pequena porção do registro geológico da Antártica está acessível para pesquisa. Afloramentos da ilha Rei George registram as mudanças climáticas e ambientais ocorridas do Oligoceno ao Mioceno, incluindo evidências do primeiro evento de glaciação perene no oeste do continente (Oligoceno). A despeito da abundância de fósseis nos estratos cenozóicos da ilha, são poucos os trabalhos taxonômicos com descrição sistemática detalhada de bivalves fósseis. O primeiro módulo do presente estudo apresenta a descrição taxonômica de invertebrados de depósitos cenozóicos aflorantes em duas localidades da ilha Rei George, Antártica ocidental. Da Formação Cape Melville (Mioceno), península Melville, foram descritos sete táxons de bivalves, incluindo seis espécies novas. Da Formação Polonez Cove (Oligoceno), Pico Vauréal, uma região previamente inexplorada paleontologicamente, foram descritos sete táxons de invertebrados (bivalves, braquiópodes, tubos de serpulídeos, briozoários e fragmentos de equinodermes), incluindo duas espécies novas. O segundo módulo corresponde à reunião dos gêneros de bivalves registrados em depósitos cenozóicos da Antártica. A análise do registro apontou para o conhecimento bastante incipiente sobre a diversidade de bivalves antárticos ao longo do Cenozóico. Além disso, a comparação entre gêneros de bivalves cenozóicos registrados na Antártica e Nova Zelândia revelou que a maior parte dos gêneros compartilhados está registrada em depósitos eocênicos, o que suporta o isolamento geográfico da Antártica e a redução do intercâmbio faunístico entre a Antártica e regiões periféricas após o Oligoceno. A análise do registro sugeriu um evento de dispersão intenso durante o Eoceno, e pequenos pulsos de dispersão após o Oligoceno. O padrão de distribuição dos táxons concorda parcialmente com as reconstituições de paleocorrentes disponíveis na literatura. A dispersão durante o Eoceno teria ocorrido da Antártica para a Nova Zelândia na direção do Atlântico para o Pacífico. Este evento de dispersão concorda com a hipótese de existência de conexões marinhas de plataforma rasa entre o oeste e o leste da Antártica (\"Passagem de Shackleton\") e da província Weddeliana do final do Cretáceo ao Eoceno. Os eventos de dispersão pósoligocênicos teriam ocorrido durante e após o estabelecimento da Corrente Circum-Antártica, não mais pela \"Passagem de Shackleton\", mas margeando a Antártica pelas bordas ocidental atlântica e oriental em direção à Nova Zelândia. A análise do registro dos bivalves cenozóicos da Antártica também concorda com a hipótese de glaciação perene a partir do início do Oligoceno na região leste do continente, e na metade do Oligoceno na região oeste, com temperaturas mais amenas que as observadas atualmente.
The research presented in this dissertation comprised part of the CNPq - PROANTAR Project 550352/02-3 \"Mudanças paleoclimáticas na Antártica durante o Cenozóico: o registro geológico terrestre\", which studies Cenozoic deposits from King George Island in order to elucidate the environmental and climatic Cenozoic histories of this Antarctic region. Cenozoic evolution of marine and atmospheric circulation in the Southern Hemisphere occurred in response to the geographic and thermal isolation of Antarctica, which resulted from the separation of Antarctica from Australia, around Eocene/Oligocene boundary, and from South America, during the late Oligocene. Thus, study of fossil organisms from Antarctic Cenozoic deposits contributes to the understanding of biological and environmental evolutions that accompanied paleogeographic, oceanographic and climatic changes during the Cenozoic. As a result of the difficult access, logistic demand and extensive ice cover, only a small part of the Cenozoic Antarctic record is available for study. King George Island records climatic and environmental changes from the Oligocene to the Miocene, including evidence of the first full-scale glaciation (Oligocene) of West Antarctica. Despite the abundance of fossils in Cenozoic deposits of the island, taxonomic studies with detailed systematic descriptions of bivalves are very rare. The first section of this work consists of taxonomic descriptions of invertebrates from Cenozoic deposits cropping out in two localities of King George Island, West Antarctica. Seven taxa of bivalves, including six new species were described from the Cape Melville Formation (Miocene), at Melville Peninsula. Seven taxa of invertebrates (bivalves, brachiopods, serpulid tubes, bryozoans, and echinoderm fragments) were described from the Polonez Cove Formation (Oligocene), at Vauréal Peak, a site previously unexplored paleontologically. The second section presents the results of a survey of the Cenozoic fossil record of Antarctic bivalves. The analysis of the fossil record confirmed that the current knowledge about the Cenozoic diversity of the group is very scarce. Moreover, comparison of Cenozoic bivalve genera from Antarctica and New Zealand showed that the greatest number of shared taxa is recorded in Eocene deposits. This finding supports the geographic isolation of Antarctic and the drop in faunal interchange between Antarctica and periphery after the Oligocene. Analysis of the fossil record suggested an intensive dispersal event during the Eocene, and restricted pulses of dispersal from the Oligocene onwards. The distribution pattern of taxa provides partial support for available reconstructions of marine currents. Eocene dispersal would have occurred from Antarctica to New Zealand in Atlantic-Pacific direction. This dispersal event is consistent with the hypothesis of shallow marine connections between West and East Antarctica (\"Shackleton Seaway\"), as well of the existence of the Weddellian Province from the Late Cretaceous to the Eocene. Dispersal events following the Oligocene would have occurred during and after the establishment of the Circum-Antarctic Current, along the West-Atlantic and East margins of Antarctica towards New Zealand, and no longer through \"Shackleton Seaway\". These analyses also support the hypothesis of full-scale glaciation in West Antarctica from the early Oligocene onwards, and in East Antarctica since the mid-Oligocene, with warmer temperatures than today.

ABSTRACT The vertebrate paleontology, lithostratigraphies, and depositional environments of the Cenozoic continental Titus Canyon and Furnace Creek Formations have been the subjects of several recent investigations. The two units are exposed in the Amargosa Range in northeastern Death Valley National Park, Inyo County, southeastern California, USA. Fossil tracks and trackways are preserved in playa mudflat deposits of the Pliocene Furnace Creek Formation at the Cow Creek tracksite on the western slope of the central Funeral Mountains. The tracksite includes footprints of birds and land mammals, as well as associated sedimentary structures. The lower red beds of the Titus Canyon Formation have produced numerous fossilized bones and teeth at Titus and upper Titanothere Canyons in the southeastern half of the Grapevine Mountains. The fossil remains represent 17 extinct genera and species of land mammals and one genus and species of pond turtle. The taxa constitute the Titus Canyon Fauna. The rodents Quadratomus? gigans and Dolocylindrodon texanus, the bear dog Daphoenictis n. sp. (small), and the tapir Colodon stovalli are associated elsewhere only in the correlative, late early late Duchesnean Upper Porvenir Local Fauna of Trans-Pecos or Far West Texas. The local fauna occurs in the Blue Cliff Horizon (i.e., above lower marker bed) in the lower part of the Chambers Tuff Formation. The two assemblages share 12 species. The age of the latter unit is constrained by corrected single-crystal laser-fusion 40Ar/39Ar dates of 37.83 ± 0.09 Ma for the underlying Buckshot Ignimbrite and 37.14 ± 0.08 Ma for the overlying Bracks Rhyolite. However, both determinations should be considered tentative and subject to change with further investigation. The first green conglomerate unit of the Titus Canyon Formation overlies the lower red beds, underlies the Monarch Canyon Tuff Bed, and has produced the first records of land mammal footprints and a land plant (petrified palm wood) from the formation. The Monarch Canyon Tuff Bed and the Unit 38 Tuff Bed, which lies at the mutual tops of the upper “red beds” and the Titus Canyon Formation, are 34.7 ± 0.7 m.y. old and 30.4 ± 0.6 m.y. old, respectively, based on recalculated 40Ar/39Ar dates. Consequently, the Titus Canyon Formation is latest middle Eocene to earliest Oligocene in age, according to the 2020 Paleogene time scale.