Molluscan radiations and landscape evolution in Miocene Amazonia

This PhD study aims to exploit the rich archive provided by the Miocene mollusc fauna of the Pebas Formation and other inland Miocene Amazonian formations to reconstruct landscape evolution and biotic development in lowland Amazonia during the Neogene. Over 160 samples from more than 70 Pebas Formation outcrops mostly collected by the author were processed for this study. Additional samples were collected in Andean areas of Colombia and Venezuela and further material from other northwestern South American basins was studied in museums. Pebas Formation samples and well log data made available by Occidental Peru from three wells in the Marañon Basin in Peru were also investigated. During this study four genera and 74 species from the Pebas Formation have been described and a further 13 species have been introduced in open nomenclature, and several species were reported for the first time. The number of mollusc species attributed to the Pebas fauna has increased from around 50 to 156. The Pebas fauna is characterised as aquatic, endemic and extinct, and is a typical representative of a long-lived lake fauna. Fluvial taxa are not common, (marginal) marine taxa are rare. An additional molluscan fauna from the Miocene Solimões Formation of Brazil, containing 13 fresh water species was also described. The newly documented fauna was used to improve biostratigraphic framework of Miocene Amazonian deposits. Twelve mollusc zones were introduced, the upper eleven of which cover a time interval of approximately seven million years covered previously by only three pollen zones. An age model calculated for the borehole data indicates that the Pebas Formation was deposited between c. 24 and 11 Ma. The areal distribution of the outcropping mollusc zones uncovered a broad dome structure, termed here the Iquitos-Araracuara anteclise in the study area. The structure appears to have influenced river courses and also contributed to edaphic heterogeneity that may have been in part responsible for the current high biodiversity in the study area. The Pebas system was a huge system (> one million km2) dominated by relatively shallow lakes, but also containing swamps and rivers. The system was fed by rivers draining the emergent Andes in the west and lowlands and cratons to the east. The Pebas system was located at sea level and was open to marine settings through a northern portal running through the Llanos Basin and East Venezuela Basin towards the Caribbean. Cyclical baselevel changes possibly related to Mylankhovitch cycles, have been documented in depositional sequences of the Pebas Formation. The composition of the Pebasian mollusc fauna implies that the system was mostly a fresh water system. Such an interpretation is matched by strontium isotope ratios as well as very negative δ18O ratios found in the shells, but is at odds with oligohaline and mesohaline ichnofacies found in the same strata. The mollusc fauna of the Pebas Formation diversified through most of the existence of the lake system. The diversification was mostly the result of in-situ cladogenesis. The success of some of the Pebasian endemic clades is explained by adaptation to fresh water, low oxygen, common unconsolidated lake bottoms (soup grounds) as well as high predation intensity. Maximum diversity was reached at the base of the late Middle to early Late Miocene Grimsdalea pollen zone, some 13 Ma. At the time some 85 species co-occurred, 67 of which are considered as Pebasian endemics. A subsequent drop in species richness coincides with indications of elevated salinities, although a causal relation still needs to be established. Apparently the Pebas fauna went (almost) entirely extinct with the replacement of the lake system into a fluvio-tidal system during the Early Late Miocene, some 11 Ma.Siirretty Doriast

What are the drivers of Caspian Sea level variation during the late Quaternary?

Quaternary Caspian Sea level variations depended on geophysical processes (affecting the opening and closing of gateways and basin size/shape) and hydro-climatological processes (affecting water balance). Disentangling the drivers of past Caspian Sea level variation, as well as the mechanisms by which they impacted the Caspian Sea level variation, is much debated. In this study we examine the relative impacts of hydroclimatic change, ice-sheet accumulation and melt, and isostatic adjustment on Caspian Sea level change. We performed model analysis of ice-sheet and hydroclimate impacts on Caspian Sea level and compared these with newly collated published palaeo-Caspian sea level data for the last glacial cycle. We used palaeoclimate model simulations from a global coupled ocean-atmosphere-vegetation climate model, HadCM3, and ice-sheet data from the ICE-6G_C glacial isostatic adjustment model. Our results show that ice-sheet meltwater during the last glacial cycle played a vital role in Caspian Sea level variations, which is in agreement with hypotheses based on palaeo-Caspian Sea level information. The effect was directly linked to the reorganization and expansion of the Caspian Sea palaeo-drainage system resulting from topographic change. The combined contributions from meltwater and runoff from the expanded basin area were primary factors in the Caspian Sea transgression during the deglaciation period between 20 and 15 kyr BP. Their impact on the evolution of Caspian Sea level lasted until around 13 kyr BP. Millennial scale events (Heinrich events and the Younger Dryas) negatively impacted the surface water budget of the Caspian Sea but their influence on Caspian Sea level variation was short-lived and was outweighed by the massive combined meltwater and runoff contribution over the expanded basin

A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru

Weprovide a synopsis of ~60million years of life history in Neotropical lowlands, based on a comprehensive survey of the Cenozoic deposits along the Quebrada Cachiyacu near Contamana in PeruvianAmazonia. The 34 fossilbearing localities identified have yielded a diversity of fossil remains, including vertebrates,mollusks, arthropods, plant fossils, and microorganisms, ranging from the early Paleocene to the lateMiocene–?Pliocene (N20 successive levels). This Cenozoic series includes the base of the Huchpayacu Formation (Fm.; early Paleocene; lacustrine/ fluvial environments; charophyte-dominated assemblage), the Pozo Fm. (middle + ?late Eocene; marine then freshwater environments; most diversified biomes), and complete sections for the Chambira Fm. (late Oligocene–late early Miocene; freshwater environments; vertebrate-dominated faunas), the Pebas Fm. (late early to early late Miocene; freshwater environments with an increasing marine influence; excellent fossil record), and Ipururo Fm. (late Miocene–?Pliocene; fully fluvial environments; virtually no fossils preserved). At least 485 fossil species are recognized in the Contamana area (~250 ‘plants’, ~212 animals, and 23 foraminifera). Based on taxonomic lists from each stratigraphic interval, high-level taxonomic diversity remained fairly constant throughout themiddle Eocene–Miocene interval (8-12 classes), ordinal diversity fluctuated to a greater degree, and family/species diversity generally declined, with a drastic drop in the early Miocene. The Paleocene–?Pliocene fossil assemblages from Contamana attest at least to four biogeographic histories inherited from (i) Mesozoic Gondwanan times, (ii) the Panamerican realm prior to (iii) the time of South America’s Cenozoic “splendid isolation”, and (iv) Neotropical ecosystems in the Americas. No direct evidence of any North American terrestrial immigrant has yet been recognized in the Miocene record at Contamana.Facultad de Ciencias Naturales y Muse

Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem

The scarcity of high-resolution empirical data directly tracking diversity over time limits our understanding of speciation and extinction dynamics and the drivers of rate changes. Here, we analyze a continuous species-level fossil record of endemic diatoms from ancient Lake Ohrid, along with environmental and climate indicator time series since lake formation 1.36 million years (Ma) ago. We show that speciation and extinction rates nearly simultaneously decreased in the environmentally dynamic phase after ecosystem formation and stabilized after deep-water conditions established in Lake Ohrid. As the lake deepens, we also see a switch in the macroevolutionary trade-off, resulting in a transition from a volatile assemblage of short-lived endemic species to a stable community of long-lived species. Our results emphasize the importance of the interplay between environmental/climate change, ecosystem stability, and environmental limits to diversity for diversification processes. The study also provides a new understanding of evolutionary dynamics in long-lived ecosystems

Reconciling the stratigraphy and depositional history of the Lycian orogen-top basins, SW Anatolia

Terrestrial fossil records from the SW Anatolian basins are crucial both for regional correlations and palaeoenvironmental reconstructions. By reassessing biostratigraphic constraints and incorporating new fossil data, we calibrated and reconstructed the late Neogene and Quaternary palaeoenvironments within a regional palaeogeographical framework. The culmination of the Taurides in SW Anatolia was followed by a regional crustal extension from the late Tortonian onwards that created a broad array of NE-trending orogen-top basins with synchronic associations of alluvial fan, fluvial and lacustrine deposits. The terrestrial basins are superimposed on the upper Burdigalian marine units with a c. 7 myr of hiatus that corresponds to a shift from regional shortening to extension. The initial infill of these basins is documented by a transition from marginal alluvial fans and axial fluvial systems into central shallow-perennial lakes coinciding with a climatic shift from warm/humid to arid conditions. The basal alluvial fan deposits abound in fossil macro-mammals of an early Turolian (MN11–12; late Tortonian) age. The Pliocene epoch in the region was punctuated by subhumid/humid conditions resulting in a rise of local base levels and expansion of lakes as evidenced by marsh-swamp deposits containing diverse fossil mammal assemblages indicating late Ruscinian (late MN15; late Zanclean) age. A second pulse of extension, accompanied by regional climatic changes, prompted subsequent deepening of the lakes as manifested by thick and laterally extensive carbonate successions. These lakes, which prevailed c. 1 myr, later shrank due to renewed progradation of alluvial fans and eventually filled up and dried out, reflected by marsh-swamp deposits at the top of a complete lacustrine succession that contains diverse micro-mammal assemblages indicating a latest Villanyian (MN17; Gelasian) age. A third pulse of tectonic reorganisation and associated extension dissected the basins into their present-day configuration from the early Pleistocene onwards under warm/humid climatic conditions. The new age data provide means to correlate deposits across various basins in the region that help to place the basin development into a regional tectonic framework, which can be attributed to the consequence of the well-articulated regional phenomena of slab-tear/detachment-induced uplift followed by crustal extension and basin formation (late Tortonian), the outward extension of the Aegean arc (early Pliocene) and eventually accompanied by westward extrusion of the Anatolian Plate (early Pleistocene)

Reconciling the stratigraphy and depositional history of the Lycian orogen-top basins, SW Anatolia

Terrestrial fossil records from the SWAnatolian basins are crucial both for regional correlations and palaeoenvironmental reconstructions. By reassessing biostratigraphic constraints and incorporating new fossil data, we calibrated and reconstructed the late Neogene andQuaternary palaeoenvironments within a regional palaeogeographical framework. The culmination of the Taurides inSWAnatolia was followed by a regional crustal extension from the late Tortonian onwards that created a broad array of NE-trending orogen-top basins with synchronic associations of alluvial fan, fluvial and lacustrine deposits. The terrestrial basins are superimposed on the upper Burdigalian marine units with a c. 7 myr of hiatus that corresponds to a shift from regional shortening to extension. The initial infill of these basins is documented by a transition from marginal alluvial fans and axial fluvial systems into central shallow-perennial lakes coinciding with a climatic shift from warm/humid to arid conditions. The basal alluvial fan deposits abound in fossil macro-mammals of an early Turolian (MN11–12; late Tortonian) age. The Pliocene epoch in the region was punctuated by subhumid/humid conditions resulting in a rise of local base levels and expansion of lakes as evidenced by marsh-swamp deposits containing diverse fossilmammal assemblages indicating late Ruscinian (lateMN15; late Zanclean) ageWe are grateful for the support of the international bilateral project between The Scientific and Technological Research Council of Turkey (TUBITAK) and The Russian Scientific Foundation (RFBR) with grant a number of 111Y192. M.C.A. is grateful to the Turkish Academy of Sciences (TUBA) for a GEBIP (Young Scientist Award) grant. T.K. and S.M. are grateful to the Ege University Scientific Research Center for the TTM/002/2016 and TTM/001/2016 projects. M.C.A., H.A., S.M. and M.B. have obtained Martin and Temmick Fellowships at Naturalis Biodiversity Center (Leiden). F.A.D. is supported by a Mehmet Akif Ersoy University Scientific Research Grant. T.A.N. is supported by an Alexander-von-Humboldt Scholarship. L.H.O. received support from TUBITAK under the 2221 program for visiting scientists

The other side of sea level change

Water levels in inland seas and lakes globally will drop, often dramatically, over the 21st century in response to climate change. Based on the case of the Caspian Sea, we argue for a concerted campaign to raise awareness of threats to people, biodiversity and geopolitical stability.EU Horizon 2020 Grant Ref Number 64297

New cockles (Bivalvia: Cardiidae: Lymnocardiinae) from Late Pleistocene Lake Karapinar (Turkey): Discovery of a Pontocaspian refuge?

4th Plenary Meeting of IGCP 610 - From the Caspian to Mediterranean - Environmental Change and Human Response during the Quaternary -- 2016 -- Tbilisi, REP OF GEORGIAWOS: 000425237100004Three species of lymnocardiine cockles (Bivalvia: Cardiidae) from Late Pleistocene deposits near Karapinar (Konya Basin, Anatolia, South Turkey) are reported. Two of the three species are described as new (Monodacna pseudocolorata and Adacna yaninae). A third species (Hypanis ?plicatum) is represented by two incomplete valves. Radiocarbon ages of circa 35-43 kA were obtained for the fauna. The lack of lymnocardiine cockles in Pleistocene Anatolian inland lake deposits raises the possibility that the new record represents a short lived occurrence. We raise the possibility that the Karapinar Basin cockles may have been introduced from the Black Sea region through avian dispersal, although we cannot rule out their cryptic existence in the region during the Pleistocene. The apparent absence of Monodacna colorata group of cockles in the Black Sea Basin during the last glacial raises the possibility that the Karapinar region may have served as a true refugium rather than just a sink for Pontocaspian biota. (c) 2016 Elsevier Ltd and INQUA. All rights reserved.IGCP 61

Anatoma equatoria Hedley 1899

Anatoma equatoria (Hedley, 1899) (Figures 6–7) 1899 Scissurella equatoria nov. spec.—Hedley: p. 551–552, fig. 61. 2012 Anatoma equatoria (Hedley, 1899) —Geiger: p. 854–862, figs 686–693. Material. Anda 1 (38) RGM 961710, Anda 2 (32) RGM 961712, Anda 3 (19) RGM 961714, Anda 4 (26) RGM 961715. Characterization. Shell turbiniform; H 1.99 mm, W 2.00 mm; P with flocculent sculpture, DN 0.08–0.10 mm; shoulder with curved axial cords and fine spiral lines; base with spiral and axial lines forming reticulate sculpture; aperture rounded; umbilicus prominent. Distribution. Indo-Mayalan Archipelago to mid-western Pacific, 46–700 m (Geiger 2012).Published as part of Helwerda, Renate A. & Wesselingh, Frank P., 2014, Revision of Scissurellidae, Anatomidae and Fissurellidae (Gastropoda: Vetigastropoda) from the Plio-Pleistocene of the Philippines, pp. 183-194 in Zootaxa 3838 (2) on page 187, DOI: 10.11646/zootaxa.3838.2.3, http://zenodo.org/record/22906

Anatoma porcellana Geiger 2012

Anatoma porcellana Geiger, 2012 (Figures 8–9) 2012 Anatoma porcellana nov. spec.—Geiger: p. 1020–1026, figs 830–833. Material. Anda 5 (1) RGM 961.716, Anda 6 (9) RGM 961.718, AndaCliff 3 (5) RGM 961.720, Tiep 1 (1) RGM 961.721. Characterization. Shell large, biconical; H 3.95 mm, W 3.97 mm; P eroded, DN 0.13–0.16 mm; shoulder with curved axial cords and 1–3 fine spiral lines; base with spiral and axial cords forming reticulate sculpture; sculpture weakens on lower third of base; aperture rounded; umbilicus closed. Distribution. Possibly tropical Indian Ocean; southern Japan, Indo-Malayan Archipelago to the Western Pacific, 49–2570 m (Geiger 2012). Remarks. The studied material mostly conforms to the description by Geiger (2012), although some specimens are larger than 3.2 mm (largest is 3.95 mm). The shoulder occasionally has three fine spiral lines instead of one to two. The density of axial cords on shoulder and base strongly increases on the last whorl of large specimens. P and T 1 are eroded in the studied material, yet T 1 appears to have only about 11 axial ribs instead of 17–20. The studied material is quite similar in its shape, sculpture and closed umbilicus to Anatoma gephyra Maxwell, 1992 from the late Eocene of New Zealand as well, but the latter has a shorter T 1 of only 0.33 whorls.Published as part of Helwerda, Renate A. & Wesselingh, Frank P., 2014, Revision of Scissurellidae, Anatomidae and Fissurellidae (Gastropoda: Vetigastropoda) from the Plio-Pleistocene of the Philippines, pp. 183-194 in Zootaxa 3838 (2) on pages 187-189, DOI: 10.11646/zootaxa.3838.2.3, http://zenodo.org/record/22906