Journal articles: 'Fossils - Namibia'

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Watters, Wesley A., and John P. Grotzinger. "Digital reconstruction of calcified early metazoans, terminal Proterozoic Nama Group, Namibia." Paleobiology 27, no. 1 (2001): 159–71. http://dx.doi.org/10.1666/0094-8373(2001)027<0159:drocem>2.0.co;2.

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A method is presented for the digital reconstruction of weakly calcified fossils within the Nama Group, Namibia. These recently described fossils (Grotzinger et al. 2000) are preserved as calcitic void-fill in a calcite matrix, and individual specimens cannot be freed by conventional techniques. The technique presented here has several integrated steps: (1) the analysis of cross-sections of fossil specimens, (2) the construction of a three-dimensional “tomographic” model that is assembled from the cross-sections, (3) the development of an idealized mathematical model based upon geometric parameters measured from the tomographic model, and (4) the visualization of randomly oriented cross-sections through the mathematical model, which can be compared with fossil cross-sections in outcrop.In this procedure, rocks containing the fossils are ground and digitally photographed at thickness intervals of 25 μm. A battery of image-processing techniques is used to obtain the contour outlines of the fossils in serial cross-sections. A Delaunay triangulation method is then used to reconstruct the morphology from tetrahedrons which connect the contours in adjacent layers. We found that most of the fossils represent a single morphology with some well-defined characters that vary slightly among individual specimens. This fossil morphology was described by Grotzinger et al. (2000) as Namacalathus hermanastes. A mathematical description of the morphology is used to obtain a database of randomly oriented synthetic cross-sections. This database reproduces the vast majority of cross-sections observed in outcrop.

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Smith, E. F., L. L. Nelson, S. M. Tweedt, H. Zeng, and J. B. Workman. "A cosmopolitan late Ediacaran biotic assemblage: new fossils from Nevada and Namibia support a global biostratigraphic link." Proceedings of the Royal Society B: Biological Sciences 284, no. 1858 (July 12, 2017): 20170934. http://dx.doi.org/10.1098/rspb.2017.0934.

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Owing to the lack of temporally well-constrained Ediacaran fossil localities containing overlapping biotic assemblages, it has remained uncertain if the latest Ediacaran ( ca 550–541 Ma) assemblages reflect systematic biological turnover or environmental, taphonomic or biogeographic biases. Here, we report new latest Ediacaran fossil discoveries from the lower member of the Wood Canyon Formation in Nye County, Nevada, including the first figured reports of erniettomorphs, Gaojiashania , Conotubus and other problematic fossils. The fossils are spectacularly preserved in three taphonomic windows and occur in greater than 11 stratigraphic horizons, all of which are below the first appearance of Treptichnus pedum and the nadir of a large negative δ 13 C excursion that is a chemostratigraphic marker of the Ediacaran–Cambrian boundary. The co-occurrence of morphologically diverse tubular fossils and erniettomorphs in Nevada provides a biostratigraphic link among latest Ediacaran fossil localities globally. Integrated with a new report of Gaojiashania from Namibia, previous fossil reports and existing age constraints, these finds demonstrate a distinctive late Ediacaran fossil assemblage comprising at least two groups of macroscopic organisms with dissimilar body plans that ecologically and temporally overlapped for at least 6 Myr at the close of the Ediacaran Period. This cosmopolitan biotic assemblage disappeared from the fossil record at the end of the Ediacaran Period, prior to the Cambrian radiation.

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Hagadorn, James W., Christopher M. Fedo, and Ben M. Waggoner. "Early Cambrian Ediacaran-type fossils from California." Journal of Paleontology 74, no. 4 (July 2000): 731–40. http://dx.doi.org/10.1017/s0022336000032832.

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Ediacara-type fossils are rare in the southwestern United States, and Cambrian occurrences of soft-bodied Ediacaran-type fossils are extremely rare. We report both discoidal and frondlike fossils comparable to Ediacaran taxa from the western edge of the Great Basin. We describe one specimen of a discoidal fossil, referred to the form species ?Tirasiana disciformis, from the upper member of the Lower Cambrian Wood Canyon Formation from the Salt Spring Hills, California. Two fragmentary specimens of frond-like soft-bodied fossils are described from the middle member of the Lower Cambrian Poleta Formation in the White Mountains, California, and the upper member of the Wood Canyon Formation in the southern Kelso Mountains, California. On the basis of similarities with fossils from the lower member of the Wood Canyon Formation and from the Spitzkopf Member of the Urusis Formation of Namibia, these specimens are interpreted as cf. Swartpuntia. All fossils were collected from strata containing diagnostic Early Cambrian body and trace fossils, and thus add to previous reports of complex Ediacaran forms in Cambrian marine environments. In this region, Swartpuntia persists through several hundred meters of section, spanning at least two trilobite zones.

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Cohen, P. A., A. Bradley, A. H. Knoll, J. P. Grotzinger, S. Jensen, J. Abelson, K. Hand, et al. "Tubular compression fossils from the Ediacaran Nama group, Namibia." Journal of Paleontology 83, no. 1 (January 2009): 110–22. http://dx.doi.org/10.1017/s0022336000058169.

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Abundant tubular macrofossils occur in finely laminated siltstones and shales of the 548–542 Ma Schwarzrand Subgroup, Nama Group, Namibia. The Nama tubes occur in both the Vingerbreek and Feldschuhhorn members commonly in dense populations and always in fine-grained, lower shore-face lithologies deposited below fair-weather wave base. The tubes are preserved mostly as compressed casts and molds that range in width from 0.6 to 2.1 mm; apparently incomplete specimens reach lengths up to 10 cm. All specimens show sinuous bending and occasional brittle fracture, indicating an original construction of strong but flexible organic matter. Feldschuhhorn specimens preserve fine longitudinal pleats or folds that record pliant organic walls, but the older Vingerbreek populations do not. Similarly, some specimens in the Feldschuhhorn Member display branching, while Vingerbreek tubes do not. The abundant Feldschuhhorn tubes are assigned to the widespread Ediacaran problematicum Vendotaenia antiqua; however, the distinctive Vingerbreek population remains in open nomenclature. The most abundant fossils in Nama rocks, these tubes resemble populations in Ediacaran successions from Russia, China, Spain, and elsewhere. Beyond their local importance, then, such tubes may turn out to be the most abundant record of Ediacaran life.

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Cohen, P. A., A. Bradley, A. H. Knoll, J. P. Grotzinger, S. Jensen, J. Abelson, K. Hand, et al. "Tubular Compression Fossils from the Ediacaran Nama Group, Namibia." Journal of Paleontology 83, no. 1 (January 2009): 110–22. http://dx.doi.org/10.1666/09-040r.1.

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Jensen, Sören, Beverly Z. Saylor, James G. Gehling, and Gerard J. B. Germs. "Complex trace fossils from the terminal Proterozoic of Namibia." Geology 28, no. 2 (February 2000): 143–46. http://dx.doi.org/10.1130/0091-7613(2000)028<0143:ctfftt>2.3.co;2.

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Jensen, Sören, Beverly Z. Saylor, James G. Gehling, and Gerard J. B. Germs. "Complex trace fossils from the terminal Proterozoic of Namibia." Geology 28, no. 2 (2000): 143. http://dx.doi.org/10.1130/0091-7613(2000)28<143:ctfftt>2.0.co;2.

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Grotzinger, John P., Wesley A. Watters, and Andrew H. Knoll. "Calcified metazoans in thrombolite-stromatolite reefs of the terminal Proterozoic Nama Group, Namibia." Paleobiology 26, no. 3 (2000): 334–59. http://dx.doi.org/10.1666/0094-8373(2000)026<0334:cmitsr>2.0.co;2.

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Reefs containing abundant calcified metazoans occur at several stratigraphic levels within carbonate platforms of the terminal Proterozoic Nama Group, central and southern Namibia. The reef-bearing strata span an interval ranging from approximately 550 Ma to 543 Ma. The reefs are composed of thrombolites (clotted internal texture) and stromatolites (laminated internal texture) that form laterally continuous biostromes, isolated patch reefs, and isolated pinnacle reefs ranging in scale from a meter to several kilometers in width. Stromatolite-dominated reefs occur in depositionally updip positions within carbonate ramps, whereas thrombolite-dominated reefs occur broadly across the ramp profile and are well developed as pinnacle reefs in downdip positions.The three-dimensional morphology of reef-associated fossils was reconstructed by computer, based on digitized images of sections taken at 25-micron intervals through 15 fossil specimens and additionally supported by observations of over 90 sets of serial sections. Most variation observed in outcrop can be accounted for by a single species of cm-scale, lightly calcified goblet-shaped fossils herein described as Namacalathus hermanastes gen. et sp. nov. These fossils are characterized by a hollow stem open at both ends attached to a broadly spheroidal cup marked by a circular opening with a downturned lip and six (or seven) side holes interpreted as diagenetic features of underlying biological structure. The goblets lived atop the rough topography created by ecologically complex microbial-algal carpets; they appear to have been sessile benthos attached either to the biohermal substrate or to soft-bodied macrobenthos such as seaweeds that grew on the reef surface. The phylogenetic affinities of Namacalathus are uncertain, although preserved morphology is consistent with a cnidarian-like bodyplan. In general aspect, these fossils resemble some of the unmineralized, radially symmetric taxa found in contemporaneous sandstones and shales, but do not appear to be closely related to the well-skeletonized bilaterian animals that radiated in younger oceans. Nama reefs demonstrate that biohermal associations of invertebrates and thrombolite-forming microorganisms antedate the Cambrian Period.

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Retallack, Gregory J. "Were the Ediacaran fossils lichens?" Paleobiology 20, no. 4 (1994): 523–44. http://dx.doi.org/10.1017/s0094837300012975.

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Ediacaran fossils are taphonomically similar to impressions of fossil plants common in quartz sandstones, and the relief of the fossils suggests that they were as resistant to compaction during burial as some kinds of Pennsylvanian tree trunks. Fossils of jellyfish are known from siderite nodules and fine-grained limestone, and even in these compaction-resistant media were more compressed during burial than were the Vendobionta. Vendobionta were constructed of materials that responded to burial compaction in a way intermediate between conifer and lycopsid logs. This comparative taphonomic study thus falsifies the concept of Vendobionta as thin soft-bodied creatures such as worms and jellyfish.Lichens, with their structural chitin, present a viable model for the observed preservational style of Vendobionta, as well as for a variety of other features that now can be reassessed from this new perspective. The diversity of Ediacaran body plans can be compared with the variety of form in fungi, algae, and lichens. The large size (ca. 1 m) of some Ediacaran fossils is reasonable for sessile photosynthetic symbioses, and much bigger than associated burrows of metazoans not preserved. Microscopic tubular structures and darkly pigmented cells in permineralized late Precambrian fossils from Namibia and China are also compatible with interpretation as lichens. The presumed marine habitat of Ediacaran fossils is not crucial to interpretation as lichens, because fungi and lichens live in the sea as well as on land.

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Macdonald, Francis A., Sara B. Pruss, and Justin V. Strauss. "Trace Fossils with Spreiten from the Late Ediacaran Nama Group, Namibia: Complex Feeding Patterns Five Million Years Before the Precambrian–Cambrian Boundary." Journal of Paleontology 88, no. 2 (March 2014): 299–308. http://dx.doi.org/10.1666/13-042.

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Here we describe large, complex trace fossils in the late Ediacaran Omkyk Member of the Zaris Formation, Nama Group, southern Namibia. The horizontal trace fossils are preserved on a number of talus blocks from a bedding plane of a cm-thick sandstone lens from a single stratigraphic horizon less than 100 m below an ash bed dated at 547.3 ± 0.7 Ma. The forms consist of overlapping U-shaped spreiten elements with parallel limbs surrounded by an outer tube. Individual U-shaped elements are 0.2 to 1 cm in diameter, the outer tube is less than 3 mm in diameter, and the forms as a whole range from 5 to 30 cm long and 3 to 10 cm wide. The specimens commonly show a change in direction and change in diameter. The morphology of these trace fossils is comparable to backfill structures, particularly specimens of Paleozoic Zoophycos from shallow water environments. Here we interpret these horizontal spreiten-burrows to record the grazing of the trace-maker on or below a textured organic surface. The identification of large late Ediacaran trace fossils is consistent with recent reports of backfilled horizontal burrows below the Precambrian–Cambrian boundary and is suggestive of the appearance of complex feeding habits prior to the Cambrian trace fossil explosion.

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GEYER, G. "The Fish River Subgroup in Namibia: stratigraphy, depositional environments and the Proterozoic–Cambrian boundary problem revisited." Geological Magazine 142, no. 5 (September 2005): 465–98. http://dx.doi.org/10.1017/s0016756805000956.

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The Fish River Subgroup of the Nama Group, southern Namibia, is restudied in terms of lithostratigraphy and depositional environment. The study is based on partly fine-scaled sections, particularly of the Nababis and Gross Aub Formation. The results are generally in accordance with earlier studies. However, braided river deposits appear to be less widely distributed in the studied area, and a considerable part of the formations of the middle and upper subgroup apparently were deposited under shallowest marine conditions including upper shore-face. Evidence comes partly from sedimentary features and facies distribution, and partly from trace fossils, particularly Skolithos and the characteristic Trichophycus pedum. Environmental conditions represented by layers with T. pedum suggest that the producer favoured shallow marine habitats and transgressive regimes. The successions represent two deepening-upward sequences, both starting as fluvial (braided river) systems and ending as shallow marine tidally dominated environments. The first sequence includes the traditional Stockdale, Breckhorn and lower Nababis formations (Zamnarib Member). The second sequence includes the upper Nababis (Haribes Member) and Gross Aub formations. As a result, the Nababis and Gross Aub formations require emendation: a new formation including the Haribes and Rosenhof and possibly also the Deurstamp members. In addition, four distinct sequence stratigraphic units are deter-minable for the Fish River Subgroup in the southern part of the basin. The Proterozoic–Cambrian transition in southern Namibia is most probably located as low as the middle Schwarzrand Subgroup. The environmentally controlled occurrence of Trichophycus pedum undermines the local stratigraphic significance of this trace fossil which is eponymous with the lowest Cambrian and Phanerozoic trace fossil assemblage on a global scale. However, occurrences of such trace fossils have to be regarded as positive evidence for Phanerozoic age regardless of co-occurring body fossils. Other suggestions strongly dispute the concept of the formal Proterozoic–Cambrian and Precambrian–Phanerozoic boundary. Carbon isotope excursions and radiometric datings for the Nama Group do not help to calibrate precisely the temporal extent of the Fish River Subgroup. Fossil content, sequence stratigraphy and inferred depositional developments suggest that this subgroup represents only a short period of late orogenic molasse sedimentation during the early sub-trilobitic Early Cambrian.

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JENSEN, S., and B. N. RUNNEGAR. "A complex trace fossil from the Spitskop Member (terminal Ediacaran–? Lower Cambrian) of southern Namibia." Geological Magazine 142, no. 5 (June 28, 2005): 561–69. http://dx.doi.org/10.1017/s0016756805000853.

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Streptichnus narbonnei igen. et isp. nov., a new trace fossil from the upper part of the Spitskop Member of the Urusis Formation, southern Namibia, consists of clusters of unidirectionally curved radial elements, in which individual elements typically are composed of imbricated sickle–shaped segments somewhat comparable to those of Treptichnus pedum. Such complex trace fossils generally are found only in Cambrian or younger strata. This opens to question the position of the Ediacaran–Cambrian boundary in the Nama Group, suggesting that it may locally be within the uppermost part of the Urusis Formation, rather than at the base of the Nomtsas Formation.

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Smith, Roger M. H., and Thomas R. Mason. "Sedimentary Environments and Trace Fossils of Tertiary Oasis Deposits in the Central Namib Desert, Namibia." PALAIOS 13, no. 6 (December 1998): 547. http://dx.doi.org/10.2307/3515346.

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Meyer, Mike, David Elliott, James D. Schiffbauer, Michael Hall, Karl H. Hoffman, Gabi Schneider, Patricia Vickers-Rich, and Shuhai Xiao. "Taphonomy of the Ediacaran Fossil Pteridinium Simplex Preserved Three-Dimensionally in Mass Flow Deposits, Nama Group, Namibia." Journal of Paleontology 88, no. 2 (March 2014): 240–52. http://dx.doi.org/10.1666/13-047.

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Ediacara-type fossils are found in a diverse array of preservational styles, implying that multiple taphonomic mechanisms might have been responsible for their preservational expression. For many Ediacara fossils, the “death mask” model has been invoked as the primary taphonomic pathway. The key to this preservational regime is the replication or sealing of sediments around the degrading organisms by microbially induced precipitation of authigenic pyrite, leading toward fossil preservation along bedding planes. Nama-style preservation, on the other hand, captures Ediacaran organisms as molds and three-dimensional casts within coarse-grained mass flow beds, and has been previously regarded as showing little or no evidence of a microbial preservational influence. To further understand these two seemingly distinct taphonomic pathways, we investigated the three-dimensionally preserved Ediacaran fossil Pteridinium simplex from mass flow deposits of the upper Kliphoek Member, Dabis Formation, Kuibis Subgroup, southern Namibia. Our analysis, using a combination of petrographic and micro-analytical methods, shows that Pteridinium simplex vanes are replicated with minor pyrite, but are most often represented by open voids that can be filled with secondary carbonate material; clay minerals are also found in association with the vanes, but their origin remains unresolved. The scarcity of pyrite and the development of voids are likely related to oxidative weathering and it is possible that microbial activities and authigenic pyrite may have contributed to the preservation of Pteridinium simplex; however, any microbes growing on P. simplex vanes within mass flow deposits were unlikely to have formed thick mats as envisioned in the death mask model. Differential weathering of replicating minerals and precipitation of secondary minerals greatly facilitate fossil collection and morphological characterization by allowing Pteridinium simplex vanes to be parted from the massive hosting sandstone.

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Morales, Jorge, and Martin Pickford. "New hyaenodonts (Ferae, Mammalia) from the Early Miocene of Napak (Uganda), Koru (Kenya) and Grillental (Namibia)." Fossil Imprint 73, no. 3-4 (December 31, 2017): 332–59. http://dx.doi.org/10.2478/if-2017-0019.

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Recent palaeontological surveys in Early Miocene sediments at Napak (Uganda), Koru (Kenya) and Grillental (Namibia) have resulted in the collection of a number of small to medium-sized hyaenodonts and carnivorans, some of which were poorly represented in previous collections. The present article describes and interprets the hyaenodonts from these localities. The new fossils permit more accurate interpretation of some of the poorly known taxa, but new taxa are also present. The fossils reveal the presence of a hitherto unsuspected morphofunctional dentognathic system in the Hyaenodontidae which is described and defined, along with previously documented dentognathic complexes. Two new tribes, three new genera and one new species are diagnosed.

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Elliott, David A., Peter W. Trusler, Guy M. Narbonne, Patricia Vickers-Rich, Nicole Morton, Mike Hall, Karl H. Hoffmann, and Gabi I. C. Schneider. "Ernietta from the late Edicaran Nama Group, Namibia." Journal of Paleontology 90, no. 6 (September 9, 2016): 1017–26. http://dx.doi.org/10.1017/jpa.2016.94.

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AbstractErnietta plateauensis Pflug, 1966 is the type species of the Erniettomorpha, an extinct clade of Ediacaran life. It was likely a gregarious, partially infaunal organism. Despite its ecological and taxonomic significance, there has not been an in-depth systematic description in the literature since the original description fell out of use. A newly discovered field site on Farm Aar in southern Namibia has yielded dozens of specimens buried in original life position. Mudstone and sandstone features associated with the fossils indicate that organisms were buried while still exposed to the water column rather than deposited in a flow event. Ernietta plateauensis was a sac-shaped erniettomorph with a body wall constructed from a double layer of tubes. It possessed an equatorial seam lying perpendicular to the tubes. The body is asymmetrical on either side of this seam. The tubes change direction along the body length and appear to be constricted together in the dorsal part of the organism.

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Mehra, Akshay, Wesley A. Watters, John P. Grotzinger, and Adam C. Maloof. "Three-dimensional reconstructions of the putative metazoanNamapoikiashow that it was a microbial construction." Proceedings of the National Academy of Sciences 117, no. 33 (August 3, 2020): 19760–66. http://dx.doi.org/10.1073/pnas.2009129117.

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Strata from the Ediacaran Period (635 million to 538 million years ago [Ma]) contain several examples of enigmatic, putative shell-building metazoan fossils. These fossils may provide insight into the evolution and environmental impact of biomineralization on Earth, especially if their biological affinities and modern analogs can be identified. Recently, apparent morphological similarities with extant coralline demosponges have been used to assign a poriferan affinity toNamapoikia rietoogensis, a modular encrusting construction that is found growing between (and on) microbial buildups in Namibia. Here, we present three-dimensional reconstructions ofNamapoikiathat we use to assess the organism’s proposed affinity. Our morphological analyses, which comprise quantitative measurements of thickness, spacing, and connectivity, reveal thatNamapoikiaproduced approximately millimeter-thick meandering and branching/merging sheets. We evaluate this reconstructed morphology in the context of poriferan biology and determine thatNamapoikialikely is not a sponge-grade organism.

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Narbonne, Guy M., Beverly Z. Saylor, and John P. Grotzinger. "The youngest Ediacaran fossils from Southern Africa." Journal of Paleontology 71, no. 6 (November 1997): 953–67. http://dx.doi.org/10.1017/s0022336000035940.

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Discovery of fossils of the Ediacara biota near the top of the Spitzkopf Member at farm Swartpunt extends the known range of these remains in Namibia more than 600 m to near the sub-Cambrian unconformity. The fossiliferous beds occur approximately 100 m above a volcanic ash dated at 543 ± 1 Ma, and thus may be the youngest Proterozoic Ediacara-type fossils reported anywhere in the world. Fossils are preserved within and on the tops of dm-thick beds of storm-deposited sandstone at two stratigraphic levels; the environment is interpreted as open marine, generally calm but with episodic disruptions by storm waves, and probably within the euphotic zone. The presence of Pteridinium carolinaense (St. Jean), which is also known from the classic sections in Ediacara and the White Sea among others, reinforces evidence from geochronology and chemostratigraphy that the Swartpunt section is terminal Neoproterozoic in age. The new genus and species Swartpuntia germsi is a large, multifoliate frond that exhibits at least three quilted petaloids. Macroscopically, Swartpuntia resembles Pteridinium and Ediacara-type fronds such as Charniodiscus traditionally interpreted as Cnidaria, whereas microscopically it exhibits segmentation that is remarkably similar to that of the putative worm Dickinsonia. Combination of diagnostic characters of these supposedly disparate groups in a single species suggests that many species of quilted Ediacaran organisms were more similar to each other than they were to any modern groups, and provides support for the concept of the “Vendobionta” as a late Neoproterozoic group of mainly multifoliate organisms with a distinctive quilted segmentation.

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PICKFORD, Martin, Serdar MAYDA, Berna ALPAGUT, Fatma Arzu DEMİREL, Ayşegül ŞARBAK, and Tümel Tanju KAYA. "Hyracoidea from the Middle Miocene hominoid locality of Paşalar (NW Turkey)." TURKISH JOURNAL OF EARTH SCIENCES 29, no. 7 (November 16, 2020): 1114–24. http://dx.doi.org/10.3906/yer-2006-2.

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Previously available samples of Hyracoidea from Paşalar (MN 6, Middle Miocene), Turkey, have indicated the presence of Pliohyracidae at the site, but the material was too scanty for confident identification. The single upper molar, an upper molar ectoloph fragment and an ascending ramal fragment were too uninformative for determining the taxonomic identity of the fossils, although several names have been proposed in the literature. Additional fossils collected from Paşalar include upper and lower premolars, which help to tie down the affinities of this hyracoid. They are attributed to the genus Prohyrax, but were not named specifically, even though they are somewhat larger than the largest previously described species, Prohyrax hendeyi, from basal Middle Miocene deposits in Namibia. The presence of cingulids on the lower cheek teeth and the strong parastyle in the upper premolars from Paşalar represent important similarities to the other species of Prohyrax, to the exclusion of other genera of Pliohyracidae.

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GRAZHDANKIN, DIMA, and ADOLF SEILACHER. "A re-examination of the Nama-type Vendian organism Rangea schneiderhoehni." Geological Magazine 142, no. 5 (July 25, 2005): 571–82. http://dx.doi.org/10.1017/s0016756805000920.

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The need to re-examine Rangea has been motivated by two factors: first, by the recent progress in the understanding of three-dimensional mouldic preservation of Vendian fossils, and second, by discoveries of this taxon outside Gondwana albeit in the same sedimentary environment as seen in Namibia. Several important features are revealed, including the in situ posture in the sediment, the double-layered quilted structure, the tripartite stemless body and the mucous-supported sheath in the sediment. It is suggested that Rangea represents an infaunal organism, and that the similarity with other members of the Nama-type biota reflects convergence in functional and fabricational constraints in relation to infaunal life habit.

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McMahon, William J., Alexander G. Liu, Benjamin H. Tindal, and Maarten G. Kleinhans. "Ediacaran life close to land: Coastal and shoreface habitats of the Ediacaran macrobiota, the Central Flinders Ranges, South Australia." Journal of Sedimentary Research 90, no. 11 (November 30, 2020): 1463–99. http://dx.doi.org/10.2110/jsr.2020.029.

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ABSTRACT The Rawnsley Quartzite of South Australia hosts some of the world's most diverse Ediacaran macrofossil assemblages, with many of the constituent taxa interpreted as early representatives of metazoan clades. Globally, a link has been recognized between the taxonomic composition of individual Ediacaran bedding-plane assemblages and specific sedimentary facies. Thorough characterization of fossil-bearing facies is thus of fundamental importance for reconstructing the precise environments and ecosystems in which early animals thrived and radiated, and distinguishing between environmental and evolutionary controls on taxon distribution. This study refines the paleoenvironmental interpretations of the Rawnsley Quartzite (Ediacara Member and upper Rawnsley Quartzite). Our analysis suggests that previously inferred water depths for fossil-bearing facies are overestimations. In the central regions of the outcrop belt, rather than shelf and submarine canyon environments below maximum (storm-weather) wave base, and offshore environments between effective (fair-weather) and maximum wave base, the succession is interpreted to reflect the vertical superposition and lateral juxtaposition of unfossiliferous non-marine environments with fossil-bearing coastal and shoreface settings. Facies comprise: 1, 2) amalgamated channelized and cross-bedded sandstone (major and minor tidally influenced river and estuarine channels, respectively), 3) ripple cross-laminated heterolithic sandstone (intertidal mixed-flat), 4) silty-sandstone (possible lagoon), 5) planar-stratified sandstone (lower shoreface), 6) oscillation-ripple facies (middle shoreface), 7) multi-directed trough- and planar-cross-stratified sandstone (upper shoreface), 8) ripple cross-laminated, planar-stratified rippled sandstone (foreshore), 9) adhered sandstone (backshore), and 10) planar-stratified and cross-stratified sandstone with ripple cross-lamination (distributary channels). Surface trace fossils in the foreshore facies represent the earliest known evidence of mobile organisms in intermittently emergent environments. All facies containing fossils of the Ediacaran macrobiota remain definitively marine. Our revised shoreface and coastal framework creates greater overlap between this classic “White Sea” biotic assemblage and those of younger, relatively depauperate “Nama”-type biotic assemblages located in Namibia. Such overlap lends support to the possibility that the apparent biotic turnover between these assemblages may reflect a genuine evolutionary signal, rather than the environmental exclusion of particular taxa.

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Conti, E., C. Mulder, and F. Lombardo. "The Present is the Key to the Past: How Living Fossils in Namibia Share Insights on the Insects of Tertiary European Forests." African Entomology 27, no. 1 (April 25, 2019): 185. http://dx.doi.org/10.4001/003.027.0185.

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23

Conway Morris, Simon. "Ediacaran survivors." Paleontological Society Special Publications 6 (1992): 69. http://dx.doi.org/10.1017/s2475262200006298.

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Ediacaran taxa are a characteristic element of latest Precambrian biotas, with an effectively global distribution. Their time range is not well understood, but with one possible exception from western Canada Ediacaran faunas appear always to post-date the late Precambrian glaciations. There is also growing evidence that many Ediacaran taxa disappeared before the Precambrian-Cambrian boundary. These disappearances traditionally have been ascribed to changes in taphonomic circumstances, but a series of extinctions is a plausible alternative. Ediacaran fossils pose two major problems: Notwithstanding the reasons for their disappearance shortly before the Precambrian-Cambrian boundary, was their demise total or did some forms persist into the Cambrian? Second, is the traditional view that Ediacaran taxa are metazoans, many of a cnidarian grade, correct? Recently Seilacher, Bergström and others have argued that the Ediacaran organisms have a distinctive bauplan, difficult to reconcile with known phyla and possibly different from any metazoan.In the Cambrian, Burgess Shale-type faunas are the principal source of information on soft-bodied metazoans. The differences between them and Ediacaran assemblages are largely self-evident, but there is now unequivocal evidence for at least one Ediacaran survivor from the Middle Cambrian Burgess Shale of British Columbia. This is a sea-pen-like animal, known from three specimens (one adult about 20 cm in length, and two juveniles). The fossils consist of a broad frond, with branches arising from a central axis on one side, while the opposite side is smooth apart from longitudinal ridges. The frond extends into a blunt holdfast that presumably was embedded in the muddy silt of the sea floor. This fossil is strikingly similar to the Ediacaran taxon Charniodiscus, best known from South Australia. The Burgess Shale example shows two important features. The first are pustule-like structures, possibly zooids, both on the branches and adjacent to the axis. The second feature is evidence for connections between the branches and axis, possibly representing canals. These features both support a comparison with extant pennatulaceans, and suggest that at least some Ediacaran taxa are correctly assigned to the metazoans.Also occurring in the Burgess Shale is an enigmatic bag-like organism Mackenzia costalis. Clear evidence exists for it being benthic, but its mode of feeding is uncertain. The interior appears to have consisted largely of a spacious cavity, probably sub-divided by longitudinal partitions. In addition, an elongate strand may represent a discrete organ, perhaps connected with digestion or reproduction. No exact equivalent to Mackenzia appears to occur in Ediacaran assemblages, but bag-like taxa are a common component. These include erniettids, best known from Namibia, and Platypholina, from the White Sea region of Russia.

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Hofmann, Hans J., and Eric W. Mountjoy. "Ediacaran body and trace fossils in Miette Group (Windermere Supergroup) near Salient Mountain, British Columbia, CanadaRevision of the paper was carried out by Dr. Guy Narbonne following the passing away of both Hans Hofmann (†deceased May 19, 2010) and Eric Mountjoy (†deceased June 18, 2010) after manuscript submission." Canadian Journal of Earth Sciences 47, no. 10 (October 2010): 1305–25. http://dx.doi.org/10.1139/e10-070.

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Siliciclastic beds in the upper part of the Miette Group in southeastern British Columbia have yielded an assemblage of late Ediacaran soft-bodied macrofossils and trace fossils. The macrofossils comprise Aspidella , Bradgatia ?, and Miettia salientensis gen. et sp. nov. The ichnofossils include Archaeonassa , Cochlichnus , Didymaulichnus ?, Gordia , Halopoa , Helminthoidichnites , Helminthopsis , Planolites , and a large, unnamed crawling trace. In addition, two types of unidentified problematica are recorded, representing either tubular Vendotaenia -like body fossils, or trace fossils. The Bradgatia? constitutes the youngest occurrence of this type of fossil, and is the first to be recorded from Laurentia, having previously been noted only in Avalonia. With Cloudina and Namacalathus in associated shallow-water platform carbonates, the Miette biota in the study area contains a combination of Namibian-type and Avalonian-type elements.

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Sallam, Hesham M., and Erik R. Seiffert. "New phiomorph rodents from the latest Eocene of Egypt, and the impact of Bayesian “clock”-based phylogenetic methods on estimates of basal hystricognath relationships and biochronology." PeerJ 4 (March 1, 2016): e1717. http://dx.doi.org/10.7717/peerj.1717.

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The Fayum Depression of Egypt has yielded fossils of hystricognathous rodents from multiple Eocene and Oligocene horizons that range in age from ∼37 to ∼30 Ma and document several phases in the early evolution of crown Hystricognathi and one of its major subclades, Phiomorpha. Here we describe two new genera and species of basal phiomorphs,Birkamys koraiandMubhammys vadumensis, based on rostra and maxillary and mandibular remains from the terminal Eocene (∼34 Ma) Fayum Locality 41 (L-41).Birkamysis the smallest known Paleogene hystricognath, has very simple molars, and, like derived Oligocene-to-Recent phiomorphs (but unlike contemporaneous and older taxa) apparently retained dP4∕4late into life, with no evidence for P4∕4eruption or formation.Mubhammysis very similar in dental morphology toBirkamys, and also shows no evidence for P4∕4formation or eruption, but is considerably larger. Though parsimony analysis with all characters equally weighted placesBirkamysandMubhammysas sister taxa of extantThryonomysto the exclusion of much younger relatives of that genus, all other methods (standard Bayesian inference, Bayesian “tip-dating,” and parsimony analysis with scaled transitions between “fixed” and polymorphic states) place these species in more basal positions within Hystricognathi, as sister taxa of Oligocene-to-Recent phiomorphs. We also employ tip-dating as a means for estimating the ages of early hystricognath-bearing localities, many of which are not well-constrained by geological, geochronological, or biostratigraphic evidence. By simultaneously taking into account phylogeny, evolutionary rates, and uniform priors that appropriately encompass the range of possible ages for fossil localities, dating of tips in this Bayesian framework allows paleontologists to move beyond vague and assumption-laden “stage of evolution” arguments in biochronology to provide relatively rigorous age assessments of poorly-constrained faunas. This approach should become increasingly robust as estimates are combined from multiple independent analyses of distantly related clades, and is broadly applicable across the tree of life; as such it is deserving of paleontologists’ close attention. Notably, in the example provided here, hystricognathous rodents from Libya and Namibia that are controversially considered to be of middle Eocene age are instead estimated to be of late Eocene and late Oligocene age, respectively. Finally, we reconstruct the evolution of first lower molar size among Paleogene African hystricognaths using a Bayesian approach; the results of this analysis reconstruct a rapid latest Eocene dwarfing event along the lineage leading toBirkamys.

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Monastersky, R. "Namibian Fossils Reveal Ancient Oddities." Science News 152, no. 21 (November 22, 1997): 326. http://dx.doi.org/10.2307/3981174.

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Strganac, C., L. L. Jacobs, M. J. Polcyn, O. Mateus, T. S. Myers, J. Salminen, S. R. May, et al. "Geological setting and paleoecology of the Upper Cretaceous Bench 19 Marine Vertebrate Bonebed at Bentiaba, Angola." Netherlands Journal of Geosciences - Geologie en Mijnbouw 94, no. 1 (December 19, 2014): 121–36. http://dx.doi.org/10.1017/njg.2014.32.

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AbstractThe Bench 19 Bonebed at Bentiaba, Angola, is a unique concentration of marine vertebrates preserving six species of mosasaurs in sediments best correlated by magnetostratigraphy to chron C32n.1n between 71.4 and 71.64 Ma. The bonebed formed at a paleolatitude near 24°S, with an Atlantic width at that latitude approximating 2700 km, roughly half that of the current width. The locality lies on an uncharacteristically narrow continental shelf near transform faults that controlled the coastal outline of Africa in the formation of the South Atlantic Ocean. Biostratigraphic change through the Bentiaba section indicates that the accumulation occurred in an ecological time dimension within the 240 ky bin delimited by chron 32n.1n. The fauna occurs in a 10 m sand unit in the Mocuio Formation with bones and partial skeletons concentrated in, but not limited to, the basal 1–2 m. The sediment entombing the fossils is an immature feldspathic sand shown by detrital zircon ages to be derived from nearby granitic shield rocks. Specimens do not appear to have a strong preferred orientation and they are not concentrated in a strand line. Stable oxygen isotope analysis of associated bivalve shells indicates a water temperature of 18.5°C. The bonebed is clearly mixed with scattered dinosaur and pterosaur elements in a marine assemblage. Gut contents, scavenging marks and associated shed shark teeth in the Bench 19 Fauna indicate biological association and attrition due to feeding activities. The ecological diversity of mosasaur species is shown by tooth and body-size disparity and by δ13C analysis of tooth enamel, which indicate a variety of foraging areas and dietary niches. The Bench 19 Fauna was formed in arid latitudes along a coastal desert similar to that of modern Namibia on a narrow, tectonically controlled continental shelf, in shallow waters below wave base. The area was used as a foraging ground for diverse species, including molluscivorus Globidens phosphaticus, small species expected near the coast, abundant Prognathodon kianda, which fed on other mosasaurs at Bench 19, and species that may have been transient and opportunistic feeders in the area.

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Brain, C. K. "Some observations on Cloudina, a terminal Proterozoic index fossil from Namibia." Journal of African Earth Sciences 33, no. 3-4 (January 2001): 475–80. http://dx.doi.org/10.1016/s0899-5362(01)00083-5.

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Vickers-Rich, Patricia, Andrey Yu Ivantsov, Peter W. Trusler, Guy M. Narbonne, Mike Hall, Siobhan A. Wilson, Carolyn Greentree, et al. "Reconstructing Rangea: new discoveries from the Ediacaran of southern Namibia." Journal of Paleontology 87, no. 1 (January 2013): 1–15. http://dx.doi.org/10.1666/12-074r.1.

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Rangea is the type genus of the Rangeomorpha, an extinct clade near the base of the evolutionary tree of large, complex organisms which prospered during the late Neoproterozoic. It represents an iconic Ediacaran taxon, but the relatively few specimens previously known significantly hindered an accurate reconstruction. Discovery of more than 100 specimens of Rangea in two gutter casts recovered from Farm Aar in southern Namibia significantly expands this data set, and the well preserved internal and external features on these specimens permit new interpretations of Rangea morphology and lifestyle. Internal structures of Rangea consist of a hexaradial axial bulb that passes into an axial stalk extending the length of the fossil. The axial bulb is typically filled with sediment, which becomes increasingly loosely packed and porous distally, with the end of the stalk typically preserved as an empty, cylindrical cone. This length of the axial structure forms the structural foundation for six vanes arranged radially around the axis, with each vane consisting of a bilaminar sheet composed of a repetitive pattern of elements exhibiting at least three orders of self-similar branching. Rangea was probably an epibenthic frond that rested upright on the sea bottom, and all known fossil specimens were transported prior to their final burial in storm deposits.

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Marais, Eugène, Louis Scott, Graciela Gil-Romera, and José S. Carrión. "The potential of palynology in fossil bat-dung from Arnhem Cave, Namibia." Transactions of the Royal Society of South Africa 70, no. 2 (January 15, 2015): 109–15. http://dx.doi.org/10.1080/0035919x.2014.999734.

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Dauphin, Yannicke, Martin Pickford, and Brigitte Senut. "Diagenetic changes in the mineral and organic phases of fossil avian eggshells from Namibia." Applied Geochemistry 13, no. 2 (March 1998): 243–56. http://dx.doi.org/10.1016/s0883-2927(97)00073-5.

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Jenkins, Richard J. F. "The enigmatic Ediacaran (late Precambrian) genus Rangea and related forms." Paleobiology 11, no. 3 (1985): 336–55. http://dx.doi.org/10.1017/s0094837300011635.

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The late Precambrian genus Rangea Gürich, 1929, a frond-like fossil composed of repeated foliate elements, is one of the first discovered forms belonging to the now widely known soft-bodied assemblages characterizing the Ediacaran Period. Rangea occurs together with the genera Pteridinium Gürich, 1933, and Ernietta Pflug, 1966, in the lower parts of the Nama Group, Namibia (South West Africa).Investigation of the preservation and structure of Rangea, utilizing a methodology similar to that established by Wade (1968, 1971), indicates that it was probably a colonial octocoral consisting of a large tapering primary polyp, or oozoid, and a number of leaf-shaped, conjoined fronds which bore the feeding polyps; it is suggested to belong to a group of early Ediacaran anthozoans which provide a fossil link between the still living Telestacea and Pennatulacea. Similar investigations of Pteridinium and Ernietta disclose that their structure is different from Rangea and does not support ideas that they are related to it.

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Gibson, Brandt M., Imran A. Rahman, Katie M. Maloney, Rachel A. Racicot, Helke Mocke, Marc Laflamme, and Simon A. F. Darroch. "Gregarious suspension feeding in a modular Ediacaran organism." Science Advances 5, no. 6 (June 2019): eaaw0260. http://dx.doi.org/10.1126/sciadv.aaw0260.

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Reconstructing Precambrian eukaryotic paleoecology is pivotal to understanding the origins of the modern, animal-dominated biosphere. Here, we combine new fossil data from southern Namibia with computational fluid dynamics (CFD) to test between competing feeding models for the Ediacaran taxon Ernietta. In addition, we perform simulations for multiple individuals, allowing us to analyze hydrodynamics of living communities. We show that Ernietta lived gregariously, forming shallow marine aggregations in the latest Ediacaran, 548 to 541 million years (Ma) ago. We demonstrate enhanced vertical mixing of the water column above aggregations and preferential redirection of current into body cavities of downstream individuals. These results support the reconstruction of Ernietta as a macroscopic suspension feeder and also provide a convincing paleoecological advantage to feeding in aggregations analogous to those recognized in many extant marine metazoans. These results provide some of the oldest evidence of commensal facilitation by macroscopic eukaryotes yet recognized in the fossil record.

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Himmelsbach, Thomas, Matthias Beyer, Markus Wallner, Ilona Grünberg, and Georg Houben. "Deep, semi-fossil aquifers in southern Africa: A synthesis of hydrogeological investigations in northern Namibia." Biodiversity & Ecology 6 (April 14, 2018): 66–74. http://dx.doi.org/10.7809/b-e.00306.

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Vilkamaa, Pekka, and Heikki Hippa. "The genus Sciarotricha gen. n. (Sciaridae) and the phylogeny of recent and fossil Sciaroidea (Diptera)." Insect Systematics & Evolution 36, no. 2 (2005): 121–43. http://dx.doi.org/10.1163/187631205788838492.

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AbstractThe phylogeny of the main groups of the Sciaroidea, including the fossil Antefungivoridae, Archizelmiridae, Mesosciophilidae, Pleciofungivoridae, Pleciomimidae, Protopleciidae and Bolitophilidae: Mangasinae, and an extant new taxon, was studied by parsimony analysis. Two cladistic analyses of seventy-eight morphological characters from adults were made. One analysis, with forty-one extant taxa in the ingroup and the other, with the addition of twelve fossil taxa, both produced two most parsimonious cladograms. The phylogenetic hypotheses obtained differed from each other, and in part also to a great extent from previous ones although most of the traditionally recognized groups appeared monophyletic, including the speciose Cecidomyiidae and Sciaridae. The Cecidomyiidae (fossil analysis) or the Keroplatidae-Ditomyiidae (extant analysis) appeared as the sister-group of the rest of the Sciaroidea. Following on from these analyses, we propose emending the current Sciaridae to include the following subfamilies: Archizelmirinae stat. n., Rangomaraminae stat. n., Sciarinae, Sciarosominae subfam. n. and Sciarotrichinae subfam. n. A new taxon from Namibia, Sciarotricha biloba gen. n., sp. n. is described, and, according to the phylogenetic analysis, is placed in the Sciaridae (Sciarotrichinae). The sister-group of the Sciaridae as newly defined is the Mycetophilidae group, in the extant analysis including the Mycetophilidae, Manotidae, Lygistorrhinidae, Pterogymnus and Sciaropota, and in the fossil analysis even including the Mesosciophilidae and the Ohakunea group (Ohakunea + Colonomyia).

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Hanz, Ulrike, Claudia Wienberg, Dierk Hebbeln, Gerard Duineveld, Marc Lavaleye, Katriina Juva, Wolf-Christian Dullo, et al. "Environmental factors influencing benthic communities in the oxygen minimum zones on the Angolan and Namibian margins." Biogeosciences 16, no. 22 (November 15, 2019): 4337–56. http://dx.doi.org/10.5194/bg-16-4337-2019.

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Abstract. Thriving benthic communities were observed in the oxygen minimum zones along the southwestern African margin. On the Namibian margin, fossil cold-water coral mounds were overgrown by sponges and bryozoans, while the Angolan margin was characterized by cold-water coral mounds covered by a living coral reef. To explore why benthic communities differ in both areas, present-day environmental conditions were assessed, using conductivity–temperature–depth (CTD) transects and bottom landers to investigate spatial and temporal variations of environmental properties. Near-bottom measurements recorded low dissolved oxygen concentrations on the Namibian margin of 0–0.15 mL L−1 (≜0 %–9 % saturation) and on the Angolan margin of 0.5–1.5 mL L−1 (≜7 %–18 % saturation), which were associated with relatively high temperatures (11.8–13.2 ∘C and 6.4–12.6 ∘C, respectively). Semidiurnal barotropic tides were found to interact with the margin topography producing internal waves. These tidal movements deliver water with more suitable characteristics to the benthic communities from below and above the zone of low oxygen. Concurrently, the delivery of a high quantity and quality of organic matter was observed, being an important food source for the benthic fauna. On the Namibian margin, organic matter originated directly from the surface productive zone, whereas on the Angolan margin the geochemical signature of organic matter suggested an additional mechanism of food supply. A nepheloid layer observed above the cold-water corals may constitute a reservoir of organic matter, facilitating a constant supply of food particles by tidal mixing. Our data suggest that the benthic fauna on the Namibian margin, as well as the cold-water coral communities on the Angolan margin, may compensate for unfavorable conditions of low oxygen levels and high temperatures with enhanced availability of food, while anoxic conditions on the Namibian margin are at present a limiting factor for cold-water coral growth. This study provides an example of how benthic ecosystems cope with such extreme environmental conditions since it is expected that oxygen minimum zones will expand in the future due to anthropogenic activities.

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Scott, Louis, Graciela Gil Romera, Eugene Marais, and George A. Brook. "Pollen in fossil hyrax dung from Marine Isotope Stages 2 and 3 reveals past environments in Namibia." Quaternary International 464 (January 2018): 260–72. http://dx.doi.org/10.1016/j.quaint.2017.06.054.

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Bamford, M. K. "Fossil woods of Karoo age deposits in South Africa and Namibia as an aid to biostratigraphical correlation." Journal of African Earth Sciences 31, no. 1 (July 2000): 119–32. http://dx.doi.org/10.1016/s0899-5362(00)00077-4.

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Segalen, Loïc, Pierre Rognon, Martin Pickford, Brigitte Senut, Laurent Emmanuel, Maurice Renard, and John Ward. "Reconstitution of dune morphologies and palaeowind regimes in the Proto-Namib since the Miocene." Bulletin de la Société Géologique de France 175, no. 6 (November 1, 2004): 537–46. http://dx.doi.org/10.2113/175.6.537.

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Abstract In the Namib Desert, indurated fossil dunes are found between the active sands. Establishment of a biostratigraphic scale based on associated mammal faunas and ratite eggshells allows the study of palaeowind fluctuations that have controlled these palaeodunes since the Middle Miocene with a temporal resolution of between 1 and 3 Ma. In the southern Namib, the Proto-Namib aeolian systems consist of crescent dunes (barkhan type). In the eastern part of the Namib Desert, the aeolianite cross-bedding corresponds to longitudinal or pyramidal dunes. These aeolian structures are also controlled by local winds, resulting from high relief and the southern trade winds : this regime is identical to that which currently sweeps, through the Namib Desert, and is related to the presence of anticyclonic conditions in the Atlantic Ocean. A regime of seasonal winds from the northeastern sector is also recorded starting in the late Miocene.

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Gil-Romera, Graciela, Louis Scott, Eugène Marais, and George A. Brook. "Middle-to late-Holocene moisture changes in the desert of northwest Namibia derived from fossil hyrax dung pollen." Holocene 16, no. 8 (December 2006): 1073–84. http://dx.doi.org/10.1177/0959683606069397.

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Darroch, Simon A. F., Alison T. Cribb, Luis A. Buatois, Gerard J. B. Germs, Charlotte G. Kenchington, Emily F. Smith, Helke Mocke, et al. "The trace fossil record of the Nama Group, Namibia: Exploring the terminal Ediacaran roots of the Cambrian explosion." Earth-Science Reviews 212 (January 2021): 103435. http://dx.doi.org/10.1016/j.earscirev.2020.103435.

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Wallner, Markus, Georg Houben, Christoph Lohe, Martin Quinger, and Thomas Himmelsbach. "Inverse modeling and uncertainty analysis of potential groundwater recharge to the confined semi-fossil Ohangwena II Aquifer, Namibia." Hydrogeology Journal 25, no. 8 (July 8, 2017): 2303–21. http://dx.doi.org/10.1007/s10040-017-1615-z.

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Bäumle, Roland, Thomas Himmelsbach, and Ursula Noell. "Hydrogeology and geochemistry of a tectonically controlled, deep-seated and semi-fossil aquifer in the Zambezi Region (Namibia)." Hydrogeology Journal 27, no. 3 (December 4, 2018): 885–914. http://dx.doi.org/10.1007/s10040-018-1896-x.

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Mühle, J., C. A. M. Brenninkmeijer, T. S. Rhee, F. Slemr, D. E. Oram, S. A. Penkett, and A. Zahn. "Biomass burning and fossil fuel signatures in the upper troposphere observed during a CARIBIC flight from Namibia to Germany." Geophysical Research Letters 29, no. 19 (October 2002): 16–1. http://dx.doi.org/10.1029/2002gl015764.

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Cribb, Alison T., Charlotte G. Kenchington, Bryce Koester, Brandt M. Gibson, Thomas H. Boag, Rachel A. Racicot, Helke Mocke, Marc Laflamme, and Simon A. F. Darroch. "Increase in metazoan ecosystem engineering prior to the Ediacaran–Cambrian boundary in the Nama Group, Namibia." Royal Society Open Science 6, no. 9 (September 25, 2019): 190548. http://dx.doi.org/10.1098/rsos.190548.

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The disappearance of the soft-bodied Ediacara biota at the Ediacaran–Cambrian boundary potentially represents the earliest mass extinction of complex life, although the precise driver(s) of this extinction remain unresolved. The ‘biotic replacement’ model proposes that an evolutionary radiation of metazoan ecosystem engineers in the latest Ediacaran profoundly altered marine palaeoenvironments, resulting in the extinction of Ediacara biota and setting the stage for the subsequent Cambrian Explosion. However, metazoan ecosystem engineering across the Ediacaran–Cambrian transition has yet to be quantified. Here, we test this key tenet of the biotic replacement model by characterizing the intensity of metazoan bioturbation and ecosystem engineering in trace fossil assemblages throughout the latest Ediacaran Nama Group in southern Namibia. The results illustrate a dramatic increase in both bioturbation and ecosystem engineering intensity in the latest Ediacaran, prior to the Cambrian boundary. Moreover, our analyses demonstrate that the highest-impact ecosystem engineering behaviours were present well before the onset of the Cambrian. These data provide the first support for a fundamental prediction of the biotic replacement model, and evidence for a direct link between the early evolution of ecosystem engineering and the extinction of the Ediacara biota.

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Darroch, Simon A. F., Erik A. Sperling, Thomas H. Boag, Rachel A. Racicot, Sara J. Mason, Alex S. Morgan, Sarah Tweedt, et al. "Biotic replacement and mass extinction of the Ediacara biota." Proceedings of the Royal Society B: Biological Sciences 282, no. 1814 (September 7, 2015): 20151003. http://dx.doi.org/10.1098/rspb.2015.1003.

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The latest Neoproterozoic extinction of the Ediacara biota has been variously attributed to catastrophic removal by perturbations to global geochemical cycles, ‘biotic replacement’ by Cambrian-type ecosystem engineers, and a taphonomic artefact. We perform the first critical test of the ‘biotic replacement’ hypothesis using combined palaeoecological and geochemical data collected from the youngest Ediacaran strata in southern Namibia. We find that, even after accounting for a variety of potential sampling and taphonomic biases, the Ediacaran assemblage preserved at Farm Swartpunt has significantly lower genus richness than older assemblages. Geochemical and sedimentological analyses confirm an oxygenated and non-restricted palaeoenvironment for fossil-bearing sediments, thus suggesting that oxygen stress and/or hypersalinity are unlikely to be responsible for the low diversity of communities preserved at Swartpunt. These combined analyses suggest depauperate communities characterized the latest Ediacaran and provide the first quantitative support for the biotic replacement model for the end of the Ediacara biota. Although more sites (especially those recording different palaeoenvironments) are undoubtedly needed, this study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering and biological interactions may have ultimately caused the first mass extinction of complex life.

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Stidham, Thomas A., K. E. Beth Townsend, and Patricia A. Holroyd. "Evidence for Wide Dispersal in a Stem Galliform Clade from a New Small-Sized Middle Eocene Pangalliform (Aves: Paraortygidae) from the Uinta Basin of Utah (USA)." Diversity 12, no. 3 (February 28, 2020): 90. http://dx.doi.org/10.3390/d12030090.

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A new bird coracoid from the Uinta Formation in the Uinta Basin in Utah (USA) records the presence of the only known pangalliform from the middle Eocene of North America, occurring in a >15 million year gap in their history. This fossil represents a new taxon, informally termed the Uintan paraortygid, which is also currently the best-supported record of the extinct Paraortygidae in North America (and among the oldest records of the group in the world). The specimen exhibits a derived enlarged procoracoid prominence with a small procoracoid process, and concave elliptical scapular cotyle that are shared with the middle Eocene paraortygids, Xorazmortyx and Scopelortyx; however, the Uintan paraortygid also has a possibly autapomorphic (pneumatic) fossa adjacent to the scapular cotyle. The similarity in body size and morphology among these widely distributed early paraortygids suggests phylogenetic affinity among them. Given their occurrence in the United States, Uzbekistan, and Namibia during the middle Eocene, these birds likely were good fliers with an increased ability to disperse; and probably had a flexible biology or diet allowing them to occupy a diversity of habitats from coasts and forests to semi-arid savannah-like habitats. The problematic early records of Odontophoridae need to be reexamined as potential members of Paraortygidae and associates of these small-bodied taxa.

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Pickford, Martin. "Fossil spider's webs from the Namib Desert and the antiquity of Seothyra (Araneae, Eresidae)." Annales de Paléontologie 86, no. 3 (July 2000): 147–55. http://dx.doi.org/10.1016/s0753-3969(00)80005-1.

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Dill, H. G., H. Pöllmann, K. Bosecker, L. Hahn, and S. Mwiya. "Supergene mineralization in mining residues of the Matchless cupreous pyrite deposit (Namibia)—a clue to the origin of modern and fossil duricrusts in semiarid climates." Journal of Geochemical Exploration 75, no. 1-3 (May 2002): 43–70. http://dx.doi.org/10.1016/s0375-6742(01)00199-6.

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Hall, Michael, Alan J. Kaufman, Patricia Vickers-Rich, Andrey Ivantsov, Peter Trusler, Ulf Linnemann, Mandy Hofmann, et al. "Stratigraphy, palaeontology and geochemistry of the late Neoproterozoic Aar Member, southwest Namibia: Reflecting environmental controls on Ediacara fossil preservation during the terminal Proterozoic in African Gondwana." Precambrian Research 238 (November 2013): 214–32. http://dx.doi.org/10.1016/j.precamres.2013.09.009.

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Journal articles on the topic 'Fossils - Namibia'

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