| 1. |
- Bassett, MG, et al.
(författare)
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Organophosphatic brachiopods : Patterns of biodiversification and extinction in the early Palaeozoic
- 1999
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Ingår i: Geobios. - : Elsevier. - 0016-6995 .- 1777-5728. ; 32:2, s. 145-163
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Tidskriftsartikel (refereegranskat)abstract
- From a database of 226 Cambrian - Ordovician genera of organophosphatic-shelled brachiopods comprisingthe Subphylum Linguliformea, 11 sets of morphological characters typify all orders and superfamilies. Seven sets of these large-scale evolutionary novelties were established already by the end of the mid Cambrian, 2 more by the end of the late Cambrian, and the remaining 2 before the end of the Arenig. The earliest linguliformeans are of Tommotian age and represent some of the oldest known benthic organisms with a mineralised skeleton. Major diversification at the generic level took place during the mid and late Cambrian, by which time members of the Order Lingulida spread from near-shore to deep-water environments and became dominant in low diversity benthic assemblages that inhabited mobile sandy bottoms. There was a significant decline in diversity of linguliformeans during the latest Cambrian. Following recovery in the late Tremadoc-early Arenig, they then became one of the most distinctive components of benthic assemblages inhabiting marginal environments, e.g. eutrophic basins, shallow mobile sands, and abyssal depths. During the Llanvirn, there was a significant, worldwide turnover in linguliformean brachiopod faunas, when the majority of epibenthic lingulides of the families Obolidae, Zhanatellidae and Elkaniidae became extinct and were replaced, in shallow marine biofacies, by assemblages dominated by bivalved molluscs and burrowing lingulides. There is no trace until the mid Ashgill of a significant decline of micromorphic taxa in linguliformean assemblages characteristic of outer shelf environments. However, all siphonotretides, paterinides and most acrotretide genera disappeared towards the end of the late Ordovician pre-Hirnantian Dicellograptus anceps Biozone.
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| 2. |
- Bordiga, Manuela, et al.
(författare)
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Reticulofenestra daviesii : Biostratigraphy and paleogeographic distribution across the Eocene-Oligocene boundary
- 2017
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Ingår i: Geobios. - : Elsevier. - 0016-6995 .- 1777-5728. ; 50:5-6, s. 349-358
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Tidskriftsartikel (refereegranskat)abstract
- Improving the biostratigraphy across the Eocene-Oligocene is fundamental to better constrain the timing and causes of an important global climate change of the Cenozoic, the Eocene-Oligocene Transition (EOT; 34-33.5 Ma). Across the EOT, only few nannofossil bioevents are considered globally synchronous and reliable. One of these is the first common occurrence (Bc) of the species Reticulofenestra daviesii that has been proven to be useful for biostratigraphical correlations in the Southern Ocean, but the potential of R. daviesii as a biostratigraphical marker at mid- and low latitudes has not been explored yet in detail. We investigate three deep-sea drill sites located across a N-S transect at mid-low latitudes of the Atlantic Ocean spanning from 34.4 to 33 Ma, reviewing the temporal and geographical distribution together with the intraspecific variability of R. daviesii. Our data quantify the occurrence of R. daviesii in (sub)tropical regions of the Atlantic Ocean, although with lower abundances (similar to 4-12%) compared to Southern Ocean assemblages (40-95%). This suggests that R. daviesii was a cosmopolitan species capable to adapt to a wider range of sea surface temperatures and environmental conditions than previously thought. However, the temporal distributions of R. daviesii at the three studied sites are not comparable to the trends recorded in the Southern Ocean. Its Bc is clearly identifiable only at the equatorial site, occurring similar to 500,000 years before the age estimated in the Southern Ocean (33.705 Ma). Thus, we suggest caution when using the Bc of R. daviesii as a reliable biostratigraphical event at mid- and low latitudes. In addition, our biometrical data reveal that up to 38% of R. daviesii coccoliths is > 8-10 mu m in major axis size, thus bigger than the medium size range (5-8 mu m) originally described. Refining the size range of R. daviesii is important for estimating its cell volume versus surface area and coccolith carbonate mass. (C) 2017 Elsevier Masson SAS. All rights reserved.
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| 3. |
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| 4. |
- Doguzhaeva, Larisa, et al.
(författare)
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Connecting stripes: An organic skeletal structure in Sepia from Red Sea
- 2012
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 45, s. 13-17
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Tidskriftsartikel (refereegranskat)abstract
- The skeletal structure, herein termed ‘‘connecting stripes’’, is demonstrated in dried cuttlebones of Sepia (Acanthosepion) savignyi de Blainville from the Gulf of Aqaba, Red Sea, Eilat, Israel. This structure consists of segmented chitinous strip-like sheets covering the outside opening to the cuttlebone chambers. Scanning electron microscope images demonstrate that the connecting stripes are tightly attached to the neighbouring septa along the septal edges and do not continue from one chamber to the next. When broken, they leave band-like remnants along the attachment sites. The connecting stripes consist of fibrous, organic, possibly mainly chitinous, laminas. Chemical analysis using energy dispersive spectrometry shows that the connecting stripes contain C, O, Na, K but lack Ca and P. The connecting stripes show perceptible, usually barely visible micropores with diameter of ca. 0.1 mm; distances between the micropores are 0.2 to 0.3 mm. The connecting stripes in Sepia are similar to connecting rings in bactritoids and ammonoids in having a segmented structure and a non-mineralized, organic composition. The microporosity of connecting stripes observed in Sepia has been also recorded in three genera of Mesozoic ammonoids. The connecting stripes may serve as a transport route of the cameral liquid in and out of the chambers and are considered to be a homologue of the connecting rings in cephalopods with a fully developed siphonal tube.
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| 5. |
- Ebbestad, Jan Ove, 1967-, et al.
(författare)
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Ordovician (Caradoc) Gastropoda of the Katkoyeh Formation, Kerman Province, Iran
- 2008
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Ingår i: Geobios. - 0016-6995 .- 1777-5728. ; 41:5, s. 605-624
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Tidskriftsartikel (refereegranskat)abstract
- Seven taxa of gastropods are described from the Ordovician (Caradoc) upper Katkoyeh Formation of the Kerman region, east-central Iran.Three are named species and four are under open nomenclature. The most abundant is the minute bellerophontiform Tritonophon peeli Horny´,1977, indicative of a shallow water plectonotid community. Shell material is not preserved in this species, but a small, simple bulbous protoconch ispresent. Two new species are Slehoferia pachyta and Nonorios kleistos, both with prominent thick-shelled conchs. Shell repair is documented inboth of these forms, interpreted as a result of failed predation. Other micromorphic species occur in the samples, but only Tropidodiscus sp. andNonorios? sp. are named. The Kerman assemblage is comparable directly with similar, closely coeval faunas in Bohemia, France, Portugal,Morocco, and Italy, corresponding with the Palaeozoic Mediterranean Province of northern peri-Gondwana.
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| 6. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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An unusual onychochilid mollusc from the Ordovician (Tremadocian) Fezouata Formation, Morocco
- 2015
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 48:6, s. 427-438
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Tidskriftsartikel (refereegranskat)abstract
- Pelecyogyra fezouataensis nov. gen., nov. sp. is described from the Lower Ordovician (Tremadocian, A. murrayi Biozone) Fezouata Formation at Oued Beni Zoli (locality Z-F5), in the central Anti-Atlas, Morocco. This is the first Onychochilidae Koken in Koken and Perner, 1925 reported from the Ordovician of Morocco. Its stratigraphical position bridges the gap between the late Cambrian and Middle to Upper Ordovician records. This new taxon draws together large specimens, reaching 27 mm in the greatest diameter, with 3 rapidly expanding whorls. All specimens are invariably preserved as dorsoventrally compressed moulds although preservation suggests that the degree of compaction was not great and that the species was generally low spired. A characteristic axe-shaped apertural lip and an ornamentation consisting of fine and dense lirae serve to distinguish the new genus from other onychochilids. The species appears to have been gregarious. In some specimens, small scalloped injuries are preserved along the apertural margins but these are not considered to reflect failed predation. Up to now, twenty-two species and eight genera of Ordovician onychochilids have been documented, being distributed in eight different terranes. The composition of the Onychochilidae is briefly reviewed and updated from the literature, to include Helicotis? Koken in Koken and Perner, 1925, Hyperstrophema Horný, 1964, Invertospira Horný, 1964, Kobayashiella Endo, 1937, Laeogyra Perner, 1903, Matherella Walcott, 1912, Matherellina Kobayashi, 1937, Onychochilus Lindström, 1884, Pelecyogyra nov. gen., Pervertina Horný, 1964, Scaevogyra Whitfield, 1878, Sinistracirsa Cossmann, 1908, Versispira Perner, 1903, and Voskopiella Frýda, 1992. Onychochilidae and Clisospiridae are placed in Mimospirida Dzik, 1983, regarding Hyperstrophina Linsley and Kier, 1984 as a junior synonym.
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| 7. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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First occurrence of Pterotheca (Gastropoda) from the Silurian (Aeronian) of Spain
- 2017
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 50:2, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- Pterotheca hispanica nov. sp. is described from the basal beds (Stimulograptus sedgwickii graptolite Zone) of the Formigoso Fm., in the Cantabrian Zone of the Iberian Massif, north-western Spain. This specialized bellerophontoid gastropod is for the first time recorded in the Silurian of peri-Gondwana; it is the only Aeronian species known so far. Its most closely allied relatives are from higher beds placed in the Telychian of Scotland. Pterotheca is considered a highly derived genus within the Pterothecinae of the Carinaropsidae, with the strongly reduced to absent coiling and the growth of the septum being synapomorphies. In the present work it is shown that not only the apical angle of the septum can be used to distinguish species, but also the relative length and width of the septum. In some cases, the slit may extend as far back as the anterior part of the internal septum. Silurian species were hitherto only found in marginal Laurentian and Eastern Avalonian settings. Pterotheca is absent from central Laurentia and Baltica, where it could be expected to be present based on its wide Ordovician distribution. In the light of this, the occurrence of the genus in the Aeronian of Spain seems difficult to explain, albeit the genus was present in peri-Gondwana prior to the end-Ordovician extinction. The extreme scarcity of described taxa recorded from Avalonia, Baltica and Iberia during the Early Silurian may explain this patchy distribution.
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| 8. |
- Ebbestad, Jan Ove R., 1967-, et al.
(författare)
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Pelecyogyra (Mollusca) from the Early Ordovician of the Montagne Noire, France
- 2020
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 63, s. 23-32
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Tidskriftsartikel (refereegranskat)abstract
- A new occurrence of the onychochilid mollusc Pelecyogyra is reported from the late Floian Landeyran Formation (Apatokephalus incisus Biozone) in the Montagne Noire, southern France, where it is associated with the two tergomyans Carcassonnella courtessolei and Thoralispira laevis, and a mollusc indet. With a low cap-shaped shell. The Montagne Noire specimens compare morphologically with Pelecyogyra fezouataensis from the late Tremadocian Fezouata Formation (Araneograptus murrayi Biozone) in Morocco and are tentatively referred to this species. Each occurrence of Pelecyogyra is from one or two localities only, but separated in time. They differ further in the deeper facies, association with Carcassonnella and Thoralispira, and non-gregarious occurrence in Montagne Noire compared to the shallower facies, lack of other molluscs and gregarious occurrence in the Fezouata Formation. In the Lower Ordovician, Pelecyogyra, Carcassonnella courtessolei, the rare C. vizcainoi and Thoralispira laevis are taxa that occur only in Montage Noire and the Anti-Atlas, while Lesueurilla prima also occurs in the Prague basin of the Czech Republic. Contrary to other faunal elements, like echinoderms and trilobites, these genera seem to have a wide environmental tolerance and are long ranging taxa. The main occurrence of the three key taxa Carcassonnella, Thoralispira and Lesueurilla in the Montagne Noire is in the lower part of the La Maurerie Formation (Taihungshania miqueli acme Zone), while the same taxa appear just slightly later in Morocco (?Cymatograptus protobalticus Biozone). Migration to the Anti-Atlas during the early Floian seems to have been possible during a period of general faunal exchange. Pelecyogyra may either have migrated from the Anti-Atlas to Montagne Noire during the same interval or possibly during the late Floian as indicated by shared faunal elements between these two regions at that time.
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| 9. |
- Georgalis, Georgios L., et al.
(författare)
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The fossil turtles of Greece : An overview of taxonomy and distribution
- 2013
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 46:4, s. 299-311
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Tidskriftsartikel (refereegranskat)abstract
- Turtle remains are common in the Miocene-Holocene deposits of Greece, and are a key focus of the growing research interest in Neogene. herpetofaunas from the Aegean region. Some of the most important finds include one of Europe's stratigraphically youngest pleurodiran taxa, Nostimochelone lampra, from the Early Miocene of Macedonia, together with arguably the richest record of fossil tortoises from the Eastern Mediterranean. This incorporates the presently oldest definitive representatives of the quintessential genus Testudo sensu stricto from the Late Miocene of Attica and Macedonia, and numerous specimens of the colossal (carapace similar to 2 m-length) testudinid Cheirogaster from Late Miocene-Late Pliocene sediments in southern and northern Greece, as well as on the eastern Aegean islands of Samos and Lesvos. Tantalising, but as yet unconfirmed Miocene accounts of the geoemydid Mauremys in Macedonia, and indeterminate emydid-like remains from Euboea, also provide potentially significant range extensions. Although hampered by a historically sparse documentation, the fossil turtles of Greece are a significant resource that record both assemblage changes and the origin of modern lineages.
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| 10. |
- Gubanov, Alexander P., et al.
(författare)
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Anabarella australis (Mollusca, Helcionelloida) from the Lower Cambrian of Greenland
- 2004
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 37:6, s. 719-724
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Tidskriftsartikel (refereegranskat)abstract
- The Early Cambrian helcionelloid mollusc Anabarella australis is described from North-East Greenland, representing the second occurrence of the species outside of Australia. Other Australian molluscs of this age are known from many localities including North China, Siberia, Altai, Transbaikalia, southern Kazakhstan, Mongolia, eastern Germany and Spain. These records, supported now by A. australis, demonstrate the close proximity of continents in the Early Cambrian.
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| 11. |
- Hoel, Ole
(författare)
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Cementing strophomenide brachiopods from the Silurian of Gotland (Sweden) : Morphology and Life habits
- 2007
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 40:5, s. 589-608
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Tidskriftsartikel (refereegranskat)abstract
- Dorsal valves of the cementing strophomenide brachiopods Leptaenoidea silurica Hedström and Liljevallia gotlandica Hedström are described for the first time, and it is shown that both these species could also live ambitopically. The lower Wenlock Scamnomena rugata (Lindström) represents young individuals of the ambitopic variant of Leptaenoidea silurica, and is placed in synonymy, resulting in the valid name for the taxon being Leptaenoidea rugata. The range of this species now spans the whole Wenlock, from the upper Visby Formation to the Klinteberg Formation, and possibly even into the Ludlow. Ambitopic gerontic specimens of L. rugata develop very thick shells, in which the ventral valves have strong curvature, and become deeper not by geniculation but by successive mantle retractions and subsequent re-growth, in a way similar to that of atrypides. This shape was probably an adaptation to “floating” on softer substrates. The thickened gerontic dorsal valves have well-developed lophophoral support, showing the shape of the lophophore, which comprises two branches that curve inwards and then backwards; the lophophore was probably ptycholophous and similar to that in living members of the Thecideidina. Ambitopic specimens of Liljevallia could grow to a much larger size than cementing forms, where the dorsal valves have very large, posterior-facing cardinal process lobes and deeply impressed muscle fields and anterior scars. The presence of a ventral process and long, posteroventrally elongated cardinal process lobes, and the absence of dental plates reveals that Liljevallia was probably an early member of the Douvillinidae and is thus removed from the Leptaenoideidae.
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| 12. |
- Li, Zhaoyu, et al.
(författare)
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Dormice (Rodentia, Gliridae) from the Middle Miocene of Hambach 6C, Northwest Germany
- 2023
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Ingår i: Geobios. - 0016-6995 .- 1777-5728. ; 78, s. 15-31
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Tidskriftsartikel (refereegranskat)abstract
- Glirid dental material is described from the Middle Miocene channel fill of the Hambach open-cast lignite mine in northwestern Germany. The fauna Hambach 6C shows a high diversity with seven species in six genera: Glirudinus undosus, Muscardinus thaleri, Muscardinus sansaniensis, Miodyromys aegercii, Paraglirulus werenfelsi, Microdyromys koenigswaldi, and Paraglis astaracensis, which are characteristic taxa in Middle Miocene European localities. Regarding the faunal composition and high diversity, the Hambach 6C assemblage is closest to that of the MN 5 locality Schönenberg in southern Germany, but also shares many taxa with late Middle Miocene faunas. The species richness of glirids, combined with other vertebrate remains in Hambach 6C indicates a warm, humid forested environment during the Mid-Miocene Climate Optimum (MCO).
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| 13. |
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| 14. |
- Pole, Mike, et al.
(författare)
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The first Cenozoic Equisetum from New Zealand
- 2017
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Ingår i: Geobios. - Amsterdam : Elsevier. - 0016-6995 .- 1777-5728. ; 50, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- Equisetum is described for the first time from Cenozoic deposits of New Zealand. The fossils derive from two early to earliest middle Miocene assemblages in South Island, New Zealand. The fossils are ascribed tentatively to subgenus Equisetum based on their possession of whorled branch scars, but they cannot be assigned with confidence to a formal species. The decline of equisetaleans, otherwise unknown from the Cenozoic of the New Zealand-Australian-Antarctic domain, was possibly a consequence of severe environmental changes – particularly, abrupt shifts in the temperature and soil moisture regime – experienced by this region in the Neogene, coupled with competition from opportunistic angiosperms.
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| 15. |
- Streng, Michael, et al.
(författare)
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New and poorly known acrotretid brachiopods (Class Lingulata) from the Cedaria-Crepicephalus zone (late Middle Cambrian) of the Great Basin, USA
- 2006
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 39:1, s. 125-154
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Tidskriftsartikel (refereegranskat)abstract
- Seven new late Middle Cambrian (Cedaria-Crepicephalus zone) acrotretid species are described from the Great Basin, USA. The species belong to five genera of which Lensotreta is new. The following new species are described: Anabolotreta? glabra, Anabolotreta mogota, Canthylotreta crista, Dactylotreta elegantula, Lensotreta perplexa, Opisthotreta transversa, and Opisthotreta indistincta. The shell structure of Canthylotreta is described for the first time based on new material of the type species Canthylotreta marjumensis and of the new species C. crista. The shell of Canthylotreta includes two types of shell fabric, camerate and columnar. Moreover, parts of the shell show transitional textures, supporting the view that the camerate shell structure may has originated from a columnar fabric. Picnotreta lophocracenta Robson and Pratt, 2001, recently described from western Newfoundland, is also described from the new occurrence in the Great Basin.
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| 16. |
- Turner, Alan, et al.
(författare)
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Taxonomy and evolutionary patterns in the fossil Hyaenidae of Europe
- 2008
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 41, s. 677-687
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Tidskriftsartikel (refereegranskat)abstract
- We review the larger pattern of appearance of the Hyaenidae in Europe and outline their part in the turnover of the guild of larger Carnivora that occurs across the Miocene–Pliocene boundary. The earliest record of the family is in MN4, although the patchy nature of the earliest records makes it difficult to be certain about the continent of origin. There is a clear pattern of morphological evolution over that long timespan, from the earliest viverrid- and herpestid-like forms through dog-like and more cursorial taxa to the larger, bone-crunching animals of the later Miocene and the Pliocene–Pleistocene epochs. Miocene dog-like hyaenas may indicate that social hunting had emerged by that time, while the appearance of larger species means that hyaena-accumulated bone assemblages may potentially occur in any late Miocene to Pleistocene locality.
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| 17. |
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| 18. |
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| 19. |
- Yun, Hao, et al.
(författare)
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Pyritized preservation of chancelloriids from the Cambrian Stage 3 ofSouth China and implications for biomineralization
- 2021
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Ingår i: Geobios. - Amsterdam : Elsevier BV. - 0016-6995 .- 1777-5728. ; 69, s. 77-86
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Tidskriftsartikel (refereegranskat)abstract
- The enigmatic Cambrian animal chancelloriids were discovered in a wide range of taphonomic settings; however, preservation of biomineralized sclerite microstructure was solely known from secondarily phosphatized skeletal remains. Here, we investigate a uniquely pyritized chancelloriid from the lowerCambrian Guojiaba Formation in southern Shaanxi Province, China, using a combination of advanced analytic techniques. Results of the energy dispersive spectroscopy (EDS), X-Ray Fluorescence (XRF), and Raman spectrum show that the sclerites and scleritomes are preserved as pyritized internal moulds witha calcitic outer layer. The outer layer enveloping the internal moulds likely represents the recrystallized counterpart of the original biomineralized sclerite wall. Distinctive fibrous microstructures are discovered in the sclerites, which echo the features seen in the phosphatized fossils of chancelloriids. The typical microstructure, along with the recrystallized calcite, corroborate the interpretation that chancelloriid sclerites were originally constructed by fibrous aragonite. The stability of the microstructure and mineral composition in both carbonate and siliciclastic backgrounds indicate that chancelloriids were adapted to exploit aragonitic fibres to build their skeletons regardless of the change of their living environments.
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| 20. |
- Zamora, Samuel, et al.
(författare)
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The Cambrian edrioasteroid Stromatocystites (Echinodermata): Systematics, palaeogeography, and palaeoecology.
- 2015
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 48:5, s. 417-426
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Tidskriftsartikel (refereegranskat)abstract
- The Cambrian edrioasteroid Stromatocystites is reported and described from Spain, Sweden and Turkey. All previously known occurrences of the genus are critically reviewed, and S. flexibilis is reinterpreted as a junior synonym of S. pentangularis. Stromatocystites was biogeographically widespread and colonized different areas of Baltica, Gondwana (Arabian, eastern and western margins) and Laurentia (western Newfoundland). Stratigraphically, it ranges from Cambrian Series 2, Stage 4 to Cambrian Series 3, Drumian. Stromatocystites lived in quiet water environments with stabilized substrates. It was attached directly to the substrate by its aboral surface. As these environments were widespread throughout Baltica, Gondwana and Laurentia, availability of suitable substrates for larval settlement and oceanic palaeocurrents led to the successful development of Stromatocystites colonies.
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| 21. |
- Zhang, Zhifei, et al.
(författare)
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Architecture and function of the lophophore in the problematic brachiopod Heliomedusa orienta (Early Cambrian, South China)
- 2009
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995 .- 1777-5728. ; 42:5, s. 649-661
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Tidskriftsartikel (refereegranskat)abstract
- The detailed structure of the lophophore is a key diagnostic character in the definition of higher brachiopod taxa. The problematic Heliomedusa orienta Sun and Hou, from the Lower Cambrian Chengjiang Lagerstatte of Yunnan, southwestern China, has a well-preserved lophophore, which is unlike that of any known extant or extinct brachiopods. Based on a comparative study of lophophore disposition in H. orienta and the extant discinid Pelagodiscus atlanticus, the in- and excurrent pattern and shell orientation of H. orienta are described and discussed. Reconstructions of lophophore shape and function are based on numerous specimens and comparison with P. atlanticus. The lophophore is composed of a pair of lophophoral arms that freely arch posteriorly rather than coiling anteriorly as commonly seen in fossil and recent lingulids. The lophophore is attached to the dorsal lobe of the mantle; it has neither calcareous nor chitinous supporting structures, and is disposed symmetrically on either side of the valve midline. The mouth can be inferred to be located at the base of the two brachial tubes, slightly posterior to the anterodorsal projection of the body wall. The lophophoral arms bear laterofrontal tentacles with a double row of cilia along their lateral edge, as in extant lingulid brachiopods. The main brachial axes are also ciliated, which presumably facilitated transport of mucous-bound nutrient particles to the mouth. The unique organization of the lophophore in Heliomedusa is not like any known fossil and living brachiopods. This clearly demonstrates that H. orienta is not a member of any crown group. It is here considered as a member of the brachiopod stem group, which challenges recent interpretations of a close discinid affinity. (C) 2009 Elsevier Masson SAS. All rights reserved.
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| 22. |
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| 23. |
- Edgecombe, GD, et al.
(författare)
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The ''Encrinurus'' variolaris plexus (Trilobita, Silurian): Relationships of Llandovery species
- 1996
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Ingår i: GEOBIOS. - : UNIV CLAUDE BERNARD-LYONI. - 0016-6995. ; 29:2, s. 209-233
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Phylogenetically basal, Llandovery parts of the diverse variolaris plexus of encrinurine trilobites have been assigned to a grade group, Nucleurus. Parsimony analysis of 24 exoskeletal characters for adequately known species of Nucleurus and allied post-l
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| 24. |
- Gamez Vintaned, Jose Antonio, et al.
(författare)
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Trace and soft body fossils from the Pedroche Formation (Ovetian, Lower Cambrian of the Sierra de Cordoba, S Spain) and their relation to the Pedroche event
- 2006
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995. ; 39:4, s. 443-468
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Tidskriftsartikel (refereegranskat)abstract
- The low Lower Cambrian rocks from the Sierra de Cordoba contain one of the best successions in Europe, which consists of well exposed mixed facies with abundant fossil assemblages showing long stratigraphical ranges throughout the Pedroche Formation. These assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobes, trace fossils and stromatolites. Trace fossils are still poorly known, and thus they are the main objective of this work. Ichnological data are obtained from the Arroyo de Pedroche 1, Arroyo de Pedroche 2 and Puente de Hierro sections. Trace fossils include the ichnogenera Bergaueria, aff. Bilinichnus, Cochlichnus, aff. Cosmorhaphe?, Cylindrichnus, Dactyloidites, Dimorphichnus, Diplichnites, Monocraterion, Palaeophycus, aff. Phycodes, Planolites, Psammichnites, Rusophycus, Skolithos, Torrowangea and Treptichnus, as well as faecal pellets, meniscate trace fossils and others. They are abundant in shales and sandstones, and indicate important changes in the benthic conditions with respect to the underlying Torrearboles Formation. Changes in fossil assemblages within Member I of the Pedroche Formation indicate palaeoccological disruptions, which led to the disappearance of numerous archaeocyath species and the decrease of stromatolite biodiversity. This was followed by dominance of trilobite and brachiopod assemblages, accompanied by trace fossils of the Psammichnites ichnosp. A ichnoassociation. This biotic turnover (Pedroche event) occurred at the lower part of the archaeocyath Zone III, within the Bigotina bivallata biozone. The diagnoses of the ichnospecies Cochlichnus anguineus and Dactyloidites cabanasi are emended. (c) 2006 Elsevier SAS. All rights reserved.
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| 25. |
- Lindgren, Johan, et al.
(författare)
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Theropod dinosaur teeth from the lowermost Cretaceous Rabekke Formation on Bornholm, Denmark
- 2008
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Ingår i: Geobios. - : Elsevier BV. - 0016-6995. ; 41:2, s. 253-262
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Tidskriftsartikel (refereegranskat)abstract
- The dinosaur fauna of the palynologically dated lower Berriasian Skyttegard Member of the Rabekke Formation on the Baltic island of Bornholm, Denmark, is represented by isolated tooth crowns. The assemblage is restricted to small maniraptoran theropods, assigned to the Dromaeosauridae incertae sedis and Maniraptora incertae sedis. The dromaeosaurid teeth are characterized by their labiolingually compressed and distally curved crowns that are each equipped with a lingually flexed mesial carina and a distinctly denticulated distal cutting edge. A morphologically aberrant tooth crown (referred to as Maniraptora incertae sedis) has triangular denticles of uneven width, a feature occasionally found in Upper Cretaceous hesperornithiform toothed diving birds, but also in premaxillary teeth of the velociraptorine Nuthetes from the Lower Cretaceous of England.
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