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  • 1.
    Doguzhaeva, Larisa
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    THE ORIGINAL COMPOSITION OF THE PROOSTRACUM OF AN EARLY SINEMURIAN BELEMNITE FROM BELGIUM DEDUCED FROM MODE OF FOSSILIZATION AND ULTRASTRUCTURE2012Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 55, nr 2, s. 249-260, artikel-id doi: 10.1111/j.1475-4983.2012.01136.xArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The pro-ostracum of the early Sinemurian belemnite Nannobelus from the Belgian Province of Luxembourg is preserved as a thin, irregularly mineralized (phosphatized and pyritized), finely laminated structure, which is situated dorsally between the calcified rostrum and phragmocone. It has a median field with a criss-cross pattern of bluntly pointed, curved growth lines and fine longitudinal ridges, as well as two lateral fields characterized by a fine ornament of closely spaced, longitudinal striae, each lateral field showing a narrow anterior belt-like portion, the width of which equals about one-third of that of the median field. Their posterior portion is remarkably asymmetrical, because its free margin (which does not about the median field) curves ventrally and the interspace between striae gradually increases here. The striation of the lateral field is formed by the longitudinally exposed narrow portions of succeeding, overlapping sublayers of the pro-ostracum. Additionally, an internal sublayer with a silicified, honeycomb-like structure is demonstrated in the pro-ostracum. Based on microlamination that is comparable to that of the chitinous gladius inextant squids and on the irregular mineralization (unlike the rest of the shell), the pro-ostracum is considered to have been originally mainly organic, containing an intermediate cartilaginous sublayer with a typical honeycomb-like structure The cartilaginous sublayer supposedly provided protection of the pro-ostracum against fractures which might have resulted from regular contractions together with the muscular mantle during jet-propulsion. Ultrastructural and chemical data on Nannobelus favour the interpretation of the pro-ostracum as a novelty of the skeleton in coleoids rather than as a dorsal projection of the phragmocone wall.

  • 2.
    Doguzhaeva, Larisa
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    THE ORIGINAL COMPOSITION OF THE PROOSTRACUM OF AN EARLY SINEMURIAN BELEMNITE FROM BELGIUM DEDUCED FROM MODE OF FOSSILIZATION AND ULTRASTRUCTURE2012Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 55, nr 2, s. 249-260Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The pro-ostracum of the early Sinemurian belemnite Nannobelus from the Belgian Province of Luxembourg is preserved as a thin, irregularly mineralized (phosphatized and pyritized), finely laminated structure, which is situated dorsally between the calcified rostrum and phragmocone. It has a median field with a criss-cross pattern of bluntly pointed, curved growth lines and fine longitudinal ridges, as well as two lateral fields characterized by a fineornament of closely spaced, longitudinal striae, each lateral field showing a narrow anterior belt-like portion, the width of which equals about one-third of that of the median field. Their posterior portion is remarkably asymmetrical, because its free margin (which does not about the median field) curves ventrally and the interspace between striae gradually increases here. The striation of the lateral field is formed by the longitudinally exposed narrow portions of succeeding, overlapping sublayers of the pro-ostracum. Additionally, an internal sublayer with a silicified, honeycomb-like structure is demonstrated in the pro-ostracum. Based on microlamination that is comparable to that of the chitinous gladius in extant squids and on the irregular mineralization (unlike the rest of the shell), the pro-ostracum is considered to have been originally mainly organic, containing an intermediate cartilaginous sublayer with a typical honeycomb-like structure. The cartilaginous sublayer supposedly provided protection of the pro-ostracum against fractures which might have resulted from regular contractions together with the muscular mantle during jet-propulsion. Ultrastructural and chemical data on Nannobelus favour the interpretation of the pro-ostracum as a novelty of the skeleton in coleoids rather than as a dorsal projection of the phragmocone wall.

  • 3. Doguzhaeva, Larisa
    et al.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    The capsule – a newly discovered organic shell structure in the Late Cretaceous belemnite Gonioteuthis from north-west Germany.2011Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Palaeontology, Vol. 54, nr 2, s. 397-415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An unusual, bilaterally symmetrical black structure that embraces the protoconch and the phragmocone and is overlain by a rostrum has been studied in the Santonian– early Campanian (Late Cretaceous) belemnite genus Gonioteuthis from Braunschweig, north-west Germany. The structure is here named the capsule. Energy dispersed spectrometry analyses of the capsule show a co-occurrence of sulphur with zinc, barium, iron, lead and titanium, suggesting their chemical association. The capsule was originally made of organic material that was diagenetically transformed into sulphur-containing matter. The material of the capsule differs from the chitin of the connecting rings in the same specimens. The capsule has a complex morphology: (1) ventral and dorsal wing-like projections that are repeated in a breviconic shape of the alveolus, (2) an aperture with lateral lobes and ventral and dorsal sinuses copied by growth lines and (3) a ventral ridge that fits with the position of the fissure in the rostrum. The alveolus in the most anterior part of the rostrum is crater-like. It is lined with thin, pyritized, laminated material, which appears to be the outermost portion of the capsule attached to the inner surface of the rostrum. A flare along the periphery of the alveolus marks a region where the rostrum was not yet formed, suggesting that the capsule extended beyond the rostrum. Modification of the skeleton in Gonioteuthis comprises a set of supposedly interrelated changes, such as innovation of the organic capsule, partial elimination of the calcareous rostrum and a diminishing of the pro-ostracum, resulting in the appearance of a new type of pro-ostracum that became narrower and shorter and lost the spatula-like shape and gently curved growth lines of a median field that are typical for the majority of Jurassic and Cretaceous belemnites. The partial replacement of a calcareous rostrum with an organic capsule in belemnitellids may have been an adaptive reaction to an unfavourable environmental condition, perhaps related to difficulties in calcium carbonate secretion during the Late Cretaceous that forced animals to reduce carbonate production and to secret an organic capsule around the protoconch and the phragmocone.

  • 4.
    Doguzhaeva, Larisa
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    THE CAPSULE: AN ORGANIC SKELETAL STRUCTURE IN THE LATE CRETACEOUS BELEMNITE GONIOTEUTHIS FROM NORTH-WEST GERMANY2011Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An unusual, bilaterally symmetrical black structure that embraces the protoconch and the phragmocone and is overlain by a rostrum has been studied in the Santonian–early Campanian (Late Cretaceous) belemnite genus Gonioteuthis from Braunschweig, north-west Germany. The structure is here named the capsule. Energy dispersed spectrometry analyses of the capsule show a co-occurrence of sulphur with zinc, barium, iron, lead and titanium, suggesting their chemical association. The capsule was originally made of organic material that was diagenetically transformed into sulphur-containing matter. The material of the capsule differs from the chitin of the connecting rings in the same specimens. The capsule has a complex morphology: (1) ventral and dorsal wing-like projections that are repeated in a breviconic shape of the alveolus, (2) an aperture with lateral lobes and ventral and dorsal sinuses copied by growth lines and (3) a ventral ridge that fits with the position of the fissure in the rostrum. The alveolus in the most anterior part of the rostrum is crater-like. It is lined with thin, pyritized, laminated material, which appears to be the outermost portion of the capsule attached to the inner surface of the rostrum. A flare along the periphery of the alveolus marks a region where the rostrum was not yet formed, suggesting that thecapsule extended beyond the rostrum. Modification of the skeleton in Gonioteuthis comprises a set of supposedly interrelated changes, such as innovation of the organic capsule, partial elimination of the calcareous rostrum and a diminishing of the pro-ostracum, resulting in the appearance of a new type of pro-ostracum that became narrower and shorter and lost the spatula-like shape and gently curved growtlines of a median field that are typical for the majority of Jurassic and Cretaceous belemnites. The partial replacement of a calcareous rostrum with an organic capsule in belemnitellids may have been an adaptive reaction to an unfavourable environmental condition, perhaps related to difficulties in calcium carbonate secretion during the Late Cretaceous that forced animals to reduce carbonate production and to secret an organic capsule around the protoconch and the phragmocone.

  • 5.
    Dong, Xi-ping
    et al.
    Peking University.
    Vargas, Kelly
    University of Bristol.
    Cunningham, John
    Naturhistoriska riksmuseet, Enheten för paleobiologi. University of Bristol.
    Zhang, Huaqiao
    Nanjing Institute of Geology and Palaeontology.
    Liu, Teng
    Peking University.
    Chen, Fang
    Peking University.
    Liu, Jianbo
    Peking University.
    Bengtson, Stefan
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Donoghue, Philip C.J.
    Developmental biology of the early Cambrian cnidarian Olivooides.2016Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 59, nr 3, s. 387-407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fossilized embryos afford direct insight into the pattern of development in extinct organisms, providing unique tests of hypotheses of developmental evolution based in comparative embryology. However, these fossils can only be effective in this role if their embryology and phylogenetic affinities are well constrained. We elucidate and interpret the development of Olivooides from embryonic and adult stages and use these data to discriminate among competing interpretations of their anatomy and affinity. The embryology of Olivooides is principally characterized by the development of an ornamented periderm that initially forms externally and is subsequently formed internally, released at the aperture, facilitating the direct development of the embryo into an adult theca. Internal anatomy is known only from embryonic stages, revealing two internal tissue layers, the innermost of which is developed into three transversally arranged walls that partly divide the lumen into an abapertural region, interpreted as the gut of a polyp, and an adapertural region that includes structures that resemble the peridermal teeth of coronate scyphozoans. The anatomy and pattern of development exhibited by Olivooides appears common to the other known genus of olivooid, Quadrapyrgites, which differs in its tetraradial, as opposed to pentaradial symmetry. We reject previous interpretations of the olivooids as cycloneuralians, principally on the grounds that they lack a through gut and introvert, in embryo and adult. Instead we consider the affinities of the olivooids among medusozoan cnidarians; our phylogenetic analysis supports their classification as totalgroup Coronata, within crown-Scyphozoa. Olivooides and Quadrapyrgites evidence a broader range of life history strategies and bodyplan symmetry than is otherwise commonly represented in extant Scyphozoa specifically, and Cnidaria more generally.

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  • 6. Gelfo, Javier
    et al.
    Mörs, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Lorente, Malena
    López, Guillermo
    Reguero, Marcelo
    The oldest mammals from Antarctica, early Eocene of La Meseta Formation, Seymour Island2014Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 58, s. 101-110Artikel i tidskrift (Refereegranskat)
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  • 7. Koren, Lee
    et al.
    Matas, Devorah
    Pecnerova, Patricia
    Dalen, Love
    Naturhistoriska riksmuseet, Enheten för bioinformatik och genetik.
    Tikhonov, Alexei
    Gilbert, M. Thomas P.
    Wynne-Edwards, Katherine E.
    Geffen, Eli
    Testosterone in ancient hair from an extinct species2018Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 61, nr 6, s. 797-802Artikel i tidskrift (Refereegranskat)
  • 8.
    Larsson, Cecilia M.
    et al.
    Uppsala Universitet.
    Skovsted, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Brock, Glenn A.
    Macquarie University, Sydney, Australia.
    Balthasar, Uwe
    University of Glasgow.
    Topper, Timothy P.
    Geological Museum, Copenhagen.
    Holmer, Lars E.
    Uppsala Universitet.
    Paterimitra pyramidalis from South Australia: scleritome, shell structure and evolution of a Lower Cambrian Ssten group brachiopod2014Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 57, nr 2, s. 417-446Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The tommotiid Paterimitra pyramidalis Laurie, 1986, is redescribed based on well-preserved material from the lower Cambrian Wilkawillina, Wirrapowie and Ajax limestones of the Flinders Ranges, South Australia. The material shows that the scleritome of Paterimitra pyramidalis includes three sclerite morphotypes (S1, S2 and L). Detailed shell microstructure studies show striking similarities with both the paterinid brachiopod Askepasma toddense and the tommotiid Eccentrotheca helenia, which strengthens the suggested evolutionary link between tommotiids and brachiopods. Based on the partly articulated specimens and similarities in shell microstructure and sclerite morphology with Eccentrotheca, Paterimitra pyramidalis is reconstructed as a tube-dwelling, epifaunal, sessile, filter-feeder with an organic pedicle-like attachment structure. The proposed reconstruction of the scleritome comprises a basal unit composed of one S1 and one S2 sclerite, as well as an unresolved number of L sclerites lining a coniform tubular structure.

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  • 9.
    Li, Luoyang
    et al.
    Frontiers Science Center for Deep Ocean Multispheres & Earth System Key Lab of Submarine Geosciences & Prospecting Techniques MOE & College of Marine Geosciences, Ocean University of China Qingdao 266100 China;Laboratory for Marine Mineral Resources Pilot National Laboratory for Marine Science & Technology (Qingdao) Qingdao 266237 China.
    Skovsted, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Topper, Timothy
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Deep origin of the crossed‐lamellar microstructure in early Cambrian molluscs2022Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 65, nr 4, artikel-id e12620Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aragonitic crossed-lamellar (CL) is one of themost commonly formed and extensively studied molluscanshell microstructures, yet its origin and early evolution within the Mollusca remains poorly understood. Here, a primitive CL microstructure from one of the oldest gastropods,Pela-giella  madianensis, and the problematic hyolith Cupitheca sp. of the Cambrian Series 2 Xinji Formation on the North China Platform, was investigated. In P. madianensis, detailed characterization has revealed a typical four-ordered hierarchical orga-nization of aragonitic crystallites, and a thick layer of organic membranes surrounding its first-order lamellae. A transitional fibrous microstructure was observed between the outer CL and inner foliated aragonite structural layers. In Cupitheca sp.,only the first and second-order lamellae were visible due to preservation limitations, and the first-order lamellae were extremely irregular in shape and size, which is consistent with modern representatives. This study demonstrates that the capability to construct highly-mineralized intricate shells was acquired in early Cambrian stem-group gastropods. The CL microstructure first emerged in the early Cambrian and as a basal synapomorphic trait in total-group molluscs. Moreover, presence of the CL microstructure in problematic lophotrochozoans (i.e.hyoliths) is confirmed. This study contributes to a more complete picture of the evolutionary origin andarchitectural diversity of biomineralized mollusc shells during the Cambrian explosion, and strengthens the phylogenetic links between hyoliths and molluscs.

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  • 10. Li, Luoyang
    et al.
    Zhang, Xingliang
    Skovsted, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Yun, Hao
    Bing, Pan
    Li, Guoxiang
    HOMOLOGOUS SHELL MICROSTRUCTURES INCAMBRIAN HYOLITHS AND MOLLUSCS2019Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 62, nr 4, s. 515-532Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hyoliths were among the earliest biomineralizingmetazoans in Palaeozoic marine environments. They havebeen known for two centuries and widely assigned tolophotrochozoans. However, their origin and relationshipswith modern lophotrochozoan clades have been a longstand-ing palaeontological controversy. Here, we provide broadmicrostructural data from hyolith conchs and opercula fromthe lower Cambrian Xinji Formation of North China, includ-ing two hyolithid genera and four orthothecid genera as wellas unidentified opercula. Results show that most hyolithconchs contain a distinct aragonitic lamellar layer that is com-posed of foliated aragonite, except in the orthothecid Newtaxon 1 that has a crossed foliated lamellar microstructure.Opercula are mostly composed of foliated aragonite andoccasionally foliated calcite. These blade or lath-likemicrostructural fabrics coincide well with biomineralizationof Cambrian molluscs rather than lophophorates, as exempli-fied by the Cambrian members of the tommotiid-brachiopodlinage. Accordingly, we propose that hyoliths and molluscsmight have inherited their biomineralized skeletons from anon-mineralized or weakly mineralized common ancestorrather than as a result of convergence. Consequently, fromthe view of biomineralization, the homologous shellmicrostructures in Cambrian hyoliths and molluscs stronglystrengthen the phylogenetic links between the two groups.

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  • 11.
    Macaluso, Loredana
    et al.
    Dipartimento di Scienze della Terra Via Valperga Caluso 35 10125 Turin Italy.
    Villa, Andrea
    Institut Català de Paleontologia Miquel Crusafont Universitat Autònoma de Barcelona Edifici ICTA‐ICP, c/ Columnes s/n Campus de la UAB, 08193 Cerdanyola del Vallès Barcelona Spain.
    Mörs, Thomas
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    A new proteid salamander (Urodela, Proteidae) from the middle Miocene of Hambach (Germany) and implications for the evolution of the family2021Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 65, nr 1, artikel-id e12585Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Members of the urodele family Proteidae currently account for eight extant species within two genera and at least four extinct species within three genera. The clade has a clear disjunct geographical range, with the extinct Paranecturus and the extant Necturus in North America and the extinct Mioproteus and the extant Proteus in Europe and Asia. A recent phylogenetic analysis supported a Eurasian clade including both fossil and living species found east of the Atlantic Ocean. However, the finding of a new proteid salamander, herein named Euronecturus grogu, from the Miocene of western Germany sheds new light on the evolution of this family, challenging the idea of all Eurasian members of the group deriving from a single lineage separated from the North American ones at least prior to the Oligocene. This new proteid taxon is based on five isolated atlases found in late Orleanian (MN 5) sediments in Hambach 6C, and displays features that are unknown in any other proteid, such as the presence of secondary dorsal crests, small and posteriorly-directed postzygapophyses, and (in at least some specimens) a wide and deep ventral fossa between the anterior cotyles. A phylogenetic analysis recovered the new taxon in an earl ybranching position within Proteidae, sister to all other proteids but the late Maastrichtian Paranecturus. It thus suggests the presence in Europe of a second proteid lineage, currently known only in the middle Miocene, that appears unrelated to the Mioproteus–Proteus clade.

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  • 12.
    Skovsted, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Clausen, Sebastien
    Universite Lille 1.
    Javier J., Alvaro
    Centro de Astrobiologıa (CSIC/INTA), Ctra. de Torrejon.
    Ponleve, Deborah
    Universite Lille 1.
    Tommotiids from the early Cambrian (Series 2, stage 3) of Morocco and the evolution of the tannuolinid scleritome and setigerous shell structures in stem group brachiopods.2014Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 57, nr 1, s. 171-192Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An assemblage of tannuolinid sclerites isdescribed from the Amouslek Formation (Souss Basin) of theAnti-Atlas Mountains in Morocco. The assemblage containstwo species, Tannuolina maroccana n. sp., which is representedby a small number of mitral and sellate sclerites, andMicrina sp., represented by a single mitral sclerite. Tannuolinamaroccana differs from other species of the genus in thepresence of both bilaterally symmetrical and strongly asymmetricalsellate sclerites. This observation suggests that thescleritome of Tannuolina was more complex than previouslythought and that this tommotiid may have held a more basalposition in the brachiopod stem group than previouslyassumed. The shell structure of both T. maroccana andMicrina sp. is well preserved and exhibits two fundamentallydifferent sets of tubular structures, only one of which waslikely to contain shell-penetrating setae. Based on these observations,the structure of the tannuolinid shell is discussed andits implications for the evolution of tubular microstructuresin stem and crown group brachiopods are analysed.

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    Skovsted et al. 2014 - Tannuolina from Morocco
  • 13.
    Steinthorsdottir, Margret
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Håkansson, Eckart
    UWA Centre for Energy Geoscience, School of Earth & Environment, University of Western Australia, Perth, WA, Australia.
    Endo- and epilithic faunal succession in a Pliocene-Pleistocene cave on Rhodes, Greece – record of a transgression2017Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 60, s. 663-681Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fossil cave and associated sediments and fossil fauna located on the Greek island of Rhodes in the eastern Aegean Sea is reported here, and the depositional history discussed. The sediments were deposited during the late Pliocene, in the interstitial space between basement boulders of up to 1500 tons. The depositional history of the cave comprises eight stages. From initial flooding, the basin experienced a continuous transgression with sea-level rise in excess of 500 m, followed by a rapid, forced regression of similar magnitude. The recognition of a succession of fossil communities illustrates this transgression, with a seemingly abrupt shift from endolithic to epilithic biota dominance late in the transgressive cycle. The communities recording the increasing water depth from 0 to >150 m are: The Gatrochaenolithes torpedo (bivalve boring) and Entobia gonioides (sponge boring) ichnocoenosis, with peak distribution between 0 and 1 m water depth; the E. gonioides – E. magna ichnocoenosis, with 1–5 m depth peak distribution; the exclusive E. magna ichnocoenosis, with 5–40 m depth peak distribution; and the E. giganteaichnocoenosis, with a peak distribution approaching 150–200 m. Below this depth, an epilithic community without boring organisms takes over, characterized by the calcareous sponge Merliacf. normani, and the inarticulate brachiopod Novocrania turbinata. Simultaneously with the succession of the endo- and epilithic cave wall fossil communities, skeletal calcarenite accumulated on the cave floor; the erosional remnants of this sediment are insufficient to further expand the overall transgression–regression model.

  • 14. Topper, Timothy, P.
    et al.
    Strotz, Luke C.
    Skovsted, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Holmer, Lars, E.
    DO BRACHIOPODS SHOW SUBSTRATE-RELATEDPHENOTYPIC VARIATION? A CASE STUDY FROM THE BURGESS SHALE2017Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 60, nr 2, s. 269-279Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As sessile, benthic filter feeders, brachiopods share an intimate relationship with their chosen substrate. Individuals of Micromitra burgessensis in the Burgess Shale Formation are preserved in life position, attached to a range of hard substrates, including skeletal debris, conspecific brachiopods, sponges and enigmatic tubes. Here we investigate the phenotypic variability of M. burgessensis associated with differing substrate attachments. We apply geometric morphometrics to test for variation by plotting landmarks on the exterior of ventral and dorsal valves of M. burgessensis specimens that are preserved attached to different substrates. Using principal component, canonical variate analyses and ANOVA, we determine that there is some variation in shape related to substrate. Canonical variate analyses, for ventral valves and dorsal valves, indicate that specimens attached to the same substrate are recognizable in shape from specimens attached to other substrate types. The strength of differentiation however, is not robust and combined with our discriminate analysis of separate populations suggests that there is the potential for substrates to exercise only weak control over the morphology of Brachiopoda.

  • 15.
    Zhang, Zhiliang
    et al.
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China;Department of Biological Sciences Macquarie University Sydney NSW 2109 Australia;Institute of Earth Sciences, Palaeobiology Uppsala University SE‐752 36 Uppsala Sweden.
    Topper, Timothy P.
    Naturhistoriska riksmuseet, Enheten för paleobiologi. State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China;Department of Palaeobiology Swedish Museum of Natural History Box 50007 SE‐104 05 Stockholm Sweden.
    Chen, Yanlong
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China.
    Strotz, Luke C.
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China.
    Chen, Feiyang
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China;Department of Biological Sciences Macquarie University Sydney NSW 2109 Australia.
    Holmer, Lars E.
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China;Institute of Earth Sciences, Palaeobiology Uppsala University SE‐752 36 Uppsala Sweden.
    Brock, Glenn A.
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China;Department of Biological Sciences Macquarie University Sydney NSW 2109 Australia.
    Zhang, Zhifei
    State Key Laboratory of Continental Dynamics Shaanxi Key Laboratory of Early Life & Environments Department of Geology Northwest University Xi’an 710069 China.
    Go large or go conical: allometric trajectory of an early Cambrian acrotretide brachiopod2021Ingår i: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 64, nr 5, s. 727-741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Acrotretides are extinct micromorphic brachiopods that exhibited considerable morphological variation during their rapid evolution in the early Palaeozoic. The plano-conical shells of acrotretides are distinct in comparison to other brachiopod groups and despite their diversity and abundance in early Palaeozoic communities, their origins, early evolution, life history and phylogeny are poorly understood. Here, we employ advanced geometric morphometrics to quantitatively investigate ontogenetic variation and allometry in the ventral valve of the oldest known acrotretide species from the early Cambrian of South China. Our results identify substantial shape variation for Eohadrotreta zhenbaensis, along with a parabolic morphological trajectory through ontogeny, demonstrating a remarkable reversal to PC1 values equivalent to those obtained for juveniles, during later ontogenetic stages. The evolutionary novel body plan (diminutive and plano-conical) of Acrotretida was established gradually during two phases of allometry, formed initially during the final stage of the Cambrian evolutionary radiation from an ancestral low, equivalved lingulide body plan. The development of a conical shaped valve seems to have resulted in an overall smaller body size, when compared with non-conical forms. The heterochronic processes responsible for generating these ontogenetic modifications at different allometric phases may have facilitated the evolutionary diversification of acrotretide brachiopods during the early Palaeozoic.

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