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  • 101.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Dunca, Elena
    Swedish Museum of Natural History, Department of Paleobiology.
    Siphonal zone structure in the cuttlebone of Sepia officinalis2015In: Swiss Journal of Palaeontology, article id 10.1007/s13358-015-0085-yArticle in journal (Refereed)
    Abstract [en]

    The evolutionary process through which the siphonal zone of the cuttlebone of Sepia replaced the tubular siphuncle seen in other shelled cephalopods is poorly understood. Recently, porous connecting stripes, interpreted as homologous to connecting rings of tubular siphuncles, were revealed in Sepia (Acanthosepion) cf. savignyi (Geobios, 45:13–17, 2012). New data on the siphonal zone structure are herein demonstrated through SEM testing of 16 beach-collected cuttlebones ofSepia officinalis from Vale do Lobo, southern Portugal. In examined cuttlebones, the organic connecting stripes are mineralized along their peripheries where they are attached to septa by inorganic–organic porous contacting ridges. The contacting ridges consist of globular crystalline units within an organic matrix; each globule is a stack of rounded alternating organic and mineralized microlaminas parallel to the septal surface; mineralized microlaminas contain carbonate microgranules. Porous connecting stripes together with the contacting ridges may serve as transport routes for the cameral liquid used in buoyancy regulation. The contacting ridges appear to reinforce contacts between the connecting stripes and septa, and may strengthen shell resistance to changing environments. Lamella–fibrillar nacre in septa is demonstrated in Sepia for the first time. Comparison of Sepia and Spirula reveals the common character of their phragmocones, the slit-like shape of the permeable zones between chambers and the siphuncle. Narrowing of the permeable zones may provide shell resistance to high hydrostatic pressure; however, the essentially dissimilar relative length of the permeable zones may results in different capabilities of two genera for buoyancy regulation. In Sepia, long narrow porous inorganic–organic permeable connecting stripes and contacting ridges may allow for rapid buoyancy regulation which would lead to environmental plasticity and higher species diversity.

  • 102.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mapes, Royal
    North Carolina Museum of Natural Sciences.
    Arm hooks and structural features in the Early Permian Glochinomorpha Gordon 1971, indicative of its coleoid affiliation.2014In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, article id DOI: 10.1111/let.12091Article in journal (Refereed)
    Abstract [en]

    Data on the re-examined-type specimens of the Early Permian Glochinomorpha stifeli Gordon 1971 (Coleoidea, Cephalopoda) gives new insight into the evolutionary origination of gladius-bearing coleoids in the Late Palaeozoic and suggests their parallel evolution with the belemnoids and phragmoteuthids. The iron-oxidized arm hooks are found in front of a gladius on an un-illustrated paratype (USNM 170614). Theyare dispersed in a maximum distance equal to 2.5 the gladius length from the incomplete anterior end of the rachis of the gladius. The hook height ranges from less than 1 mm to as much as 4 mm. They have a massive curved base, and a strongly curved shaft with a long thin distal part. The hooks confirm the cephalopod and the coleoid affiliation of G. stifeli that is widely rejected. The iron-oxidized gladii (preserved length is less than 20 mm) show micro-laminations and a fibrous ultrastructure; the fibre bundles are approximately 0.5 lm thick. Lack of calcium and the high content of nitrogen (up to 12% of total weight) confirm the originally non-biomineralized (apparently chitin) composition of the gladii suggested by their fibrous ultrastructure. These data lead to the conclusion that in the evolutionary history of gladius-bearing coleoids, the biomaterial (biochemical) development of the skeleton preceded its morphological transformation. This phenomenon resulted in a recombination of an advanced composition (being non-biomineralized) with archaic features (sensu morphological structure of the posterior part) in the gladius of G. stifeli. The data castdoubt on the hypothesized origination of a gladius from a phragmoteuthid pro-ostracum as well as the evolutionary origination of the gladius-bearing coleoids from pro-ostracum-bearing phragmoteuthids or belemnitids.

  • 103.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mapes, Royal
    American Museum of Natural History, USA.
    Beak from the body chamber of the Early Carboniferous (Visean) shelled longiconic coleoid (Cephalopoda) from Arkansas, USA: -2017In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931Article in journal (Refereed)
    Abstract [en]

    Here we report the discovery of an Early Carboniferous (Late Visean) 3D cephalopod beak displaying significant similarity to the lower beak of Recent coleoids. It was uncovered in a fragmentarily preserved, longiconic shell from the Moorefield Formation in Arkansas, USA. This shell comprises a fractured 29-mm-long body chamber having a maximum diameter of ~14 mm and showing an indistinct pro-ostracum-like structure. The beak-bearing shell could easily have been mistaken for a bactritid or orthocerid if it were not for a coleoid-type, weakly mineralized, evidently organic-rich shell wall which shows a lamello-columnar ultrastructure of a bulk of shell wall thickness and plate ultrastructure of thin outer layer. The specimen is assigned to an as-yet unnamed shelled coleoid of a so far unknown high-level taxonomic group. A partially exposed, 4.0-mm-long portion of the beak is the lower beak in oblique view from its left side. It exhibits fractured anthracite-like black, apparently originally chitin material, helmet-like general shape, broad hood with narrow shallow median groove and small notch posteriorly, pronounced pointed, non-biomineralized upside belt rostrum, high shoulder and about a 90–100 degrees jaw angle. A broad hood and massive rostrum emphasize its similarity to the lower mandible of Recent Vampyroteuthis and signify that its unique, among living coleoids, structure has been existed for at least since Late Visean time (~333 my).

  • 104.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mapes, Royal
    2Department of Geological Sciences, Ohio University, Athens, Ohio, USA.
    Mutvei, Harry
    Swedish Museum of Natural History, Department of Paleobiology.
    Evolutionary patterns of Carboniferous coleoid cephalopods based on their diversity and morphological plasticity2010In: Cephalopods - Present and Past / [ed] Tanabe, K., Shigeta, Y., Sasaki, T. & Hirano, H., Tokyo, Japan: Tokai University Press , 2010, First, p. 171-180Chapter in book (Refereed)
    Abstract [en]

    The morphological traits of the Carboniferous coleoids were analyzed to discover re-occurring combinations of different characteristic features during the early evolution of coleoid cephalopods. The early coleoid evolution in the Carboniferous is characterized by (1) a complex mosaic combination of the "old" and "new" morphological traits, (2) the parallel appearance and variations of new morphological features, and (3) relatively rapid changes in basic morphology. A mosaic combination is exemplified with Donovaniconus, which possesses a body chamber (bactritoid trait), a pro-ostracum-like structure (a novelty), and an ink sac (coleoid trait), or Mutveiconites, which combines a body chamber (bactritoid trait) and a rostrum (coleoid trait). A novelty or new feature can appear at any evolutionary stage, but "old" traits can continue to exist for a long period after the appearance of a novelty in another form. An example of this phenomenon is demonstrated by the evolutionary loss of the body chamber in the Lower Carboniferous (ca. 325 MY) taxon Hematites, which is the earliest recorded coleoid, and the retention of the body chamber in the Late Carboniferous (ca. 290 MY) taxa Shimanskya, Mutveiconites, Donovaniconus, and Saundersites. The parallel appearance of new morphological traits is illustrated by the appearance of the massive rostrum in the Early Carboniferous Hematites and the development of a cap-like small loosely calcified rostrum in the Late Carboniferous Mutveiconites.

  • 105.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Meléndez, Guillermo
    University of Zaragoza, Spain.
    The embryonic conch structure as a supposed imperative factor on the hatchling dispersal and geographical expansion of belemnites: an example of Callovian (Middle Jurassic) pachybelemnopseins from Aragόn (NE Spain): -2017In: Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, ISSN 0077-7749, Vol. 283, no 3, p. 317-334, article id 10.1127/njgpa/2017/0645Article in journal (Refereed)
    Abstract [en]

    Scanning electron microscopy, energy dispersive spectrometry and taphonomic analysis are applied for studying of about 250 shells of the pachybelemnopsein belemnites Hibolithes and Pachybelemnopsis. They are abundantly exposed on solid carbonate bedding surfaces of the middle-late Callovian deposits in the vicinity of the village Ricla, Iberian Range, Aragón, NE Spain. The evidences of their autochthonous burial are as follows: (i) high occurrence of very small, small, and medium-size specimens; the maximum diameter of the rostrum in each category is 2-3 mm, 3-6 mm, 6-10 mm, respectively, whereas large specimens are rare; (ii) small and medium-size shells are dispersed or grouped in small accumulations comprising 3-10 specimens lacking a common orientation or size selection; large shells are disperse; (iii) the apical part of the phragmocones commonly retains fragile embryonic and early post-hatching parts; (iv) the mechanical abrasion is minor; (v) a large number of shells are “hollow belemnites” lacking the diagenetic filling of the protoconch and the apical chambers of the phragmocones. The above set of characters illuminates a high mortality of juvenile and immature pachybelemnopsein belemnites as well as their fast in situ burial. This suggests that the adults did not live constantly in a shallow-water environment. The studied belemnites support a viewpoint on the adaptation of the embryonic conch of the belemnites for a nekto-pelagic lifestyle of the hatchlings. This may provide their effective dispersal and growing expansion from the late Early Jurassic onwards.

  • 106.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mutvei, Harry
    Swedish Museum of Natural History, Department of Paleobiology.
    Connecting stripes: An organic skeletal structure in Sepia from Red Sea2012In: Geobios, ISSN 0016-6995, E-ISSN 1777-5728, Vol. 45, p. 13-17Article in journal (Refereed)
    Abstract [en]

    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.

  • 107.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mutvei, Harry
    Swedish Museum of Natural History, Department of Paleobiology.
    The additional external shell layer indicative of "Endocochleate experiments" in some ammonoids2015In: Topics in Geobiology, Vol. 43, no 15, p. 585-609Article in journal (Refereed)
  • 108.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Mutvei, Harry
    Swedish Museum of Natural History, Department of Paleobiology.
    The Additional External Shell Layers Indicative of “Endocochleate Experiments” in Some Ammonoids2015In: Ammonoid paleobiology: From anatomy to ecology / [ed] Ch. Klug et al., Dordrecht: Springer, 2015, 2nd, p. 585-609Chapter in book (Refereed)
  • 109.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Summesberger, Herbert
    Museum of Natural History, Vienn.
    Pro-ostraca of Triassic belemnoids (Cephalopoda) from Northern Calcareous Alps, with observations on their mode of preservation in an environment of northern Tethys which allowed for carbonization of non-biomineralized structures.2012In: N. Jb. Geol. Paläont. Abh., Vol. 266, no 1, p. 31-38Article in journal (Refereed)
    Abstract [en]

    A pro-ostracum – the anterior dorsal plate subdivided into three longitudinal fields – is

    developed in Triassic phragmoteuthids (Phragmoteuthis, Breviconoteuthis) and the belemnotheutid? (Lunzoteuthis) but is missing in aulacocerids which have a pro-ostracum-like structure – the dorsal apertural crest with arched growth lines. Two types of pro-ostraca: a Phragmoteuthis-type, characterized by arched growth lines in each field, and a Lunzoteuthis-type, in which the median field has arched growth lines and lateral fields bear converging longitudinal ridges, are distinguished. The pro-ostracum with the ridged lateral fields evidently obtained further rapid development; in the Sinemurian belemnite Nannobelus the ridged lateral fields are already formed by the longitudinally exposed narrow portions of succeeding, overlapping sublayers of the pro-ostracum. This structure apparently enabled efficient mantle/shell linkage that facilitated effective manoeuvring, an active mode of life and global radiation of Jurassic belemnites. Exceptional, large scale, preservation of pro-ostraca in lower Carnian of Schindelberg, Lower Austria, and Raibl, North Italy, was possibly due to the concurrency of (1) an environment of the northern Tethys that allowed for post-mortem carbon substitution of chitin and other non-biomineralized material, such as ink and mantle tissue, and (2) the inorganic-organic composition of pro-ostracum as indicated by micro-laminations typical of chitin-containing material and characterized by alteration of chitinous and carbonate laminas similar to those in cuttlebones of Recent Sepia.

  • 110.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Weaver, Patricia
    North Carolina Museum of Natural Sciences; U.S.A..
    Ciampaglio, Charles
    Department of Geology, Wright State University−Lake Campus.
    A unique late Eocene coleoid cephalopod Mississaepia from Mississippi, USA: New data on cuttlebone structure, and their phylogenetic implications.2014In: Acta Palaeontologica Polonica, ISSN 0567-7920, E-ISSN 1732-2421, Vol. 59, no 1, p. 147-162Article in journal (Refereed)
    Abstract [en]

    A new family, Mississaepiidae, from the Sepia–Spirula branch of decabrachian coleoids (Cephalopoda), is erected on the basis of the following, recently revealed, morphological, ultrastructural and chemical traits of the cuttlebone in the late Eocene Mississaepia, formerly referred to Belosaepiidae: (i) septa are semi−transparent, largely chitinous (as opposed to all other recorded cephalopods having non−transparent aragonitic septa); (ii) septa have a thin lamello−fibrillar nacreous covering (Sepia lacks nacre altogether, Spirula has fully lamello−fibrillar nacreous septa, ectochochleate cephalopods have columnar nacre in septa); (iii) a siphonal tube is present in early ontogeny (similar to siphonal tube development of the Danian Ceratisepia, and as opposed to complete lack of siphonal tube in Sepia and siphonal tube development through its entire ontogeny in Spirula); (iv) the lamello−fibrillar nacreous ultrastructure of septal necks (similar to septal necks in Spirula); (v) a sub−hemispherical protoconch (as opposed to the spherical protoconchs of the Danian Ceratisepia and Recent Spirula); (vi) conotheca has ventro−lateral extension in early ontogenetic stages (as opposed to Sepia that has no ventro−lateral extention of the conotheca and to Spirula that retains fully−developed phragmocone throughout its entire ontogeny). Chitinous composition of septa in Mississaepia is deduced from (i) their visual similarity to the chitinous semi−transparent flange of Sepia, (ii) angular and rounded outlines and straight compressive failures of the partial septa and mural parts of septa similar to mechanically−damaged dry rigid chitinous flange of Sepia or a gladius of squid, and (iii) organics consistent with [1]−chitin preserved in the shell. The family Mississaepiidae may represent a unknown lineage of the Sepia–Spirula branch of coleoids, a conotheca lacking a nacreous layer being a common trait of the shell of this branch. However, Mississaepiidae is placed with reservation in Sepiida because of similarities between their gross shell morphology (a cuttlebone type of shell) and inorganic−organic composition. In Mississaepia, as in Sepia, the shell contains up to 6% of nitrogen by weight; phosphatised sheets within the dorsal shield may have been originally organic, like similar structures in Sepia; accumulations of pyrite in peripheral zones of aragonitic spherulites and in−between the spherulites of the dorsal shield may also indicate additional locations of organics in the shell of living animal.

  • 111.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Weaver, Patricia
    North Carolina Museum of Natural Sciences.
    Ciampaglio, Charles N.
    Wright State University−Lake Campus, Department of Geology.
    A unique late Eocene coleoid cephalopod Mississaepia from Mississippi, USA: New data on cuttlebone structure, and their phylogenetic implications.2014In: Acta Palaeontologfica Polonica, Vol. 59, no 1, p. 147-162Article in journal (Refereed)
    Abstract [en]

    A new family, Mississaepiidae, from the SepiaSpirula branch of decabrachian coleoids (Cephalopoda), is erected on the basis of the following, recently revealed, morphological, ultrastructural and chemical traits of the cuttlebone in the late Eocene Mississaepia, formerly referred to Belosaepiidae: (i) septa are semi−transparent, largely chitinous (as opposed to all other recorded cephalopods having non−transparent aragonitic septa); (ii) septa have a thin lamello−fibrillar nacreous covering (Sepia lacks nacre altogether, Spirula has fully lamello−fibrillar nacreous septa, ectochochleate cephalopods have columnar nacre in septa); (iii) a siphonal tube is present in early ontogeny (similar to siphonal tube development of the Danian Ceratisepia, and as opposed to complete lack of siphonal tube in Sepia and siphonal tube development through its entire ontogeny in Spirula); (iv) the lamello−fibrillar nacreous ultrastructure of septal necks (similar to septal necks in Spirula); (v) a sub−hemispherical protoconch (as opposed to the spherical protoconchs of the Danian Ceratisepia and Recent Spirula); (vi) conotheca has ventro−lateral extension in early ontogenetic stages (as opposed to Sepia that has no ventro−lateral extention of the conotheca and to Spirula that retains fully−developed phragmocone throughout its entire ontogeny). Chitinous composition of septa in Mississaepia is deduced from (i) their visual similarity to the chitinous semi−transparent flange of Sepia, (ii) angular and rounded outlines and straight compressive failures of the partial septa and mural parts of septa similar to mechanically−damaged dry rigid chitinous flange of Sepia or a gladius of squid, and (iii) organics consistent with chitin preserved in the shell. The family Mississaepiidae may represent a unknown lineage of the SepiaSpirula branch of coleoids, a conotheca lacking a nacreous layer being a common trait of the shell of this branch. However, Mississaepiidae is placed with reservation in Sepiida because of similarities between their gross shell morphology (a cuttlebone type of shell) and inorganic−organic composition. In Mississaepia, as in Sepia, the shell contains up to 6% of nitrogen by weight; phosphatised sheets within the dorsal shield may have been originally organic, like similar structures in Sepia; accumulations of pyrite in peripheral zones of aragonitic spherulites and in−between the spherulites of the dorsal shield may also indicate additional locations of organics in the shell of living animal.

     

     

     

     

     

  • 112.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Weis, Robert
    Musee national d’histoire naturelle, Luxembourg.
    Delsate, Domenique
    Musee national d’histoire naturelle, Luxembourg.
    Mariotti, Nino
    Dipartimento di Scienze della Terra, Universita ‘La Sapienza’, Rome, Italy.
    Embryonic shell structure of Early–Middle Jurassic belemnites, and its significance for belemnite expansion and diversification in the Jurassic2014In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 47, p. 49-65Article in journal (Refereed)
    Abstract [en]

    Early Jurassic belemnites are of particular interest to the study of the evolution of skeletal

    morphology in Lower Carboniferous to the uppermost Cretaceous belemnoids,

    because they signal the beginning of a global Jurassic

    –Cretaceous expansion and diversification

    of belemnitids. We investigated potentially relevant, to this evolutionary pattern,

    shell features of Sinemurian

    –Bajocian Nannobelus, Parapassaloteuthis, Holcobelus

    and

    Pachybelemnopsis from the Paris Basin. Our analysis of morphological, ultrastructural

    and chemical traits of the earliest ontogenetic stages of the shell suggests that

    modified embryonic shell structure of Early

    –Middle Jurassic belemnites was a factor

    in their expansion and colonization of the pelagic zone and resulted in remarkable

    diversification of belemnites. Innovative traits of the embryonic shell of Sinemurian

    Bajocian belemnites include: (1) an inorganic

    –organic primordial rostrum

    encapsulating the protoconch and the phragmocone, its non-biomineralized component,

    possibly chitin, is herein detected for the first time; (2) an organic rich closing

    membrane which was under formation. It was yet perforated and possessed a foramen;

    and (3) an organic rich pro-ostracum earlier documented in an embryonic shell of

    Pliensbachian

    Passaloteuthis. The inorganic–organic primordial rostrum tightly coating

    the protoconch and phragmocone supposedly enhanced protection, without

    increase in shell weight, of the Early Jurassic belemnites against explosion in deepwater

    environment. This may have increased the depth and temperature ranges of

    hatching eggs, accelerated the adaptation of hatchlings to a nektonic mode of life and

    promoted increasing diversity of belemnoids. This study supports the hypothesis that

    belemnite hatchlings were ‘a miniature of the adults’.

  • 113.
    Doguzhaeva, Larisa
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Weis, Robert
    Musee national d’histoire naturelle, Luxembourg.
    Delsate, Dominique
    Musee national d’histoire naturelle, Luxembourg.
    Mariotti, Nino
    Dipartimento di Scienze della Terra, Universita ‘La Sapienza’.
    Embryonic shell structure of Early–Middle Jurassic belemnites, and its significance for belemnite expansion and diversification in the Jurassic.2014In: Lethaia: an international journal of palaeontology and stratigraphy, ISSN 0024-1164, E-ISSN 1502-3931, Vol. 47, p. 49-65, article id DOI 10.1111/let.12037Article in journal (Refereed)
    Abstract [en]

    Early Jurassic belemnites are of particular interest to the study of the evolution of skeletal morphology in Lower Carboniferous to the uppermost Cretaceous belemnoids, because they signal the beginning of a global Jurassic–Cretaceous expansion and diversification of belemnitids. We investigated potentially relevant, to this evolutionary pattern, shell features of Sinemurian–Bajocian Nannobelus, Parapassaloteuthis, Holcobelus and Pachybelemnopsis from the Paris Basin. Our analysis of morphological, ultrastructural and chemical traits of the earliest ontogenetic stages of the shell suggests that modified embryonic shell structure of Early–Middle Jurassic belemnites was a factor in their expansion and colonization of the pelagic zone and resulted in remarkable diversification of belemnites. Innovative traits of the embryonic shell of Sinemurian–Bajocian belemnites include: (1) an inorganic–organic primordial rostrum encapsulating the protoconch and the phragmocone, its non-biomineralized component, possibly chitin, is herein detected for the first time; (2) an organic rich closing membrane which was under formation. It was yet perforated and possessed a foramen; and (3) an organic rich pro-ostracum earlier documented in an embryonic shell of Pliensbachian Passaloteuthis. The inorganic–organic primordial rostrum tightly coating the protoconch and phragmocone supposedly enhanced protection, without increase in shell weight, of the Early Jurassic belemnites against explosion in deep water environment. This may have increased the depth and temperature ranges of hatching eggs, accelerated the adaptation of hatchlings to a nektonic mode of life andpromoted increasing diversity of belemnoids. This study supports the hypothesis thatbelemnite hatchlings were ‘a miniature of the adults’.

  • 114. Dong, Xi-ping
    et al.
    Cunningham, John A.
    University of Bristol.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Thomas, Ceri-Wyn
    Liu, Jianbo
    Stampanoni, Marco
    Donoghue, Philip C.J.
    University of Bristol.
    Embryos, polyps and medusae of the early Cambrian scyphozoan Olivooides.2013In: Proceedings of the Royal Society Biological Sciences Series B, ISSN 0962-8452, Vol. 280, no 2130071, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The Early Cambrian organism Olivooides is known from both embryonic and post-embryonic stages and, consequently, it has the potential to yield vital insights into developmental evolution at the time that animal body plans were established. However, this potential can only be realized if the phylogenetic relationships of Olivooides can be constrained. The affinities of Olivooides have proved controversial because of the lack of knowledge of the internal anatomy and the limited range of developmental stages known. Here, we describe rare embryonic specimens in which internal anatomical features are preserved. We also present a fuller sequence of fossilized developmental stages of Olivooides, including associated specimens that we interpret as budding ephyrae ( juvenile medusae), all of which display a clear pentaradial symmetry. Within the framework of a cnidarian interpretation, the new data serve to pinpoint the phylogenetic position of Olivooides to the scyphozoan stem group. Hypotheses about scalidophoran or echinoderm affinities of Olivooides can be rejected.

  • 115.
    Dong, Xi-ping
    et al.
    Peking University.
    Vargas, Kelly
    University of Bristol.
    Cunningham, John
    Swedish Museum of Natural History, Department of Paleobiology. 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
    Swedish Museum of Natural History, Department of Paleobiology.
    Donoghue, Philip C.J.
    Developmental biology of the early Cambrian cnidarian Olivooides.2016In: Palaeontology, ISSN 0031-0239, E-ISSN 1475-4983, Vol. 59, no 3, p. 387-407Article in journal (Refereed)
    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.

  • 116. Donoghue, Philip C.J.
    et al.
    Cunningham, John
    Swedish Museum of Natural History, Department of Paleobiology.
    Dong, Xi-ping
    Peking University.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Embryology in deep time.2015In: Evolutionary Developmental Biology of Invertebrates 1 / [ed] Wanninger, Andreas, Wien: Springer Science+Business Media B.V., 2015, p. 45-63Chapter in book (Refereed)
    Abstract [en]

    For anyone who has cared for animal embryos, it beggars belief that these squishy cellular aggregates could be fossilised. Hence, with hindsight, it is possible to empathise with palaeontologists who found such fossils and, in their naming of Olivooides, Pseudooides, etc., drew attention to their likeness to animal eggs and embryos but without going so far as to propose such an interpretation. However, in 1994, Zhang Xi-guang and Brian Pratt described microscopic balls of calcium phosphate from Cambrian rocks of China, one or two of which preserved polygonal borders that resembled blastomeres on the surface of an early cleaving animal embryo. In retrospect, these fossils are far from remarkable, some of them may not be fossils at all, and it is not as if anyone ever conceived Cambrian animals as having lacked an embryology. But Zhang Xi-guang and Brian Pratt dared the scientific world, not least their fellow palaeontologists, to believe that the fragile embryonic stages of invertebrate animals could be fossilised, that there was a fossil record of animal embryology, that this record hailed from the interval of time in which animal body plans were first established, and that it had been awaiting discovery in the rocks, for want of looking. The proof of this concept came a few years later, when phosphatised Cambrian fossils from China and Siberia were shown to display indisputable features of animal embryonic morphologies. In the case of Olivooides, a series of developmental stages from cleavage to morphogenesis through hatching and juvenile growth could be tentatively identified; in Markuelia, the coiled-up body of an annulated worm-like animal could be clearly seen within its fertilisation envelope.

  • 117. Drake, Henrik
    et al.
    Heim, Christine
    Roberts, N.M.W
    Zack, Tomas
    Tillberg, M
    Broman, Curt
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Whitehouse, Martin
    Åström, M
    Isotopic evidence for microbial production and consumption of methane in the upper continental crust throughout the Phanerozoic eon2017In: Earth and Planetary Science Letters, Vol. 470, p. 108-118Article in journal (Refereed)
  • 118.
    Drake, Henrik
    et al.
    Linnæus University, Department of Biology and Environmental Science, 39182 Kalmar, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    The role of anaerobic fungi in fundamental biogeochemical cycles in the deep biosphere2018In: Fungal Biology Reviews, ISSN 1749-4613, E-ISSN 1878-0253, Vol. 32, p. 20-25Article in journal (Refereed)
    Abstract [en]

    A major part of the biologic activity on Earth is hidden underneath our feet in an environment coined the deep biosphere which stretches several kilometers down into the bedrock. The knowledge about life in this vast energy-poor deep system is, however, extremely scarce, particularly for micro-eukaryotes such as fungi, as most studies have focused on prokaryotes. Recent findings suggest that anaerobic fungi indeed thrive at great depth in fractures and cavities of igneous rocks in both the oceanic and the continental crust. Here we discuss the potential importance of fungi in the deep biosphere, in particular their involvement in fundamental biogeochemical processes such as symbiotic relationships with prokaryotes that may have significant importance for the overall energy cycling within this vast subsurface realm. Due to severe oligotrophy, the prokaryotic metabolism at great depth in the crust is very slow and dominantly autotrophic and thus dependent on e.g. hydrogen gas, but the abiotic production of this gas is thought to be insufficient to fuel the deep autotrophic biosphere. Anaerobic fungi are heterotrophs that produce hydrogen gas in their metabolism and have therefore been put forward as a hypothetical provider of this substrate to the prokaryotes. Recent in situ findings of fungi and isotopic signatures within co-genetic sulfide minerals formed from bacterial sulfate reduction in the deep continental biosphere indeed seem to confirm the fungi-prokaryote hypothesis. This suggests that fungi play a fundamental biogeochemical role in the deep biosphere.

  • 119. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Heim, Christine
    Siljeström, Sandra
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Åström, Mats E.
    Anaerobic consortia of fungi and sulfate reducing bacteria in deep granite fractures2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, no 55, p. 1-9Article in journal (Refereed)
    Abstract [en]

    The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused on prokaryotes and neglected microeukaryotes, recent discoveries have revealed existence of fossil and active fungi in marine sediments and sub-seafloor basalts, with proposed importance for the subsurface energy cycle. However, studies of fungi in deep continental crystalline rocks are surprisingly few. Consequently, the characteristics and processes of fungi and fungus-prokaryote interactions in this vast environment remain enigmatic. Here we report the first findings of partly organically preserved and partly mineralized fungi at great depth in fractured crystalline rock (-740 m). Based on environmental parameters and mineralogy the fungi are interpreted as anaerobic. Synchrotron-based techniques and stable isotope microanalysis confirm a coupling between the fungi and sulfate reducing bacteria. The cryptoendolithic fungi have significantly weathered neighboring zeolite crystals and thus have implications for storage of toxic wastes using zeolite barriers.

  • 120.
    Drake, Henrik
    et al.
    Linnæus University, Department of Biology and Environmental Science, 39182 Kalmar, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Tillberg, Mikael
    Department of Biology and Environmental Science, Linnaeus University, 392 31 Kalmar, Sweden.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient microbial activity in deep hydraulically conductive fracture zones within the Forsmark target area for deep geological nuclear waste disposal, Sweden2018In: Geosciences, Vol. 8, article id 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of 13Ccalcite (􀀀36.2 to +20.2‰V-PDB) and 34Spyrite (􀀀11.7 to +37.8‰V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of 18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • 121.
    Dunca, Elena
    Swedish Museum of Natural History, Department of Paleobiology.
    Growth and chemical analyses of  freshwater pearl mussel, Margaritifera margaritifera, shells from Haukåselva river, Norway2014Report (Other academic)
    Abstract [en]

    Age determination and annual growth analyses of two M. margaritifera shells from river Haukåselva, Norway, was carried on thin transversal sections prepared using the method developed at the Swedish Museum of Natural History in Stockholm, Sweden. In one of the shells (the oldest) elemental distribution was analysed using ICP-MS. 

    The growth analyses showed that mussel B is younger and had higher growth rate than mussel A indicating that the two locations where the shells were found had different growth conditions. As such, the annual growth pattern of the two shells had a poor match but in both shells the growth was found decreasing after 2008, which indicated that some environmental factors had caused distress in both locations in the last living years.

    Variations in annual growth showed lower growth in the periods 1961-1978 (except 1967) and 1996-2013. In the same periods of time an increased amount of Fe, Mn, P, Ba and Sr was measured in the shell, while the levels of Cu, Co and Pb were lower. This together with the absence of heavy metals (such as Al, As, Cd and Cr) in the shell indicated that the freshwater pearl mussels in Haukåselva are not affected by the pH condition of the water, but highly affected by low O levels possibly due to eutrophication.

     

  • 122.
    Dunca, Elena
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Larsen, Bjørn Mejdell
    Skillnader i skaltillväxt hos flodpärlmusslor från reglerade och icke-reglerade vattendrag i Norge2013Report (Refereed)
    Abstract [en]

    Age determination and growth analyses of freshwater pearl mussel shells from Fallselva, Begna, Numedalslågen, Skauga, Teksdalselva, Borråselva, Mossa and Aursunda, together with published data from Hunnselva, Simoa, Håelva, Ogna and Figga, here enable us to investigate potential effects of water regulation on shell growth.

     

    The shell length of the bivalves in this study was expressed as a function of their age in growth diagrams and then compared with general growth curves for the species. Shell size varied between the mussel localities and even between collection sites within the same water system. As a result, in order to estimate the age of the mussels by their shell length, growth curves need to be constructed for each water system and in some cases even for collection sites in the same river, especially if the populations have different species of host fish.

     

    The compiled results of our measurements showed that annual growth rates of freshwater pearl mussels from regulated river are similar to the ones from non-regulated rivers. Although, when we analysed each river individually and the growth rate through time we did find many examples that indicated that water regulation and construction work related to water regulation, influence negatively the growth rate of freshwater pearl mussel.

     

    Shells from Mossa showed lower growth rate and strongly reduced recruitment of juvenile shells when the construction work at the power plant began in the early 80’s until late 90’s when the water flow was increased. Mossa shells collected in1984, before the construction of the power plant had a higher frequency of growth disturbances in comparison with shells collected in 2010, from the same locality after the power plant started to work. Shells from Borråselva shells had one of the highest frequencies of growth disturbances in comparison to all other shells analysed in the present study. They had also lower growth rate since the reconstruction of the dam began in 2008. In Fallselva the water flow was redirected when the power plant was moved to another location, which caused extreme low water levels at several mussel localities. Shells collected in these localities had low growth rates and high frequencies of growth disturbances. The construction work at the power plant in Begna did not show any indications of negative influence on shell growth and the annual growth had similar variations both upstream and downstream the power plant.

    Our results indicate that the regulation of the water flow may affect negatively the growth rate of freshwater pearl mussels when it results in extreme low water levels. There are also indications that the water regulation may indirectly affect the shell growth rate by changing the water temperature, nutrients and the velocity of the water.

     

     

     

     

    Elena Dunca, NRM, Box 50007, 10405 Stocholm, Sverige; elena.dunca@nrm.se;

    Bjørn Mejdell Larsen, NINA, Postboks 5685 Sluppen, 7485 Trondheim; bjorn.larsen@nina.no

     

  • 123. Dyer, Adrian G
    et al.
    Boyd-Gerny, Skye
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Rosa, Marcello G P
    Simonov, Vera
    Wong, Bob B M
    Parallel evolution of angiosperm colour signals: common evolutionary pressures linked to hymenopteran vision.2012In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, no 1742, p. 3606-15Article in journal (Refereed)
    Abstract [en]

    Flowering plants in Australia have been geographically isolated for more than 34 million years. In the Northern Hemisphere, previous work has revealed a close fit between the optimal discrimination capabilities of hymenopteran pollinators and the flower colours that have most frequently evolved. We collected spectral data from 111 Australian native flowers and tested signal appearance considering the colour discrimination capabilities of potentially important pollinators. The highest frequency of flower reflectance curves is consistent with data reported for the Northern Hemisphere. The subsequent mapping of Australian flower reflectances into a bee colour space reveals a very similar distribution of flower colour evolution to the Northern Hemisphere. Thus, flowering plants in Australia are likely to have independently evolved spectral signals that maximize colour discrimination by hymenoptera. Moreover, we found that the degree of variability in flower coloration for particular angiosperm species matched the range of reflectance colours that can only be discriminated by bees that have experienced differential conditioning. This observation suggests a requirement for plasticity in the nervous systems of pollinators to allow generalization of flowers of the same species while overcoming the possible presence of non-rewarding flower mimics.

  • 124.
    Edirisooriya, Geetha
    et al.
    Department of Geology, University of Peradeniya, Peradeniya, Sri Lanka.
    Dharmagunawardhane, H.A.
    Department of Geology, University of Peradeniya, Peradeniya, Sri Lanka.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    The first record of the Permian Glossopteris flora from Sri Lanka: implications for hydrocarbon source rocks in the Mannar Basin2018In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, p. 907-920Article in journal (Refereed)
    Abstract [en]

    Strata exposed near Tabbowa Tank, Tabbowa Basin, western Sri Lanka have yielded the

    first representatives of the distinctive Permian Glossopteris flora from that country. The assemblage

    includes gymnosperm foliage attributable to Glossopteris raniganjensis, roots referable to Vertebraria

    australis, seeds assigned to Samaropsis sp., sphenophyte axes (Paracalamites australis) and

    foliage (Sphenophyllum emarginatum), and fern foliage (Dichotomopteris lindleyi). This small macroflora

    is interpreted to be of probable Lopingian (late Permian) age based on comparisons with the

    fossil floras of Peninsula India. Several Glossopteris leaves in the assemblage bear evidence of terrestrial

    arthropod interactions including hole feeding, margin feeding, possible lamina skeletonization,

    piercing-and-sucking damage and oviposition scarring. The newly identified onshore Permian strata

    necessitate re-evaluation of current models explaining the evolution of the adjacent offshore Mannar

    Basin. Previously considered to have begun subsiding and accumulating sediment during Jurassic

    time, we propose that the Mannar Basin may have initiated as part of a pan-Gondwanan extensional

    phase during late Palaeozoic – Triassic time. We interpret the basal, as yet unsampled, seismically

    reflective strata of this basin to be probable organic-rich continental strata of Lopingian age, equivalent

    to those recorded in the Tabbowa Basin, and similar to the Permian coal-bearing successions

    in the rift basins of eastern India and Antarctica. Such continental fossiliferous strata are particularly

    significant as potential source rocks for recently identified natural gas resources in the Mannar

    Basin.

  • 125. El Albani, Abder
    et al.
    Mangano, M. Gabriela
    Buatois, Luis A.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Riboulleau, Armelle
    Bekker, Andrey
    Konhauser, Kurt
    Lyons, Timothy
    Rollion-Bard, Claire
    Bankole, Olabode
    Lekele Baghekema, Stellina Gwenaelle
    Meunier, Alain
    Trentesaux, Alain
    Mazurier, Arnaud
    Aubineau, Jeremie
    Laforest, Claude
    Fontaine, Claude
    Recourt, Philippe
    Chi Fru, Ernest
    Machiarelli, Roberto
    Reynaud, Jean Yves
    Gauthier-Lafaye, François
    Canfield, Donald E.
    Organism motility in an oxygenated shallow-marine environment 2.1 billion years ago2019In: Proceedings of the National Academy of Sciences, ISSN 1091-6490, Vol. 116, no 9, p. 3431-3436Article in journal (Refereed)
    Abstract [en]

    The 2.1 billion-year-old sedimentary strata contain exquisitely preserved fossils that provide an ecologic snapshot of the biota inhabiting an oxygenated shallow-marine environment. Most striking are the pyritized string-shaped structures, which suggest that the producer have been a multicellular or syncytial organism able to migrate laterally and vertically to reach for food resources. A modern analogue is the aggregation of amoeboid cells into a migratory slug phase in modern cellular slime molds during time of food starvation. While it remains uncertain whether the amoeboidlike organisms represent a failed experiment or a prelude to subsequent evolutionary innovations, they add to the growing record of comparatively complex life forms that existed more than a billion years before animals emerged in the late Neoproterozoic.Evidence for macroscopic life in the Paleoproterozoic Era comes from 1.8 billion-year-old (Ga) compression fossils [Han TM, Runnegar B (1992) Science 257:232–235; Knoll et al. (2006) Philos Trans R Soc Lond B 361:1023–1038], Stirling biota [Bengtson S et al. (2007) Paleobiology 33:351–381], and large colonial organisms exhibiting signs of coordinated growth from the 2.1-Ga Francevillian series, Gabon. Here we report on pyritized string-shaped structures from the Francevillian Basin. Combined microscopic, microtomographic, geochemical, and sedimentologic analyses provide evidence for biogenicity, and syngenicity and suggest that the structures underwent fossilization during early diagenesis close to the sediment–water interface. The string-shaped structures are up to 6 mm across and extend up to 170 mm through the strata. Morphological and 3D tomographic reconstructions suggest that the producer may have been a multicellular or syncytial organism able to migrate laterally and vertically to reach food resources. A possible modern analog is the aggregation of amoeboid cells into a migratory slug phase in cellular slime molds at times of starvation. This unique ecologic window established in an oxygenated, shallow-marine environment represents an exceptional record of the biosphere following the crucial changes that occurred in the atmosphere and ocean in the aftermath of the great oxidation event (GOE).

  • 126. El Albani, Abderrazak
    et al.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Canfield, Donald E.
    Riboulleau, Armelle
    Rollion Bard, Claire
    Macchiarelli, Roberto
    Ngombi Pemba, Lauriss
    Hammarlund, Emma
    Meunier, Alain
    Moubiya Mouele, Idalina
    Benzerara, Karim
    Bernard, Sylvain
    Boulvais, Philippe
    Chaussidon, Marc
    Cesari, Christian
    Fontaine, Claude
    Chi-Fru, Ernest
    Garcia Ruiz, Juan Manuel
    Gauthier-Lafaye, François
    Mazurier, Arnaud
    Pierson-Wickmann, Anne Catherine
    Rouxel, Olivier
    Trentesaux, Alain
    Vecoli, Marco
    Versteegh, Gerard J. M.
    White, Lee
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Bekker, Andrey
    The 2.1 Ga old Francevillian biota: biogenicity, taphonomy and biodiversity.2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6:e99438, p. 1-18Article in journal (Refereed)
    Abstract [en]

    The Paleoproterozoic Era witnessed crucial steps in the evolution of Earth’s surface environments following the first appreciable rise of free atmospheric oxygen concentrations ~2.3 to 2.1 Ga ago, and concomitant shallow ocean oxygenation. While most sedimentary successions deposited during this time interval have experienced thermal overprinting from burial diagenesis and metamorphism, the ca. 2.1 Ga black shales of the Francevillian B Formation (FB2) cropping out in southeastern Gabon have not. The Francevillian Formation contains centimeter-sized structures interpreted as organized and spatially discrete populations of colonial organisms living in an oxygenated marine ecosystem. Here, new material from the FB2 black shales is presented and analyzed to further explore its biogenicity and taphonomy. Our extended record comprises variably sized, shaped, and structured pyritized macrofossils of lobate, elongated, and rodshaped morphologies as well as abundant non-pyritized disk-shaped macrofossils and organic-walled acritarchs. Combined microtomography, geochemistry, and sedimentary analysis suggest a biota fossilized during early diagenesis. The emergence of this biota follows a rise in atmospheric oxygen, which is consistent with the idea that surface oxygenation allowed the evolution and ecological expansion of complex megascopic life.

  • 127.
    Elgorriaga, Andrés
    et al.
    Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón nº 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
    Escapa, Ignacio
    Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Avenida Fontana 140, U9100GYO Chubut, Argentina.
    Bomfleur, Benjamin
    Swedish Museum of Natural History, Department of Paleobiology.
    Cúneo, Rubén
    Consejo Nacional de Investigaciones Científicas y Técnicas, Museo Paleontológico Egidio Feruglio, Avenida Fontana 140, U9100GYO Chubut, Argentina.
    Ottone, Eduardo
    Instituto de Estudios Andinos Don Pablo Groeber-Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón n° 2, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina.
    Reconstruction and phylogenetic significance of a new Equisetum Linnaeus species from the Lower Jurassic of Cerro Bayo (Chubut province, Argentina)2015In: Ameghiniana, ISSN 1851-8044, Vol. 52, p. 135-152Article in journal (Refereed)
    Abstract [en]

    We describe Equisetum dimorphum sp. nov. from the Lower Jurassic of Chubut Province, Patagonia, Argentina. This new species is based on fertile and vegetative remains preserved as impressions of stems, leaves, strobili, transversal sections of the stems showing their anatomy, and terminal pagoda-like structures. The fine-grained sedimentary matrix also preserved detailed impressions of epidermal features. The morphological characters allow a whole-plant reconstruction and assignment to Equisetum. Equisetum dimorphum sp. nov. shows a mosaic of morphological characters that are commonly present in other Mesozoic forms and representatives of the two extant Equisetum subgenera, e.g., sunken stomata and a blunt strobilus apex. Compared to other well-known Mesozoic equisetalean taxa, Equisetum dimorphum sp. nov. appears to be most closely related to a group of Jurassic Equisetum-like plants including Equisetum laterale Phillips and Equisetites ferganensis Seward. Additional evidence for the morphological stasis of the fertile and vegetative organs of extant horsetails is supplied with this new material, adding further support to the hypothesis that the extant horsetails are a successful group that has undergone only little morphological changeover time and that has been present, nearly worldwide, since Jurassic times.

  • 128. Elliott, T. A.
    et al.
    Forey, P. L.
    Williams, C. T.
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    Application of the solubility profiling technique to recent and fossil fish teeth1998In: Bulletin de la Société Géologique de France, ISSN 0037-9409, E-ISSN 1777-5817, Vol. 169, p. 443-451Article in journal (Refereed)
  • 129. ENGELBRECHT, Andrea
    et al.
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO,, Marcelo
    KRIWET, Jürgen
    A new sawshark, Pristiophorus laevis, from the Eocene of Antarctica with comments on Pristiophorus lanceolatus2016In: Historical Biology, ISSN 0891-2963, E-ISSN 1029-2381Article in journal (Refereed)
  • 130. ENGELBRECHT, Andrea
    et al.
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, Marcelo
    KRIWET, Jürgen
    Eocene squalomorph sharks (Chondrichthyes, Elasmobranchii) from Antarctica2017In: Journal of South American Earth Sciences, ISSN 0895-9811, E-ISSN 1873-0647Article in journal (Refereed)
  • 131. ENGELBRECHT, Andrea
    et al.
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, Marcelo
    KRIWET, Jürgen
    New carcharhiniform sharks (Chondrichthyes, Elasmobranchii) from the early to middle Eocene of Seymour Island, Antarctic Peninsula2017In: Journal of Vertebrate Paleontology, ISSN 0272-4634, E-ISSN 1937-2809Article in journal (Refereed)
  • 132. ENGELBRECHT, Andrea
    et al.
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, Marcelo
    KRIWET, Jürgen
    Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula2016In: Journal of Systematic Palaeontology, ISSN 1477-2019, E-ISSN 1478-0941Article in journal (Refereed)
  • 133. ENGELBRECHT, Andrea
    et al.
    Mörs, Thomas
    Swedish Museum of Natural History, Department of Paleobiology.
    REGUERO, Marcelo
    KRIWET, Jürgen
    Skates and Rays (Elasmobranchii, Batomorphii) from the Eocene La Meseta and Submeseta formations, Seymour Island, Antarctica2019In: Historical Biology, ISSN 0891-2963, E-ISSN 1029-2381Article in journal (Refereed)
  • 134. Faurby, Sören
    et al.
    Silvestro, Daniele
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    Antonelli, Alexandre
    Brain expansion in early hominins predicts carnivore extinctions in East Africa2020In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 23, p. 537-544Article in journal (Refereed)
    Abstract [en]

    While the anthropogenic impact on ecosystems today is evident, it remains unclear if the detrimental

    effect of hominins on co-occurring biodiversity is a recent phenomenon or has also been

    the pattern for earlier hominin species. We test this using the East African carnivore fossil record.

    We analyse the diversity of carnivores over the last four million years and investigate whether any

    decline is related to an increase in hominin cognitive capacity, vegetation changes or climatic

    changes. We find that extinction rates in large carnivores correlate with increased hominin brain

    size and with vegetation changes, but not with precipitation or temperature changes. While temporal

    analyses cannot distinguish between the effects of vegetation changes and hominins, we

    show through spatial analyses of contemporary carnivores in Africa that only hominin causation

    is plausible. Our results suggest that substantial anthropogenic influence on biodiversity started

    millions of years earlier than currently assumed.

  • 135. Faurby, Søren
    et al.
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    Svenning, Jens-Christian
    The difference between trivial and scientific names: There were never any true cheetahs in North America2016In: Genome Biology, ISSN 1465-6906, E-ISSN 1474-760XArticle in journal (Other academic)
  • 136. Feng, Dong
    et al.
    Peckmann, Jörn
    Li, Niu
    Kiel, Steffen
    Swedish Museum of Natural History, Department of Paleobiology.
    Qiu, Jian-Wen
    Liang, Qianyong
    Carney, robert
    Peng, Yongbo
    Tao, Jun
    Chen, Duofu
    The stable isotope fingerprint of chemosymbiosis in the shell organic matrix of seep-dwelling bivalves2018In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 479, p. 241-250Article in journal (Refereed)
  • 137.
    Field, Daniel J
    et al.
    Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
    Bercovici, Antoine
    2Department of Paleobiology MRC-121, National Museum of Natural History, Smithsonian Institution, 10th Street and Constitution Avenue, NW, Washington, DC 20560-0121, USA.
    Berv, Jacob S
    Department of Ecology & Evolutionary Biology, Cornell University, 215 Tower Road, Ithaca, NY 14853, USA.
    Dunn, Regan
    Integrated Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605, USA.
    Fastovsky, David E
    Department of Geosciences, University of Rhode Island, 9 East Alumni Avenue, Kingston, RI 02881, USA.
    Lyson, Tyler R
    6Department of Earth Sciences, Denver Museum of Nature and Science, 2001 Colorado Boulevard, Denver, CO 80205, USA.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Gauthier, Jacques A
    Department of Geology & Geophysics, Yale University 210 Whitney Avenue, New Haven, CT 06511, USA.
    Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction2018In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 28, p. 1825-1831Article in journal (Refereed)
    Abstract [en]

    The fossil record and recent molecular phylogenies support an extraordinary early-Cenozoic radiation of crown birds (Neornithes) after the Cretaceous-Paleogene (K-Pg) mass extinction [1–3 ]. However, questions remain regarding the mechanisms underlying the survival of the deepest lineages within crown birds across the K-Pg boundary, particularly since this global catastrophe eliminated even the closest stem-group relatives of Neornithes [4 ]. Here, ancestral state reconstructions of neornithine ecology reveal a strong bias toward taxa exhibiting predominantly non-arboreal lifestyles across the K-Pg, with multiple convergent transitions toward predominantly arboreal ecologies later in the Paleocene and Eocene. By contrast, ecomorphological inferences indicate predominantly arboreal lifestyles among enantiornithines, the most diverse and widespread Mesozoic avialans [5–7 ]. Global paleobotanical and palynological data show that the K-Pg Chicxulub impact triggered widespread destruction of forests [8, 9 ]. We suggest that ecological filtering due to the temporary loss of significant plant cover across the K-Pg boundary selected against any flying dinosaurs (Avialae [10 ]) committed to arboreal ecologies, resulting in a predominantly non-arboreal postextinction neornithine avifauna composed of totalclade Palaeognathae, Galloanserae, and terrestrial total-clade Neoaves that rapidly diversified into the broad range of avian ecologies familiar today. The explanation proposed here provides a unifying hypothesis for the K-Pg-associated mass extinction of arboreal stem birds, as well as for the post-K-Pg radiation of arboreal crown birds. It also provides a baseline hypothesis to be further refined pending the discovery of additional neornithine fossils from the Latest Cretaceous and earliest Paleogene.

  • 138.
    Fielding, Christopher
    et al.
    University of Nebraska.
    Frank, Tracy
    University of Nebraska.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    Mays, Chris
    Swedish Museum of Natural History, Department of Paleobiology.
    Tevyaw, Allen
    University of Nebraska.
    Winguth, Arne
    University of Texas at Arlington.
    Winguth, Cornelia
    University of Texas at Arlington.
    Nicoll, Robert
    Geoscience Australia.
    Bocking, Malcolm
    Bocking Associates.
    Crowley, James
    Boise State University.
    Age and pattern of the southern high-latitude continental end-Permian extinction constrained by multiproxy analysis2019In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, no 385, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Past studies of the end-Permian extinction (EPE), the largest biotic crisis of the Phanerozoic, have not resolved the timing of events in southern high-latitudes. Here we use palynology coupled with high-precision CA-ID-TIMS dating of euhedral zircons from continental sequences of the Sydney Basin, Australia, to show that the collapse of the austral Permian Glossopteris flora occurred prior to 252.3 Ma (~370 kyrs before the main marine extinction). Weathering proxies indicate that floristic changes occurred during a brief climate perturbation in a regional alluvial landscape that otherwise experienced insubstantial change in fluvial style, insignificant reorganization of the depositional surface, and no abrupt aridification. Palaeoclimate modelling suggests a moderate shift to warmer summer temperatures and amplified seasonality in temperature across the EPE, and warmer and wetter conditions for all seasons into the Early Triassic. The terrestrial EPE and a succeeding peak in Ni concentration in the Sydney Basin correlate, respectively, to the onset of the primary extrusive and intrusive phases of the Siberian Traps Large Igneous Province.

  • 139. Forsten, A.
    et al.
    Fortelius, M.Werdelin, LarsSwedish Museum of Natural History, Department of Paleobiology.
    Björn Kurtén - a memorial volume1991Collection (editor) (Refereed)
  • 140. Fortelius, M.
    et al.
    Andrews, P.
    Bernor, R. L.
    Viranta, S.
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    Preliminary analysis of taxonomic diversity, turnover and provinciality in a subsample of large land mammals from the later Miocene of western Eurasia.1996In: Acta zoologica cracoviensia, Vol. 39, p. 167-178Article in journal (Refereed)
    Abstract [en]

    We have recently reviewed the later Miocene (MN 6-13; ca 15-5 Ma ago) primates, hipparions, rhinocerotids, suoids and carnivores of Europe and the eastern Mediterranean. This work is still unpublished and analyses are underway, but a preliminary indication of some coarse patterns is given here for the sample consisting of the groups listed above: 1) There is a clear-cut difference between western and Central Europe on one hand and the eastern Mediterranean on the other. This is especially clear for species richness, which shows a rising trend throughout the Vallesian and earlier Turolian for the eastern regions and a falling trend for the western ones. 2) The major drops in species richness occurred between MN 6 and MN 7, between MN 9 and MN 10, and between MN 12 and MN 13. Of these, the "mid-Vallesian crisis" (MN 9-10) seems to have been entirely absent in the eastern Mediterranean, where species richness rose sharply during this interval. Correspondingly, the drop in MN 12-13, associated with the Messinian crisis, was predominantly an eastern phenomenon. 3) Taxon free analysis of body size and ecomorphology strongly supports the view that a diachronous opening up of the landscape from east to west took place in western Eurasia during the Astaracian and Vallesian. We postulate that the difference seen in faunal dynamics between east and west reflects habitat-related effects of this diachrony in response to the same global event of rapid physical change. 4) The early Turolian (MN 11) was characterized by high diversity and high faunal similarity, which both decreased during the later Turolian and ended with the Messinian crisis. 5) Despite highly uniform diversity and turnover patterns throughout the interval, western and Central Europe developed distinct ecological differences from about MN 10 onwards. These differences may have been associated with the persistence of closed habitats in Central Europe.

  • 141. Fortelius, M.
    et al.
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    Andrews, P.
    Bernor, R. L.
    Gentry, A.
    Humphrey, L.
    Mittmann, H.-W.
    Viranta, S.
    Provinciality, diversity, turnover, and paleoecology in land mammal faunas of the later Miocene of western Eurasia1996In: The Evolution of Western Eurasian Miocene Mammal Faunas / [ed] Bernor, R.L., Fahlbusch, V. & Mittmann, H.-W., New York: Columbia University Press, 1996, p. 414-448Chapter in book (Refereed)
  • 142. Fortelius, Mikael
    et al.
    Žliobaitė, Indre
    Kaya, Ferhat
    Bibi, Faysal
    Bobe, René
    Leakey, Louise
    Leakey, Meave
    Patterson, David
    Rannikko, Janina
    Werdelin, Lars
    Swedish Museum of Natural History, Department of Paleobiology.
    An ecometric analysis of the fossil mammal record of the Turkana Basin2016In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 371, article id 20150232Article in journal (Refereed)
    Abstract [en]

    Although ecometric methods have been used to analyse fossil mammal faunas and environments of Eurasia and North America, such methods have not yet been applied to the rich fossil mammal record of eastern Africa. Here we report results from analysis of a combined dataset spanning east and west Turkana from Kenya between 7 and 1 million years ago (Ma). We provide temporally and spatially resolved estimates of temperature and precipitation and discuss their relationship to patterns of faunal change, and propose a new hypothesis to explain the lack of a temperature trend. We suggest that the regionally arid Turkana Basin may between 4 and 2 Ma have acted as a ‘species factory’, generating ecological adaptations in advance of the global trend. We show a persistent difference between the eastern and western sides of the Turkana Basin and suggest that the wetlands of the shallow eastern side could have provided additional humidity to the terrestrial ecosystems. Pending further research, a transient episode of faunal change centred at the time of the KBS Member (1.87–1.53 Ma), may be equally plausibly attributed to climate change or to a top-down ecological cascade initiated by the entry of technologically sophisticated humans.

  • 143.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter R.
    Pedersen, Kaj Raunsgaard
    Early flowers and angiosperm evolution2011Book (Other academic)
  • 144.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Chlamydospermous seeds document the diversity andabundance of extinct gnetalean relatives in Early Cretaceous vegetation2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, p. 643-666Article in journal (Refereed)
    Abstract [en]

    Premise of research. The recognition of diverse and abundant chlamydospermous seeds from the Early Cretaceous of Denmark, Portugal, and eastern North America has been an unexpected outcome of studies of mesofloras that were initially focused on early angiosperms. These seeds provide structural information critical for understanding morphological and structural diversity in an important Mesozoic group of extinct gnetalean relatives.

    Methodology. The fossil seeds were picked from Early Cretaceous mesofossil floras from localities in western Portugal and Virginia using a stereomicroscope. Selected seeds were studied in more detail for morphological and anatomical traits using SEM and synchrotron radiation X-ray tomographic microscopy.

    Pivotal results. Six new species of chlamydospermous seeds are described that add substantially to the known diversity of Early Cretaceous chlamydosperms. In general seed organization, the fossils are similar to seeds of extant Gnetales, but none of the fossils can be assigned to any of the three living genera of Gnetales (Ephedra, Gnetum, and Welwitschia). All six species have similar closure of the micropylar canal but show considerable variation in the anatomy of the seed envelope. In micropylar closure, the fossils are most similar to extant Gnetum, but they differ in other respects from seeds of extant Gnetum, and one of the new seed taxa has polyplicate, ephedroid pollen in the micropyle. A well-preserved embryo with two cotyledons is preserved in seeds of Rothwellia foveata and provides the first information on the embryo in this Early Cretaceous chlamydospermous complex.

    Conclusions. The chlamydospermous seeds described here show similarities to seeds of extant Gnetales. However, most of the fossils exhibit combinations of features that are unknown among extant species of Gnetales and clearly represent an extinct complex of plants that were important in Early Cretaceous vegetation, along with other extinct plant groups, including Bennettitales and Erdtmanithecales.

  • 145.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Extinct diversity among Early Cretaceous angiosperms: mesofossilevidence of early Magnoliales from Portugal2019In: International Journal of Plant Sciences, Vol. 180, p. 93-127Article in journal (Refereed)
    Abstract [en]

    Premise of research. Small angiosperm fossils are diverse in Early Cretaceous mesofossil floras from Portugal and eastern North America. Investigations of these fossils have revealed an unexpectedly high diversity of extinct angiosperms related to lineages that are now species poor, such as Austrobaileyales, Nymphaeales, and Chloranthaceae. Here we analyze Early Cretaceous fruits and seeds from Portugal that are related to eumagnoliid angiosperms and that are also important for understanding extinct diversity in early angiosperms.

    Methodology. The fossils were prepared by sieving in water; cleaned with HF, HCl, and water; and studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. The systematic conclusion based on comparative studies was tested in a phylogenetic analysis.

    Pivotal results. We recognize a new group of angiosperms based on fruits and seeds united by features that are otherwise unusual among angiosperms. Two genera, Serialis and Riaselis, are established and 10 species described. Both have unilocular fruiting units formed from a single carpel. Serialis has fruits with two or more seeds, while fruits of Riaselis are always one seeded. In Serialis, seeds are permanently attached to each other and dispersed as a unit. Both genera have anatropous and mesotestal-endotestal seeds with a tiny embryo and a distinctive vasculature in the testa extending from the hilum to the chalaza and then also on the antiraphal side to the micropyle. The fossils are most similar to seeds of Magnoliales but also share some features with seeds of Austrobaileya.

    Conclusions. Serialis and Riaselis are the earliest fossils that can be assigned to the Magnoliales but are sufficiently different from those of all Magnoliales that they cannot be assigned to any extant family. Serialis and Riaselis provide further documentation of extensive extinct diversity among early angiosperms, and their abundance in the mesofossil floras suggests that they were common and widespread in early angiosperm communities.

  • 146.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Garden Foundation.
    Pedersen, Kaj Raunsgaard
    Århus University.
    Extinct taxa of exotestal seeds close toAustrobaileyales and Nymphaeales from the Early Cretaceous of Portugal2018In: Fossil Imprint, ISSN ISSN 2533-4050, Vol. 74, p. 135-158Article in journal (Refereed)
    Abstract [en]

    Early Cretaceous mesofossil floras from Portugal and North America include a surprising diversity of small, bitegmic angiosperm seeds with a hard exotestal seed coat. This study describes six different kinds of these seeds from three Portuguese mesofossil localities; Vale de Agua, Torres Vedras, and especially from Famalicão, which has yielded a flora exceptionally rich in exotestal seeds. All the seeds are almost smooth with a characteristic jigsaw puzzle-shaped surface pattern that is formed from the strongly undulate anticlinal walls of the sclerenchyma cells that comprise the exotesta. Several specimens have internal details preserved, including remains of a cellular nutritive tissue interpreted as endosperm, and a tiny embryo with two rudimentary cotyledons. Based on differences in details of the seed coat, and configuration of hilum and micropyle, the fossil seeds are assigned to six new genera, as six new species: Gastonispermum portugallicum gen. et sp. nov., Pazlia hilaris gen. et sp. nov., Pazliopsis reyi gen. et sp. nov., Reyispermum parvum gen. et sp. nov., Lusitanispermum choffatii gen. et sp. nov. and Silutanispermum kvacekiorum gen. et sp. nov. The characteristic exotestal cells with undulate anticlinal walls, details of the hilar and micropylar region, together with the tiny dicotyledonous embryos with rudimentary cotyledons, suggest close relationships to seeds of Nitaspermum and Tanispermum described previously from Early Cretaceous mesofossil floras from eastern North America. These exotestal seeds from Portugal and North America indicate the presence of diverse extinct early angiosperms close to the lineages that today include extant Austrobaileyales and Nymphaeales.

  • 147.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Garden Foundation.
    Pedersen, Kaj Raunsgaard
    Århus University.
    Fossil seeds with affinities to Austrobaileyales andNymphaeales from the Early Cretaceous (early-middle Albian) of Virginia andMaryland, U.S.A: new evidence for extensive extinction near the base of theangiosperm tree2018In: Transformative Paleobotany: Papers to Commemorate theLife and Legacy of Thomas N. Taylor / [ed] Krings M, Harper CJ, Cúneo NR, Rothwell GW, London: Academic Press, 2018, p. 417-435Chapter in book (Refereed)
    Abstract [en]

    Early Cretaceous seeds from Virginia and Maryland, USA, part of a diverse complex of exotestal seeds in Early Cretaceous mesofossil floras from North America and Europe, provide new evidence of extensive extinction among early angiosperms. The seeds are assigned to a new genus, Nitaspermum, with six species: N. taylorii, N. hopewellense, N. crassum, N. virginiense, N. marylandense, and Nitaspermum sp. All seeds are small, anatropous, bitegmic, and exotestal, with the exotesta composed of a single layer of short, columnar sclerenchyma with strongly folded walls. Nitaspermum shows features of extant Austrobaileyales (Illiciaceae) and Nymphaeales but also critical differences precluding assignment to extant families. These discoveries are consistent with predictions from molecular phylogenetics that indicate the differentiation of Illiciaceae and Nymphaeales early in angiosperm evolution, but the diversity of such seeds underlines the extent to which the pattern of extant angiosperm diversity has been shaped by widespread extinction early in angiosperm evolution.

  • 148.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Geminispermum, an Early Cretaceous (early–middle Albian) cupulate unit from the angiosperm-dominated Puddledock flora of eastern North America2019In: Acta Palaeobotanica, ISSN 0001-6594, E-ISSN 1427-6402, Vol. 59, p. 229-239Article in journal (Refereed)
    Abstract [en]

    A new genus and species, Geminispermum virginiense, is described based on a well-preserved coalified cupulate reproductive unit recovered from the Early Cretaceous (early–middle Albian) Puddledock locality, Virginia, U.S.A. The reproductive unit is bisymmetrical and consists of an axis that bifurcates into two cupule-bearing stalks, each in the axil of a bract. Each cupule stalk bears a single non-valvate cupule recurved towards the center of the reproductive unit. The cupule opens distally by a short transverse slit with a distinct upper margin. Each cupule almost completely encloses a single orthotropous seed that is free from the cupule except at the base. The nucellus is also free from the integument except at the basal point of attachment. Geminispermum combines features of the ovulate structures of Caytoniales, Umkomasiales (= Corystospermales, including Doyleales) and Petriellales, but cannot be included in any of these existing orders as they are currently understood. The recurved, closed, non-valvate cupules are particularly similar to those of Caytonia, Petriellaea and Reymanownaea in external morphology, but differ in being one-seeded. The cupules of Geminispermum differ from the one-seeded cupules of Umkomasiales in being non-valvate and in having only a single cupule per bract. Geminispermum is perhaps most similar to the one- or two-seeded non-valvate cupules of Ktalenia from the Early Cretaceous of Argentina, but Ktalenia is poorly preserved, details of cupule architecture are uncertain, and the cupules appear to be associated with a single strongly dissected bract. Geminispermum is currently the only unequivocal seed plant cupule recovered from the Early Cretaceous Potomac Group and is distinct from all previously described cupulate reproductive structures.

  • 149.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Hedyosmum-like fossils in the Early Cretaceous diversification of angiosperms2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, p. 232-239Article in journal (Refereed)
    Abstract [en]

    Premise of research. Early Cretaceous Hedyosmum-like fossils are important because they provide information on the pistillate flowers and fruits of plants that produced Asteropollis pollen, which is common and widely distributed very early in the history of angiosperms. Hedyosmum (Chloranthaceae) is also the only extant genus for which there is a plausible fossil presence at such an early stage of angiosperm evolution.

    Methodology. The fossils were sieved out of unconsolidated sediments and cleaned with HF, HCl, and water. External morphology and internal anatomy were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy.

    Pivotal results. New information on Hedyosmum-like fossils is provided based on pistillate flowers and fruits with adhering Asteropollis pollen from the Early Cretaceous of Portugal. The fossils are assigned to a new Early Cretaceous taxon, Hedyflora crystallifera, which in external morphology is closely similar to extant Hedyosmum. However, the fossils differ from the extant genus in having a crystalliferous endotesta with cells that have endoreticulate infillings, a feature characteristic of all extant Chloranthaceae except Hedyosmum. Extant Hedyosmum has a thin, unspecialized seed coat. This new discovery confirms earlier predictions that an endotestal seed coat is ancestral for Chloranthaceae as a whole but has been lost in the lineage leading to extant Hedyosmum.

    Conclusions. Hedyflora confirms the divergence of the Hedyosmum lineage from other Chloranthaceae very early in the angiosperm radiation but refutes these early fossils as evidence of extant Hedyosmum in the Early Cretaceous.

  • 150.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Garden Foundation.
    Pedersen, Kaj Raunsgaard
    Århus University.
    Rightcania and Kvacekispermum: Early Cretaceous seeds from eastern North America and Portugal provide further evidence of the early chloranthoid diversification2018In: Fossil imprint, ISSN ISSN 2533-4050, Vol. 74, p. 65-76Article in journal (Refereed)
    Abstract [en]

    Abundant flowers, fruits, seeds and stamens that are closely related to extant Chloranthaceae have been reported from the Early Cretaceous floras of Portugal. Among these are small berries with endotestal seeds assigned to the extinct genera Canrightia and Canrightiopsis. Here we describe two new genera, each including a single species, based on fossil fruits and seeds from the Early Cretaceous of eastern North America and Portugal. Both genera have pendent, orthotropous, bitegmic and endotestal ovules/seeds, in which the endotesta consists of a layer of cubic to palisade-shaped crystal cells with endoreticulate fibrous infillings, a combination of features that also characterize Canrightia and Canrightiopsis and that among extant angiosperms are known only for members of the Chloranthaceae. Rightcania kvacekii gen. et sp. nov. from the early to middle Albian Puddledock mesofossil flora of Virginia, USA, is the first representative in the Early Cretaceous floras of North America of a chloranthaceous fossil related to Canrightia and Canrightiopsis. It has three- to five-seeded fruits very similar to fruits and seeds of Canrightia, also with a pronounced tegmen that probably functioned as a nutritive tissue for the developing embryo. Fruits and seeds of Rightcania are larger than those of Canrightia, and also differ in details of the seed coat. Kvacekispermum rugosum gen. et sp. nov. is rare in the late Aptian to early Albian Portuguese mesofossil flora from Vale de Água. It differs from Canrightiopsis in the coarsely rugulate outer surface of the endotesta and its larger size, but is closely similar in the general structure of seed coat and nutritive tissue. Together, Rightcania and Kvacekispermum provide further evidence of the early diversity achieved by chloranthoid angiosperms before the end of the Early Cretaceous.

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