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Candle wax shells, morphodynamics, and the Cambrian explosion

100%

Seilacher A.

Acta Palaeontologica Polonica

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1993

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tom 38

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nr 3-4

2

Upper Cambrian trilobite ichnocoenosis from Wielka Wisniowka (Holy Cross Mountains, Poland)

72%

Radwanski A., Roniewicz P.

Acta Palaeontologica Polonica

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1963

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tom 08

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nr 2

Description is given of the Upper Cambrian trilobite ichnocoenosls, i.e. a trace assemblage of the various life activities of trilobites, from the shallow-water marine deposits at Wielka Wiśniówka in the Holy Cross Mountains (Góry Świętokrzyskie). These traces occur either on the upper sides of layers (true traces) or on the lower sides of layers covering grooves made by trilobites on the sea bottom (sole markings = hieroglyphs). Hieroglyphs are the more common forms. Out of them, Rusophycus sp., Cruziana sp., Diplichnites sp. and Dimorphichnus sp. have been described in greater detail. Bergaueria perata Prantl and Diplocraterion sp. hieroglyphs are also encountered in the trilobite ichnocoenosis here reported.

3

An enigmatic, possibly chemosymbiotic, hexactinellid sponge from the early Cambrian of South China

72%

Botting J. P., Muir L. A., Li X.-F., Lin J.-P.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 3

Six specimens of a strongly curved, cylindrical hexactinellid sponge have been recovered from the Tommotian– Atdabanian Hetang Biota of South China, and are described as Decumbispongia yuani gen. et sp. nov. The robust, thick−walled sponge shows no evidence of an osculum or basal structures, and the body form is inconsistent with an upright, filter−feeding life position. Interpretations as a detritivore feeding by amoeboid extensions, or as a facultative chemosynthetic symbiosis of sponge and bacteria are considered. The latter interpretation is preferred due to the highly constrained body shape, and the body form is interpreted from this perspective. The species indicates that Cambrian sponges occupied at least some autecological niches that appear to have been vacant since that time.

4

The oldest isorophid edrioasteroid [Echinodermata] and the evolution of attachment strategies in Cambrian edrioasteroids

72%

Zamora S., Smith A. B.

Acta Palaeontologica Polonica

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2010

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tom 55

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nr 3

487-494

Two new middle Cambrian edrioasteroid (Echinodermata), Protorophus hispanicus gen. et sp. nov., and Isorophida gen. et sp. indet., are described from the early middle Cambrian (Cambrian Series 3, Stage 5) of Spain. These are the oldest and probably the most primitive isorophids, a clade previously known from the upper Cambrian onwards. Specimens are attached to trilobite fragments indicating that edrioasteroids had by this time separated into two lineages each with different strategies for attachment, sediment attachers and hard substrate attachers. The single U−shaped ambulacral flooring plates of Protorophus are unique while Isorophida gen. et sp. indet. shares the presence of spines in common with some pyrgocystitid isorophids. The shift from facultative soft−bottom attachment to obligate hard−ground attachment in edrioasteroids involved the retention of a juvenile trait into adulthood and was already underway by the middle Cambrian.

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A Marrella-like arthropod from Cambrian of Australia: A new link between "Orsten"-type and Burgess Shale assemblages

72%

Haug J. T., Castellani C., Haug C., Waloszek D., Maas A.

Acta Palaeontologica Polonica

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2013

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tom 58

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nr 3

An isolated exopod in uncompressed three−dimensional “Orsten”−type preservation from the Cambrian of Australia represents a new species of Marrellomorpha, Austromarrella klausmuelleri gen. et sp. nov. The exopod is composed of at least 17 annuli. Each of the proximal annuli carries a pair of lamellae: one lamella on the lateral side and one on the median side. The distal annuli bear stout spines in the corresponding position instead of lamellae, most likely representing early ontogenetic equivalents of the lamellae. The new find extends the geographical range of the taxon Marrellomorpha. Additionally, it offers a partial view into marrellomorph ontogeny. The occurrence of a marrellomorph fragment in “Orsten”−type preservation provides new palaeo−ecological insights into the possible connections between the “Orsten” biotas and other fossil Lagerstätten. Finding such connections is necessary for understanding the complex ecosystems of early Palaeozoic times.

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The new stem-group brachiopod Oymurania from the lower Cambrian of Siberia

72%

Kouchinsky A., Holmer L. E., Steiner M., Ushatinskaya G. T.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 4

A stem-group brachiopod, Oymurania gravestocki Ushatinskaya gen. et sp. nov. is described herein from the middle Atdabanian-lower Botoman Stages (-Cambrian Stage 3) of the Siberian Platform. The fossils were extracted from limestone beds of the Emyaksin, Perekhod, and Pestrotsvet formations as assemblages of disarticulated orthoconic to cyrtoconic porous shells in apatite preservation. The originally organophosphatic shells of Oymurania are externally similar to mitral sclerites (ventral valves) of the stem-group brachiopod Micrina, although no sellate-like sclerites, nor differentiated subapical area with apophyses were recognised in our material. The range of Oymurania shells with sub-central to posteromarginal apex is similar to that of ventral valves ofMickwitzia. Oymurania is also characterised by the system of radial and orthogonal canals open in pairs or triplets in small depressions or indentations of growth lamellae in the outer shell surface. The orthogonal (Micrina-Setatella type) and radial (horizontal setigerous tubes) canals are widespread among the early Cambrian stem-group brachiopods, such as Micrina, Mickwitzia, and Setatella. In addition to these canals, Oymurania exhibits a well-developed acrotretoid columnar microstructure, also known from Setatella. A broad subapical platform in cyrtoconic shells (presumably ventral valves) of Oymurania is interpreted homologous to the deltoid area in mitrals of Micrina and pseudointerarea/interarea in ventral valves of Setatella/paterinid brachiopods. Except with probable cell imprints and openings of orthogonal canals, no morphological differentiation was, however, reflected by the shell interior of Oymurania gravestocki. Being closely related to tannuolinids and mickwitziids, Oymurania complements the picture of diversification of the early Cambrian stem-group brachiopods that occurred in parallel with radiation of paterinids and other crow-group brachiopods on the Siberian Platform and worldwide.

7

Bradoriid arthropods from the lower - middle Cambrian of Scania, Sweden

72%

Dies Alvarez M. E., Gozalo R., Cederstrom P., Ahlberg P.

Acta Palaeontologica Polonica

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2008

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tom 53

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nr 4

Three species of bradoriid arthropods from the lower to middle Cambrian transitional interval of Scania, southern Sweden, are described and illustrated: Beyrichona tinea from the top of the traditional lower Cambrian (Gislöv Formation; Ornamentaspis? linnarssoni Zone), and Hipponicharion eos and Alutella sp. from the basal portion of the traditional middle Cambrian (lowermost part of the Alum Shale Formation). The bradoriid fauna compares most closely with others previously described from western and eastern Avalonia (New Brunswick and England). The record of B. tinea suggests a correlation between the “Protolenus Zone” (Hupeolenus Zone) of western Avalonia and the O.? linnarssoni Zone of Scandinavia. Hipponicharion eos appears to be a fairly long−ranging species as it has previously been recorded from upper lower Cambrian or lower middle Cambrian strata in New Brunswick, Poland, and probably Sardinia. The record of H. eos from the lowermost part of the Alum Shale Formation suggests that this largely unfossiliferous interval in the Scanian succession is not younger than the Acadoparadoxides oelandicus Superzone. The genus Alutella has not previously been recorded from the Acado−Baltic Province.

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The fine structure of zooidal tubes in Sabelliditida and Pogonophora with reference to their affinity

72%

Urbanek A., Mierzejewska G.

Acta Palaeontologica Polonica

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1977

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tom 22

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nr 3

Organic tubes of Sabelliditidae are a characteristic element of Lower Cambrian faunas. They were commonly compared with tubes of sedentary polychaetes, until Sokolov (1965) suggested their close affinity with Recent pogonophores. The aim of the present paper is to verify the latter hypothesis through a better understanding of ultrastructural features of zooidal tubes in both groups considered. The ultrastructure of the tube in Sabelliditida recognized for the first time by Urbanek, 1976 (in press), reveals that the wall of the tube is composed of two almost homogenous layers - the outer one and the inner one, and of the middle distinctly laminar layer. Characteristic wrinkles on the outer surface of the tube are made solely of the outer layer which is almost homogenous or with faint traces of some lammiation. The tubes in all Pogonophora under study display an entirely laminar structure. Wrinkles observed on certain areas of the tube are due to foldings involving numerous layers of the tube wall. Earlier biochemical and ultrastructural data and results of our ultrahistochemical observations are indicative of the presence of chitin, proteins (probably sclerotins) and mucopolysaccharides in the pogonophore tubes. The above results contribute to a better knowledge of the organic skeleton in both groups in question, but the problem of sabelliditid/pogonophore affinities remains unresolved. The degree and specificity of resemblance recognized at the submicroscopic level is not sufficient to confirm or disprove the hypothesis on close relationship between both groups considered.

9

Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

72%

Ahlberg P., Szaniawski H., Clarkson E. N. K., Bengtson S.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Secondarily phosphatised olenid trilobites from organic−rich limestones (orsten) in the Furongian (Upper Cambrian) of Västergötland, south−central Sweden, are described and illustrated. All trilobites originate from the Peltura scarabaeoides Zone and were collected on the western slope of Kinnekulle. Only the dorsal exoskeletons have become secondarily phosphatised, and the ventral appendages are not preserved. Yet the material is otherwise remarkably well preserved and reveals the morphology of the olenid trilobites in greater detail than hitherto known. Species belonging to the genera Ctenopyge, Sphaerophthalmus, Parabolina, and Peltura are identified, and several juvenile specimens are present in the material. The material is disarticulated and fragmentary, and it has only been possible to identify a few specimens to species level. In addition to chaetognaths and conodonts, the trilobites are associated with pelmatozoan columnals, a possible camaroid, and fossils of uncertain affinities. These fossils, along with a probable conulariid fragment from the Peltura minor Zone, are also described and discussed. The presence of a benthic fauna of pelmatozoans, and possible conulariids and camaroids, indicates that at least parts of the Peltura zones were deposited during dysoxic rather than anoxic periods. Moreover, the sea floor must have been firm enough to allow colonisation by sessile organisms.

10

Problematic microfossils from calc-silicate rocks of the Owiesno amphibolites [Gory Sowie Gneissic Block, SW Poland] - Preliminary results

72%

Gunia T.

Bulletin of the Polish Academy of Sciences. Earth Sciences

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1997

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tom 45

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nr 2-4

11

Outline of palaeozoic geology of the Southern Lublin Region

72%

Pawlowski S.

Bulletin of the Polish Academy of Sciences. Earth Sciences

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1992

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tom 40

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nr 2

12

The Early Cambrian origin of thylacocephalan arthropods

72%

Vannier J., Chen J. Y., Huang D. Y., Charbonnier S., Wang X. Q.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 2

Zhenghecaris shankouensis gen. et sp. nov. is one of the largest “bivalved” arthropods of the Lower Cambrian Maotianshan Shale fauna. Its non−mineralized carapace was dome−like, laterally compressed, armed with rostral features, and probably enclosed the entire body of the animal. Zhenghecaris was provided with elliptical stalked lateral eyes. The carapace design, external ornament and visual organs of Zhenghecaris suggest affinities with the Thylacocephala, an extinct (Lower Silurian to Upper Cretaceous) group of enigmatic arthropods whose origins remain poorly understood. The bivalved arthropodsIsoxys and Tuzoia (Lower and Middle Cambrian) are two other potential thylacocephalan candidates making this group of arthropods a possible new component of Cambrian marine communities. Zhenghecaris, Isoxys, and Tuzoia are interpreted as nektonic animals that probably inhabited the lower level of the water column in shallow shelf settings at depths of perhaps 100–150 m or less. Their feeding mode either in the water column (e.g., mesozooplankton) or on the substrate (e.g., small epibenthos, detritus) is uncertain, although some of these arthropods were possibly mid−water predators (e.g., Isoxys with raptorial appendages).

13

Upper Cambrian trilobite biostratigraphy and taphonomy at Kakeled on Kinnekulle, Vastergotland, Sweden

72%

Terfelt F.

Acta Palaeontologica Polonica

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2003

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tom 48

|

nr 3

A section through the Upper Cambrian black shales and limestones at Kakeled on Kinnekulle, Västergötland, Sweden, extends from the lower–middle part of the Agnostus pisiformis Zone into the Peltura scarabaeoides Zone. Fossils are usually preserved only in the stinkstones, but in the A. pisiformis Zone trilobites can be found also in the shales. Lithologically, the stinkstones can be subdivided into primary coquinoid limestone, which include the majority of the fossils, and early diagenetically formed limestone. The orientation of cephala and pygidia of A. pisiformis were measured on four shale surfaces and one stinkstone surface. The majority of the shields were deposited with the convex side up and showed a preferred orientation, suggesting that their positions were affected by currents. Above the A. pisiformis Zone the section comprises the Olenus/Homagnostus obesus Zone (0.30 m), the upper part of the Parabolina spinulosa Zone (0.05 m), the Peltura minor Zone (1.15 m), and the Peltura scarabaeoides Zone (2.50 m). The Leptoplastus and Protopeltura praecursor zones are missing. The Olenus/H. obesus Zone is represented only by the O. gibbosus and O. wahlenbergi subzones, whereas the O. truncatus, O. attenuatus, O. dentatus, and O. scanicus subzones are missing.

14

Shell microstructures in Early Cambrian molluscs

72%

Kouchinsky A.

Acta Palaeontologica Polonica

|

2000

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tom 45

|

nr 2

The affinities of a considerable part of the earliest skeletal fossils are problematical, but investigation of their microstructures may be useful for understanding biomineralization mechanisms in early metazoans and helpful for their taxonomy. The skeletons of Early Cambrian mollusc-like organisms increased by marginal secretion of new growth lamellae or sclerites, the recognized basal elements of which were fibers of apparently aragonite. The juvenile part of some composite shells consisted of needle-like sclerites; the adult part was built of hollow leaf-like sclerites. A layer of mineralized prism-like units (low aragonitic prisms or flattened spherulites) surrounded by an organic matrix possibly existed in most of the shells with continuous walls. The distribution of initial points of the prism-like units on a periostracurn-like sheet and their growth rate were mostly regular. The units may be replicated on the surface of internal molds as shallow concave polygons, which may contain a more or less well-expressed tubercle in their center. Tubercles are often not enclosed in concave polygons and may co-occur with other types of textures. Convex polygons seem to have resulted from decalcification of prism-like units. They do not co-occur with tubercles. The latter are interpreted as casts of pore channels in the wall possibly playing a role in biomineralization or pits serving as attachment sites of groups of mantle cells. Casts of fibers and/or lamellar units may overlap a polygonal texture or occur without it. They may reflect an inner layer consisting of aragonitic fibers fused into more or less well-developed lamellar units. It seems that nacreous and crossed-lamellar aragonitic microstructures evolved in the Cambrian from such lamellar aragonitic microstructures independently in different groups of molluscs.

15

Correlation of Proterozoic and Cambrian lithostratigraphic units across Torellbreen, Wedel Jarlsberg Land, Spitsbergen

72%

Birkenmajer K.

Bulletin of the Polish Academy of Sciences. Earth Sciences

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1994

|

tom 42

|

nr 4

16

Phosphate replicated and replaced microstructure of molluscan shells from the earliest Cambrian of China

72%

Feng W., Sun W.

Acta Palaeontologica Polonica

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2003

|

tom 48

|

nr 1

The earliest Cambrian Meishucunian phosphoritic succession in eastern Yunnan,China,contains well−preserved molluscan shells that offer insights into the early evolution of skeletonization. Phosphate internal moulds,phosphate replaced originally carbonate shells,and phosphate coatings show lamello−fibrillar structure,prismatic structure,and regularly foliated structure. The lamello−fibrillar structure appears earlier in the fossil record than laminar structures such as nacreous or foliated structures. It has been identified in fossil mollusks,which occur in China as early as the lower phosphate layer of the Zhongyicun Member of the Meishucunian. Therefore,the lamello−fibrillar structure appears to be primitive in mollusks. The lamello−fibrillar and prismatic aragonite is the most common shell material of molluscan skeletons in the Early Cambrian Meishucunian and equivalents around the world. Although the early molluscan microstructure is not so diverse as that of extant mollusks,it may be of use in high rank taxonomic classification as shown by the early conchiferan mollusks discussed here. These mollusks are characterized by the horizontal fibrillae that are layered and parallel,and thereby differ from hyoliths,in which the horizontal fibrillae appear to be in the form of the bundles of fibres that can branch or anastomose.

17

Early introduction of major morphological innovations

72%

Erwin D. H.

Acta Palaeontologica Polonica

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1993

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tom 38

|

nr 3-4

The origin of major morphological innovations poses a major problem for macroevolutionary biologists. Such innovations appear to be overwhelmingly concentrated early in the history of major clades; subsequent evolution involves elaboration and variation on these early themes. Although confirmation of this pattern requires morphometric techniques only now being developed, it seems too firmly established to be an illusion. A variety of explanations have been advanced for the extensive morphologic innovation during the Cambrian radiation, including the ecospace hypothesis which relies on more extensive ecospace, and a variety of genomic hypotheses ranging from a more rapid rate of real or apparent mutation, to novel types of genetic change, or novel effects within a more plastic developmental system. Recently some theorists have suggested the inherent properties of complex dynamic systems are a sufficient explanation. However, most discussions have emphasized the ecosystem and genomic hypotheses. These have proven difficult to disentangle because no unique predictions about expected patterns have been proposed, but I suggest here phylogenetic tests which do discriminate between these possibilities. There is a curious distinction between the empty ecospace hypothesis and one variant of the developmental hypothesis: Under the former, extensive morphologic innovation should be possible whenever extensive ecospace becomes available. The constraints on innovation are atemporal and extrinsic. In contrast, under the second scenario the formation of developmental systems itself constrains further innovation. Thus the concentration of innovation early in the history of clades may stem from irreversible changes associated with the origin, rather than subsequent modification, of development.

18

Middle Cambrian lingulate brachiopods from the Tarbagatay Range, Kazakhstan

72%

Popov L. E., Holmer L. E., Gorjansky V. J.

Acta Palaeontologica Polonica

|

1996

|

tom 41

|

nr 3

Early Middle Cambrian (Amgian) lingulate brachiopods from the Tarbagatay Range in eastern Kazakhstan represent mostly endemic taxa, which may suggest that the Tarbagatay Range was relatively isolated from adjacent terranes during that time; only Kleithriatreta indicate similarity with the Australian part of Gondwana, as well as with the south and central Kazakhstanian terranes. Late Middle Cambrian (Mayan) taxa from the same area are mostly cosmopolitan. Kostjubella relaxata gen. et sp. n., Prototreta (?) dolosa sp. n. and Stilpnotreta galinae sp. n. are proposed.

19

The lobopod Onychodictyon from the Lower Cambrian Chengjiang Lagerstatte revisited

72%

Liu J., Shu D., Han J., Zhang Z., Zhang X.

Acta Palaeontologica Polonica

|

2008

|

tom 53

|

nr 2

Onychodictyon ferox, from the Lower Cambrian Chengjiang Lagerstätte, is a worm−like armored lobopod with 10 pairs of dorsal plates and a pair of probable sensory appendages (“antennae”). Newly discovered complete specimens show that Onychodictyon is represented by two species: O. ferox with a “head” bearing a pair of dorsal “antennae” and a trunk with 11 pairs of limbs, whereas O. gracilis has a blunt anterior end without any appendages and a trunk with 12 pairs of limbs. Because of the close resemblance of the “antennae” of O. ferox and those of the lobopod Miraluolishania, they are considered to be homologous structures. The “antennae” of Cambrian lobopodians are proposed to be homologous with the arthropod antennulae.

20

Cambrian chaetognaths recognized in Burgess Shale fossils

72%

Szaniawski H.

Acta Palaeontologica Polonica

|

2005

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tom 50

|

nr 1

Oesia disjuncta, one of the species of the soft−bodied fauna collected and described by Walcott (1911) from the Middle Cambrian Phyllopod Bed (Burgess Shale, British Columbia, Canada) is recognized as a chaetognath. For anatomical comparisons many specimens of Recent chaetognaths were specially compressed and dried to obtain forms similar to the fossils preserved in shales. The most characteristic features shared by the fossil and Recent specimens include: strongly elongated, transversely striated and very flexible body, large size, and characteristically diversified shape of head, pronounced intestine and horizontally oriented caudal fin. Possible traces of other chaetognath structures—grasping apparatus, lateral fins, seminal vesicles, ventral ganglion, ovaries and anus—are also present but preserved in one specimen only. Among extant genera, those showing the closest similarity to Oesia Walcott, 1911 are the hyperbenthic Archeterokrohnia Casanova, 1986¹, and Heterokrohnia Ritter−Záhony, 1911, which are considered by some authors as evolutionarily most primitive.

Ograniczanie wyników

Candle wax shells, morphodynamics, and the Cambrian explosion

Upper Cambrian trilobite ichnocoenosis from Wielka Wisniowka (Holy Cross Mountains, Poland)

An enigmatic, possibly chemosymbiotic, hexactinellid sponge from the early Cambrian of South China

The oldest isorophid edrioasteroid [Echinodermata] and the evolution of attachment strategies in Cambrian edrioasteroids

A Marrella-like arthropod from Cambrian of Australia: A new link between "Orsten"-type and Burgess Shale assemblages

The new stem-group brachiopod Oymurania from the lower Cambrian of Siberia

Bradoriid arthropods from the lower - middle Cambrian of Scania, Sweden

The fine structure of zooidal tubes in Sabelliditida and Pogonophora with reference to their affinity

Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

Problematic microfossils from calc-silicate rocks of the Owiesno amphibolites [Gory Sowie Gneissic Block, SW Poland] - Preliminary results

Outline of palaeozoic geology of the Southern Lublin Region

The Early Cambrian origin of thylacocephalan arthropods

Upper Cambrian trilobite biostratigraphy and taphonomy at Kakeled on Kinnekulle, Vastergotland, Sweden

Shell microstructures in Early Cambrian molluscs

Correlation of Proterozoic and Cambrian lithostratigraphic units across Torellbreen, Wedel Jarlsberg Land, Spitsbergen

Phosphate replicated and replaced microstructure of molluscan shells from the earliest Cambrian of China

Early introduction of major morphological innovations

Middle Cambrian lingulate brachiopods from the Tarbagatay Range, Kazakhstan

The lobopod Onychodictyon from the Lower Cambrian Chengjiang Lagerstatte revisited

Cambrian chaetognaths recognized in Burgess Shale fossils