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Journal articles on the topic 'Pterobranchs'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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1

Rigby, Susan, and P. Noel Dilly. "Growth rates of pterobranchs and the lifespan of graptolites." Paleobiology 19, no. 4 (1993): 459–75. http://dx.doi.org/10.1017/s0094837300014081.

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Pterobranchs are the closest living relatives of graptolites. Their skeleton is constructed from the same material, and in a homologous manner. Growth rates of the pterobranch Cephalodiscus gracilis are described for the first time and, along with rhabdopleuran growth rates, they are used to estimate the amount of time invested by a graptolite colony in growing its rhabdosome. This is a measure of minimum age. The significance of age calculations is shown for individuals and large communities of graptoloids. Large individuals can be shown to be much older than the time it would have taken them to settle through seawater and so it is shown that graptoloids moved up, as well as down, through the water column. Life tables constructed for biserial graptoloids from the Utica shale in Quebec, Canada, suggest that these graptoloids died from constant environmental stress. Graptoloid length can thus be a function of environment and should only cautiously be considered to be of taxonomic significance.

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2

Sato, Atsuko. "Seasonal reproductive activity in the pterobranch hemichordate Rhabdopleura compacta." Journal of the Marine Biological Association of the United Kingdom 88, no. 5 (June 24, 2008): 1033–41. http://dx.doi.org/10.1017/s0025315408001604.

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Pterobranchs are small marine filter feeders in the phylum Hemichordata. Their phylogenetic position and anatomical structure has resulted in pterobranchs featuring in many scenarios concerning the evolution of chordates. Despite this interest, the basic reproductive biology of pterobranchs is still poorly known. To address this issue, the reproductive season of Rhabdopleura compacta was investigated by collecting specimens in 2004–2007 from a population growing on disarticulated bivalve shells off the south coast of Devon, UK. I analysed reproductive status by categorizing shells according to the condition of the colonies growing on them. The frequency of shells having mature females was almost constant from spring to autumn among shells with active colonies. However, it was apparent that: (a) shells having mature females were more likely to be incubating embryos or larvae in June and July than other months; and (b) the production of embryos was high in June, and then decreased by July. Thus, despite the previous speculation that the species is capable of successful sexual reproduction throughout the year, the present study shows seasonality in reproduction of R. compacta, with at least a peak season during summer.

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3

LoDuca, Steven T., Jean-Bernard Caron, James D. Schiffbauer, Shuhai Xiao, and Anthony Kramer. "A reexamination of Yuknessia from the Cambrian of British Columbia and Utah." Journal of Paleontology 89, no. 1 (January 2015): 82–95. http://dx.doi.org/10.1017/jpa.2014.7.

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AbstractTo investigate the phylogenetic affinity of Yuknessia simplex Walcott, 1919, scanning electron microscopy was applied to the Burgess Shale (Cambrian Series 3, Stage 5) type material and to new material from the Trilobite Beds (Yoho National Park) and specimens from the Cambrian of Utah. On the basis of fine-scale details observed using this approach, including banding structure interpreted as fusellae, Yuknessia Walcott, 1919 is transferred from the algae, where it resided for nearly a century, to the extant taxon Pterobranchia (Phylum Hemichordata). Considered as such, Yuknessia specimens from the Trilobite Beds and Spence Formation (Utah) are amongst the oldest known colonial pterobranchs. Two morphs regarded herein as two different species are recognized from the Trilobite Beds based on tubarium morphology. Yuknessia simplex has slender erect tubes whereas Yuknessia stephenensis n. sp., which is also known in Utah, has more robust erect tubes. The two paratypes of Y. simplex designated by Walcott (1919) are formally removed from Yuknessia and are reinterpreted respectively as an indeterminate alga and Dalyia racemata Walcott, 1919, a putative red alga.

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4

Dilly, P. N. "Modern pterobranchs: observations on their behaviour and tube building." Geological Society, London, Special Publications 20, no. 1 (1986): 261–69. http://dx.doi.org/10.1144/gsl.sp.1986.020.01.27.

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5

Hu, Shixue, Bernd-D. Erdtmann, Michael Steiner, Yuandong Zhang, Fangchen Zhao, Zhiliang Zhang, and Jian Han. "Malongitubus: a possible pterobranch hemichordate from the early Cambrian of South China." Journal of Paleontology 92, no. 1 (December 4, 2017): 26–32. http://dx.doi.org/10.1017/jpa.2017.134.

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AbstractMalongitubus kuangshanensis Hu, 2005 from the early Cambrian Chengjiang Lagerstätte of China is redescribed as a pterobranch and provides the best evidence to demonstrate that hemichordates were present as early as Cambrian Stage 3. Interpretation of this taxon as a hemichordate is based on the morphology of the branched colony and the presence of resistant inner threads consistent with the remains of an internal stolon system. The presence of fusellar rings in the colonial tubes cannot be unambiguously proven for Malongitubus, probably due to early decay and later diagenetic replacement of the thin organic material of the tubarium, although weak annulations are still discernible in parts of the tubes. The description of M. kuangshanensis is revised according to new observations of previously reported specimens and recently collected additional new material. Malongitubus appears similar in most features to Dalyia racemata Walcott, 1919 from the Cambrian Stage 5 Burgess Shale, but can be distinguished by the existence of disc-like thickenings at the bases of tubarium branching points in the latter species. Both species occur in rare mass-occurrence layers with preserved fragmentary individuals of different decay stages, with stolon remains preserved as the most durable structures. Benthic pterobranchs may have occurred in some early Cambrian shallow marine communities in dense accumulations and provided firm substrates and shelter for other benthic metazoans as secondary tierers.

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6

MALETZ, JÖRG, MICHAEL STEINER, and OLDRICH FATKA. "Middle Cambrian pterobranchs and the Question: What is a graptolite?" Lethaia 38, no. 1 (March 2005): 73–85. http://dx.doi.org/10.1080/00241160510013204.

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7

Melchin, Michael J., and M. Edwin DeMont. "Possible propulsion modes in Graptoloidea: a new model for graptoloid locomotion." Paleobiology 21, no. 1 (1995): 110–20. http://dx.doi.org/10.1017/s0094837300013105.

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The mode of locomotion of any swimming animal is constrained by its size, architecture, and phylogenetic history. Considering these factors and the range of locomotory systems used by extant zooplankton, the range of possible modes of locomotion for graptoloids can be effectively limited. Three assumptions have been made: (1) graptoloids did not use a mode of locomotion unknown among modern organisms; (2) all graptoloids employed essentially the same mode of locomotion except, possibly, in their early growth stages; and (3) graptoloids did not rely entirely on passive buoyancy—no extant zooplankton groups in the size range of the graptoloids do. Structures that increase buoyancy or drag are often found in actively swimming zooplankton. They enhance feeding efficiency and reduce sinking rates during nonswimming periods.The modes of locomotion utilized by extant zooplankton groups are ciliary propulsion, elongate body undulation, jet propulsion, rowing with skeletonized appendages, and rowing or undulation with muscular appendages. Of these, all but the last can be rejected for the graptoloids on the basis of scale or architecture. It is concluded that graptoloids probably used a rowing or undulatory motion with muscular appendages for swimming. Using a pterobranch model for the graptoloid zooids, the lophophore is considered an unlikely propulsive structure because the design requirements would conflict with those of a ciliarly suspension-feeding organ. Winglike, lateral extensions of the muscular cephalic shield, the same structure used for creeping locomotion in the benthic pterobranchs, is regarded as the most likely propulsive organ, analogous to the pteropod swimming wings.

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8

SATO, ATSUKO, BARRIE RICKARDS, and PETER W. H. HOLLAND. "The origins of graptolites and other pterobranchs: a journey from ‘Polyzoa’." Lethaia 41, no. 4 (December 2008): 303–16. http://dx.doi.org/10.1111/j.1502-3931.2008.00123.x.

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9

Lambert, Charles C. "Historical introduction, overview, and reproductive biology of the protochordates." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 1–7. http://dx.doi.org/10.1139/z04-160.

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This issue of the Canadian Journal of Zoology exhaustively reviews most major aspects of protochordate biology by specialists in their fields. Protochordates are members of two deuterostome phyla that are exclusively marine. The Hemichordata, with solitary enteropneusts and colonial pterobranchs, share a ciliated larva with echinoderms and appear to be closely related, but they also have many chordate-like features. The invertebrate chordates are composed of the exclusively solitary cephalochordates and the tunicates with both solitary and colonial forms. The cephalochordates are all free-swimming, but the tunicates include both sessile and free-swimming forms. Here I explore the history of research on protochordates, show how views on their relationships have changed with time, and review some of their reproductive and structural traits not included in other contributions to this special issue.

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10

TOLMACHEVA, TATIANA, LARS HOLMER, LEONID POPOV, and IVAN GOGIN. "Conodont biostratigraphy and faunal assemblages in radiolarian ribbon-banded cherts of the Burubaital Formation, West Balkhash Region, Kazakhstan." Geological Magazine 141, no. 6 (November 2004): 699–715. http://dx.doi.org/10.1017/s0016756804009902.

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Biostratigraphical study of the early to mid-Ordovician conodont fauna from ribbon-banded radiolarian cherts of the middle Burubaital Formation in Central Kazakhstan reveals an almost complete succession of conodont biozones from the late Tremadocian to the early Darriwilian. During this interval, biosiliceous sediments were deposited in basinal environments, inhabited by lingulate brachiopods, sponges, pterobranchs and caryocaridids in conditions of high fertility and primary productivity of surface water. The community structure of taxonomically diverse conodont assemblages typifying open oceanic environments is not significantly different from that of epicratonic basins of the North Atlantic conodont province. The regional increase of oxygenated bottom waters at the base of the Oepikodus evae Biozone is possibly related to considerable changes in palaeo-oceanographical circulation patterns. The finds of three natural clusters of Prioniodus oepiki (McTavish) enable us to propose an emended diagnosis of this species.

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11

ZALASIEWICZ, JAN A., ALEX PAGE, R. BARRIE RICKARDS, MARK WILLIAMS, PHILIP R. WILBY, MICHAEL P. A. HOWE, and ANDREA M. SNELLING. "Polymorphic organization in a planktonic graptoloid (Hemichordata: Pterobranchia) colony of Late Ordovician age." Geological Magazine 150, no. 1 (August 9, 2012): 143–52. http://dx.doi.org/10.1017/s0016756812000349.

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AbstractGraptolites are common fossils in Early Palaeozoic strata, but little is known of their soft-part anatomy. However, we report a long-overlooked specimen ofDicranograptusaff.ramosusfrom Late Ordovician strata of southern Scotland that preserves a strongly polymorphic, recalcitrant, organic-walled network hitherto unseen in graptoloid graptolites. This network displays three morphologies: proximally, a strap-like pattern, likely of flattened tubes; these transform distally into isolated, hourglass-shaped structures; then, yet more distally, revert to a (simpler) strap-like pattern. The network most likely represents a stolon-like system, hitherto unknown in graptoloids, that connected individual zooids. Its alternative interpretation, as colonial xenobionts that infested a graptoloid colony and mimicked its architecture, is considered less likely on taphonomic and palaeobiological grounds. Such polymorphism is not known in non-graptolite pterobranchs, which are less diverse and morphologically more conservative: a division of labour between graptoloid zooids for such functions as feeding, breeding and rhabdosome construction may have been the key to their remarkable evolutionary success.

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12

Rigby, Susan, and Margaret Sudbury. "Graptolite ontogeny and the size of the graptolite zooid." Geological Magazine 132, no. 4 (July 1995): 427–33. http://dx.doi.org/10.1017/s0016756800021488.

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AbstractTwo methods of estimating the size of the graptolite zooid are described and discussed. It is possible to size a zooid by reference to cortical bandages or with reference to modem Rhabdopleura and its tubes. These two methods give very different results, with the first suggesting small zooids relative to thecal size and the second suggesting zooids that filled their thecae completely. Comparison is made with the evidence available from rare cases of preserved zooids. When all these observations are considered in the light of the ontogeny of modem pterobranchs, an ontogenetic sequence for the graptolite zooid can be inferred which helps to reconcile the two methods of estimating zooid size. This sequence postulates that most skeletal building occurred early in the life of the zooid, before it developed the capacity to feed or to reproduce, and it implies that only the first of three stages in the zooid's life is recorded in the skeleton. The later stages occurred without normally leaving any trace on the preservable remains of the colony. Finally, there is discussion of the effects which different zooid sizes would have had on some aspects of the functional morphology of a theca and on the hydrodynamic behaviour of the rhabdosome as a whole.

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13

Cameron, C. B. "A phylogeny of the hemichordates based on morphological characters." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 196–215. http://dx.doi.org/10.1139/z04-190.

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A comprehensive review of literature on all 15 genera constituting the phylum Hemichordata resulted in a morphological matrix of 105 characters. The echinoderms, tunicates, cephalochordates, and vertebrates were included in the analysis, and the cnidarians, polychaetes, and sipunculids were employed as outgroup taxa. The consensus tree supported the traditional view of a monophyletic Hemichordata, Echinodermata, Ambulacraria, and Chordata. The enteropneust families Spengelidae and Ptychoderidae were each monophyletic and sister-taxa, but there was no resolution among the family Harrimaniidae. A detailed sensitivity analysis provided (i) tree lengths of competing evolutionary hypothesis and (ii) a test of monophyly of groups under a variety of evolutionary models. It is argued that the ancestral deuterostome was a benthic vermiform organism with a terminal mouth and anus, well-developed circular and longitudinal muscles, a simple nerve plexus with little sign of regionalization, a pharynx with gill slits and collagenous gill bars, a cluster of vacuolated cells with myofilaments, produced iodotyrosine, and displayed direct development. The pterobranchs have lost many of these features as a consequence of evolving a small body size and living in tubes, but these features exist in present-day enteropneusts, suggesting that they are a plausible model for the proximate ancestor of deuterostomes.

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14

Carlson, Sandra J. "Inarticulata, brachiopoda, Lophophorata: what do they signify?" Paleontological Society Special Publications 6 (1992): 51. http://dx.doi.org/10.1017/s2475262200006110.

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Higher taxonomic ranks typically distinguish morphologically disparate groups whose within-group common ancestry is assumed to be more recent than that between groups. Because in practice this assumption is rarely tested, common wisdom now advocates that the relationship between traditional classifications and phylogenies be made more explicit. Classifications of organisms were established originally to serve a variety of purposes, which may or may not have had an evolutionary rationale. Thus, if named superspecific taxa are to play an interpretable role in macroevolutionary studies, their status as clades should at least be investigated, if not demonstrated unambiguously.The monophyly of the Brachiopoda is supported by a large number of synapomorphies, both morphological and embryological. Within the Brachiopoda, systematists have focused historically on single character (“key innovation”) definitions of higher taxa (e.g., attitude of the pedicle relative to the valves, nature of articulation between the valves, valve mineralogy); this procedure has resulted in intraphylum divisions whose evolutionary significance is uncertain. For example, monophyly of the Inarticulata continues to be debated vigorously; the position of the calcareous inarticulates (craniaceans) is particularly contentious. The traditional classification, based largely on the presence or absence of teeth and sockets, has been challenged recently by the following arguments: lack of articulation is primitive for brachiopods and, as a symplesiomorphy, cannot define a major clade; valve mineralogy is a more reliable indicator of phylogenetic affinity because phosphatic and calcareous-shelled brachiopods both appear very early in the fossil record.To test these arguments in the broader context of metazoan phylogeny, I chose to investigate not only relationships among brachiopod higher taxa, but also of brachiopods to other lophophorates and selected protostome and deuterostome taxa. I analyzed (using PAUP 3.0) the phylogenetic relationships among the seven Recent brachiopod superfamilies (assuming each to be monophyletic), using 119 characters of soft and hard anatomy and embryology. Four outgroup taxa were used: Phoronida, Bryozoa, Sipunculida, Pterobranchia. One most parsimonious cladogram of length 219, C.I. = .722, resulted. In this cladogram, Inarticulata and Articulata are each monophyletic, with 9 and 32 synapomorphies, respectively. Calcareous skeletal mineralogy is clearly primitive for metazoans; there is no justification for claiming it as a synapomorphy of a clade within the Brachiopoda. Outgroup analysis has no power, in this instance, to determine the polarity of articulation, since no outgroups possess two valves (molluscs and other animals have evolved the bivalved condition independently, based on numerous other characters); thus, the lack of valve articulation is not unambiguously primitive, by this polarity criterion.Although many textbooks continue to refer to Lophophorates as a group distinct from other metazoans, presumably by virtue of common ancestry, “lophophorates” do not appear to be monophyletic unless the possession of a lophophore is selectively weighted; among the outgroups in this cladogram, bryozoans cluster with sipunculids, and phoronids with pterobranchs. The notion that lophophorates, as a group, are in some sense “intermediate” between protostomes and deuterostomes must be investigated in greater detail, phylogenetically.

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15

Dilly, Peter N. "Cephalodiscusreproductive biology (Pterobranchia, Hemichordata)." Acta Zoologica 95, no. 1 (January 16, 2013): 111–24. http://dx.doi.org/10.1111/azo.12015.

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16

URBANEK, ADAM. "When is a pterobranch a graptolite?" Lethaia 27, no. 4 (December 1994): 324. http://dx.doi.org/10.1111/j.1502-3931.1994.tb01582.x.

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17

Sato, Atsuko, John D. D. Bishop, and Peter W. H. Holland. "Developmental biology of pterobranch hemichordates: History and perspectives." genesis 46, no. 11 (November 2008): 587–91. http://dx.doi.org/10.1002/dvg.20395.

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18

Maletz, Jörg. "Hemichordata (Pterobranchia, Enteropneusta) and the fossil record." Palaeogeography, Palaeoclimatology, Palaeoecology 398 (March 2014): 16–27. http://dx.doi.org/10.1016/j.palaeo.2013.06.010.

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19

Dilly, P. N., and J. S. Ryland. "An intertidal Rhabdopleura (Hemichordata, Pterobranchia) from Fiji." Journal of Zoology 205, no. 4 (August 20, 2009): 611–23. http://dx.doi.org/10.1111/j.1469-7998.1985.tb03548.x.

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20

DlLLY, P. N. "The prosicular stage of Rhabdopleura (Pterobranchia: Hemichordata)." Journal of Zoology 206, no. 2 (August 20, 2009): 163–74. http://dx.doi.org/10.1111/j.1469-7998.1985.tb05642.x.

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21

Lester, Susan M. "Settlement and Metamorphosis ofRhabdopleura normani(Hemichordata: Pterobranchia)." Acta Zoologica 69, no. 2 (June 1988): 111–20. http://dx.doi.org/10.1111/j.1463-6395.1988.tb00907.x.

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22

Gonzalez, Paul, and Christopher B. Cameron. "Ultrastructure of the coenecium of Cephalodiscus (Hemichordata: Pterobranchia)." Canadian Journal of Zoology 90, no. 10 (October 2012): 1261–69. http://dx.doi.org/10.1139/z2012-096.

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The ultrastructure of the coenecia of Cephalodiscus (Cephalodiscus) hodgsoni Ridewood, 1907, Cephalodiscus (Idiothecia) nigrescens Lankester, 1905, and Cephalodiscus (Orthoecus) densus Andersson, 1907 was characterized using light microscopy, transmission electron microscopy, and scanning electron microscopy. The coenecium of Cephalodiscus is composed of layers of coenecial material of variable thickness laid down one upon the next and separated by sheets. Thick fusellar-like layers (up to 160 μm thick) and thin cortical-like layers (down to 15 nm thick) are present, but do not form two distinct components. Instead, a continuum exists in the thickness and shape of these layers. At the ultrastructural level, both fusellar-like and cortical-like layers are composed of thin (16–23 nm) long and straight fibrils, similar to the fibrils described in extant Rhabdopleura Allman, 1869. In C. densus, fibrils in the outer secondary deposits show a parallel arrangement, similar to the arrangement of fibrils in the graptolite eucortex. Although similarities in the shape and arrangement of growth increments between Cephalodiscus, Rhabdopleura, and graptolites probably reflect homologous zooidal behaviors and secretion mechanisms, differences at the ultrastructural level show that fibril types and fibril arrangement can evolve independently from larger scale features of the coenecium.

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23

Rehkämper, G., U. Welsch, and P. N. Dilly. "Fine structure of the ganglion ofCephalodiscus gracilis(pterobranchia, hemichordata)." Journal of Comparative Neurology 259, no. 2 (May 8, 1987): 308–15. http://dx.doi.org/10.1002/cne.902590210.

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24

Sato, Atsuko, and Peter W. H. Holland. "Asymmetry in a pterobranch hemichordate and the evolution of left-right patterning." Developmental Dynamics 237, no. 12 (December 2008): 3634–39. http://dx.doi.org/10.1002/dvdy.21588.

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25

Schweigert, Günter, and Gerd Dietl. "A questionable pterobranch from the Upper Jurassic Nusplingen Lithographic Limestone (SW Germany)." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 270, no. 1 (October 1, 2013): 83–90. http://dx.doi.org/10.1127/0077-7749/2013/0361.

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26

Miyamoto, Norio, Teruaki Nishikawa, and Hiroshi Namikawa. "Cephalodiscus planitectus sp. nov. (Hemichordata: Pterobranchia) from Sagami Bay, Japan." Zoological Science 37, no. 1 (January 24, 2020): 79. http://dx.doi.org/10.2108/zs190010.

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27

Maletz, Jörg. "Tracing the evolutionary origins of the Hemichordata (Enteropneusta and Pterobranchia)." Palaeoworld 28, no. 1-2 (March 2019): 58–72. http://dx.doi.org/10.1016/j.palwor.2018.07.002.

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28

Halanych, K. M. "Suspension Feeding by the Lophophore-like Apparatus of the Pterobranch Hemichordate Rhabdopleura normani." Biological Bulletin 185, no. 3 (December 1993): 417–27. http://dx.doi.org/10.2307/1542482.

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29

Halanych, Kenneth M. "The Phylogenetic Position of the Pterobranch Hemichordates Based on 18S rDNA Sequence Data." Molecular Phylogenetics and Evolution 4, no. 1 (March 1995): 72–76. http://dx.doi.org/10.1006/mpev.1995.1007.

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30

Dilly, P. N. "The habitat and behaviour of Cephalodiscus gracilis (Pterobranchia, Hemichordata) from Bermuda." Journal of Zoology 207, no. 2 (August 20, 2009): 223–39. http://dx.doi.org/10.1111/j.1469-7998.1985.tb04926.x.

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31

Maletz, Jörg, and Michael Steiner. "Graptolite (Hemichordata, Pterobranchia) preservation and identification in the Cambrian Series 3." Palaeontology 58, no. 6 (October 9, 2015): 1073–107. http://dx.doi.org/10.1111/pala.12200.

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32

Stach, Thomas, Alexander Gruhl, and Sabrina Kaul-Strehlow. "The central and peripheral nervous system of Cephalodiscus gracilis (Pterobranchia, Deuterostomia)." Zoomorphology 131, no. 1 (January 10, 2012): 11–24. http://dx.doi.org/10.1007/s00435-011-0144-x.

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33

Dilly, P. N. "Feeding and gut contents inCephalodiscus nigrescens(Hemichordata, Pterobranchia) from the Weddell Sea." Journal of Zoology 230, no. 1 (May 1993): 63–67. http://dx.doi.org/10.1111/j.1469-7998.1993.tb02672.x.

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34

Rigby, Susan. "Erect tube growth inRhabdopleura compacta(Hemichordata: Pterobranchia) from off Start Point, Devon." Journal of Zoology 233, no. 3 (July 1994): 449–55. http://dx.doi.org/10.1111/j.1469-7998.1994.tb05276.x.

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35

Dilly, Peter Noel, Ulrich Welsch, and Gerd Rehkämper. "On the Fine Structure of the Alimentary Tract ofCephalodiscus gracilis(Pterobranchia, Hemichordata)." Acta Zoologica 67, no. 2 (June 1986): 87–95. http://dx.doi.org/10.1111/j.1463-6395.1986.tb00852.x.

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36

Stach, Thomas. "Larval anatomy of the pterobranch Cephalodiscus gracilis supports secondarily derived sessility concordant with molecular phylogenies." Naturwissenschaften 100, no. 12 (December 2013): 1187–91. http://dx.doi.org/10.1007/s00114-013-1117-3.

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37

Beli, Elena, Stefano Piraino, and Christopher B. Cameron. "Fossilization processes of graptolites: insights from the experimental decay of Rhabdopleura sp. (Pterobranchia)." Palaeontology 60, no. 3 (March 20, 2017): 389–400. http://dx.doi.org/10.1111/pala.12290.

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38

Dilly, Peter Noel, Ulrich Welsch, and Gerd Rehkämper. "Fine Structure of Heart, Pericardium and Glomerular Vessel inCephalodiscus gracilisM'Intosh, 1882 (Pterobranchia, Hemichordata)." Acta Zoologica 67, no. 3 (September 1986): 173–79. http://dx.doi.org/10.1111/j.1463-6395.1986.tb00861.x.

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39

Dilly, Peter Noel, Ulrich Welsch, and Gerd Rehkämper. "Fine Structure of Tentacles, Arms and Associated Coelomic Structures ofCephalodiscus gracilis(Pterobranchia, Hemichordata)." Acta Zoologica 67, no. 3 (September 1986): 181–91. http://dx.doi.org/10.1111/j.1463-6395.1986.tb00862.x.

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40

Halanych, K. M. "Convergence in the Feeding Apparatuses of Lophophorates and Pterobranch Hemichordates Revealed by 18S rDNA: An Interpretation." Biological Bulletin 190, no. 1 (February 1996): 1–5. http://dx.doi.org/10.2307/1542669.

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41

Russel, Jennifer C., Michael J. Melchin, and Tatjana N. Koren'. "Development, taxonomy, and phylogenetic relationships of species of Paraclimacograptus (Graptoloidea) from the Canadian Arctic and the Southern Urals of Russia." Journal of Paleontology 74, no. 1 (January 2000): 84–91. http://dx.doi.org/10.1017/s0022336000031267.

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An investigation of the morphology and astogenetic pattern of isolated specimens of two species of Paraclimacograptus permits an assessment of the phylogenetic relationships of this genus. Forty-two specimens previously assigned to Paraclimacograptus innotatus ssp. isolated from turbiditic limestone from the Southern Urals of Russia (Cystograptus vesiculous Zone) and limestone concretions from the Canadian Arctic (Coronograptus cyphus Zone) were examined using the method of infrared video microscopy. Paraclimacograptus has a Pattern H astogeny and is therefore a member of the family Normalograptidae. At least three species can be distinguished using biometric criteria, P. innotatus, P. exquisitus, and P. obesus. Rhabdosomal characteristics of Paraclimacograptus indicate that it is phylogenetically related to early species of the genus Neodiplograptus. The point of divergence of the proximal thecae is defined by the interfingering of fuselli of markedly different widths. This suggests that fuselli were not necessarily secreted at a constant rate. In addition, this pattern of fusellar interfingering is here regarded as more consistent with a pterobranch mode of secretion than with a model of growth under an enveloping extrathecal mantle.

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Pettit, George R., Jun-Ping Xu, Jean M. Schmidt, and Michael R. Boyd. "Isolation and structure of the exceptional Pterobranchia human cancer inhibitors cephalostatins 16 and 171." Bioorganic & Medicinal Chemistry Letters 5, no. 17 (September 1995): 2027–32. http://dx.doi.org/10.1016/0960-894x(95)00346-u.

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Keupp, Helmut, Bernd Doppelstein, and J�rg Maletz. "First evidence of in situ rhabdopleurids (Pterobranchia, Hemichordata) from the Lower Jurassic of Southern Germany." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 282, no. 3 (December 1, 2016): 263–69. http://dx.doi.org/10.1127/njgpa/2016/0617.

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44

Lester, Susan M. "Ultrastructure of Adult Gonads and Development and Structure of the Larva ofRhabdopleura normani(Hemichordata: Pterobranchia)." Acta Zoologica 69, no. 2 (June 1988): 95–109. http://dx.doi.org/10.1111/j.1463-6395.1988.tb00906.x.

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45

Mayer, Georg, and Thomas Bartolomaeus. "Ultrastructure of the stomochord and the heart?glomerulus complex in Rhabdopleura compacta (Pterobranchia): phylogenetic implications." Zoomorphology 122, no. 3 (August 1, 2003): 125–33. http://dx.doi.org/10.1007/s00435-003-0078-z.

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Strano, F., V. Micaroni, E. Beli, S. Mercurio, G. Scarì, R. Pennati, and S. Piraino. "On the larva and the zooid of the pterobranch Rhabdopleura recondita Beli, Cameron and Piraino, 2018 (Hemichordata, Graptolithina)." Marine Biodiversity 49, no. 4 (January 7, 2019): 1657–66. http://dx.doi.org/10.1007/s12526-018-0933-2.

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47

Beli, Elena, Giorgio Aglieri, Francesca Strano, Davide Maggioni, Max J. Telford, Stefano Piraino, and Christopher B. Cameron. "The zoogeography of extant rhabdopleurid hemichordates (Pterobranchia : Graptolithina), with a new species from the Mediterranean Sea." Invertebrate Systematics 32, no. 1 (2018): 100. http://dx.doi.org/10.1071/is17021.

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The early origin and evolutionary radiation of graptolites (Hemichordata:Pterobranchia) is a story told almost entirely in the fossil record, but for four extant species of the genus Rhabdopleura Allman, 1869. Here we report the discovery of a fifth species, Rhabdopleura recondita, sp. nov., at a depth range of 2–70m from the Adriatic and Ionian Seas, always associated with bryozoans in coralligenous habitats. This is the first pterobranch record in Italian waters, and the second in the Mediterranean Sea. The new species is characterised by: (1) tubaria with smooth creeping tubes adherent to the inside of empty bryozoan zooecia; (2) erect outer tubes with a graptolite, fusellar-like organisation; and (3) zooids that extend from a black stolon, which is free from the creeping tube. Each of the paired feeding arms has two rows of tentacles that do not extend to the arm tip. The distal ends of the arms, the collar and the cephalic shield are replete with black granules. Phylogenetic analyses of individual and concatenated gene sequences of mitochondrial 16S rDNA and nuclear 18S rDNA support the validity of R. recondita as a new species. Finally, we discuss the global biogeographic and habitat distributions of the extant Rhabdopleura representatives. http://zoobank.org/urn:lsid:zoobank.org:pub:82C6A51E-F8F4-44AF-AD8F-16873BE80D03

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Ramírez-Guerrero, Greta M., Kevin M. Kocot, and Christopher B. Cameron. "Zooid morphology and molecular phylogeny of the graptolite Rhabdopleura annulata (Hemichordata, Pterobranchia) from Heron Island, Australia." Canadian Journal of Zoology 98, no. 12 (December 2020): 844–49. http://dx.doi.org/10.1139/cjz-2020-0049.

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Rhabdopleura Allman, 1869 is one of the longest surviving animal genera. The five-known species are the only living Graptolithina, a group well known from their diverse Paleozoic fossil record. Here we add information on the soft-bodied zooids and molecular phylogenetics of Rhabdopleura annulata Norman, 1921, which was previously only known from its tubes. Tubes and zooids were collected from Heron Island, Queensland, Australia. Zooids have a single pair of tentaculated arms. Dark pigment granules are found throughout the body, and particularly dense in the pair of arms and the anterior lip of the cephalic shield. Colonies grow encrusted in and on coral debris. The tubes are either creeping or erect, but no stolon has been found. Inside of the coral matrix lacunae, the tube cortex formed a parchment-like wallpaper. Phylogenetic analysis based on combined 18S+16S rRNA sequences placed R. annulata as sister to the remaining rhabdopleurids, albeit with weak support. The biogeographic range of R. annulata extends from Indonesia to Tasmania, and New Zealand. Its occurrence on Heron Island does not extend this range, but highlights that rhabdopleurids may be more common, and in shallower waters, than previously appreciated, permitting further studies that may shed light on graptolite paleobiology.

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Merker, Sebastian, Alexander Gruhl, and Thomas Stach. "Comparative anatomy of the heart–glomerulus complex of Cephalodiscus gracilis (Pterobranchia): structure, function, and phylogenetic implications." Zoomorphology 133, no. 1 (September 5, 2013): 83–98. http://dx.doi.org/10.1007/s00435-013-0200-9.

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Lester, S. M. "Cephalodiscus sp. (Hemichordata: Pterobranchia): observations of functional morphology, behavior and occurrence in shallow water around Bermuda." Marine Biology 85, no. 3 (March 1985): 263–68. http://dx.doi.org/10.1007/bf00393246.

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