Fossil Polychaete Research Articles

Kimmeridgian and early Tithonian cephalopods from the Kisújbánya Limestone Formation, Zengővárkony (Mecsek Mountains, southern Hungary), their faunal composition, palaeobiogeographic affinities, and taphonomic character

A new collection at Zengővárkony (Mecsek Mountains, Hungary) provided a rich and diverse but poorly preserved cephalopod-dominated fossil assemblage representing the Kimmeridgian and the lower Tithonian. The material came from mixed scree, soil, and amongst roots affected by weathering processes having been exposed to the elements for a long time. The nautiloid Pseudaganides strambergensis is the first record from the Mecsek Mountains. Due to the weathering, the ammonite fauna consists of mainly fragmentary and dissolved individuals that comprises 528 specimens belonging to 34 species and 30 genera out of which 20 species and 15 genera are reported for the first time from the Mecsek Mountains. The fauna includes specimens of known taxa. No new taxa are introduced. Based on the comparison with other faunas, this assemblage most closely resembles the fauna of the Venetian Alps (Italy). Additional faunal elements include aptychi (Laevaptychus latus, Lamellaptychus murocostatus), belemnites (Hibolithes semisulcatus), and an indetermined brachiopod. The first record of Spiraserpula spirolinites, an encrusting fossil polychaete preserved on the internal mould of a Taramelliceras shell fragment indicates favourable bottom conditions for the epifauna. The presence of Aspidoceras caletanum, Gravesia aff. gigas, and Pseudowaagenia inerme indicates faunal connections with the Submediterranean Province of the Tethys, which is in line with the tectonic and palaeogeographical position of the Mecsek Zone during the Late Jurassic. The ammonite assemblage represents elements of five Tethysian ammonite zones of the Kimmeridgian and Tithonian. The lower Kimmeridgian Herbichi Zone is indicated by Streblites tenuilobatus and Praesimoceras herbichi. The upper Kimmeridgian Acanthicum Zone is indicated by Aspidoceras acanthicum, and the Cavouri Zone by Mesosimoceras cavouri and Aspidoceras caletanum. The upper Kimmeridgian Beckeri Zone is suggested by Hybonoticeras pressulum and Pseudowaagenia inerme. Whereas Gravesia aff. gigas, Lithacoceras aff. siliceum, and Malagasites? denseplicatus are faunal elements characterising the Early Tithonian Hybonotum Zone. Phylloceratid and lytoceratid specimens account only for 12% of the fauna, while the majority of the specimens belong to the Oppeliidae and Ataxioceratidae (60%).

A Cambrian crown annelid reconciles phylogenomics and the fossil record.

The phylum of annelids is one of the most disparate animal phyla and encompasses ambush predators, suspension feeders and terrestrial earthworms1. The early evolution of annelids remains obscure or controversial2,3, partly owing to discordance between molecular phylogenies and fossils2,4. Annelid fossils from the Cambrian period have morphologies that indicate epibenthic lifestyles, whereas phylogenomics recovers sessile, infaunal and tubicolous taxa as an early diverging grade5. Magelonidae and Oweniidae (Palaeoannelida1) are the sister group of all other annelids but contrast with Cambrian taxa in both lifestyle and gross morphology2,6. Here we describe a new fossil polychaete (bristle worm) from the early Cambrian Canglangpu formation7 that we name Dannychaeta tucolus, which is preserved within delicate, dwelling tubes that were originally organic. The head has a well-defined spade-shaped prostomium with elongated ventrolateral palps. The body has a wide, stout thorax and elongated abdomen with biramous parapodia with parapodial lamellae. This character combination is shared with extant Magelonidae, and phylogenetic analyses recover Dannychaeta within Palaeoannelida. To our knowledge, Dannychaeta is the oldest polychaete that unambiguously belongs to crown annelids, providing a constraint on the tempo of annelid evolution and revealing unrecognized ecological and morphological diversity in ancient annelids.

Fosildiagénesis del anélido Rotularia spirulaea (Lamarck, 1818) (Polychaeta, Serpulidae) en el Eoceno del dominio pirenaico occidental

The presence of the fossil polychaete Rotularia spirulaea (Lamarck, 1818) in Eocene deposits (middle Lutecian – upper Bartonian and (?) Priabonian) belonging to the western Pyrenean Domain is verified. In this paper, a fossildiagenetic study has been carried out. Fossils from three areas, corresponding to diff erent depositional settings, have been analysed. In area 1, sediments of the Ardanatz Sandstone and Ilundain Marls formations [Pamplona Basin and adjoining areas (Navarre)], were sampled. Here, the specimens of R. spirulaea were not substantially affected by taphonomic reworking and the original microstructure of the carbonate tube is preserved. The test consists of a thick external shell layer, composed of three zones in succession, and another extremely thin inner shell layer. The lumen of the tube is filled in by fine-grained sediment and/or calcitic cement. In area 2 , which includes the town of Anderatz and several outcrops of the Urbasa mountain range (Navarre), Urbasa-Andia Formation and overlying deposits, as well as in area 3 , located on the upper part of the calciclastic fl ysch of Punta Galea (Biscay), fossils are included in sediments deposited in high-energy environments. In this case, the microstructure of R. spirulaea tube is not completely recognized due to intense, early diagenetic silicifi cation aff ecting the tests. The lumen is filled in with fragments of foraminifera and calcareous algae, quartz-feldespathic sediment and cemented by calcite. Therefore, in zones 2 and 3 the fossildiagenetic processes are substantially different from those recognized in zone 1.

Solving a cold case: New occurrences reinforce juvenile callianassids as the Ophiomorpha puerilis tracemakers

The ichnotaxon Ophiomorpha puerilis was erected based on material from late Pleistocene shallow-marine, siliciclastic deposits of southeastern Brazil. These tiny burrows with a distinctive lining of cylindrical pellets having rounded ends were originally interpreted as burrows of juvenile callianassid shrimp, with polychaetes also considered as a possible tracemaker. Recent discoveries of O. puerilis in late Pleistocene shallow-marine carbonates from two localities in the Bahamas and from the Miami Limestone of south Florida, described herein, have expanded significantly the geographic range of the ichnotaxon and provided numerous, well preserved specimens for detailed structural analysis of its burrow form and pellets. The new information strengthens the interpretation of juvenile callianassids as the tracemakers, resolving the “cold case” of the burrow's tracemaker. Microscopic analyses revealed that the pellets of O. puerilis are constructional, not fecal. Furthermore, larger forms of Ophiomorpha are common and occur in close association with O. puerilis at each locality. These new data allowed close comparison of O. puerilis pellets with those of Sergio mirim, a modern callianassid from southeastern Brazilian beaches, Ophiomorpha nodosa from Brazilian Pleistocene deposits, and fossil polychaete burrows filled with fecal pellets as described in the literature. The combined evidence allows us to exclude polychaetes as potential O. puerilis tracemakers. Rather, O. puerilis records the settling and initial burrowing behavior of callianassid decapodids. The characteristics of an Ophiomorpha ichnofabric with the addition of O. puerilis also is described and explored. An emended diagnosis for the O. puerilis ichnotaxon is provided, based on the new structural data for this burrow.

An Early Cambrian stem polychaete with pygidial cirri.

The oldest annelid fossils are polychaetes from the Cambrian Period. They are representatives of the annelid stem group and thus vital in any discussion of how we polarize the evolution of the crown group. Here, we describe a fossil polychaete from the Early Cambrian Sirius Passet fauna, Pygocirrus butyricampum gen. et sp. nov., with structures identified as pygidial cirri, which are recorded for the first time from Cambrian annelids. The body is slender and has biramous parapodia with chaetae organized in laterally oriented bundles. The presence of pygidial cirri is one of the characters that hitherto has defined the annelid crown group, which diversified during the Cambrian-Ordovician transition. The newly described fossil shows that this character had already developed within the total group by the Early Cambrian.

Ordovician Polychaeturid Polychaetes: Taxonomy, Distribution and Palaeoecology

The fossil polychaete family Polychaeturidae is considered as monogeneric and comprises four species of the genus Pteropelta. Pteropelta, originally established on isolated scolecodonts (the carriers), is revised and the apparatus-based Polychaetura is shown to be a junior synonym of Pteropelta. In addition to Pteropelta gladiata and Pteropelta kielanae, Pteropelta huberti sp. nov., and Pteropelta sp. A are herein described from the Upper Ordovician of Estonia and Sweden. Polychaeturids include some of the most common and characteristic scolecodont-bearing polychaetes in the Ordovician of Baltoscandia. They first appeared in the early Darriwilian (Mid Ordovician), flourished in the Late Ordovician and disappeared in the early Silurian. The distribution patterns of individual polychaeturid species infer regional biostratigraphical potential. Polychaeturids were geographically widespread during the Ordovician and have been recorded from at least three palaeocontinents.

Two new genera of the pelagic family Yndolaciidae (Polychaeta) from the Arctic Ocean with an addition to the description of Yndolacia lopadorrhynchoides Støp-Bowitz

Until recently, the pelagic family Yndolaciidae was considered to include a single genus and species Yndolacia lopadorrhynchoides Stop-Bowitz, 1987 from the Gulf of Guinea. Yndolaciella polarsterni gen. et sp. nov. and Paryndolacia tomopteroides gen. et sp. nov. are described from the deep sea of the Arctic Ocean. Additions and refining of the diagnoses of the genus Yndolacia and the family are given. The absence of cephalic tentacles, a weakly developed brain, simple biramous parapodia with equal rami, similar cirri without cirrophores, a superficial position of the nervous system, the presence of two nerve cords and the lack of ganglionic swellings are assumed to constitute ancestral characters of the family. Some resemblance of the family to Tomopteridae is noted. It is supposed that fossil polychaete Eotomopteris aldridgei Briggs & Clarkson, 1987 belongs to Yndolaciidae.

A three-dimensionally preserved fossil polychaete worm from the Silurian of Herefordshire, England.

Polychaete body fossils are rare, and are almost invariably compressed and too poorly preserved for meaningful comparison with extant forms. We here describe Kenostrychus clementsi gen. et sp. nov. from the Silurian Herefordshire Konservat-Lagerstätte of England, in which three-dimensional external morphology is preserved with a fidelity unprecedented among fossil polychaetes. The fossils, which are preserved in calcite, were serially ground and photographed at 30 microm intervals to produce computer-generated reconstructions of the original external surface. The new genus has a generalized polychaete morphology with large biramous parapodia, unspecialized anterior segments and a small prostomium with median and lateral antennae and ventral prostomial palps. Cirriform branchiae arise from the ventral surface of each notopodium, and may be homologous with the inter-ramal branchiae of the extant nephtyids. Through cladistic analysis, Kenostrychus is interpreted as a member of a stem group of either the Phyllodocida or the Aciculata (Phyllodocida + Eunicida). Direct comparison with other fossil forms is difficult, but hints that inter-ramal respiratory structures may be primitive within the Phyllodocida and/or the Aciculata.

Paranomenclature and the rules of zoological nomenclature; with examples from fossil polychaete jaws (scolecodonts)

Names of zoological taxa are governed by a set of laws, the International Code of Zoological Nomenclature or ICZN. In contrast to taxonomy, where decisions are based on interpretations, the laws of nomenclature are explicit and must be obeyed. One of the consequences, as discussed herein, is that paranomenclature, that reflects parataxonomic classifications based on parts of organisms independently of other parts, is not recognized under the ICZN and thus cannot be applied to formally diagnosed taxa. In the case of jawed polychaete annelids, parataxonomic treatments of the jaw elements as well as ICZN-governed naming of the reconstructed apparatus has divided their fossil record into separate but biologically overlapping groups of element-based and apparatus-based taxa. The independent treatment of groups created in this way has the potential for much confusion, if their names are used in formal systematics. Other recommendations of ICZN for effective diagnosis and illustration should also be considered in proposing names within groups such as this, where paranomenclature has been customary in the past.

Taxonomic discussion of the scolecodont generaNereidavusGrinnell, 1877, andProtarabellitesStauffer, 1933 (Annelida: Polychaeta)

The scolecodont generaNereidavusGrinnell, 1877, andProtarabellitesStauffer, 1933, have been used for several different fossil polychaete taxa over the years.Nereidavusis here considered a nomen dubium, as the holotype of the type species is lost and the original information is insufficient for identification.Protarabellitesis reevaluated and constitutes, besidesRamphoprion, a second genus in the family Ramphoprionidae. The “paratype” ofN. varians(namedRamphoprionsp. in this paper), and the holotype ofP. humilisare redescribed.

The generation at hot springs of sedimentary ore deposits, microbialites and life

Notwithstanding the current fashion which favours an epigenetic origin for what used to be termed SEDEX deposits, there are several lines of evidence to indicate that Phanerozoic base-metal orebodies of this type have at least some exhalative aspects. The fossil polychaete worms, which occur in Lower Carboniferous pyrite mounds at Tynagh and Silvermines in Ireland, have affinities to Paralvinella, an organism that lives attached to hydrothermal chimneys at the Juan de Fuca hot spring site in the Northeast Pacific. In addition, fossil tube worms, and their moulds, occur both in silica masses underlying the Carboniferous giant Red Dog sulphide orebody in Alaska and in Devonian barite and base-metal deposits in North America and in Russia, respectively. The development of sulphide and carbonate fossil microbialites over exhalative centres further supports generation of some mineral deposits on sea or lake floors. Carbonate microbialite mounds are also developing today over warm springs and seepages. The existence of an environment in which sulphide mineralisation developed at the sea floor has implications also in a different sphere. Life itself may have emerged in a similar milieu at ∼ 4.2 Ga from iron monosulphide bubbles. A primitive metabolism could have been driven by the high, long-lived and constant, redox potential of ∼ 300 mV made available across an iron monosulphide membrane which would have been spontaneously generated where sulphide-bearing, submarine, alkaline springs issued into the acidic, iron-bearing, Hadean ocean. The alkaline spring provided bisulphide to the iron-rich (carbonic) acid ocean for the precipitation of iron-monosulphide bubbles (probotryoids), as well as acetate (Shock, 1992) — the feeder to the biochemical Krebs cycle, driven in reverse by the high partial pressure of CO 2. In addition to its scientific significance, an understanding of these beginnings may well benefit research into many aspects of economic geology. Even more extreme redox contrasts are revealed by the presence of sedimentary jasper or iron formation in three of the major Carboniferous sulphide orebodies in Ireland. Pyritic sulphide microbialites also grew over some of the associated fossil hot-spring sites and may be recognised by their bacteriogenic δ 34S values (−20 to −40‰). Recognition of such fossil hot-spring sites could lead to further discoveries of SEDEX deposits.

A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa Walcott

The enigmatic fossil Wiwaxia corrugata is organically preserved in the Burgess Shale (Middle Cambrian, British Columbia) and is therefore extractable by careful acid maceration of the mineralic matrix. High magnification transmitted light microscopy and SEM of macerated Wiwaxia sclerites reveal a substantial amount of previously undescribed structural and microstructural detail. Anatomical and histological comparison with modern organisms indicates that Wiwaxia sclerites are polychaete paleae (flattened setae) and that Wiwaxia was a jawed annelid broadly related to the extant polychaete families Chrysopetalidae and/or Aprhoditidae (Palmyra). Canadia spinosa, an uncontested fossil polychaete from the same beds, shows a paleal microstructure identical to that of Wiwaxia, as well as a closely comparable gross anatomy and taphonomic grade. The unique combination of taxonomically significant characters shared by Wiwaxia and Canadia suggest that they are more closely related to each other than either is to any other fossil or extant polychaete. Thus they constitute a separate superfamily, Canadiacea superfam. nov., in the order Phyllodocida.

Taphonomy of Recent Polychaete Jaws from Florida and Belize

Polychaete jaws are widely distributed in sediment samples from Florida and Belize, in densities up to 0.25 jaws/ cm3. Most jaws recovered passed through a 0.5 mm mesh. Glycerid and arabellid jaws are common, and in Belize occur in densities consistent with the size of living populations. Nereidid jaws are slightly under-represented, and most specimens are partially degraded. Nereidid jaws may thus not survive into the fossil record. Eunicid and onuphid jaws are completely absent from all samples, in spite of the abundance of onuphids throughout the sampled locations. Lumbrinerid jaws are rare (Belize samples only), and may not be preserved as fossils. These results are broadly consistent with predictions based on laboratory study of jaw composition, and with the published record of fossil polychaete jaws (scolecodonts).

Polychaetes of the lower and middle paleozoic: A multi-element analysis and a phylogenetic outline

Biostratigraphers have largely ignored fossil polychaete jaws due, in part, to the confusing and complex nomenclature of the form and natural classification systems. An analysis of one hundred complete and near-complete jaw apparatuses suggests that the taxonomic problems are not so extensive as is generally believed. The multi-element analysis indicates that polychaete jaw apparatuses are comprised of three element groups: the anterior maxillae, the posterior maxillae, and the carriers. The biologic distribution of these groups permit the development of a phylogenetic outline which relates 22 genera into three morphoclines. Further, the analysis isolates the MI elements, of the posterior maxillar group, as the most useful element for diagnostic purposes. In each genus, at least one of the MI elements is morphologically distinct and diagnostic of the apparatus. Thus, it is possible to determine which natural genera are present in an assemblage of discrete polychaete jaw elements. The multi-element analysis also suggests that the family Polychaetaspidae should be emended to include the Rhamphoprionidae and the Polychaeturidae.