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Enigmatic worm-like fossils from the Silurian Waukesha Lagerstätte, Wisconsin, USA

Westberg, Märta LU (2019) In Dissertations in Geology at Lund University GEOL01 20191
Department of Geology
Abstract
The lower Silurian Waukesha Lagerstätte of Wisconsin, USA, is a Konservat-Lagerstätte which has yielded a diverse assemblage of exceptionally well-preserved soft-bodied organisms. This study comprises first-hand descriptions and assessments of 23 enigmatic worm-like specimens from the Waukesha Lagerstätte, alongside a literature review. The study focuses on the depositional environment in which the strata of the Waukesha Lagerstätte was formed, as well as which morphologies, mode of preservation and taxonomic affinities of the fossils. In total, eight different worm-like taxa have been identified, not only including annelids, but probably also arthropods and a poriferan. This suggests that worms and worm-like organisms formed an important... (More)
The lower Silurian Waukesha Lagerstätte of Wisconsin, USA, is a Konservat-Lagerstätte which has yielded a diverse assemblage of exceptionally well-preserved soft-bodied organisms. This study comprises first-hand descriptions and assessments of 23 enigmatic worm-like specimens from the Waukesha Lagerstätte, alongside a literature review. The study focuses on the depositional environment in which the strata of the Waukesha Lagerstätte was formed, as well as which morphologies, mode of preservation and taxonomic affinities of the fossils. In total, eight different worm-like taxa have been identified, not only including annelids, but probably also arthropods and a poriferan. This suggests that worms and worm-like organisms formed an important and diverse component of the past biotas that are now preserved in the Waukesha Lagerstätte. Despite their exceptional preservation, the worm-like fossils of Waukesha Lagerstätte are difficult to interpret and unambiguously assign to specific taxa. Specimens previously interpreted to represent leeches are herein rather considered to be palaeoscolecid worms, based on detailed scanning electron microscopy (SEM)-studies which revealed the presence of external plates and nodes, closely similar to those reported from other palaeoscolecidans. One of these taxa could belong to Wronascolex because of its raspberry-like plates. SEM-based elemental mapping of one specimen shows enrichment of calcium and phosphorous in the fossil compared to the surrounding host rock, suggesting that the Waukesha fossils might be preserved as calcium phosphate. Future studies that could be of interest regarding this collection of fossils include more detailed investigations of fine structures in SEM in the specimens interpreted as palaeoscolecidans. (Less)
Abstract (Swedish)
Den äldre siluriska Waukesha Lagerstätte från Wisconsin, USA, är en Konservat-Lagerstätte som uppvisar en diverse samling av exceptionellt välbevarade mjukvävnadsorganismer. Den här studien innefattar förstahandsbeskrivningar och bedömningar av 23 gåtfulla masklika fossila exemplar från Waukesha Lagerstätte, tillsammans med en litteraturstudie. Studien fokuserar på avsättningsmiljön i vilken strata av Waukesha Lagerstätte bildades, såväl som vilka morfologier, bevaringstillstånd och taxonomiska tillhörigheter som fossilerna har. Totalt har åtta olika masklika taxa identifieras, inte bara inkluderande annelider, men förmodligen även arthropoder och en poriferan. Detta tyder på att maskar och masklika organismer utgör en viktig och diverse... (More)
Den äldre siluriska Waukesha Lagerstätte från Wisconsin, USA, är en Konservat-Lagerstätte som uppvisar en diverse samling av exceptionellt välbevarade mjukvävnadsorganismer. Den här studien innefattar förstahandsbeskrivningar och bedömningar av 23 gåtfulla masklika fossila exemplar från Waukesha Lagerstätte, tillsammans med en litteraturstudie. Studien fokuserar på avsättningsmiljön i vilken strata av Waukesha Lagerstätte bildades, såväl som vilka morfologier, bevaringstillstånd och taxonomiska tillhörigheter som fossilerna har. Totalt har åtta olika masklika taxa identifieras, inte bara inkluderande annelider, men förmodligen även arthropoder och en poriferan. Detta tyder på att maskar och masklika organismer utgör en viktig och diverse komponent av det dåtida biota som nu är bevarat i Waukesha Lagerstätte. Trots de masklika fossilernas exceptionella bevaring, är de svåra att tolka och att entydigt tilldela ett specifikt taxa. Fossiler som tidigare har tolkats tillhöra iglar är i denna studie snarare tolkade till att vara palaeoscolecid maskar baserade på detaljerade scanning electron microscopy (SEM)-studier som visar förekomsten av yttre plattor och noder, mycket lika dem rapporterade från andra palaeoscolecider. Ett av dessa taxa kan möjligtvis tillhöra Wronascolex på grund av dess hallonliknande plattor. SEM-baserad elemental mapping på ett av fossilexemplaren visar en anrikning av kalcium och fosfat i fossilet jämfört med den omkringliggande stenen, vilket tyder på att Waukesha fossilerna kan vara bevarade som kalciumfosfat. Framtida studier som kan vara av intresse att utföra med avseende på denna fossilsamling inkluderar fler detaljerade undersökningar av finstrukturer i SEM i fossilerna tolkade som palaeoscolecider. (Less)
Please use this url to cite or link to this publication:
author
Westberg, Märta LU
supervisor
organization
course
GEOL01 20191
year
type
M2 - Bachelor Degree
subject
keywords
Waukesha Lagerstätte, Silurian, soft-tissue preservation, Palaeoscolecida, Annelida, Arthropoda Waukesha Lagerstätte, silur, mjukvävnadsbevaring, Arthropoda
publication/series
Dissertations in Geology at Lund University
report number
560
language
English
additional info
Supervisor: Andrew Wendruff, Ohio State University
id
8982414
date added to LUP
2019-06-12 13:30:33
date last changed
2019-07-09 09:33:19
@misc{8982414,
  abstract     = {The lower Silurian Waukesha Lagerstätte of Wisconsin, USA, is a Konservat-Lagerstätte which has yielded a diverse assemblage of exceptionally well-preserved soft-bodied organisms. This study comprises first-hand descriptions and assessments of 23 enigmatic worm-like specimens from the Waukesha Lagerstätte, alongside a literature review. The study focuses on the depositional environment in which the strata of the Waukesha Lagerstätte was formed, as well as which morphologies, mode of preservation and taxonomic affinities of the fossils. In total, eight different worm-like taxa have been identified, not only including annelids, but probably also arthropods and a poriferan. This suggests that worms and worm-like organisms formed an important and diverse component of the past biotas that are now preserved in the Waukesha Lagerstätte. Despite their exceptional preservation, the worm-like fossils of Waukesha Lagerstätte are difficult to interpret and unambiguously assign to specific taxa. Specimens previously interpreted to represent leeches are herein rather considered to be palaeoscolecid worms, based on detailed scanning electron microscopy (SEM)-studies which revealed the presence of external plates and nodes, closely similar to those reported from other palaeoscolecidans. One of these taxa could belong to Wronascolex because of its raspberry-like plates. SEM-based elemental mapping of one specimen shows enrichment of calcium and phosphorous in the fossil compared to the surrounding host rock, suggesting that the Waukesha fossils might be preserved as calcium phosphate. Future studies that could be of interest regarding this collection of fossils include more detailed investigations of fine structures in SEM in the specimens interpreted as palaeoscolecidans.},
  author       = {Westberg, Märta},
  keyword      = {Waukesha Lagerstätte,Silurian,soft-tissue preservation,Palaeoscolecida,Annelida,Arthropoda Waukesha Lagerstätte,silur,mjukvävnadsbevaring,Arthropoda},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Enigmatic worm-like fossils from the Silurian Waukesha Lagerstätte, Wisconsin, USA},
  year         = {2019},
}