Taphonomy and Paleoecology of an Ophiuroid-Stylophoran Obrution Deposit From the Lower Devonian Bokkeveld Group, South Africa

Reid, Mhairi; Taylor, Wendy L.; Brett, Carlton E.; Hunter, Aaron W.; Bordy, Emese M.

doi:10.2110/palo.2018.048

Cited by 10 publications

(7 citation statements)

References 63 publications

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“…The proportion of incomplete skeletons is high (46%) and abundant isolated arms (>600) are preserved near the base of the obrution bed, probably due to a mass autotomy event during stressful deposition of a sandy tempestite. Ripple marks and irregular cross-bedding are also common in adjacent beds and support the scenario of a shallow continental shelf disturbed by periodic storms (Reid et al 2019).…”

Section: Palaeontological Implicationsmentioning

confidence: 65%

“…Another relevant case has also been documented in the Lower Devonian Voorstehoek Formation of South Africa (Reid et al . 2019). Hundreds of ophiuroids and stylophorans were preserved in this unit along a 5 cm thick sandy lenticular bed.…”

Section: Discussionmentioning

confidence: 99%

“…Ripple marks and irregular cross‐bedding are also common in adjacent beds and support the scenario of a shallow continental shelf disturbed by periodic storms (Reid et al . 2019).…”

Section: Discussionmentioning

confidence: 99%

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How does rapid burial work? New insights from experiments with echinoderms

Fraga,

Vega

2024

Palaeontology

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This research explores the significance of rapid burial in preserving fossils, with a particular focus on free‐living echinoderms. Experiments were based on ophiuroids to simulate burial under different turbiditic flows. The results showed that a bed thickness of around 10 cm is a limit for the preservation of whole skeletons in most cases. The type of sediment can affect the integrity of the buried skeletons, with sand deposition resulting in higher rates of autotomy. However, mud deposition did not show any numbing effect, as previously believed for echinoderms. In contrast, freshwater‐rich sediments can play a critical role, paralysing specimens and preventing escape postures through rapid changes in salinity. From this, the study highlights the importance of extrabasinal turbidites, generated outside the marine basin, in the fossilization of marine invertebrates. Such sediments are rich in fresh water and can be more efficient burial traps compared to other intrabasinal deposits generated by storm waves or submarine landslides.

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Section: Palaeontological Implicationsmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 99%

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How does rapid burial work? New insights from experiments with echinoderms

Fraga,

Vega

2024

Palaeontology

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“…Subsequently, Reid et al . [ 8 ] have described an additional taxon from the Voorstehoek Formation, Bokkeveld Group, which is considered to be Early Devonian in age. Bokkeveld Group ophiuroids comprise part of a well-studied cold water endemic faunal province known as the Malvinokaffric Realm (Malvinoxhosan sensu [ 9 ]) [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Earliest known ophiuroids from high palaeolatitude, southern Gondwana, recovered from the Pragian to earliest Emsian Baviaanskloof Formation (Table Mountain Group, Cape Supergroup) South Africa

Reddy,

Thuy,

Reid

et al. 2023

PLoS ONE

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For the first time, ophiuroids have been found in South African strata predating the lowermost Bokkeveld Group. These comprise natural moulds and casts from two localities in the ‘upper unit’ of the Baviaanskloof Formation (Table Mountain Group). As a Pragian to earliest Emsian age has been inferred for this member, the new taxa comprise the earliest high-palaeolatitude ophiuroid records from southern Gondwana. Morphological analysis of the specimens revealed the presence of two distinct taxa. One is here described as Krommaster spinosus gen. et sp. nov., a new encrinasterid characterised by very large spines on the dorsal side of the disc, the ventral interradial marginal plates and the arm midlines. The second taxon is a poorly preserved specimen of Hexuraster weitzi, a cheiropterasterid previously described from the slightly younger Bokkeveld Group.

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“…Three-dimensional imaging and digital visualization have been used previously to reveal the morphology of the water vascular system of the Ordovician ophiuroid Protasterina from Kentucky [ 35 ] and to interpret accumulations of ophiuroids in the Lower Devonian Bokkeveld Group of South Africa [ 36 , 37 ]. We developed three-dimensional digital reconstructions of six Hunsrück Slate ophiuroids based on micro-CT images of representative well-preserved, fully articulated fossil specimens as a preliminary test of previous interpretations of their mode of locomotion via tube feet or musculoskeletally-driven movement.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional visualization as a tool for interpreting locomotion strategies in ophiuroids from the Devonian Hunsrück Slate

2020

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Living brittle stars (Echinodermata: Ophiuroidea) employ a very different locomotion strategy to that of any other metazoan: five or more arms coordinate powerful strides for rapid movement across the ocean floor. This mode of locomotion is reliant on the unique morphology and arrangement of multifaceted skeletal elements and associated muscles and other soft tissues. The skeleton of many Palaeozoic ophiuroids differs markedly from that in living forms, making it difficult to infer their mode of locomotion and, therefore, to resolve the evolutionary history of locomotion in the group. Here, we present three-dimensional digital renderings of specimens of six ophiuroid taxa from the Lower Devonian Hunsrück Slate: four displaying the arm structure typical of Palaeozoic taxa ( Encrinaster roemeri, Euzonosoma tischbeinianum, Loriolaster mirabilis, Cheiropteraster giganteus ) and two ( Furcaster palaeozoicus , Ophiurina lymani ) with morphologies more similar to those in living forms. The use of three-dimensional digital visualization allows the structure of the arms of specimens of these taxa to be visualized in situ in the round, to our knowledge for the first time. The lack of joint interfaces necessary for musculoskeletally-driven locomotion supports the interpretation that taxa with offset ambulacrals would not be able to conduct this form of locomotion, and probably used podial walking. This approach promises new insights into the phylogeny, functional morphology and ecological role of Palaeozoic brittle stars.

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Taphonomy and Paleoecology of an Ophiuroid-Stylophoran Obrution Deposit From the Lower Devonian Bokkeveld Group, South Africa

Cited by 10 publications

References 63 publications

How does rapid burial work? New insights from experiments with echinoderms

How does rapid burial work? New insights from experiments with echinoderms

Earliest known ophiuroids from high palaeolatitude, southern Gondwana, recovered from the Pragian to earliest Emsian Baviaanskloof Formation (Table Mountain Group, Cape Supergroup) South Africa

Three-dimensional visualization as a tool for interpreting locomotion strategies in ophiuroids from the Devonian Hunsrück Slate

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