A new crustacean from the Early Devonian Rhynie chert, Aberdeenshire, Scotland

2002 ◽  
Vol 93 (4) ◽  
pp. 355-382 ◽  
Author(s):  
Stephen R. Fayers ◽  
Nigel H. Trewin
Keyword(s):  
Hydrothermal Activity ◽  
The Body ◽  
Early Devonian ◽  
Rhynie Chert

ABSTRACTA new crustacean, Castracollis wilsonae is described from a loose block of the Early Devonian Rhynie chert, found in the vicinity of Rhynie, Aberdeenshire, Scotland. It differs markedly from Lepidocaris rhyniensis, Scourfield 1926, the only other crustacean found in the Rhynie chert.The material comprises complete individuals up to 8 mm long and fragmentary remains. The head is normally damaged and detached from the body, and damage to the anterior of the trunk suggests the specimens are exuviae. The head appears domed with a labrum, robust mandibles, and long biramous antennae. A few specimens exhibit a probable detached cephalo-thoracicshield. The trunk is multi-segmented, comprising similar ring-like somites. The thorax variably comprises up to 26 segments. The anterior 11 segments possess similar long, phyllopodous appendages, the remainder variably possess 10 to 15 phyllopodous appendages with a disposition of one per somite. The abdomen comprises up to 28 apodous segments. The posterior of the body comprises a telson with two furcal rami.The crustacean is most probably a calmanostracan branchiopod. It occurs associated with Lepidocaris, charophytes, cyanobacteria and coprolites within a ‘clotted’ chert texture, indicating subaqueous deposition, most probably in a temporary freshwater pool in an area of surficial hydrothermal activity.

scholarly journals An evidence-based 3D reconstruction of Asteroxylon mackiei, the most complex plant preserved from the Rhynie chert

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Alexander J Hetherington ◽  
Siobhán L Bridson ◽  
Anna Lee Jones ◽  
Hagen Hass ◽  
Hans Kerp ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Vascular Plants ◽  
3D Structure ◽  
Terrestrial Ecosystem ◽  
The Body ◽  
Evidence Based ◽  
Ancestral State ◽  
Early Devonian ◽  
Rhynie Chert ◽  
Development And Evolution

The Early Devonian Rhynie chert preserves the earliest terrestrial ecosystem and informs our understanding of early life on land. However, our knowledge of the 3D structure, and development of these plants is still rudimentary. Here we used digital 3D reconstruction techniques to produce the first well-evidenced reconstruction of the structure and development of the rooting system of the lycopsid Asteroxylon mackiei, the most complex plant in the Rhynie chert. The reconstruction reveals the organisation of the three distinct axis types – leafy shoot axes, root-bearing axes, and rooting axes – in the body plan. Combining this reconstruction with developmental data from fossilised meristems, we demonstrate that the A. mackiei rooting axis – a transitional lycophyte organ between the rootless ancestral state and true roots – developed from root-bearing axes by anisotomous dichotomy. Our discovery demonstrates how this unique organ developed and highlights the value of evidence-based reconstructions for understanding the development and evolution of the first complex vascular plants on Earth.

The first zosterophyll from the Lower Devonian Rhynie Chert, Aberdeenshire

1991 ◽  
Vol 82 (4) ◽  
pp. 324-332 ◽  
Author(s):  
A. G. Lyon ◽  
Dianne Edwards
Keyword(s):  
Lower Devonian ◽  
New Genus ◽  
New Genus And Species ◽  
Early Devonian ◽  
Precise Positioning ◽  
Cortical Zone ◽  
Lack Of Information ◽  
Rhynie Chert

ABSTRACTFragmentary remains of a vascular sporophyte from the Rhynie Chert are described as a new genus and species, Trichopherophyton teuchansii. The plant, which is characterised by the possession of unicellular spinous hairs, exarch xylem and laterally attached, marginally dehiscent sporangia, is assigned to the Zosterophyllophytina, but lack of information on the arrangement of sporangia prevents its more precise positioning within the subdivision. Unusual features include the combination of circinate tips to axes with almost terete xylem strands, and the lack of a thick-walled outer cortical zone. Associated axes, lacking spinous hairs, but having papillate or rhizoid-like epidermal emergences, are interpreted as likely rhizomes of Trichopherophyton. Features, such as unicellular spinous hairs, rhizoid-like emergences, circinate tipsand parenchymatous cortex are considered in relation to the functioning and growth of aplant inhabiting an early Devonian wetland.

Fungi from the Rhynie chert: a view from the dark side

2003 ◽  
Vol 94 (4) ◽  
pp. 457-473 ◽  
Author(s):  
T. N. Taylor ◽  
S. D. Klavins ◽  
M. Krings ◽  
E. L. Taylor ◽  
H. Kerp ◽  
...  
Keyword(s):  
Fossil Record ◽  
Molecular Data ◽  
Host Responses ◽  
Dark Side ◽  
Early Devonian ◽  
Mycorrhizal Associations ◽  
Rhynie Chert ◽  
Complex Ecosystem ◽  
Taxonomic Groups ◽  
Fungal Interactions

ABSTRACTThe exquisite preservation of organisms in the Early Devonian Rhynie chert ecosystem has permitted the documentation of the morphology and life history biology of fungi belonging to several major taxonomic groups (e.g., Chytridiomycota, Ascomycota, Glomeromycota). The Rhynie chert also provides the first unequivocal evidence in the fossil record of fungal interactions that can in turn be compared with those in modern ecosystems. These interactions in the Rhynie chert involve both green algae and macroplants, with examples of saprophytism, parasitism, and mutualism, including the earliest mycorrhizal associations and lichen symbiosis known to date in the fossil record. Especially significant are several types of specific host responses to fungal infection that indicate that these plants had already evolved methods of defence similar and perhaps analogous to those of extant plants. This suggests that mechanisms underlying the establishment and sustenance of associations of fungi with land plants were well in place prior to the Early Devonian. In addition, a more complete understanding of the microbial organisms involved in this complex ecosystem can also provide calibration points for phylogenies based on molecular data analysis. The richness of the microbial community in the Rhynie chert holds tremendous potential for documenting additional fungal groups, which permits speculation about further interactions with abiotic and biotic components of the environment.

Potassium–Argon Ages of the Eagle Granodiorite, Southern British Columbia

1972 ◽  
Vol 9 (5) ◽  
pp. 596-599 ◽  
Author(s):  
J. C. Roddick ◽  
E. Farrar
Keyword(s):  
British Columbia ◽  
Hydrothermal Activity ◽  
The Body ◽  
South Central ◽  
Intrusive Activity

Eight potassium–argon ages from the Eagle granodiorite of south-central British Columbia indicate that the body was intruded over a period of about 10 m.y. with the predominant intrusive activity occurring 104 m.y. ago. Hydrothermal activity continued at least until 72 m.y. ago.

Evidence for an early terrestrial food web: coprolites from the Early Devonian Rhynie chert

2003 ◽  
Vol 94 (4) ◽  
pp. 371-389 ◽  
Author(s):  
Kate S. Habgood ◽  
Hagen Hass ◽  
Hans Kerp
Keyword(s):  
Distinct Group ◽  
Terrestrial Ecosystems ◽  
Freshwater Ecosystems ◽  
The Other ◽  
List Type ◽  
Early Devonian ◽  
Amorphous Content ◽  
Nutritional Strategy ◽  
Rhynie Chert ◽  
The Continuum

ABSTRACTFossils in the Pragian Rhynie cherts, Aberdeenshire, Scotland, are preserved with exquisite cellular detail, and provide much information on Early Devonian terrestrial and freshwater ecosystems. The fossils include abundant and diverse coprolites which demonstrate the existence of consumers differing in life-habit and diet. The coprolites are small (0.5–3 mm) and diverse in morphology and content, including groups of amorphous coprolites as well as coprolites with identifiable, particulate content. The present authors define three new ichnogenera to accommodate these coprolites: •Lancifaex encompasses elongate coprolites with particulate content, and includes three ichnospecies, distinguished on morphology, L. simplex, L. divisa and L. moniliforma.•Rotundafaex encompasses rotund coprolites with particulate content, and includes a single ichnospecies, R. aggregata.•Bacillafaex encompasses rod-shaped coprolites with amorphous content, and includes two ichnospecies, distinguished on size, B. constipatus and B. mina. Typically, plant spores do not dominate the content of these coprolites, but the population does include some spore-rich coprolites. The presence of spore-rich coprolites in this diverse assemblage adds evidence to the debate on spore-feeding as a nutritional strategy in early terrestrial ecosystems. The authors conclude that the coprolites described here indicate at least four types of consumer including detritivores and herbivores. Spore-rich coprolites might suggest sporivory; however, comparison with the faeces of modern millipedes demonstrates that they might equally well be the product of detritivores. The continuum observed here between spore-rich and spore-poor coprolites implies that, in this assemblage, spore-rich coprolites do not constitute a distinct group. Rather, they are part of a group of elongate, ellipsoidal coprolites with heterogeneous content that includes, at one extreme, coprolites which lack plant spores, and at the other, coprolites which contain abundant plant spores. Most coprolites in this group fall somewhere between the two extr

The geology of the northern half of the Rhynie Basin, Aberdeenshire, Scotland

2003 ◽  
Vol 94 (4) ◽  
pp. 299-308 ◽  
Author(s):  
C. M. Rice ◽  
W. A. Ashcroft
Keyword(s):  
Surface Expression ◽  
Hydrothermal Activity ◽  
Magnetic Survey ◽  
Early Devonian ◽  
Small Areas ◽  
Andesitic Lava ◽  
Northern Half ◽  
Basin Formation ◽  
Ground Magnetic ◽  
Middle Unit

ABSTRACTA new geological map of the Early Devonian Rhynie Basin has been produced by traditional methods supplemented by trenching to bedrock and a ground magnetic survey. This shows that the basin margins are mostly fault-controlled and three trends are recognised: NE–SW, NNE–SSW and N–S. Three sets of open folds are distinguished with axial traces trending NE–SW, E–W and roughly NW–SE. The faults defining the basin margin and the folding may be related to basin formation within a regional strike-slip system of Early Devonian age.The stratigraphic succession comprises three mappable units: a lower mixed unit of sandstones, shales, conglomerates and andesitic lava (>700 m), a middle unit of laminated grey shale and siltstone (>300 m); and an upper unit of laminated sandstones and shales (>300 m). These correlate with the Tillybrachty Sandstone and Quarry Hill Sandstone Formations (lower unit), and the Dryden Flags Formation (middle and upper units).Small areas containing abundant chert float found outside the Rhynie SSSI may represent the surface expression of chert pods within the middle unit of laminated grey shale and siltstone, which also hosts the Rhynie cherts. The Windyfield cherts occur within the upper unit. No further centres of hydrothermal activity have been found in the northern half of the basin

New gametophytes from the Early Devonian Rhynie chert

2003 ◽  
Vol 94 (4) ◽  
pp. 411-428 ◽  
Author(s):  
Hans Kerp ◽  
Nigel H. Trewin ◽  
Hagen Hass
Keyword(s):  
Reproductive Cycle ◽  
Land Plants ◽  
Monotypic Genus ◽  
Early Devonian ◽  
Male And Female ◽  
Rhynie Chert ◽  
Dense Stand

ABSTRACTSeveral new gametophytes are described from the Early Devonian Rhynie chert. The new monotypic genus Remyophyton, being the gametophyte of Rhynia, is represented by a dense stand of in situ preserved gametophytes with antheridia- and archegonia-bearing axes. The gametophytes are remarkably small in comparison to those of other Rhynie chert plants. The generic diagnoses of Lyonophyton and Langiophyton are emended to include archegonia- and antheridiabearing axes. All essential stages of the reproductive cycle, i.e. sporophytes, and male and female gametophytes, can now be demonstrated for three of the six land plants from the Rhynie chert, i.e. Rhynia gwynne-vaughanii, Aglaophyton major and Horneophyton lignieri.

scholarly journals Ornamentation of dermal bones of Placodermi from the Lower Devonian of Morocco as a measure of biodiversity

Geologos ◽  
2017 ◽  
Vol 23 (2) ◽  
pp. 65-73
Author(s):  
Mateusz Antczak ◽  
Błażej Berkowski
Keyword(s):  
Lower Devonian ◽  
Interspecific Variation ◽  
Species Level ◽  
The Body ◽  
Early Devonian ◽  
Terrestrial Vertebrates ◽  
Evolutionary Changes ◽  
Early Vertebrates ◽  
Dermal Bones ◽  
Scanning Electron

AbstractDermal bones are formed early during growth and thus constitute an important tool in studies of ontogenetic and evolutionary changes amongst early vertebrates. Ornamentation of dermal bones of terrestrial vertebrates is often used as a taxonomic tool, for instance in Aetosauria, extant lungfishes (Dipnoi) and ray-finned fishes (Actinopterygii), for which it have been proved to be of use in differentiating specimens to species level. However, it has not been utilised to the same extent in placoderms. Several features of the ornamentation of Early Devonian placoderms from Hamar Laghdad (Morocco) were examined using both optical and scanning electron microscopy to determine whether it is possible to distinguish armoured Palaeozoic fishes. Four distinct morphotypes, based on ornamentation of dermal bones, are differentiated. These distinct types of ornamentation may be the result of either different location of dermal plates on the body or of ontogenetic (intraspecific) and/or interspecific variation.

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