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The Devonian period is known as "The Age of Fish", but could also be known as "The Age of Brachiopods." In the Early / Lower Devonian, brachiopods reached the height of their diversity towards its end in the Emsian. We see the ancestral groups occurring, lingulids, craniids, orthids, protorthids, pentamerids, rhynchonellids and strophomenids, as well as the later successful groups we have seen before such as atrypids, athyrids and orthotetids, plus the rise of spiriferids, spiriferinids and productids and the beginning of the terebratulids. By the end of the Devonian , several of these groups are extinct or severely reduced in importance and brachiopods never quite recover. Also, the Devonian is the last time we see trilobites with such variation, large sizes and numbers and orthocerids too are much more uncommon after the rise of the goniatites. The massive tabulate coral reefs also disappear after the Devonian. Fascinating period and I hope to share some of its wonders with you. Equally, a lot of this is rather new to me, so I would be very grateful for any assistance, corrections or further information on my specimens. Thank you. The Early Devonian epoch is split into three stages, so let's start with the first of those, the Lochkovian, that began about 419 mya and finished roughly 411 mya. I have been sent a nice selection of brachiopods from the Kalkberg Formation, Helderberg Group by the Mighty @Misha, mostly. But the kind gentleperson also sent me this fascinating little bryozoan hash : It is dominated by fenestellids, which is usually the case in the Devonian, but other orders sill occur. These ones, I think, are Fenestella, but there are so many species in the formation that I wont take a guess as to species : Not sure what this one is ;
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- cordillera cantabrica
- cryptoschisma schultzii
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- colorado quarry
- becraft
- becraft mountain
- becraft formation
- schizophoria
- schizop
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I would be very grateful for any help regarding ids of these tiny oddments found in a matrix piece from the Early Devonian Helderberg Group, Kalkberg Formation of the Rickard Hill Road cut, Schoharie, New York state. The piece contains four really nice brachiopods, the horn coral Enterolasma strictum and a lot of tiny crinoid ossicles. Perhaps, in strict alphabetical order, @Darktooth @Fossildude19 @Jeffrey P@Misha or @Nautiloid might be able to throw some light on them? Thank you. This first one seems to be encrusting along the growth lines of large, flat specimen of Discomyorths oblata. Could it be a cornulitid of some sort? About 2.5mm long. This first picture seems to show it as pointy, but if you look, the wider end is actually sort of horseshoe shaped ans seems to have an opening infilled with sediment. It seems to show growth lines. The second specimen I thoght might be a tentaculitid, but now I'm leaning towards a gastropod? Note the very fine striations. About 3mm. What about these, please? Some are clearly stemmed echinoderm ossicles, but is that a tiny lingulid. Are there ostracods? These are all only a millimetre or two across. These last two may be burrows? A white one: And a darker one: Finally, tis nice to know they had McDonalds in New York back in the Early Devonian. Thanks to everyone for looking and for any assistance.
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Details of two Rhinopteraspid Fish's Ventral Preoral Regions
Biotalker posted a topic in General Fossil Discussion
I thought I would share this recent fossil purchase. I was fortunate to obtain this fossil from the lower Devonian in the southwestern region (Podolia) of Ukraine. Two ventral snout regions of type of heterostracan (jawless) fish called rhinopteraspid are exposed. The bone detail is simply remarkable. There is “tiling” of the underside of the long (rhino) snouts with dentine and/or aspidine (acellular enamel-like substance) in parallel lines arrays with a more uniform bone matrix underneath. The pre-oral-plate is angled in toward the mouth and displays many external textures of bone that presumably aided the fish’s feeding. I didn't expect to see this level of detail.- 4 replies
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- lower devonian
- pteraspidomorph
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The Presence or Absence of Lateral Denticulations on the Pygidium of Acastella tiro
Isotelus2883 posted a topic in Fossil ID
In connection to a school project, I asked my dad if he could buy me this representative trilobite of Ukraine, as I wrote a little bit on the trilobites of the Silurian-Devonian boundary there. The problem is that the label is probably wrong as Acastella is not found in the Lower Silurian, and searches of the locality in which the trilobite was supposedly found had no results. I think it is much more likely that the trilobite was found in the Borschiv Horizon, around Podolia, as the shell preservation and trilobite looks similar. The question I have though, is: does Acastella tiro have denticulations on its pygidium, or is that A. heberti? A paper on the trilobites of the Iberian Chains says that A. tiro has denticulations on its pygidium, yet a paper on the trilobites of Arctic North America says that is distinct to A. heberti. I would greatly appreciate any information. 1. Acastella tiro and A. heberti form the Iberian Chain 2. From North America 3. My own little specimen, which I am unsure of what species it is.- 3 replies
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- lochkovian
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Hello, friends. This specimen comes from the Catskills, New York and is from the Helderberg Group, Lochkovian or Lowermost Early Devonian in age. It could be from Becraft Mountain. It's not a rhynchonellid, it's too flat and there's no notable fold or sulcus. It develops second second order costellae half way toward the anterior margin : I have a couple of not very convincing thoughts but would be very interested in your opinions. Thank You.
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- catskills
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Probably Gosslingia breconensis Heard 1927. Taxonomy from Fossilworks.org. Edwards 1970, p. 226: “In his preliminary report in 1925, Heard had called the plant Psilophyton, but he renamed it Gosslingia when he presented an account of its anatomy and morphology in 1927.” Emended diagnosis for the genus (Edwards 1970, p. 237): "Plant rootless and leafless. Gregarious erect axes cylindrical, dichotomously and pseudomonopodially branched, arising from dichotomously branched rhizomes with rhizoids. Stems circinately coiled in apical regions: surfaces of some axes with protuberances; large projections (axillary tubercles) occur below branching points. Axes have elliptical xylem strands composed of tracheids with scalariform and reticulate pitting; protoxylem exarch, xylem surrounded by phloem; axillary tubercles with vascular strands circular in cross-section. Outer cortex composed of many layers of thick-walled elongate cells. Epidermis with stomata. Stalked sporangia borne laterally at intervals over a definite fertile region. Sporangial shape variable ranging from reniform to globose, with heavily carbonized convex margin. Spores variable in shape, with part of exine smooth and part ornamented by spini, coni and bacculae.” Reconstruction from Edwards 1970, p. 231: References: Heard, A. (1925) Psilophyton breconensis. Rep. Brit. . (Southampton), pp. 311-312. Heard, A. (1927) On Old Red Sandstone plants showing structure from Brecon (South Wales). Quart. J. geol. Soc. Lond. 85, 195-209. Edwards, D. (1970) Further observations on the Lower Devonian plant, Gosslingia breconensis Heard. Phil. Trans. R. Soc. Lond. B258225–243 http://doi.org/10.1098/rstb.1970.0034. Kenrick, P. & Edwards, D. (1988). The anatomy of Lower Devonian Gosslingia breconensis Heard based on pyritized axes, with some comments on the permineralization process. , 97(2), 95–123. doi:10.1111/j.1095-8339.1988.tb02456.x
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- tff-oilshale-pfl2623
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