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Showing results for tags 'rhynchonellid'.
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I am fortunate enough to have such a huge amount of Middle Devonian Givetian material that I thought it best to put the older Middle Devonian stage, the Eifelian, in its own thread. There are some spectacular fossils here as well though! I thought a good place to start would be in the Formosa Reef, which I believe is quite early Eifelian. This tabulate coral and stromatoporoid reef continues similar complexes found from the Middle Silurian, see my: https://www.thefossilforum.com/topic/84678-adams-silurian/page/3/ thread from page three onwards for details. All these Formosa Reef specimens come from a delightful gift from my good friend @Monica who is a tad busy with life at the moment but is fine and still thinking of the forum. This outcrop can be found on Route 12 near Formosa/Amherstburg, Bruce County, Ontario, Canada. This beautiful-looking specimen came to me with only a third of it revealed but I managed to get it this far after nine days of painful pin prepping. Monica found another one and posted it for ID here: https://www.thefossilforum.com/topic/105528-weird-circular-imprints-formosa-reef-lower-devonian/#comment-1172285 The specimen was identified by another Canny Canadian @Kane to be the little stromatoporoid sponge Syringostroma cylindricum. Hardly a reef-builder, but gorgeous nonetheless. It does have a little thickness to it, but not much. Beautiful! Pretty thin, actually. I love this Monica, thank you!
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- acanthopyge
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Hoooooooooooorrrrrrrrrrrraaaaaaayyyyyyyyyyy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Here we are at last, into Adam's Silurian. Thanks for looking. First up is the Lower Silurian or Llandovery and I begin with a problem. I posted this one incorrectly in Adam's Ordovician as it had got it's label muddled up with an Ordovician Favosites I had that has vanished in the move here, but is being replaced by kind forum member @Herb Anyway, this, I remember now I've found the correct label, is from the greenish Browgill Formation, part of the Stockdale Group from a cutting near Skelgill (Skelghyll) in Cumbria, Northern England. It seems to be a tabulate coral, but I can't find any listed for this location, only mentions of small, rare, rugose corals. It has the star shaped corallites of a Heliolitidid, but seems to be tightly packed together like a Favositidid. A couple of species of Palaeofavosites seem to be close and are a bit star-shaped,, but anyone know any better? @TqB@piranha hmm who else? The coral bit, an external mold, is a maximum of 3.5 cm across and each corallite up to 2 mm.
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From the album: Lower Carboniferous fossils of Ireland
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- dublin ireland
- lower carboniferous limestone
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The thread http://www.thefossilforum.com/index.php?/topic/84678-adams-silurian/ was getting rather enormous, so I have decided to leave that one to deal with the Llandovery and Wenlock and put my specimens from the Late / Upper Silurian here, though I don't have a great deal of material from the Ludlow and Pridoli yet. However, I do still have some jolly nice specimens to show off here. Here are my other collection threads for the Cambrian and Ordovician ; http://www.thefossilforum.com/index.php?/topic/78887-adams-cambrian/&tab=comments#comment-832018 and : http://www.thefossilforum.com/index.php?/topic/78974-adams-ordovician/&tab=comments#comment-832912 In the mid 1980's, on the way home from one of my annual visits to the Hay-on-Wye second-hand bookshops, I managed to persuade my girlfriend at the time to take a bit of a detour and stop off at a roadcuttting just outside Aymestrey,, Herefordshire in the Welsh Borderlands. The rock here is the Aymestry (sic) Limestone Formation, part of the Upper Bringewood Beds and is Gorstian, Lower Ludlow in age, so about 426 mya and a little younger than the Much Wenlock Shale Formation. Many species of coral, trilobites and brachiopods found in the formation are the same as those found at Dudley, but the bed is noted for its massive numbers of the brachiopod Kirkidium knighti (was K. knightii),a lovely, large pentamerid. In fact, during my hour or so searching, I found almost nothing but this species, the only exception being a couple of Atrypa reticularis. The problem was that this limestone is thick and seriously hard, even the broken bits are generally huge, but I managed to obtain half a dozen reasonable specimens and about the same number of fragments. Over the years I have traded, given away or sold them, so that now I only have the best one left. Here is Kirkidium knighti : It's a shame the tip of the beak is broken off : I make index cards for all my fossils, this is the one I made for the specimens at the time, back in the mid 1980's : And today's version : There was a minor extinction between the Wenlock and the Ludlow, known as the Mulde event and it is often said to have primarily effected graptolites and conodonts, but it seems to me it had a massive impact on the bryozoan faunas of the time too. Gone are the varied stony stick and mound trepostomes that made up such an integral part of many faunas from the Middle Ordovician through to the Middle Silurian and even cystoporid groups such as the Constellariidae became extinct at this time. Trepostomes and cystoporids did survive until the end of the Triassic, but were never as important again, the bryozoan faunas would start to become dominated by fenestrids in the Devonian, though they reached their peak of diversity and distribution in the Carboniferous. I will look closely at my limited number of rocks, but I don't think I have a single Late Silurian bryozoan. I know our friend @Mainefossils studies the Late Silurian Leighton Formation in microscopic detail, but I can't recall him posting any bryozoans. Are there any, Asher, old chap? Interesting.
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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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- aguion formation
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From the album: Lower Devonian fossils
Pleiopleurina pleiopleura Rhynchonellid brachiopods Lower Devonian Glenerie Limestone Tristates group Eastern NY -
From the album: Lower Devonian fossils
Camarotoechia dryope? Rhynchonellid brachiopod Lower Devonian Glenerie Limestone Tristates group Eastern NY -
I have a set of very small brachiopods from the Ozan Formation (Upper Cretaceous, Campanian) of north Texas (Fannin County, near the North Sulphur River). Some pictures have scale bars, others do not, but the largest of these shells is ~4mm (they are roughly equidimensional). They are not a rare shell in the matrix, but are small and are not abundant. I collected 57 pieces of them out of 3-4000 fossil items picked from the 12 mesh matrix fraction. I have not found a direct match in my literature and website searches so far, so I am looking for some help from our brachiopods gurus @Tidgy's Dad, @Misha, @Jeffrey P, @Thomas.Dodson @Fossildude19 and anyone else who might care to voice an opinion. Also our North (or even Central) Texas folks surely might have some valuable insight: @BobWill, @JamieLynn @ThePhysicist @JohnJ @erose, @grandpa, @Uncle Siphuncle just to call out a few. Maybe the Dallas Paleo Society has looked into these. I'll start with just a bit of background info first. These brachiopods are not new, but may be as yet officially unidentified, but that is what I hope to find out. Cretaceous brachiopods in Texas are not that common, other than Kingena (Waconella) wacoensis and these are clearly not that species. The 2019 version of the Fossils Collectors Guidebook to the North Sulphur River shows some similar looking specimens on Page 45 (Figure 8) but lists them as "small indeterminate rhynchonellid brachiopods". G.A. Cooper in a 1973 publication named a new terebratulid genus, Cricosia, which was found rarely in the Upper Cretaceous of Texas which bears some similarities and D.V. Ager, et al published a Journal of Paleontology paper in 1963 which discussed two genera (Cyclothyris and Lamellorhynchia) of rhynchonellid brachiopods which bear a passing resemblance (but have some major differences) and I have seen on other websites attributed to specimens from north Texas. As far as I know, that is about the extent of published brachiopods from the Cretaceous of Texas. If I have missed any others, perhaps that are too dissimilar from mine to have come across my radar, but if you are aware of others, please let me know. So my first question as I started looking for an ID, which Order of brachiopods do mine belong to? I thought this would be easy, I was wrong. While brachiopod diversity was very high in the Paleozoic, by the late Mesozoic (specifically Cretaceous) there were only two Orders of articulate brachiopods left, the Terebratulida and Rhynchonellida. That should be easy, only two to choose from. Unfortunately, the brachiopods in question don't fit nicely into the common forms of either one. I made a little table of the common features of the two orders based on information from the Treatise of Invertebrate Paleontology (Part H) and highlighted which features are present (check mark) or absent (no go sign) in the specimens in question. Probably the most important feature that distinguishes the two orders, is the support of the lophophore, (the internal feeding mechanism) and I don't have preserved features which make this obvious. On the outside, terebratulids are normally smooth with a curved hinge, mine are ribbed with a straight hinge. Rhynchonellids are normally very biconvex, have a strong fold and sulcus and the line where the two valves join is zig-zig due to very coarse ribbing, mine have none of these features. I can not see any punctae in the shells, but I always struggle with this and maybe the preservation in just not good enough to preserve this microscopic feature. One last thing I read is that rhynchonellids have strong hinge teeth and tend to be most commonly preserved as complete shells (both valves together). I have a couple of articulated specimens, but most of mine are isolated brachial or (less common) pedicle valves. So I am leaning to Terebratulid, but not positive. OK, enough yakking, lets look at them: The brachial valve interiors I think hold some of the most important features for determining an ID. In these you can see that the pedicle opening is not closed, but is an open triangular shape. On this one you can see that the ribbing is somewhat beaded and that the umbo area is somewhat smooth. You don't see that preserved on all of them. I know this is a lousy picture, but you can see the biconvex profile with the pedicle valve on the left and the pedicle opening at the top. In all cases the pedicle valve is quite inflated and the brachial valve is either flat or slightly convex. Here are two different shells in anterior view showing the straight line of junction between the two valves (sorry from the glob of sticky stuff on the top specimen). One is very biconvex, the other is planoconvex. Thee is no hint of a fold or sulcus. Here is a detailed view of the brachial valve interior with some lighting from the side to try and show the crura (right one is in red circle) which are paired processes that stick up and I believe were the base of the calcareous loop that supported the lophophore. So I am asking for any help in pinning a name to these. I'd be happy with a genus but will even settle for a family. Based on searching through the Treatise and reading several publications, I believe they are Terebratulids in the Family Cancellothyrididae. I believe the very distinct processes I see sticking up (red circles), the shape of the cardinal process and the lack of a median septum rule out any rhynchonellids, but I could be mistaken. The genus Cricosia is the closest I can find and it has been reported from Texas, but these are definitely different from Cricosia filosa (Conrad), which I believe is the only species described. Below are snippets from The 1973 Cooper paper of Cricosia and the one on the right is from the Treatise. You can see the shape is similar (straight hinge is very uncommon in terebratulids), the cardinal process is very similar, but the ornamentation is very different (the whole family is one of the few in terebratulida that has ribbing). Of course, my specimens are missing the whole loop feature that is so important, I only have the base of the feature (and is the Treatise diagram, those are reconstructed). Thanks for looking and I appreciate any insights. I can provide more info or other pictures if needed. Mike
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From the album: Misha's Silurian
Stegerhynchus sp.? Middle Siluran Waldron Shale Waldron Indiana-
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- brachiopod
- rhynchonellid
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From the album: Misha's Silurian
Stegerhynchus neglecta Middle Siluran Waldron Shale Waldron Indiana-
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- brachiopod
- pyrite
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Rhynchonellid brachiopod from the Kalkberg Formation
Nautiloid posted a gallery image in Member Collections
From the album: Lower Devonian Helderberg Group in Eastern NY
Ancillotoechia acutiplicata Lower Devonian Helderberg Gr. Kalkberg Fm. Rickard Hill Roadcut Schoharie, New York Collected 5/31/20 -
Fossil hunting in the shed like many of us - I thought I'd lost this nice globular rhynchonellid in a house move years ago. From the top Campanian/bottom Maastrichtian Chalk of Norfolk, UK. I think it's Cretirhynchia sp.
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Brachiopods, perhaps rhynchonellids most of all, are notoriously hard to identify without their internal features exposed. However, if you know the formation and rough location and have faunal lists it can be possible. Rhynchonella ainsliei, for example, has 26-34 costae with 5-7 of these appearing on the fold. This specimen has 30 and 5 respectively and is the only species that has so many found in this formation. It also has the correct shape and size to support the match.
