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Tommotiid
Tommotiids are an extinct group of Cambrian invertebrates thought to be early lophophorates (the group containing Bryozoa, Brachiopoda, and Phoronida). The majority of tommotiids are mineralised with calcium phosphate rather than calcium carbonate. although silicified examples hint that some species bore carbonate or carbonaceous sclerites. '' Micrina'' and '' Paterimitra'' possess bivalved shells in their larval phases, which preserve characters that might position them in the Linguliformea and Rhynchonelliformea stem lineages respectively. This would indicate that the brachiopod shell represents the retention of a larval character. For a long part of their history, the tommotiids were only known from disarticulated shells - a complete organism had not been found. The 2008 discovery of '' Eccentrotheca'' offered the first insight into a complete organism, and permitted a reconstruction of the animal as a sessile, tube-like animal made up of a spiral of overlapping plates. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically-oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wufengella
''Wufengella'' is a genus of extinct camenellan " tommotiid" that lived during the Early Cambrian ( Stage 3). Described in 2022, the only species ''Wufengella bengtsonii'' was discovered from the Maotianshan Shales of Chiungchussu (Qiongzhusi) Formation in Yunnan, China. The fossil indicates that the animal was an armoured worm that close to the common ancestry of the phyla Phonorida, Brachiozoa and Bryozoa, which are collectively grouped into a clade called Lophophorata. Discovery ''Wufengella'' is known from a single specimen. The fossil was discovered by Chinese palaeontologists Jin Guo and Peiyun Cong at the Yunnan University. An almost complete fossil, parts of the anterior end are missing. The location of the specimen, Chiungchussu Formation at Haikou, Kunming, Southwest China, is member of the Chengjian Lagerstätte that is established to belong to Cambrian Stage 3 (between 521 and 514 million year ago). The same fossil deposit had yielded worm-like lobopod ''Facive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wufengella Phlyogeny
''Wufengella'' is a genus of extinct camenellan "tommotiid" that lived during the Early Cambrian (Stage 3). Described in 2022, the only species ''Wufengella bengtsonii'' was discovered from the Maotianshan Shales of Chiungchussu (Qiongzhusi) Formation in Yunnan, China. The fossil indicates that the animal was an armoured worm that close to the common ancestry of the phyla Phonorida, Brachiozoa and Bryozoa, which are collectively grouped into a clade called Lophophorata. Discovery ''Wufengella'' is known from a single specimen. The fossil was discovered by Chinese palaeontologists Jin Guo and Peiyun Cong at the Yunnan University. An almost complete fossil, parts of the anterior end are missing. The location of the specimen, Chiungchussu Formation at Haikou, Kunming, Southwest China, is member of the Chengjian Lagerstätte that is established to belong to Cambrian Stage 3 (between 521 and 514 million year ago). The same fossil deposit had yielded worm-like lobopod ''Facivermis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrina
''Micrina'' is an extinct genus of tommotiids with affinities to brachiopods. ''Micrina'' can be considered a stem group brachiopod based on its larval shell Its microstructure is very brachiopod like and its adult morphology is similarly bivalved, even though it was once thought to be halkieriid-like. ''Micrina'' is quite similar to'' Mickwitzia Mickwitziids are a Cambrian group of shelly fossils with originally phosphatic valves, belonging to the Brachiopod stem group, and exemplified by the genus ''Mickwitzia'' – the other genera are ''Heliomedusa'' (a possible junior synonym of ''Mi ...'' in terms of shell microstructure. The two genera are evidently closely related. Species *''M. etheridgei'' (Tate, 1892) *''M. pusilla'' Gravestock ''et al.'', 2001 *''M. ridicula'' (Barskova, 1988) *''M. xiaotanensis'' Li & Xiao, 2004 References Prehistoric brachiopod genera Cambrian brachiopods {{Palaeo-protostome-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod Fold Hypothesis
The origin of the brachiopods is uncertain; they either arose from reduction of a multi-plated tubular organism, or from the folding of a slug-like organism with a protective shell on either end. Since their Cambrian origin, the phylum rose to a Palaeozoic dominance, but dwindled during the Mesozoic. Origins Brachiopod fold hypothesis The long-standing hypothesis of brachiopod origins, which has recently come under fire, suggests that the brachiopods arose by the folding of a ''Halkieria''-like organism, which bore two protective shells at either end of a scaled body. For a summary, see The tannuolinids were thought to represent an intermediate form, although the fact that they do not, as thought, possess a scleritome means that this is now considered unlikely. Under this hypothesis, the Phoronid worms share a similar evolutionary history; molecular data also appear to indicate their membership of Brachiopoda. Under the Brachiopod Fold Hypothesis, the "dorsal" and "ventr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camenellan
The camenellans, consisting of the genera ''Camenalla'', ''Dailyatia'', ''Kennardia'', ''Kelanella'', ''Wufengella'' and ''Lapworthella'', are a (probably monophyletic) group of Tommotiid invertebrates from the Cambrian period, reconstructed as sister to all others (plus brachiopods and phoronids). They are primarily known from isolated sclerites, but are believed to have a scleritomous, ''Halkieria''-like construction.Skovsted, C. B., Betts, M. J., Topper, T. P. & Brock, G. A. The early Cambrian tommotiid genus ''Dailyatia'' from South Australia. Mem. Assoc. Australas. Palaeontol. 48, 1–117 (2015).Murdock, D. J. E., Donoghue, P. C. J., Bengtson, S. & Marone, F. Ontogeny and micro-structure of the enigmatic Cambrian tommotiid ''Sunnaginia'' Missarzhevsky, 1969. Palaeontology 55, 661–676 (2012). This was confirmed by the discovery of ''Wufengella,'' known from articulated remains, which showed camenellans to be mobile, worm-like animals. ''Dailyatia'' and ''Camenella'' have dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camenella
The camenellans, consisting of the genera ''Camenalla'', ''Dailyatia'', ''Kennardia'', ''Kelanella'', ''Wufengella'' and ''Lapworthella'', are a (probably monophyletic) group of Tommotiid invertebrates from the Cambrian period, reconstructed as sister to all others (plus brachiopods and phoronids). They are primarily known from isolated sclerites, but are believed to have a scleritomous, ''Halkieria''-like construction.Skovsted, C. B., Betts, M. J., Topper, T. P. & Brock, G. A. The early Cambrian tommotiid genus ''Dailyatia'' from South Australia. Mem. Assoc. Australas. Palaeontol. 48, 1–117 (2015).Murdock, D. J. E., Donoghue, P. C. J., Bengtson, S. & Marone, F. Ontogeny and micro-structure of the enigmatic Cambrian tommotiid ''Sunnaginia'' Missarzhevsky, 1969. Palaeontology 55, 661–676 (2012). This was confirmed by the discovery of ''Wufengella,'' known from articulated remains, which showed camenellans to be mobile, worm-like animals. ''Dailyatia'' and ''Camenella'' have dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoronid
Phoronids (scientific name Phoronida, sometimes called horseshoe worms) are a small phylum of marine animals that filter-feed with a lophophore (a "crown" of tentacles), and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long. The name of the group comes from its type genus: ''Phoronis''. Overview The bottom end of the body is an ampulla (a flask-like swelling), which anchors the animal in the tube and enables it to retract its body very quickly when threatened. When the lophophore is extended at the top of the body, cilia (little hairs) on the sides of the tentacles draw food particles to the mouth, which is inside and slightly to one side of the base of the lophophore. Unwanted mater ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eccentrotheca
''Eccentrotheca'' is a genus of "tommotiid" known from Cambrian deposits. Its sclerites form rings that are stacked to produce a widening-upwards conical scleritome. Individual plates have been homologized with the valves of brachiopods, and a relationship with the phoronid Phoronids (scientific name Phoronida, sometimes called horseshoe worms) are a small phylum of marine animals that filter-feed with a lophophore (a "crown" of tentacles), and build upright tubes of chitin to support and protect their soft bodies. ...s is also likely at a stem-group level. Its pointed end terminated in a stub that probably fastened it to a hard sea floor; its open end has been interpreted as a filter-feeding aperture. References Prehistoric protostome genera Cambrian animals of North America Paleozoic life of Nova Scotia {{Cambrian-animal-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mickwitzia
Mickwitziids are a Cambrian group of shelly fossils with originally phosphatic valves, belonging to the Brachiopod stem group, and exemplified by the genus ''Mickwitzia'' – the other genera are ''Heliomedusa'' (a possible junior synonym of ''Mickwitzia''?) and ''Setatella''. The family Mickwitziidae is conceivably paraphyletic with respect to certain crown-group brachiopods. Shell microstructure Punctae or tubes penetrate through multiple shell wall layers, and individual punctae often develop a single, axial phosphatic tube. The shell comprises multiple phosphatic laminae; the region closest to the edge of the shell was presumably more organic-walled than phosphatized as it tends to be more flimsily preserved. Members of the genus appear to share characteristic shell microstructure in common with Tommotiids such as ''Micrina'', and like this taxon, mickwitziids may not have been able to enclose their entire body within a bivalved shell. The shells are punctuated with in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tannuolina
''Tannuolina'' is a genus of tommotiid, belonging to the brachiopod stem lineage. Its phosphatic shells exhibit a complex series of open pores/chambers/channels in outer shell layer.Kouchinsky, A., Bengtson, S. & Murdock, D. J. E. A new tannuolinid problematic from the lower Cambrian of the Sukharikha River in northern Siberia. Acta Pal. Pol. 55, 321–331 (2010). It is conventionally interpreted as an essentially bivalved organism, similar to '' Micrina'', though some use the unequal ratio of stellate to mitrate sclerites to argue for a halkieriid The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is ''Halkieria'' , which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the smal ...-like anatomy.Li, G.-X. & Xiao, S.-H. ''Tannuolina'' and ''Micrina'' (Tannuolinidae) from the Lower Cambrian of Eastern Yunnan, South China, and Their Scleritome Reconstruction. J. Paleo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lophophorata
The Lophophorata are a Lophotrochozoan clade consisting of the Brachiozoa and the Bryozoa. They have a lophophore. Molecular phylogenetic analyses suggest that lophophorates are protostomes, but on morphological grounds they have been assessed as deuterostomes. Fossil finds of a segmented worm named Wufengella ''Wufengella'' is a genus of extinct camenellan " tommotiid" that lived during the Early Cambrian ( Stage 3). Described in 2022, the only species ''Wufengella bengtsonii'' was discovered from the Maotianshan Shales of Chiungchussu (Qiongzhusi) F ... suggest that they evolved from a worm close to annelids. References {{Protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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