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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 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 "vent ... [...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] |
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-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. Paleontol. 78(5), 900–913 (2004). More recently a tube-like construction inspired by ''Eccentrotheca ''Eccentrotheca'' is a genus of " tommotiid" known from Cambrian deposits. Its sclerites form rings that are stacked to produce a widening-upwards con ... [...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 deuterostome Deuterostomia (; in Greek) are animals typically characterized by their anus forming before their mouth during embryonic development. The group's sister clade is Protostomia, animals whose digestive tract development is more varied. Some exa ...s. Fossil finds of a segmented worm named Wufengella suggest that they evolved from a worm close to annelids. References {{Protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tannuolinidae
''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-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. Paleontol. 78(5), 900–913 (2004). More recently a tube-like construction inspired by ''Eccentrotheca ''Eccentrotheca'' is a genus of " tommotiid" known from Cambrian deposits. Its sclerites form rings that are stacked to produce a widening-upwards con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Askepasma
''Askepasma'' is an extinct genus of brachiopods which existed in what is now Australia and southern China during the Lower Cambrian. The type species is ''A. toddense''. ''A. transversalis'' occurs in Guizhou, and ''A. saproconcha'' is the oldest known southern Australian brachiopod from the lower Cambrian. References External links ''Askepasma''at the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Paleo ... {{Taxonbar, from=Q4807170 Prehistoric brachiopod genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
