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Hyolitha
Hyoliths are animals with small conical surface, conical Exoskeleton, shells, known from fossils from the Palaeozoic era. They are at least considered as being lophotrochozoan, and possibly being lophophorates, a group which includes the brachiopods (hyoliths may even be brachiopods themselves), while others consider them as being basal lophotrochozoans, or even Mollusca, molluscs. Morphology The shell of a hyolith is typically one to four centimeters in length, triangular or elliptical in cross section. Some species have rings or stripes. It comprises two parts: the main conical shell (previously referred to as a ‘conch’) and a cap-like Operculum (animal), operculum. Some also had two curved supports known as ''helens'' They are calcium carbonate, calcareous – probably aragonitic All of these structures grew by marginal accretion. Shell microstructure The orthothecid shell has an internal layer with a microstructure of transverse bundles, and an external layer compri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyolithida
The Hyolithida are lophophorates, one of the two orders of hyolithid, the other being the Orthothecida. Most of our knowledge of the hyolithids comes from studies on the Hyolithida. Both orders had an operculum (gastropod), operculum that was not hinged to the conch. However, the Hyolithida are distinct from the Orthothecida in having additional paired, curved, tusk-like appendages. The Hyolithida were probably bottom feeders living in shallow water, and had tentacules. References Further reading * * Paleozoic invertebrates Prehistoric brachiopod orders Hyolitha Cambrian first appearances Permian extinctions {{paleo-protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haplophrentis
''Haplophrentis'' is a genus of tiny shelled hyolithid which lived in the Cambrian Period. Its shell was long and conical, with the open end protected by an operculum, from which two fleshy arms called ''helens'' protruded at the sides. These arms served to elevate the opening of the shells above the sea floor, acting like stilts. Morphology Shell length of ''H. reesi'' reached up to while ''H. carinatus'' reached up to . Juveniles could of course be smaller. It is distinguished from '' Hyolithes'' by the presence of a longitudinal septum on the middle of the inner surface of the top of the shell. Its soft anatomy comprises 12 (''H. carinatus'') to 16 (''H. reesi'') tentacles attached to a horseshoe-shaped lophophore. A pair of wide structures of uncertain function extend along the length of the conical shell. A larval shell is attached to the shell apex. Affinity The soft anatomy of ''Haplophrentis'' was key to establishing the hyoliths as members of the Lophophorata, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthothecida
The orthothecids are one of the two hyolith Hyoliths are animals with small conical shells, known from fossils from the Palaeozoic era. They are at least considered as being lophotrochozoan, and possibly being lophophorates, a group which includes the brachiopods (hyoliths may even be ... orders. Marek diagnoses the order thus: Conchs with a flat or concave ventral surface — opercula with large, flat cardinal processes but without clavicles – tightly sigmoidal, sediment-filled intestine – helens absent. Sometimes the Circothecidae and Tetrathecidae are split out into a separate order 'Circothecida', which is defined by the bottom surface not being flat, the cardinal processes being pronounced, and a circular rim sometimes showing hints of differentiation into clavicles. Internal taxonomy Marek gives the following diagnoses: * Orthothecidae: Flat or concave bottom surface of conical shell. Transverse aperture. Kouchinsky lists the following taxonomic criteria: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lophophore
The lophophore () is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata.Introduction to the Lophotrochozoa – Retrieved 3 May 2010 All lophophores are found in aquatic organisms. Etymology ''Lophophore'' is derived from the Greek ''lophos'' (crest, tuft) and ''-phore'', ''-phoros'' (φορος) (bearing), a derivative of ''phérein'' (φέρειν) (to bear); thus crest-bearing.Characteristics The lophophore can most easily be described as a ring of ted tentacles surrounding the mouth, but it is often horseshoe-shap ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lophophorate
The Lophophorata (also called Tentaculata; not to be confused with Tentaculata Eschscholtz 1825, a class within the Ctenophora) 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 the "tommotiid" ''Wufengella'' suggest that they evolved from worm-like animals that resembled annelids The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to vario .... References {{Protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of 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 brachio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lophophorata
The Lophophorata (also called Tentaculata; not to be confused with Tentaculata Eschscholtz 1825, a class within the Ctenophora) are a Lophotrochozoan clade consisting of the Brachiozoa and the Bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe .... 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 the " tommotiid" '' Wufengella'' suggest that they evolved from worm-like animals that resembled annelids. References {{Protostome-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spence Shale
The Spence Shale is the middle member of the Langston Formation in southeastern Idaho and northeastern Utah. It is exposed in the Bear River Range, the Wasatch Range and the Wellsville Mountains. It is known for its abundant Cambrian trilobites and the preservation of Burgess Shale-type fossils. The type locality is Spence Gulch in southeastern Idaho, near the town of Liberty. It was first described by Charles Doolittle Walcott in 1908. Stratigraphy The Spence Shale spans the '' Albertella'' and '' Glossopleura'' biozones. Fauna Generic list of the fauna of the Spence Shale:Hammersburg, S.R., Hasiotis, S.T., Robison, R.R. 2018. Ichnotaxonomy of the Cambrian Spence Shale Member of the Langston Formation, Wellsville Mountains, Northern Utah, USA. Paleontological Contributions, 20, 1–66. Arthropoda Soft-bodied *''Anomalocaris'' *'' Canadaspis'' *''Caryosyntrips'' *'' Dioxycaris'' *'' Hurdia'' *''Isoxys'' *''Leanchoilia'' *'' Meristosoma'' *'' Mollisonia'' *''Sidneyia' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
