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Protocarididae
Hymenocarina is an order of extinct marine arthropods known from the Cambrian. They possess bivalved carapaces, typically with exposed posteriors. Members of the group are morphologically diverse and had a variety of ecologies, including as filter feeders and as predators. Recent research has generally considered them to be stem or crown group members of Mandibulata, due to the presence of mandibles in well-preserved species. Taxonomy Hymenocarines are characterized by the combination of the following characters: bivalved, convex carapace covering cephalothoracic (combined head and thorax) region; cephalothorax bearing multisegmented antennae (though as an exception antennae are absent in ''Odaraia'') and rounded mandibles and likely maxillae, post maxillae limbs with spiny, subdivided basis and endopods (lower, leg-like parts) with well-developed terminal claws; absence of appendages between antennae and mandibles; median sclerite and lobate protrusions located between compou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waptia
''Waptia'' is an extinct genus of marine arthropod from the Middle Cambrian of North America. It grew to a length of , and had a large bivalved carapace and a segmented body terminating into a pair of tail flaps. It was an active swimmer and likely a predator of soft-bodied prey. It is also one of the oldest animals with direct evidence of Parental investment, brood care. ''Waptia fieldensis'' is the only species classified under the genus ''Waptia'', and is known from the Burgess Shale ''Lagerstätte'' of British Columbia, Canada. Specimens of ''Waptia'' are also known from the Spence Shale of Utah, United States. Based on the number of individuals, ''Waptia fieldensis'' is the third most abundant arthropod from the Burgess Shale Formation, with thousands of specimens collected. It was among the first fossils found by the American paleontologist Charles D. Walcott in 1909. He described it in 1912 and named it after two mountains near the discovery site – Wapta Mountain and Moun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadaspis
''Canadaspis'' ("Shield of Canada") is an extinct genus of bivalved Cambrian marine arthropod, known from North America and China. They are thought to have been benthic feeders that moved mainly by walking and possibly used its biramous appendages to stir mud in search of food. They have been placed within the Hymenocarina, which includes other bivalved Cambrian arthropods. Description ''Canadaspis'' ''perfecta'' The bivalved carapaces of ''Canadaspis'' ''perfecta'' are typically in length, which taper towards the front end. The head had a small pair of eyes borne on short stalks. Between the eyes is a forward pointing spine, as well as a pair of short antennae, which appear to lack segmentation. Similar antennae are known from '' Waptia'', and are probably homologous to the hemi-ellipsoid bodies of crustaceans, and thus likely have an olfactory function. The head also has another pair of larger, segmented antennae, probably with more than 12 segments, the segments increased ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Odaraia
''Odaraia'' is an extinct genus of bivalved Hymenocarina, hymenocarine arthropod with a single known species ''Odaraia alata'', found in the Middle Cambrian Burgess Shale in British Columbia, Canada. History of research and taxonomy The genus and species were first described by Charles Doolittle Walcott, Charles Walcott in 1912. It was placed into its own family, Odaraiidae by Simonetta and Delle Cave in 1975,Simonetta AM, Delle Cave L . 1975 The Cambrian non-trilobite arthropods from the Burgess Shale of British Columbia: a study of their comparative morphology, taxonomy and evolutionary significance. ''Palaeontogr. Ital.'' which has been used to include other genera of bivalved Cambrian arthropods. The species was redescribed by Derek Briggs 1981, and again redescribed in 2024 by Izquierdo-López and Caron. While originally ''Odaraia'' and other odaraiids have been interpreted as Basal (phylogenetics), basal euarthropods not closely related to any living arthropod group, the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
20191022 Kerygmachela Kierkegaardi Without Lobopods
Year 191 ( CXCI) was a common year starting on Friday of the Julian calendar. At the time, it was known as the Year of the Consulship of Apronianus and Bradua (or, less frequently, year 944 ''Ab urbe condita''). The denomination 191 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Parthia * King Vologases IV of Parthia dies after a 44-year reign, and is succeeded by his son Vologases V. China * A coalition of Chinese warlords from the east of Hangu Pass launches a punitive campaign against the warlord Dong Zhuo, who seized control of the central government in 189, and held the figurehead Emperor Xian hostage. After suffering some defeats against the coalition forces, Dong Zhuo forcefully relocates the imperial capital from Luoyang to Chang'an. Before leaving, Dong Zhuo orders his troops to loot the tombs of the Han emperors, and then destroy Luoyang b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerygmachela
''Kerygmachela kierkegaardi'' is a Kerygmachelidae, kerygmachelid Lobopodia#Gilled lobopodians, gilled lobopodian from the Cambrian Stage 3 aged Sirius Passet Lagerstätte in northern Greenland. Its anatomy strongly suggests that it, along with its relative ''Pambdelurion whittingtoni'', was a close relative of radiodont (''Anomalocaris'' and relatives) and euarthropods. The Generic name (biology), generic name "''Kerygmachela''" derives from the Greek language, Greek words ''Kerygma'' (proclamation) and ''Chela'' (claw), in reference to the flamboyant frontal appendages. The Specific name (zoology), specific name, "''kierkegaardi''" honors Denmark, Danish philosopher Søren Kierkegaard. Morphology The head of ''Kerygmachela'' possesses a pair of well-developed frontal appendages which correspond to those of other Dinocaridida, dinocaridids and Lobopodia#Siberion and similar taxa, siberiid lobopodians. Each of them terminates in a series of long spines. A pair of sessile, sli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pambdelurion
''Pambdelurion'' is an extinct genus of Panarthropoda, panarthropod from the Cambrian aged Sirius Passet site in northern Greenland. Like the morphologically similar ''Kerygmachela'' from the same locality, ''Pambdelurion'' is thought to be closely related to arthropods, combining characteristics of "lobopodians" with those of primitive arthropods. Description ''Pambdelurion'' was large for a Cambrian animal, and is estimated to have reached a length of . ''Omnidens'', an organism from China that closely resembles ''Pambdelurion'' and may even be synonymous with it, reached even larger sizes, estimated to be based on the proportions of ''Pambdelurion''. The head of ''Pambdelurion'' bore a large pair of frontal appendages, homologous to the antennae of onychophorans and frontal appendages of Radiodonta, radiodonts. These frontal appendages were weakly muscled and relatively soft, suggesting they may have served primarily as sensory organs, rather than for grasping prey. Between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chuandianella
''Chuandianella ovata'' is an extinct bivalved arthropod that lived during Cambrian Stage 3 of the Early Cambrian (about 520 to 516 million years ago). It is the only species classified under the genus ''Chuandianella''. Its fossils were recovered from the Chengjiang Biota in Yunnan, China. Taxonomy It was originally described in 1975 under the "ostracod"-like genus '' Mononotella'', as ''Mononotella ovata''. In 1991, the paleontologists Hou Xian-guang and Jan Bergström reclassified it under the new genus ''Chuandianella'' when additional discoveries of more complete specimens made its resemblance to '' Waptia fieldensis'' more apparent. In 2004, paleontologist Jun-Yuan Chen tentatively transferred it to the genus ''Waptia''. However, ''C. ovata'' had eight abdominal somites in contrast to five in ''W. fieldensis''. Its limbs were biramous and were undifferentiated, unlike those of ''W. fieldensis''. Other authors deemed these differences to be enough to separate it from ''W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatocopina
Phosphatocopina (alternatively Phosphatocopida) is an extinct group of bivalved arthropods known from the Cambrian period. They are generally sub-milimetric to a few millimetres in size. They are typically only known from isolated carapaces, but some found in Orsten-type phosphatized preservation have their bodies preserved in high fidelity in three dimensions. Description The phosphatized bivalved carapace covered the entire body. Members typically grew to a maximum of in length, though ''Cyclotron'' grew up to . In some species, spines were present on the carapace. The head either bore a pair of stalked eyes or a pair of dome-shaped medial eyes. The first appendage pair, dubbed the " antennulae", were uniramous, with the remaining appendage pairs being biramous. The basipods and endopods of the biramous limbs had prominently developed endites, while the exopods were typically annulated, and bore setae. The earliest larval stages of phosphatocopines are known as "head larv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bradoriida
Bradoriida, also called bradoriids, are an extinct order of small marine arthropods with a bivalved carapace, which globally distributed, forming a significant portion of the Cambrian and Early Ordovician soft-bodied communities. Affinity Whilst the Bradoriida were traditionally considered as relatives of the modern bivalved arthropod group Ostracoda, the anatomy of their appendages does not support such a relationship; neither are they related to the Cambrian bivalved arthropod group Phosphatocopina. They have been alternatively recovered as stem-group crustaceans, as stem-group mandibulates, or stem-group arthropods, depending on the analysis. Description Most bradoriids are only known from their bivalved carapaces, which are small in size, typically up to around in length. Preserved soft tissues known from some members, such as '' Kunmingella, Kunyangella'' and ''Indiana'' suggest that the group was morphologically diverse. ''Indiana'' had a pair of antennae followed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isoxyida
Isoxyids are members of the order Isoxyida and the family Isoxyidae, a group of basal arthropods that existed during the Cambrian period. It contains two genera, ''Isoxys'', with 20 species found worldwide, and ''Surusicaris'' known from a single species found in the Burgess Shale of Canada. They are distinguished by their bivalved carapaces and pair of upward curving grasping frontal appendages. Description Isoxyids have a combination of features seen in both stem-group arthropods, as well as more advanced taxa. Isoxyids have semicircular bivalved Carapace, carapaces, large, spherical Arthropod eye, eyes, a pair of large upward curling frontal appenages covered in spines, and pairs of biramous limbs running along the body. The trunk region appears to be unsegmented and lacks sclerotisation, similar to Radiodonta, radiodonts, with a segmented and sclerotised (arthropodized) trunk being characteristic of most arthropods. Currently only two genera have been accepted to be members ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphyletic
A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies, which are explained as a result of convergent evolution. The arrangement of the members of a polyphyletic group is called a polyphyly .. [Source for pronunciation.] It is contrasted with monophyly and paraphyly. For example, the biological characteristic of warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds; "warm-blooded animals" is therefore a polyphyletic grouping. Other examples of polyphyletic groups are algae, C4 photosynthesis, C4 photosynthetic plants, and Xenarthra#Evolutionary relationships, edentates. Many taxonomists aim to avoid homoplasies in grouping taxa together, with a goal to identify and eliminate groups that are found to be polyphyletic. This is often the stimulus for major re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic grouping (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term received currency during the debates of the 1960s and 1970s accompanying the rise of cladistics, having been coined by zoologist Willi Hennig to apply to well-known taxa like Reptilia (reptiles), which is paraphyletic with respect to birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor exc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
