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Canadaspidida
Hymenocarina is an order of extinct 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 the presence of mandibles in at least some species. Taxonomy Hymenocarines are characterized by the combination of following characters: bivalved, convex carapace covering cephalothoracic region; cephalothorax bearing multisegmented antennules and rounded mandibles, alongside post-maxillular limbs with spiny, subdivided basis and endopods with well-developed terminal claws; absence of appendages between antennules and mandibles; median sclerite and lobate protrusions located between compound eyes; posterior tagma (abdomen) with ring-like segments and terminated by a pair of well-developed caudal rami. Based on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waptia
''Waptia fieldensis'' is an extinct species of arthropod from the Middle Cambrian Burgess Shale ''Lagerstätte'' of Canada. 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 brood care. ''Waptia fieldensis'' is the only species classified under the genus ''Waptia''. Other specimens of ''Waptia'' are known from the Spence Shale in Utah. 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 Mount Field, other specimens Although it bears a remarkable resemblance to modern cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occacaris
''Occacaris oviformis'' is an extinct nektonic predatory arthropod from the Lower Cambrian Maotianshan shale Lagerstätte. It bears a superficial resemblance to the Cambrian arthropod, ''Canadaspis'', though, was much smaller, and had a pair of "great appendages", with which it may have grasped prey. It was originally considered to belong to Megacheira, however it is questioned in later study. It had a bivalved carapace that covered most of its body, leaving only the last two tergites of its trunk, with the telson jutting out of the posterior end of the carapace, and the eyes, antennae (possibly isolated endopod), and great appendages jutting out of the anterior end. The spines of the great appendages are paired, setting it apart from '' Forfexicaris valida'' and megacheirans like '' Fortiforceps foliosa''. Suggestions have been made that ''Occacaris'' is closely related to megacheirans, or to mandibulates. See also * Arthropod * Cambrian explosion * Chengjiang biota ** List ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropods
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an exoskeleton, external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order (biology)
Order ( la, wikt:ordo#Latin, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between Family_(biology), family and Class_(biology), class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families. What does and does not belong to each order is determined by a taxonomist, as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with a capital letter. Fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pauloterminus
''Pauloterminus'' is an extinct genus of bivalved arthropod known from Early Cambrian (about 520 to 516 million years ago) Sirius Passet locality of northern Greenland. It is tentatively classified under the family Waptiidae. The genus only has a single species ''P. spinodorsalis''. It was first described by the paleontologist Rod S. Taylor in 2002. Its generic name is derived from Latin '' paulus'' ("small") and ''terminus'' ("end"). The specific name is from Latin ''spina'' ("thorn") and ''dorsalis'' ("of the back"). Description The ovoid-shaped bivalved carapace encloses the head and the anterior section of the trunk. The carapace is slightly less than twice as long as it is tall, and becomes wider posteriorly. The largest known carapace is long and wide, while in the smallest known specimens it is less than a centimere in length. The head is poorly known, though it is suggested that they lacked eyes. One specimen has partially preserved pair of segmented antennae, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protocaris
''Protocaris marshi'' is an extinct species of bivalved arthropod known from a single specimen collected from the Cambrian Series 2 aged Parker Formation from the Parker Quarry of northwestern Vermont, United States The specimen is preserved in top-down view and has a bivalved carapace, a segmented trunk and a forked tail. Its precise taxonomic position is uncertain, due to the limited nature of known remains, but it is suggested to be a member of Hymenocarina belonging to the family Protocarididae, which also includes '' Tokummia'' and ''Branchiocaris ''Branchiocaris'' is an extinct genus of Cambrian bivalved arthropod. The type and best known species, ''Branchiocaris pretiosa,'' was described from the Burgess Shale of British Columbia, Canada, in 1929, originally placed in '' Protocaris'', a ....'' References Cambrian arthropods {{branchiopoda-stub Hymenocarina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branchiocaris
''Branchiocaris'' is an extinct genus of Cambrian bivalved arthropod. The type and best known species, ''Branchiocaris pretiosa,'' was described from the Burgess Shale of British Columbia, Canada, in 1929, originally placed in '' Protocaris'', and was placed into its own distinct genus by Briggs in 1976. Several other possible species have been described from Cambrian deposits in China, and it is also possibly known from Cambrian deposits in Utah. ''Branchiocaris pretiosa'' is around in length, with a highly segmented trunk, consisting of at least 44 ring-like segments, terminating in a forked tail telson. At the front of the animal is a pair of short segmented tapered antennules with at least 20 segments, as well as a pair of claw appendages. It was likely an active swimmer, and used the claw appendages to bring food to the mouth. The discovery of '' Tokummia'' from the Burgess Shale, believed to be a close relative of ''Branchiocaris'', has shed light on the evolutionary plac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tokummia
''Tokummia katalepsis'' is a fossil hymenocarine arthropod from the Burgess Shale as found in a quarry in Marble Canyon in Canada, lived during middle Cambrian (508 million years old). The animal has maxillipeds, mandibles, ring-shaped around 50 body segments, and subdivided basipods. At the front of the animal, there are a pair of antennae, possible eyes and mandibles with pincers. ''Tokummia'' shows the oldest record of arthropod pincers. Carapaces had length up to long. Its biramous legs had endites (small spikes). It is suggested to be a bottom feeder, being able to walk on the sea floor, and to occasionally swim, and used its pincers to catch prey. The genus name ''Tokummia'' named after Tokumm Creek which runs through the Marble Canyon where it was found. The species name ''katalepsis'' means Greek word for "seizing", "gasping" or "holding". According to research of ''Tokummia'', Hymenocarines like ''Tokummia'', ''Branchiocaris'', ''Canadaspis'' and '' Odaraia'' are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplapex
''Duplapex'' is an extinct genus of bivalved arthropod known from the Cambrian Stage 3 aged Qingjiang biota of Hubei, China, with a single species. ''D. anima''. It is thought to be a close relative of ''Tuzoia ''Tuzoia'' (from Mount Tuzo, a mountain in the Canadian Rockies) is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The larg ...'', but unlike it, the reticulated (net patterned) bivalved carapace was interpreted to have opened at a wide angle. The carapace had a pair of spines projecting posteriorly. In its original description, it was suggested to have eyes on annulated stalks, but later research suggested that these may have been preservational artifacts instead. References {{Reflist Cambrian arthropods Hymenocarina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuzoia
''Tuzoia'' (from Mount Tuzo, a mountain in the Canadian Rockies) is an extinct genus of large bivalved arthropod known from Early to Middle Cambrian marine environments from what is now North America, Australia, China, Europe and Siberia. The large, domed carapace reached lengths of , making them amongst the largest known Cambrian arthropods. Description The largest carapaces of ''Tuzoia'' are known to reach in length, suggesting a total body length of approximately . Along the sides of the carapace a spiked ridge is present, and the edges and midline of the carapace are also spiked in many species. These spines likely functioned to aid stability while swimming. The carapaces are marked with a reticulate (net-like) pattern, which was likely to increase the structural integrity of the valves while remaining lightweight. The head had a anterior/ocular sclerite at the top, a single pair of large stalked eyes, and a pair of segmented antennae. The head has pairs of cephalic append ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
