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Cantabrigiaster Fezouataensis
''Villebrunaster'' is an extinct genus of starfish-like animal belonging to Asterozoa that lived around 480 million years ago during Early Ordovician Period in modern-day southern France and Morocco. As of 2022, it contains two species, namely ''V. thorali'' and ''V. fezouataensis''. ''V. thorali'' was described in 1951 and ''V. fezouataensis'' was described in 2021. ''Villebrunaster'' represents one of the oldest members of asterozoans, and perhaps, according to a description in 2021, the earliest divergent stem-group (ancestral members) of Asterozoa. Discovery and species The first species was discovered and described by British palaeontologist William Kingdon Spencer in 1951. The fragmentary specimens were collected from Saint-Chinian Formation in southern France. Spencer recognised it as among "the earliest starfish known." Another British palaeontologist Juliette Dean Shackleton identified new specimens as ''Ampullaster ubaghsi'' in 2005, which were later reclassified as '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saint-Chinian Formation
The Saint-Chinian Formation is a geological formation composed of shales with limestone inclusions, dating from the Lower Ordovician (Tremadocian). It is one of the six geological formations from the Saint-Chinian Cambro-Ordovician basin, comprising, from the most ancient to the most recent : La Dentelle Formation, Saint-Chinian Formation, La Maurerie Formation, Cluse de l'Orb Formation and Setso member, Foulon Formation and Landeyran Formation. This formation outcrops on the southern flanks of the Montagne Noire in Southern France.. The formation received its name from the small city of Saint-Chinian, a commune located in the Hérault department in Occitania. It is dated from the biostratigraphic sub-zone characterized by Taihungshania miqueli and Asaphelina barroisi berardi. Paleoenvironment The thin nature of the silico-clastics deposits, the presence of slump, combined with a trilobite fauna dominated by members of the Asaphidae family indicates a marine environment of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Asterozoa Genera
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 1951
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the abso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basket Star
The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristic repeatedly branched arms (a shape known as "basket stars", which includes most Gorgonocephalidae and two species in the family Euryalidae), while the other species have very long and curling arms, and go rather by the name of "snake stars" (mostly abyssal species). Many of them live in deep sea habitats or cold waters, though some basket stars can be seen at night in shallow tropical reefs. Most young basket stars live on specific type of coral. In the wild they may live up to 35 years. They weigh up to Like other echinoderms, basket stars lack blood and achieve gas exchange via their water vascular system. The basket stars are the largest ophiuroids with '' Gorgonocephalus stimpsoni'' measuring up to 70 cm in arm length with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brittle Star
Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to in length on the largest specimens. The Ophiuroidea contain two large clades, Ophiurida (brittle stars) and Euryalida (basket stars). Over 2,000 species of brittle stars live today. More than 1,200 of these species are found in deep waters, greater than 200 m deep. Range The ophiuroids diverged in the Early Ordovician, about 500 million years ago. Ophiuroids can be found today in all of the major marine provinces, from the poles to the tropics. Basket stars are usually confined to the deeper parts of this range; Ophiuroids are known even from abyssal (>6,000 m) depths. However, brittle stars are also common members of reef communities, where t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ossicle (echinoderm)
Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms. They form part of the endoskeleton and provide rigidity and protection. They are found in different forms and arrangements in sea urchins, starfish, brittle stars, sea cucumbers, and crinoids. The ossicles and spines (which are specialised sharp ossicles) are the only parts of the animal likely to be fossilized after an echinoderm dies. Formation Ossicles are created intracellularly by specialised secretory cells known as sclerocytes in the dermis of the body wall of echinoderms. Each ossicle is composed of microcrystals of calcite arranged in a three-dimensional lattice known as a stereom. Under polarized light the ossicle behaves as if it were a single crystal because the axes of all the crystals are parallel. The space between the crystals is known as the stroma and allows entry to sclerocytes for enlargement and repair. The honeycomb structure is light but tough and collage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem-group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinodermata
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian. The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. Geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morocco
Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to the east, and the disputed territory of Western Sahara to the south. Mauritania lies to the south of Western Sahara. Morocco also claims the Spanish exclaves of Ceuta, Melilla and Peñón de Vélez de la Gomera, and several small Spanish-controlled islands off its coast. It spans an area of or , with a population of roughly 37 million. Its official and predominant religion is Islam, and the official languages are Arabic and Berber; the Moroccan dialect of Arabic and French are also widely spoken. Moroccan identity and culture is a mix of Arab, Berber, and European cultures. Its capital is Rabat, while its largest city is Casablanca. In a region inhabited since the Paleolithic Era over 300,000 years ago, the first Moroccan s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
