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Zenaspis
''Zenaspis'' is an extinct genus of jawless fish which existed during the early Devonian period. Due to it being jawless, ''Zenaspis'' was probably a bottom feeder. The fish was around 10 inches (25 cm) in length. It had a horseshoe shaped head that probably sheltered a small brain. References Osteostraci genera Devonian jawless fish Early Devonian fish of Europe {{Devonian-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zenaspis NT Small
''Zenaspis'' is an extinct genus of jawless fish which existed during the early Devonian period. Due to it being jawless, ''Zenaspis'' was probably a bottom feeder. The fish was around 10 inches (25 cm) in length. It had a horseshoe shaped head that probably sheltered a small brain. References Osteostraci genera Devonian jawless fish Early Devonian fish of Europe {{Devonian-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zenaspidida
Zenaspidida is an extinct order of osteostracans, a group of jawless stem-gnathostomes. They possessed a distinct headshield, which varied in width to length ratio by species. Description The head shield is dome-shaped and extremely large in comparison to the main body. The abdominal section of this shield has a less developed median dorsal crest. As a rule for this order, the nasohypophysial opening is larger than the nasal division. The pineal plate seen in other osteostracans is barely developed or completely absent. The median dorsal field is notably broad, and the lateral fields are widened in the posterior, but reach back no further than the proximal section of the dorsal surface of the cornual processes. The ornamentation on the head shield can have singular, large tubercles, or groups of tubercles which range in size. This is often used to speciate. Classification The cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zenaspididae
Zenaspididae is an extinct family of jawless fish in the order Zenaspida Zenaspidida is an extinct order of osteostracans, a group of jawless stem-gnathostomes. They possessed a distinct headshield, which varied in width to length ratio by species. Description The head shield is dome-shaped and extremely large in ....A New Osteostracan Fauna From The Devonian Of The Welsh Borderlands And Observations On The Taxonomy And Growth Of Osteostraci. Joseph N. Keating, Robert S. Sansom and Mark A. Purnell, Journal of Vertebrate Paleontology 32(5):1002–1017, September 2012 References External links * Osteostraci Prehistoric jawless fish families {{Paleo-jawless-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornuata
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteostraci Genera
The class Osteostraci (meaning "bony shells") is an extinct taxon of bony-armored jawless fish, termed "ostracoderms", that lived in what is now North America, Europe and Russia from the Middle Silurian to Late Devonian. Anatomically speaking, the osteostracans, especially the Devonian species, were among the most advanced of all known agnathans. This is due to the development of paired fins, and their complicated cranial anatomy. The osteostracans were more similar to lampreys than to jawed vertebrates in possessing two pairs of semicircular canals in the inner ear, as opposed to the three pairs found in the inner ears of jawed vertebrates. They are thought to be the sister-group to pituriaspids, and together, these two taxa of jawless vertebrates are the sister-group of gnathostomes. Several synapomorphies support this hypothesis, such as the presence of: sclerotic ossicles, paired pectoral fins, a dermal skeleton with three layers (a basal layer of isopedin, a middle layer of ... [...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] |
Chordate
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name “chordate” comes from the first of these synapomorphies, the notochord, which plays a significant role in chordate structure and movement. Chordates are also Bilateral symmetry, bilaterally symmetric, have a coelom, possess a circulatory system, and exhibit Metameric, metameric segmentation. In addition to the morphological characteristics used to define chordates, analysis of genome sequences has identified two conserved signature indels (CSIs) in their proteins: cyclophilin-like protein and mitochondrial inner membrane protease ATP23, which are exclusively shared by all vertebrates, tunicates and cep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ray Lankester
Sir Edwin Ray Lankester (15 May 1847 – 13 August 1929) was a British zoologist.New International Encyclopaedia. An invertebrate zoologist and evolutionary biologist, he held chairs at University College London and Oxford University. He was the third Director of the Natural History Museum, London, and was awarded the Copley Medal of the Royal Society. Life Ray Lankester was born on 15 May 1847 on Burlington Street in London, the son of Edwin Lankester, a coroner and doctor-naturalist who helped eradicate cholera in London, and his wife, the botanist and author Phebe Lankester. Ray Lankester was probably named after the naturalist John Ray: his father had just edited the memorials of John Ray for the Ray Society. In 1855 Ray went to boarding school at Leatherhead, and in 1858 to St Paul's School. His university education was at Downing College, Cambridge, and Christ Church, Oxford; he transferred from Downing, after five terms, at his parents' behest because Christ Church ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Jawless Fish
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
