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Weejasperaspidae
Weejasperaspididae ("Shields of Wee Jasper") is a family of three extinct acanthothoracid placoderms indigenous to the Early Devonian of Victoria and New South Wales, Australia. Description The Weejasperaspids are known from median dorsal plates with distinctive, blade-like crests in the median-posterior portion, and ossified eye capsules. Evolutionary relationships The main reasons why the weejasperaspids are not considered to be closely related to other non-acanthothoracid placoderms, as opposed to the palaeacanthaspids, are that their skull anatomies and plate histologies are generalized, and do not bear any similarities to any specific non-acanthothoracid group, and that the patterns of ornamentation on their dermal plates are unique to this family. The placoderm '' Brindabellaspis stensioi'' was once regarded as a weejasperaspid because of the similarities between its dermal plates to the other weejasperaspids. Even before it was split off into its own order, it stoo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brindabellaspis Stensioi
''Brindabellaspis stensioi'' ("Erik Stensiö's Brindabella Ranges Shield") is a placoderm with a flat, platypus-like snout from the Early Devonian of the Taemas-Wee Jasper reef in Australia. When it was first discovered in 1980, it was originally regarded as a Weejasperaspid acanthothoracid due to anatomical similarities with the other species found at the reef. According to Philippe Janvier, anatomical similarities of ''B. stensiois brain and braincase with those of jawless fish, such as the Osteostraci and the Galeaspida Galeaspida (from Latin, 'Helmet shields') is an extinct taxon of jawless marine and freshwater fish. The name is derived from ''galea'', the Latin word for ''helmet'', and refers to their massive bone shield on the head. Galeaspida lived in shallo ..., strongly suggest that ''B. stensioi'', and also the antiarchs, are basal placoderms closest to the ancestral placoderm. New findings show ''B. stensioi'' may have evolutionary traits which connect its morph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emsian
The Emsian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.62 ±1.95 million years ago to 393.47 ±0.99 million years ago. It was preceded by the Pragian Stage and followed by the Eifelian Stage. It is named after the Ems river in Germany. The GSSP is located in the Zinzil'ban Gorge in the Kitab State Geological Reserve of Uzbekistan , image_flag = Flag of Uzbekistan.svg , image_coat = Emblem of Uzbekistan.svg , symbol_type = Emblem of Uzbekistan, Emblem , national_anthem = "State Anthem of Uzbekistan, State Anthem of the Republ ..., above the contact with the Madmon Formation. In North America the Emsian Stage is represented by Sawkill or Sawkillian time. Biological events During this period, earliest known agoniatitid ammonoid fossils began appearing within this stage after first appearing in previous stage and began to evolutionarily radiate within this stage, in which a new ammonoid or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderm Families
Placoderms (from Ancient Greek πλάξ 'plax'', ''plakos''' plate' and δέρμα 'derma'''skin') are vertebrate animals of the class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armoured plates (hence the name), and the rest of the body was scaled or naked depending on the species. Placoderms were among the first jawed fish (their jaws likely evolved from the first pair of gill arches), as well as the first vertebrates to have true teeth. They were also the first fish clade to develop pelvic fins, the second set of paired fins and the homologous precursor to hindlimbs in tetrapods. 380-million-year-old fossils of three other genera, '' Incisoscutum'', ''Materpiscis'' and '' Austroptyctodus'', represent the oldest known examples of live birth. Placoderms are thought to be paraphyletic, consis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderms Of Australia
Placoderms (from Ancient Greek πλάξ [''plax'', ''plakos''] 'Plate (animal anatomy), plate' and δέρμα [''derma''] 'skin') are vertebrate animals of the class (biology), class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian geological period, periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armour (zoology), armoured plates (hence the name), and the rest of the body was scale (zoology), scaled or naked depending on the species. Placoderms were among the first jawed fish (their fish jaw, jaws likely Evolution, evolved from the first pair of gill arches), as well as the first vertebrates to have true tooth, teeth. They were also the first fish clade to develop pelvic fins, the second set of paired fins and the homology (biology), homologous precursor to hindlimbs in tetrapods. 380-million-year-old fossils of three other genera, ''Incisoscutum'', ''M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthothoracids
Acanthothoraci (''spine chests'') is an extinct group of chimaera-like placoderms closely related to the rhenanid placoderms. Superficially, the acanthoracids resembled scaly chimaeras and (relatively) heavily armored ptyctodonts. They were distinguished from chimaeras by their large scales and plates, a pair of large spines that emanate from their chests (thus, the order's name), tooth-like beak plates, and the typical bone-enhanced placoderm eyeball. They were distinguished from other placoderms by differences in skull anatomy and by patterns on the skull plates and thoracic plates that are unique to this order. Fossil record Fossils of the acanthothoracids are found in various deposits from the Lower Devonian throughout the world. Fossils of the Palaeacanthaspids are found in Eurasia and Canada, while the Weejasperaspids have only been found in the Taemas Wee Jasper reef, in Southeastern Australia. Ecology From what can be inferred from the mouthplates of fossil specim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galeaspid
Galeaspida (from Latin, 'Helmet shields') is an extinct taxon of jawless marine and freshwater fish. The name is derived from ''galea'', the Latin word for ''helmet'', and refers to their massive bone shield on the head. Galeaspida lived in shallow, fresh water and marine environments during the Silurian and Devonian times (430 to 370 million years ago) in what is now Southern China, Tibet and Vietnam. Superficially, their morphology (biology), morphology appears more similar to that of Heterostraci than Osteostraci, there being currently no evidence that the galeaspids had paired fins. A galeaspid ''Tujiaaspis vividus'' from the Silurian period of China was described in 2022 as having a precursor condition to the form of paired fins seen in Osteostraci and gnathostomes. Earlier than this, Galeaspida were already in fact regarded as being more closely related to Osteostraci, based on the closer similarity of the morphology of the braincase. Morphology The defining characterist ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skull
The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent parts: the neurocranium and the facial skeleton, which evolved from the first pharyngeal arch. The skull forms the frontmost portion of the axial skeleton and is a product of cephalization and vesicular enlargement of the brain, with several special senses structures such as the eyes, ears, nose, tongue and, in fish, specialized tactile organs such as barbels near the mouth. The skull is composed of three types of bone: cranial bones, facial bones and ossicles, which is made up of a number of fused flat and irregular bones. The cranial bones are joined at firm fibrous junctions called sutures and contains many foramina, fossae, processes, and sinuses. In zoology, the openings in the skull are called fenestrae, the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller islands. It has a total area of , making it the list of countries and dependencies by area, sixth-largest country in the world and the largest in Oceania. Australia is the world's flattest and driest inhabited continent. It is a megadiverse countries, megadiverse country, and its size gives it a wide variety of landscapes and Climate of Australia, climates including deserts of Australia, deserts in the Outback, interior and forests of Australia, tropical rainforests along the Eastern states of Australia, coast. The ancestors of Aboriginal Australians began arriving from south-east Asia 50,000 to 65,000 years ago, during the Last Glacial Period, last glacial period. By the time of British settlement, Aboriginal Australians spoke 250 distinct l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Victoria (Australia)
Victoria, commonly abbreviated as Vic, is a States and territories of Australia, state in southeastern Australia. It is the second-smallest state (after Tasmania), with a land area of ; the second-most-populated state (after New South Wales), with a population of over 7 million; and the most densely populated state in Australia (30.6 per km2). Victoria's economy is the List of Australian states and territories by gross state product, second-largest among Australian states and is highly diversified, with service sectors predominating. Victoria is bordered by New South Wales to the north and South Australia to the west and is bounded by the Bass Strait to the south (with the exception of a small land border with Tasmania located along Boundary Islet), the Southern Ocean to the southwest, and the Tasman Sea (a marginal sea of the South Pacific Ocean) to the southeast. The state encompasses a range of climates and geographical features from its temperate climate, temperate coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New South Wales
New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South Australia to the west. Its coast borders the Coral Sea, Coral and Tasman Seas to the east. The Australian Capital Territory and Jervis Bay Territory are Enclave and exclave, enclaves within the state. New South Wales' state capital is Sydney, which is also Australia's most populous city. , the population of New South Wales was over 8.3 million, making it Australia's most populous state. Almost two-thirds of the state's population, 5.3 million, live in the Greater Sydney area. The Colony of New South Wales was founded as a British penal colony in 1788. It originally comprised more than half of the Australian mainland with its Western Australia border, western boundary set at 129th meridian east in 1825. The colony then also includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
