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Gemuendina Stuertzi
''Gemuendina stuertzi'' (named for Gemünden from where it was discovered) is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, ''Gemuendina'' resembled a scaly ray with an upturned head, or a large-finned stargazer. ''G. stuertzi'' is often invoked as an example of convergent evolution- with its flat body and huge, wing-like pectoral fins it has a strong, albeit superficial similarity to rays. Unlike rays, however, both ''Gemuendina''`s eyes and nostrils were placed atop the head, facing upward. Furthermore, ''G. stuertzis upturned mouth would have enabled it to suction prey that swam overhead, rather than swallow sediment or suction prey out of the substrate like modern rays. Unlike most other placoderm orders, such as the Antiarchs, or the Arthrodires, ''Gemuendina'' and its four other known relatives (or seven, if the three species of the ichthyolith genus '' Ohioaspis'' are confirmed to be rhenanids) had armor made up of a mosaic of u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemuendina Stuertzi By Avancna
''Gemuendina stuertzi'' (named for Gemünden from where it was discovered) is a placoderm of the order Rhenanida, of the seas of Early Devonian Germany. In life, ''Gemuendina'' resembled a scaly ray with an upturned head, or a large-finned stargazer. ''G. stuertzi'' is often invoked as an example of convergent evolution- with its flat body and huge, wing-like pectoral fins it has a strong, albeit superficial similarity to rays. Unlike rays, however, both ''Gemuendina''`s eyes and nostrils were placed atop the head, facing upward. Furthermore, ''G. stuertzis upturned mouth would have enabled it to suction prey that swam overhead, rather than swallow sediment or suction prey out of the substrate like modern rays. Unlike most other placoderm orders, such as the Antiarchs, or the Arthrodires, ''Gemuendina'' and its four other known relatives (or seven, if the three species of the ichthyolith genus '' Ohioaspis'' are confirmed to be rhenanids) had armor made up of a mosaic of unf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhenanida
Rhenanida ("Rhine (fish)") is an Order (biology), order of scaly placoderms. Unlike most other placoderms, the rhenanids' armor was made up of a mosaic of unfused scales and tubercles. The patterns and components of this "mosaic" correspond to the plates of armor in other, more advanced placoderms, suggesting that the ancestral placoderm had armor made of unfused components, as well. All rhenanids were flattened, Batoidea, ray-like, bottom-dwelling predators that lived in marine environments. Evolution The rhenanids were once presumed to be the most primitive, or at least the closest to the ancestral placoderm, as their armor was made up of a mosaic of tubercles, as opposed to the solidified plates of "advanced" placoderms, such as antiarchs and arthrodires. Through comparing the skull anatomies of ''Jagorina pandora'' with those of antiarchs, the rhenanids are considered to be the sister group of the antiarchs (together with their respective Acanthothoracid relatives). Presen ... [...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 407.6 ± 2.6 million years ago to 393.3 ± 1.2 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, 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 order Goniatitida rises in the end of Zlichovian stage (Siberian representation; corresponds to early Eifelian and after the end of Early Devonian, before 391.9 mya). Later agoniatitid ammonoids would die out in the Taghanic event in the upper middle Givetian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placoderms Of Europe
Placodermi (from Greek πλάξ 'plate' and δέρμα 'skin', literally 'plate-skinned') is a class of armoured prehistoric fish, known from fossils, which lived from the Silurian to the end of the Devonian period. Their head and thorax were covered by articulated armoured plates 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 of their gill arches. Placoderms are thought to be paraphyletic, consisting of several distinct outgroups or sister taxa to all living jawed vertebrates, which originated among their ranks. In contrast, one 2016 analysis concluded that placodermi are likely monophyletic, though these analyses have been further dismissed with more transitional taxa between placoderms and modern gnathosthomes, solidifying their paraphyletic status. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagerstätte
A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus delaying the decomposition of both gross and fine biological features until long after a durable impression was created in the surrounding matrix. ''Lagerstätten'' span geological time from the Neoproterozoic era to the present. Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan shales and Burgess Shale, the Silurian Waukesha Biota, the Devonian Hunsrück Slates and Gogo Formation, the Carboniferous Mazon Creek, the Jurassic Posidonia Shale and Solnhofen Limestone, the Cretaceous Yixian, Santana, and Agua Nueva formations, the Eocene Green River Formation, the Miocene Foulden Maar and Ashfall F ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Record
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 absolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyolith
An ichthyolith (from Greek, “fish“ and ”stone”, “rock“, literally "fish-rock") is any disarticulated remains of a fish found in the fossil record, most often a scale, denticle or tooth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear .... The term was coined by Doyle, Kennedy and Riedel (1974) to denote 'fish skeletal debris'. The term 'stratignathy', proposed in the same paper for the time relationships of ichthyoliths, did not gain currency. References Prehistoric fish Fossil record of animals {{paleo-fish-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthrodire
Arthrodira (Greek for "jointed neck") is an Order (biology), order of extinct armored, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches. Arthrodires were the largest and most diverse of all groups of Placoderms. Description Arthrodire placoderms are notable for the movable joint between armor surrounding their heads and bodies. Like all placoderms, they lacked distinct teeth; instead, they used the sharpened edges of a bony plate on their jawbone as a biting surface. The eye sockets are protected by a bony ring, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus ''Arctolepis'', were well-armoured fishes with flattened bodies. The largest member of this group, ''Dunkleosteus'', was a true superpredator of the latest Devonian period, reaching as much as 6 m in length. In contrast, the long-nosed ''Rolfosteus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiarch
Antiarchi ("opposite anus") is an order of heavily armored placoderms. The antiarchs form the second-most successful group of placoderms after the arthrodires in terms of numbers of species and range of environments. The order's name was coined by Edward Drinker Cope, who, when examining some fossils that he thought were armored tunicates related to '' Chelysoma'', mistakenly thought that the orbital fenestra (i.e., the hole in the headshield for the eyes, nose and pineal foramen) was the opening for the mouth, or oral siphon, and that the opening for the anal siphon was on the other side of the body, as opposed to having both oral and anal siphons together at one end. The front portions of their bodies were heavily armored, to the point of literally resembling a box with eyes, with the sometimes scaled, sometimes naked rear portions often becoming sinuous, particularly with later forms. The pair of pectoral fins were modified into a pair of caliper-like, or arthropod-like l ... [...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] |
