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Brittagnathus
''Brittagnathus'' is an extinct genus of four-limbed vertebrate ("tetrapod") from the Late Devonian of Greenland. It contains a single species, ''Brittagnathus minutus'', which is based on a complete lower jaw recovered from an ''Acanthostega'' bonebed in the Britta Dal Formation. It is the fourth named genus of "tetrapod" (more precisely a stem-tetrapod or stegocephalian) from the Late Devonian of Greenland, after ''Ichthyostega'', ''Acanthostega'', and ''Ymeria''. The jaw is only 4.5 cm (1.8 in.) long, making ''Brittagnathus'' the smallest known Devonian "tetrapod". A phylogenetic analysis places it among Carboniferous stegocephalians, particularly the small whatcheeriid ''Pederpes ''Pederpes'' ("Peter's Foot") is an extinct genus of early Carboniferous tetrapod, dating from 348 to 347.6 Ma in the Tournaisian age (lower Mississippian). ''Pederpes'' contains one species, ''P. finneyae'', 1 m long. This most basal Carbonife ...'', rather than the contemporary Devonian stem- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stegocephalia
Stegocephali (often spelled Stegocephalia) is a group containing all four-limbed vertebrates. It is equivalent to a broad definition of Tetrapoda: under this broad definition, the term "tetrapod" applies to any animal descended from the first vertebrate with limbs and toes, rather than fins. This includes both the modern lineage of limbed vertebrates (the crown group, including modern amphibians, mammals, reptiles and birds) as well as a portion of the stem group, limbed vertebrates that evolved prior to the origin of the crown group. Members of the tetrapod stem group include the earliest limbed tetrapodomorphs such as '' Ichthyostega'' and '' Acanthostega,'' which evolved in the Devonian Period long before any modern form of tetrapod. Many paleontologists prefer a stricter definition of Tetrapoda which applies solely to the crown group, excluding earlier types of limbed tetrapodomorphs. Stegocephali was re-established to replace the broad definition of Tetrapoda, resolving th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jenny Clack
Jennifer Alice Clack, (''née'' Agnew; 3 November 1947 – 26 March 2020) was an English palaeontologist and evolutionary biologist. She specialised in the early evolution of tetrapods, specifically studying the "fish to tetrapod" transition: the origin, evolutionary development and radiation of early tetrapods and their relatives among the lobe-finned fishes. She is best known for her book ''Gaining Ground: the Origin and Early Evolution of Tetrapods'', published in 2002 (second edition, 2012) and written with the layperson in mind. Clack was curator at the Museum of Zoology and Professor of Vertebrate Palaeontology at the University of Cambridge, where she devoted her career to studying the early development of tetrapods, the "four-legged" animals said to have evolved from Devonian lobe-finned fishes and colonised the freshwater swamps of the Carboniferous period. Early life and education Clack was born on 3 November 1947, the only child of Ernest and Alice Agnew. She was b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stegocephalians
Stegocephali (often spelled Stegocephalia) is a group containing all four-limbed vertebrates. It is equivalent to a broad definition of Tetrapoda: under this broad definition, the term "tetrapod" applies to any animal descended from the first vertebrate with limbs and toes, rather than fins. This includes both the modern lineage of limbed vertebrates (the crown group, including modern amphibians, mammals, reptiles and birds) as well as a portion of the stem group, limbed vertebrates that evolved prior to the origin of the crown group. Members of the tetrapod stem group include the earliest limbed tetrapodomorphs such as ''Ichthyostega'' and ''Acanthostega,'' which evolved in the Devonian Period long before any modern form of tetrapod. Many paleontologists prefer a stricter definition of Tetrapoda which applies solely to the crown group, excluding earlier types of limbed tetrapodomorphs. Stegocephali was re-established to replace the broad definition of Tetrapoda, resolving the us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of Greenland
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 absol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian Greenland
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] |
Pederpes
''Pederpes'' ("Peter's Foot") is an extinct genus of early Carboniferous tetrapod, dating from 348 to 347.6 Ma in the Tournaisian age (lower Mississippian). ''Pederpes'' contains one species, ''P. finneyae'', 1 m long. This most basal Carboniferous tetrapod had a large, somewhat triangular head, similar to that of later American sister-genus ''Whatcheeria'', from which it is distinguished by various skeletal features, such as a spike-like latissimus dorsi (an arm muscle) attachment on the humerus and several minor skull features. The feet had characteristics that distinguished it from the paddle-like feet of the Devonian Ichthyostegalia and resembled the feet of later, more terrestrially adapted Carboniferous forms. ''Pederpes'' is the earliest-known tetrapod to show the beginnings of terrestrial locomotion and despite the probable presence of a sixth digit on the forelimbs it was at least functionally pentadactyl. Discovery and classification ''Pederpes'' was discovered in 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whatcheeriidae
Whatcheeriidae is an extinct family of tetrapods which lived in the Mississippian sub-period, a subdivision of the Carboniferous period. It contains the genera ''Pederpes'', '' Whatcheeria'', and possibly '' Ossinodus''. Fossils of a possible whatcheeriid have been found from the Red Hill locality of Pennsylvania. If these remains are from a whatcheeriid, they extend the range of the family into the Late Devonian and suggest that advanced tetrapods may have lived alongside primitive tetrapod ancestors like ''Hynerpeton'' and ''Densignathus''. They also imply that a very long ghost lineage of whatcheeriids lived through Romer's gap, a period during the Early Carboniferous conspicuously lacking in tetrapod remains. Classification Currently, using modern cladistic taxonomy, Whatcheeriidae is not placed in Amphibia Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin '' carbō'' (" coal") and '' ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceding Devonian, became pentadactylous in and diversified during the Carboniferous, including early amphibian lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic Analysis
In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditar ..., phylogenetics (; from Greek language, Greek wikt:φυλή, φυλή/wikt:φῦλον, φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, Protein, protein Amino acid, amino acid sequences, or Morphology (biology), morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ymeria
''Ymeria'' is an extinct genus of early stem tetrapod from the Devonian of Greenland. Of the two other genera of stem tetrapods from Greenland, ''Acanthostega'' and ''Ichthyostega'', ''Ymeria'' is most closely related to ''Ichthyostega'', though the single known specimen is smaller, the skull about 10 cm in length. A single interclavicle resembles that of ''Ichthyostega'', an indication ''Ymeria'' may have resembled this genus in the post-cranial skeleton. Discovery ''Ymeria'' is primarily known from a partial holotype skull including the lower jaws and palate, as well as impressions of the shoulder girdle. The holotype comes from the southern slope of Mt. Celsius on Ymer Island in northeast Greenland. Fossils of Devonian tetrapods like ''Ichthyostega'' have been known from Ymer Island since 1929. The skull of ''Ymeria'' found in 1947 by a team of paleontologists from Sweden and Denmark. It came from a talus slope or pile of rock fragments at the base of Mount Celsius, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyostega
''Ichthyostega'' (from el, ἰχθῦς , 'fish' and el, στέγη , 'roof') is an extinct genus of limbed tetrapodomorphs from the Late Devonian of Greenland. It was among the earliest four-limbed vertebrates in the fossil record, and was one of the first with weight-bearing adaptations for terrestrial locomotion. ''Ichthyostega'' possessed lungs and limbs that helped it navigate through shallow water in swamps. Although ''Ichthyostega'' is often labelled a 'tetrapod' due to the possession of limbs and fingers, it evolved long before true crown group tetrapods, and could more accurately be referred to as a stegocephalian or stem tetrapod. Likewise, while undoubtedly of amphibian build and habit, it is not considered a true member of the group in the narrow sense, as the first modern amphibians (members of the group Lissamphibia) appeared in the Triassic Period. Until finds of other early stegocephalians and closely related fishes in the late 20th century, ''Ichthyostega'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
