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Hesperornithid
Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as '' Hesperornis'', ''Parahesperornis'', '' Baptornis'', ''Enaliornis'', and ''Potamornis'', all strong-swimming, predatory divers. Many of the species most specialized for swimming were completely flightless. The largest known hesperornithean, '' Canadaga arctica'', may have reached a maximum adult length of . Hesperornitheans were the only Mesozoic avialans to colonize the oceans. They were wiped out in the Cretaceous–Paleogene extinction event, along with enantiornitheans and all other non-avian dinosaurs, and many other diverse plant and animal groups. Anatomy and ecology Most of what is known about this group rests on analyses of single species, as few provide sufficiently complete fossils for analysis. Although some of the smaller and more bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadaga Arctica
''Canadaga'' (meaning "Canadian bird") is a flightless bird genus from the Late Cretaceous. The single known species is ''Canadaga arctica''. It lived in the shallow seas around what today is Bylot Island in Nunavut, Canada. Its fossils were found in rocks dated to the mid-Maastrichtian age, about 67 million years ago. It was a member of the Hesperornithes, flightless toothed seabirds of the Cretaceous. Among these, it belonged to the Hesperornithidae, along with ''Hesperornis'', the well-known namesake genus. ''C. arctica'' is one of the largest known members of the Hesperornithes, reaching a length of . It also represents one of the last known members of the lineage.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'Winter 2010 Supplementary Information Unlike its relatives which are mainly known from subtropical or tropical waters, this species seems to have ranged in temperate or even subarctic areas. The sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enaliornis
''Enaliornis'' is a genus of hesperornithine birds which lived in the early Late Cretaceous, making them the oldest known hesperornithines. Fossils have been found near Cambridge, England. Due to its lack of certain hesperornithid apomorphies, they were much more "conventional" birds and were initially held to be Gaviiformes (loons/divers). Description Based on the remnants that have been studied, it has not been determined if these birds had teeth like the others from this order. However, they were believed to not have well-developed wings. Like other hesperornithines, they probably had lobed feet for swimming, rather than webbed feet.Lim, J. D., Zhou, Z., Martin, L. D., Baek, K. S., & Yang, S. Y. (2000). The oldest known tracks of web-footed birds from the Lower Cretaceous of South Korea. ''Naturwissenschaften'', 87(6), 256-259. Classification ''Enaliornis'' was originally named ''Pelagornis'' ("sea bird") by Seeley in 1866, but that name was preoccupied by a Miocene bird rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperornis Regalis
''Hesperornis'' (meaning "western bird") is a genus of cormorant-like bird that spanned the first half of the Campanian age of the Late Cretaceous period (83.5–78 mya). One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for ''Hesperornis'' fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia. Description ''Hesperornis'' was a large bird, reaching up to in length. It had virtually no wings, and swam with its powerful hind legs. Studies on the feet initially indicated that ''Hesperornis'' and kin had lobed toes similar to modern-day grebes, as opposed to webbed toes as seen in most aquatic birds such as loons. More recent work looking at the morphometrics of the feet in hesperornithiformes and mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperornis
''Hesperornis'' (meaning "western bird") is a genus of cormorant-like bird that spanned the first half of the Campanian age of the Late Cretaceous period (83.5–78 mya). One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for ''Hesperornis'' fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia. Description ''Hesperornis'' was a large bird, reaching up to in length. It had virtually no wings, and swam with its powerful hind legs. Studies on the feet initially indicated that ''Hesperornis'' and kin had lobed toes similar to modern-day grebes, as opposed to webbed toes as seen in most aquatic birds such as loons. More recent work looking at the morphometrics of the feet in hesperornithiformes and mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadaga
''Canadaga'' (meaning "Canadian bird") is a flightless bird genus from the Late Cretaceous. The single known species is ''Canadaga arctica''. It lived in the shallow seas around what today is Bylot Island in Nunavut, Canada. Its fossils were found in rocks dated to the mid-Maastrichtian age, about 67 million years ago. It was a member of the Hesperornithes, flightless toothed seabirds of the Cretaceous. Among these, it belonged to the Hesperornithidae, along with ''Hesperornis'', the well-known namesake genus. ''C. arctica'' is one of the largest known members of the Hesperornithes, reaching a length of . It also represents one of the last known members of the lineage.Holtz, Thomas R. Jr. (2008) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages'Winter 2010 Supplementary Information Unlike its relatives which are mainly known from subtropical or tropical waters, this species seems to have ranged in temperate or even subarctic areas. The sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potamornis
''Potamornis'' is a prehistoric bird genus that dated back to the late Maastrichtian age of the late Cretaceous period. Its scrappy remains were found in the Lance Formation at Buck Creek, USA, and additional possible remains were found in the upper Hell Creek Formation of Montana, dated to the Danian age of the Paleogene period, though these may have been reworked. A single species was named and described in 2001: ''Potamornis skutchi''. This was almost certainly a member of the Hesperornithes, the hefty and toothed flightless diving birds of the Mesozoic seas. Its precise relationships are not all too clear; the quadrate bone is unique in some respects but apparently shares more apomorphies with the family Hesperornithidae - the "typical" Hesperornithes - in cladistic analysis.Mortimer (2004) Consequently, it might be considered a fossil hesperornithid with a different feeding specialization. Though it was heavily built like many (flying and flightless) diving birds, it weighe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hesperornis BW (white Background)
''Hesperornis'' (meaning "western bird") is a genus of cormorant-like bird that spanned the first half of the Campanian age of the Late Cretaceous period (83.5–78 mya). One of the lesser-known discoveries of the paleontologist O. C. Marsh in the late 19th century Bone Wars, it was an early find in the history of avian paleontology. Locations for ''Hesperornis'' fossils include the Late Cretaceous marine limestones from Kansas and the marine shales from Canada. Nine species are recognised, eight of which have been recovered from rocks in North America and one from Russia. Description ''Hesperornis'' was a large bird, reaching up to in length. It had virtually no wings, and swam with its powerful hind legs. Studies on the feet initially indicated that ''Hesperornis'' and kin had lobed toes similar to modern-day grebes, as opposed to webbed toes as seen in most aquatic birds such as loons. More recent work looking at the morphometrics of the feet in hesperornithiformes and mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enaliornithidae
''Enaliornis'' is a genus of hesperornithine birds which lived in the early Late Cretaceous, making them the oldest known hesperornithines. Fossils have been found near Cambridge, England. Due to its lack of certain hesperornithid apomorphies, they were much more "conventional" birds and were initially held to be Gaviiformes (loons/divers). Description Based on the remnants that have been studied, it has not been determined if these birds had teeth like the others from this order. However, they were believed to not have well-developed wings. Like other hesperornithines, they probably had lobed feet for swimming, rather than webbed feet.Lim, J. D., Zhou, Z., Martin, L. D., Baek, K. S., & Yang, S. Y. (2000). The oldest known tracks of web-footed birds from the Lower Cretaceous of South Korea. ''Naturwissenschaften'', 87(6), 256-259. Classification ''Enaliornis'' was originally named ''Pelagornis'' ("sea bird") by Seeley in 1866, but that name was preoccupied by a Miocene bird rela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enantiornithes
The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over eighty species of Enantiornithes have been named, but some names represent only single bones, so it is likely that not all are valid. The Enantiornithes became extinct at the Cretaceous–Paleogene boundary, along with Hesperornithes and all other non-avian dinosaurs. Discovery and naming The first Enantiornithes to be discovered were incorrectly referred to modern bird groups. For example, the first known species of Enantiornithes, ''Gobipteryx minuta'', was originally considered a paleognath related to ostriches and tinamou. The Enantiornithes were first recognized as a distinct lineage, or "subclass" of birds, by Cyril A. Walker in 1981. Walker mad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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