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Topic: Hesperornithiformes


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  Introduction to the Hesperornithiformes   (Site not responding. Last check: 2007-10-24)
Despite the retention of certain very primitive characters (such as teeth), the Hesperornithiformes was a highly specialized taxon of Cretaceous birds.
The legs were powerful, but were set so far back that walking on land was probably awkward -- hesperornithiform birds probably spent almost all their time in the water, except, presumably, the breeding and egg-laying season.
In fact, hesperornithiform birds were the only true dinosaurs to colonize the oceans; the aquatic "reptiles" of the time, such as the ichthyosaurs and plesiosaurs, were not true dinosaurs.
www.ucmp.berkeley.edu /diapsids/birds/hesper.html   (447 words)

  
  Hesperornithiformes - Wikipedia, the free encyclopedia
Hesperornithiformes must have been powerful swimmers but ungainly on the land, and probably spent little time ashore except to nest; some think that on land they had to slide on their bellies and push with their legs.
The earliest known Hesperornithiform is the Early Cretaceous Enaliornis; the majority are known from the Late Cretaceous.
Hesperornithiform birds were the only Mesozoic dinosaurs to colonize the oceans; (the aquatic reptiles of the time, such as the ichthyosaurs and plesiosaurs, were not dinosaurs).
en.wikipedia.org /wiki/Hesperornithiformes   (375 words)

  
 Hesperornithiformes
Hesperornithiforms most likely evolved during the early Cretaceous from loon-like forms, which, having lost their powers of flight, quickly became common in the oceans of the Northern Hemisphere.
Unquestionably the strangest of the hesperornithiforms, the archers are famous for their possession of what the rest of their family lacks; archers have wings.
Since the discovery of the first hesperornithiforms as fossils, paleontologists assumed to clade to be entirely flightless, its species specialized for their marine existence at the expense of their wings.
www.bowdoin.edu /~dbensen/Spec/Aves-NZ.html   (843 words)

  
 Attorney deaths in under are confidential ruled in reviews of John Cornyn state prisons that General state 2001 law.   (Site not responding. Last check: 2007-10-24)
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yardcolazal.xoompages.com /hesperornithiformes/makita.html   (2457 words)

  
 Hesperornithiformes: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-10-24)
Hesperornithiformes are an extinct and highly specialized order of Cretaceous (From 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants)
Small hesperornithiform bones are known from the freshwater deposits of the Late Cretaceous of the Judith River Group as well as the Hell Creek and Lance Formations, Exception Handler: No article summary found.
Hesperornithiform birds were the only Mesozoic dinosaurs to colonize the oceans; (the aquatic "reptile (Any cold-blooded vertebrate of the class Reptilia including tortoises turtles snakes lizards alligators crocodiles and extinct forms)
www.absoluteastronomy.com /ref/hesperornithiformes   (786 words)

  
 Cretaceous - Wikipedia, the free encyclopedia
The Hesperornithiformes were flightless, marine diving birds that swam like grebes.
The Cretaceous also saw the first radiation of the diatoms in the oceans (freshwater diatoms did not appear until the Miocene).
The last of the pterosaurs went extinct and the vast majority of birds did as well, including the Enantiornithes and Hesperornithiformes.
en.wikipedia.org /wiki/Cretaceous   (1095 words)

  
 Hesperornithiformes
Hesperornithiforms, the sea parrots and seaguins, most likely evolved during the Cretaceous and are the only group of toothed birds which have survived to the present day.
Throughout the intervening time between the clades inception and the present day, the hesperornithiforms have proven quite conservative, and their basic body type has changed little.
A hesperornithiform resembles nothing so much as a loon stretched and then flattened.
www.specdinos.0catch.com /Spec/Aves-NZ.html   (570 words)

  
 Hesperornithiformes
Hesperornithiforms, the sea parrots and seaguins, most likely evolved during the Cretaceous and are the only group of toothed birds which have survived to the present day.
Throughout the intervening time between the clades inception and the present day, the hesperornithiforms have proven quite conservative, and their basic body type has changed little.
A hesperornithiform resembles nothing so much as a loon stretched and then flattened.
specdinos.0catch.com /Spec/Aves-NZ.html   (570 words)

  
 Cretaceous   (Site not responding. Last check: 2007-10-24)
The Hesperornithiformes were flightless, marine diving birds which swam like grebes.
At the end of the Cretaceous, a significative number of marine forms including most shelled cephalopod s (all ammonite s, most nautilid s), reef-forming rudist molluscs disappeared, as well as all marine reptiles except turtle s and crocodile s.
The last of the pterosaurs went extinct and the vast majority of bird s did as well, including the enantiornithines and Hesperornithiformes.
www.serebella.com /encyclopedia/article-Cretaceous.html   (914 words)

  
 InfoHub Forums - View Single Post - Article on Enaliornis
The title is Postcranial anatomy and systematics of Enaliornis SEELEY, 1876, a foot-propelled diving bird (Aves: Ornithurae: Hesperornithiformes) from the Early Cretaceous of England.
The vertebrae, pelvic girdle and hind limb bones from the Cambridge Greensland (upper Lower Cretaceous, Albian, Stoliczkaia dispar zone ~ 100 m.y.a.) near Cambridge, southern England, show that the ornithuran foot-propelled diving bird Enaliornis is a basal hesperornithiform, not a primitive loon.
The shapes of distal tarsometatarsal trochlea indicate that the feet were lobbed, as in all hesperornithiformes and grebes, rather than webbed as in loons.
www.infohub.com /forums/showpost.php?p=11765&postcount=1   (255 words)

  
 Grebe - Wikipedia, the free encyclopedia
Recent experimental work has shown that these lobes work like the hydrofoil blades of a propeller.
Curiously, the same mechanism seems to have evolved independently in the extinct Cretaceous-age Hesperornithiformes.
It is dense and waterproof, and on the underside the feathers are at right-angles to the skin, sticking straight out to begin with and curling at the tip.
www.wikipedia.org /wiki/Grebe   (473 words)

  
 Hesperornithiformes - EvoWiki   (Site not responding. Last check: 2007-10-24)
These enigmatic diving seabirds from the Upper Cretaceous are among the most aberrant birds, and indeed vertebrates to have ever lived, in multiple ways.
Hesperornithiformes display an autapomorphic form of cranial kinesis which Gingerich (1976) referred to as "maxillokinesis" in which the maxillae are capable of sliding cranio-caudally over subnarial bars formed by the premaxillae and nasals.
Martin and Tate (1976) reviewed the taxonomy and amended the diagnosis of Hesperornithiformes, but their assessment included plesiomorphic characters in the analysis, (e.g.
wiki.cotch.net /index.php/Hesperornithiformes   (194 words)

  
 Palaeos Vertebrates 350.500  Aves: Ornithothoraces
They are clearly not Enantiornithines, as evidenced by the distal to proximal pattern of fusion in the leg bones.
Compared to modern divers, then, the hesperornithiforms may have been sprinters, rather than long distance pursuit hunters; able to accelerate rapidly and use their slender bodies and long necks to snatch prey, rather than running it down and outmaneuvering it.
Supraorbital salt gland may have been present; intramandibular joint as in Hesperornithiformes; teeth apparently in open groove and sockets developed ontogenetically; sternum well-developed and carinate; wings large and muscular; feet small.
www.palaeos.com /Vertebrates/Units/350Aves/350.500.html   (2080 words)

  
 Bird Cyclopedia @ 216.92.85.60 ()   (Site not responding. Last check: 2007-10-24)
A more recent, radically different classification based on molecular data has been developed (the so-called Sibley-Monroe classification or Sibley-Ahlquist taxonomy), and is gaining acceptance.
Other Mesozoic birds include the Confuciusornithidae, Enantiornithes, Ichthyornis, and Hesperornithiformes, a group of flightless divers resembling grebes and loons.
The recently discovered dromaeosaur, Cryptovolans, was capable of powered flight, contained a keel and had ribs with uncinate processes.
216.92.85.60 /encyclopedia/Bird   (1685 words)

  
 Parsimony and its role in Phylogenetic Reconstruction - EvoWiki   (Site not responding. Last check: 2007-10-24)
a) Gaviiformes, Podicipediformes, and Hesperornithiformes (Stolpe 1935, Sibley and Ahlquist 1990--convergence).
The formation and homology of the cnemial crest is related to the entire developmental architecture of the hindlimb and the lack of homology across the cnemial crests of loons, grebes, and the Hesperornithiformes, demonstrates that in these lineages the modification of hindlimb in response to a diving habitus, followed different ontogenetic pathways and constraints.
Cracraft, J. Phylogenetic relationships and monophyly of loons, grebes, and hesperornithiform birds, with comments on the early history of birds.
wiki.cotch.net /index.php/Parsimony_and_its_role_in_Phylogenetic_Reconstruction   (2481 words)

  
 Bird - Facts, Information, and Encyclopedia Reference article
The basal bird Archaeopteryx, from the Jurassic, is well-known as one of the first "missing links" to be found in support of evolution in the late 19th century.
Other Mesozoic birds include the Confuciusornithidae, Enantiornithes, Ichthyornis, and Hesperornithiformes, a group of flightless divers resembling grebes and loons.
The recently discovered dromaeosaur, Cryptovolans, was capable of powered flight, contained a keel and had ribs with uncinate processes.
www.startsurfing.com /encyclopedia/b/i/r/Bird.html   (2630 words)

  
 Bird Replicas - Hanman's Fossils & Minerals   (Site not responding. Last check: 2007-10-24)
Three orders are recognized from this time: (1) Enanthiornithiformes; (2) Hesperornithiformes, and (3) Ichthyornithiformes.
Hesperornithiformes are large, marine, flightless birds known only from North America.
They had long necks and their feet were adapted for swimming.
www.hanmansfossils.com /catalogs/fossil_replicas/birds/birds_2.shtml   (431 words)

  
 Hesperornithiformes | THG Lexikon   (Site not responding. Last check: 2007-10-24)
Die Hesperornithiformes sind eine Gruppe bezahnter flugunfähiger Tauchvögel, deren Fossilien in Sedimentgesteinen der Kreidezeit Nordamerikas, Eurasiens und Antarktikas vorkommen.
Einige kleinere Arten der Hesperornithiformes, welche die Größe von Kormoranen erreichten, waren eventuell noch flugfähig.
An Land dürften hesperornithiforme Vögel ähnliche wie die rezenten Seetaucher eher unbeholfen gewesen sein.
www.thgweb.de /lexikon/Hesperornithiformes   (382 words)

  
 Untitled Document   (Site not responding. Last check: 2007-10-24)
Mesozoic birds are more diverse and numerous than thought previously and the most diverse known group of Cretaceous birds, the Enantiornithes, was not even recognized until 1981.
The vast majority of Mesozoic bird groups have no Tertiary records: Enantiornithes, Hesperornithiformes, Ichthyornithiformes and several other lineages disappeared by the end of the Cretaceous.
By that time, a few Linnean 'Orders' of extant birds had appeared, but none of these taxa belongs to extant 'families', and it is not until the Paleocene or (in most cases) the Eocene that the majority of extant bird 'Orders' are known in the fossil record.
www.amnh.org /exhibitions/expeditions/dinosaur/patagonia/abstract_biol_rev.html   (335 words)

  
 Bird poop Cleanup   (Site not responding. Last check: 2007-10-24)
Both may be predated by Protoavis texensis, though the fragmentary nature of this fossil leaves it open to considerable doubt if this was a bird ancestor.
Other Mesozoic birds include the Enantiornithes, Yanornis, Ichthyornis, Gansus and the Hesperornithiformes, a group of flightless divers resembling grebes and loons.
The recently discovered dromaeosaur Cryptovolans was capable of powered flight, possessed a sternal keel and had ribs with uncinate processes.
www.bird-poop-cleanup.com   (2335 words)

  
 Cretaceous - Article from FactBug.org - the fast Wikipedia mirror site
The Hesperornithiformes were flightless, marine diving birds that swam like grebes.
The Cretaceous also saw the first radiation of the diatoms in the oceans (freshwater diatoms did not appear until the Miocene).
The last of the pterosaurs went extinct and the vast majority of birds did as well, including the Enantiornithes and Hesperornithiformes.
www.factbug.org /cgi-bin/a.cgi?a=5615   (983 words)

  
 Results in
The Enantiornithes were the dominant land bird group, and they coexisted with a separate lineage, the Ornithurae (including the Hesperornithiformes) and the Neornithes from which modern birds derive (Chiappe 1995).
Neither did several groups of ornithurines, but there is no positive evidence that these extinctions occurred at the K T boundary.
According to Feduccia (1995), birds appear to have suffered a bottleneck across the K T boundary, a massive extinction from which only transitional shorebird morphotypes survived as the basis for a Tertiary bird radiation.
www.findarticles.com /p/articles/mi_qa3721/is_199703/ai_n8738406/pg_51   (428 words)

  
 Seabird   (Site not responding. Last check: 2007-10-24)
Seabirds, by virtue of living in a geologically depositional environment (that is, in the sea where sediments are readily laid down) are well represented in the fossil record.
They are first known to occur in the Cretaceous era, the earliest being the Hesperornithiformes, like Hesperornis regalis, a flightless loon-like seabird that dove in a similar fashion to loons and cormorants (using its feet to move underwater) but had a beak filled with sharp teeth.
While Hesperornis is not thought to have left descendants, the earliest extant seabirds also occurred in the Cretaceous, with a species called Tytthostonyx glauconiticus, which has been placed in the Procellariiformes.
www.free-download-soft.com /info/web-hosting-shared-web-hosting.html   (1629 words)

  
 Taxon Search : View Taxon Details
Marsh (1873) erected this taxon to include Ichthyornis and Apatornis, taxa that do not appear to be each other’s closest relatives (Clarke 2004).
Marsh and others have used Odontornithes to encompass a paraphyletic clade of toothed birds including Hesperornithiformes and Ichthyornithiformes.
Given that some of the material Marsh described under this taxon may be eventually allied even farther afield within Aves (Clarke 2004), it is just as well that the taxon has fallen from use.
www.taxonsearch.org /dev/taxon_edit.php?Action=View&tax_id=219   (75 words)

  
 Evolution of the Amniote Brain
The Enantiornithes ("opposite birds") were so named because of their metatarsals being fused proximal to distal, which is opposite that of modern birds (Feduccia, 1996).
The Ornithurines eventually led to currently existing modern forms, along with extinct loon-like Hesperornithiformes (toothed birds, mostly flightless swimmers) and tern-like Ichthyornithiformes (toothed flying birds which probably fed on fish).
From existing evidence, it appears none of the toothed birds survived the Cretaceous extinction.
www.pigeon.psy.tufts.edu /avc/husband/avc2amnt.htm   (3508 words)

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