Factbites
 Where results make sense
About us   |   Why use us?   |   Reviews   |   PR   |   Contact us  

Topic: Chronospecies


Related Topics

In the News (Mon 21 Dec 09)

  
 Chronospecies.   (Site not responding. Last check: 2007-10-13)
A species over time or chronospecies can be described as a population between branch points which generate sister species.
If it is much older then its roots might lie in africa with a population of different homo and apiths that range in age from 3.0 to 1.8 and could simply represent variation within a species that gave rise at various times to fission products like paranthrops, erectus, africanus, or others.
Even if one argues that these were a single species it does not tell one how to deal with other earlier hominid finds that do not appear to be inline with homo or minimally represent even earlier variants of some chronospecies that the underwent formal speciation of which later apiths/homo was one result.
www.usenet.com /newsgroups/sci.anthropology.paleo/msg06207.html   (732 words)

  
 ELASMO.COM Fossil Genera: Carcharocles
Taxa assigned to Carcharocles continue the morphing of tooth-designs reflected in the Otodus-Carcharocles chronospecies.
The 'chronospecies' serves that function for descriptive purposes -- a specific name ascribed for a particular characteristic-set.
In earlier chronospecies the basal margin is U-shaped, this gradually evolves to a more V-shaped appearance.
www.elasmo.com /genera/cenozoic/sharks/carcharocles.html   (1865 words)

  
 chronospecies - OneLook Dictionary Search   (Site not responding. Last check: 2007-10-13)
We found 2 dictionaries with English definitions that include the word chronospecies:
Tip: Click on the first link on a line below to go directly to a page where "chronospecies" is defined.
chronospecies : The On-line Medical Dictionary [home, info]
www.onelook.com /?w=chronospecies   (68 words)

  
 [No title]
If an average chronospecies lasts nearly a million years, or even longer, and we have at our disposal only ten million years, then we have only ten or fifteen chronospecies to align, end-to-end, to form a continuous lineage connecting our primitive little mammal with a bat or a whale.
Chronospecies, by definition, grade into each other, and encompass very little change..
The chain of ten or fifteen chronospecies may form a new species, but certainly not a whale or a bat.
members.tripod.com /~dlane5/create.html   (2284 words)

  
 What I did on My Summer Vacation: A Book Report and Summary of Steven Stanley’s The New Evolutionary Timetable ...
A chronospecies is a segment of a population in time which undergoes a small amount of evolution during a span of time such that the individuals during the span can be recognized as members of that same species.
However, chronospecies of Cenozoic mammals typically exist for more than a million years before they exhibit enough change to be considered a new species.
Because differences between successive chronospecies typically only slight, there is simply not enough time in the fossil record to allow for this change under the gradualistic model.
www.ideacenter.org /contentmgr/showdetails.php/id/1262   (11340 words)

  
 Heaton: Great Plains Ischyromys
Statistical investigation of large samples suggest instead that two closely related species coexisted, and the shift in mean size that was thought to represent anagenesis actually represents replacement.
The levels in Table 4 with the highest and lowest mean size values do not exhibit a shift in the entire size range, but merely a preponderance of either large or small specimens, and in most cases the largest specimens do not occur at the highest level.
In both cases, the increase in mean size is so small compared to the range of variation at each level that the division of the lineage into chronospecies is definitely not warranted.
www.usd.edu /~theaton/ischyrom/orella.html   (6400 words)

  
 www.infosquali.it   (Site not responding. Last check: 2007-10-13)
In this scenario, the currently recognized species are deemed morphospecies or chronospecies, wherein temporal snapshots (the fossil record) of various fauna suggest the presence of multiple species.
Following this logic, the basal Cenozoic tooth morphology would be represented by Otodus appendiculata (AGASSIZ, 1843) (see: Cretolamna appendiculata) which transitions into O. obliquus during the Late Paleocene, and Carcharocles auriculatus (BLAINVILLE, 1818) [= O. subserratus] in the Middle Ypresian.
The chronospecies arguments (unpublished) are very strong and may become more relevant in the future.
www.squali.com /fossili/otodus.php   (416 words)

  
 Homo heidelbergensis
Many researchers argue that heidelbergensis is invalid, and is simply a chronospecies (though, that is exactly what some proponents argue for, among those who see anagenesis as a valid speciation event).
Due to the fact that there have been so many different specimens attributed to the erectus offshoots, it is difficult to create a list of features that differentiate heidelbergensis from erectus or H.
The validity of heidelbergensis as a chronospecies depends on whether one accepts anagenesis as a valid method of speciation.
www.archaeologyinfo.com /homoheidelbergensis.htm   (1720 words)

  
 Gradualistic views of the transition to Homo sapiens (from human evolution) --  Britannica Concise Encyclopedia - The ...
The boundaries between chronospecies seem almost impossible to determine by any objective anatomic or functional criteria; what is left is the guesswork of “ruling off” at a moment in time to draw the boundary.
Thus, competent authorities have seriously suggested that, in the last analysis, such a chronological boundary may have to be drawn arbitrarily between the last survivors of H.
The problem of defining the limits of chronospecies is not peculiar to H.
www.britannica.com /ebc/article-67316   (733 words)

  
 Middle East Open Encyclopedia: Chronospecies   (Site not responding. Last check: 2007-10-13)
A chronospecies is a species which which changes physically, morphologically, genetically, and/or behaviorally over time on an evolutionary scale such that the originating species and the species it becomes could not be classified as the same species had they existed at the same point in time.
Throughout the change of a chronospecies, there is only one species at any point in time, as opposed to an evolutionary species which branches off into many diverse species.
Iraq Museum International always displays the most recent published revision of the source article, Chronospecies; all previous versions may be viewed here.
www.baghdadmuseum.org /ref/index.php?title=Chronospecies   (241 words)

  
 Gradualistic views of the transition to Homo sapiens (from human evolution) --  Encyclopædia Britannica   (Site not responding. Last check: 2007-10-13)
A traditional view held by many paleontologists is that a species may be transformed gradually into a succeeding species in the same lineage.
Such successive species in the evolutionary sequence are called chronospecies.
The boundaries between chronospecies seem almost impossible to determine by any objective anatomic or functional criteria; what is left…
www.britannica.com /eb/article-67316?tocId=67316   (110 words)

  
 Dzik publications   (Site not responding. Last check: 2007-10-13)
On the contrary, the course of phyletic evolution is potentially observable in a single geological section, with application of the Steno’s rule of superposition as the only guide to the time distribution of evolutionary events.
However, only rarely and in extremely stable environments can a complete time range of a morphologically recognisable segment of the evolution (chronospecies) be established.
The stratophenetically documented phyletic evolution of both pelagic (Ordovician and Carboniferous conodonts) and benthic (Ordovician ostracods) organisms from such unusual sites provides evidence that ranges of chronospecies observed in particular sections represent generally only a minor part of their actual durations.
www.paleo.pan.pl /people/Dzik/Dzik1999a.htm   (398 words)

  
 [No title]   (Site not responding. Last check: 2007-10-13)
It is generally accepted that both Neanderthals and Homo sapiens evolved from an earlier "archaic" Homo sapiens, but the classification of Neanderthals depends on when in time modern humans are considered a separate species from the "archaic" forms.
This complication is introduced because the "archaic" forms are a chronospecies.
A Neanderthal skull was first discovered in Forbes' Quarry, Gibraltar in 1848, eight years prior to the "original" discovery in a limestone quarry of the Neander Valley (near Düsseldorf) in August, 1856, and three years before Charles Darwin's On the Origin of Species was published.
mindwallet.com /wiki/Homo_neanderthalensis   (2095 words)

  
 Evolution - August 1999: Re: re-whales from rodents   (Site not responding. Last check: 2007-10-13)
> chronospecies to align, end to end, to form a continuous lineage
once every 10,000 years would give us 1000 "chronospecies".
"chronospecies" is enough to produce a new genus, 100 should be more than
www.asa3.org /archive/evolution/199908/0200.html   (291 words)

  
 Homo erectus
Those who see erectus as a modern human ancestor, either see the Asian specimens as a dead-end side branch, or see all the ergaster, heidelbergensis, and erectus specimens as belonging to Homo sapiens.
This view has some validity in that these species are usually considered "chronospecies" due to anagenesis.
Some researchers do not support the concept of anagenesis as a valid mechanism of speciation, since there is a "fuzzy" area where the transition between species occurs, whereas in cladogenesis (the splitting of a species into two new species or the branching off of one species from another) there is a "clear" boundary.
www.archaeologyinfo.com /homoerectus.htm   (2344 words)

  
 sci.anthropology.paleo: Jul-96: Re: Morgan and creationists
: three chronospecies during which it was adapted to woodland foraging
: three chronospecies during which it was adapted to littoral foraging
: three chronospecies during which it was adapted to savanna foraging
www.anatomy.usyd.edu.au /danny/anthropology/sci.anthropology.paleo/archive/july-1996/0103.html   (917 words)

  
 CWS Talk! - View Single Post - Evolution   (Site not responding. Last check: 2007-10-13)
Macro evolution can be defined as changes in species frequency over time.
It relates to the whole new species arising, old ones dying out, contiguous chronospecies surviving through the ages etc. This part of the theory is supported by oodles of fossil and genetic evidence.
This is the strong part of the theory around which there would be little argument were it not for a bunch of bronze age nomads recording an imaginative story in a book that is held up to be "absolutely true" by people living today.
www.botcw.com /talk/showpost.php?p=124824&postcount=6   (258 words)

  
 Evolution - August 1999: Re: re-whales from rodents
chronospecies lasts nearly a million years, or even longer, and we have at
chronospecies to align, end-to-end, to form a continuous lineage
Chronospecies, by definition, grade into each other, and each
www.asa3.org /archive/evolution/199908/0233.html   (734 words)

  
 David L. Hull, "A Career in the Glare of Public Acclaim," 2002   (Site not responding. Last check: 2007-10-13)
If species change their form gradually; then chronospecies are very hard to individuate.
But if one accepts a punctuational view of evolution, as Niles Eldredge and Gould do, then one need not worry about how to subdivide gradually evolving lineages into chronospecies, because such gradual change is exceedingly rare.
Even if evolutionary change is not as concentrated at speciation events as Eldredge and Gould once thought, speciation is still almost always punctuational (pp.
www.stephenjaygould.org /reviews/hull_structure.html   (3676 words)

  
 Dzik publications   (Site not responding. Last check: 2007-10-13)
A general trend toward cooling, which is partially reversed close to the end of carbonate sedimentation in the area, is shown.
The phyletic succession of Amorphognathus chronospecies is shown stratophenetically.
This is used to propose a provisional correlation of the events recorded in the Holy Cross Mountains with those within the carbonate sedimentation intervals in areas closer to Gondwana.
www.paleo.pan.pl /people/Dzik/Dzik1998a.htm   (298 words)

  
 sci.anthropology.paleo: Jul-96: Re: Morgan and creationists
> : three chronospecies during which it was adapted to woodland foraging
> : three chronospecies during which it was adapted to littoral foraging
> : three chronospecies during which it was adapted to savanna foraging
www.anatomy.usyd.edu.au /danny/anthropology/sci.anthropology.paleo/archive/july-1996/0138.html   (1030 words)

  
 Macroevolution I
To answer this question we consider evolutionary rates.
Potential problems when taxonomy is based on morphology: high rate of morphological evolution may lead to the division of organisms into many chronospecies.
This can result in a high rate of taxonomic evolution: with pseudoextinction and pseudoorignination, taxonomic rates of evolution can be correlated with morphological rates of evolution (graph A).
biomed.brown.edu /Courses/BIO48/36.Tempo&Mode.1.HTML   (902 words)

  
 Volume 31 No. 1
University of Nebraska paleontologists excavating from 1981 to 1990 at the carnivore den site, Beardog Hill, Agate Fossil Beds National Monument, Nebraska, discovered rare fossil remains of the giant terrestrial mustelid Megalictis.
Found only in the Early Miocene of North America, the approximately 19 known individuals can be grouped into a single chronospecies, M. ferox Matthew, 1907.
Size dimorphic postcranial bones interpreted as small females and large robust males provide the earliest evidence of sexual dimorphism in New World Mustelidae.
pubs.gg.uwyo.edu /CTGs/CTG_31-1.htm   (934 words)

  
 Macroevolution: The origin of species
if we decide to consider the cat-sized rodents a new species, it would be a chronospecies (also called paleospecies)
chronospecies: arbitrary divisions of a lineage of a single population into two or more "species", in order to reflect gradual changes over time
but dividing changing species over time into chronospecies is just a convention to clarify discussion, not a reflection of "real", natural categories
bruceowen.com /introbiological/20104s09.htm   (4028 words)

  
 Kingsnake.com - Herpforum - RE: Californian "species"
That is, Wiley would apply his evolutionary species concept only in ways that are consistent with recovered historical relationships; Simpson would not.
Simpson believed that his lineage concept, because of its continuity, required that arbitrary “chronospecies” be recognized; Wiley did not, arguing instead, like Hennig (1966), that species are delimited from speciation to speciation.
At least for biparentals, one is hard pressed to find any difference of substance in terms of application between Simpson’s (1961) concept of species and the biological species concept of Mayr (1942, 1969)."
forums.kingsnake.com /view.php?id=647274,658550   (760 words)

  
 Timothy H. Heaton
McDonald (1977) demonstrated that Pleistocene Megalonyx comprise a single lineage that underwent a steady increase in size and can be conveniently divided into three chronospecies: M.
Wheatleyi based on its size and the associated taxa; the Kuchta fauna slightly predates the Bergner Pit fauna (Pinsof 1985, 1986).
If these identifications are correct, South Dakota deposits have produced all three chronospecies of Megalonyx, but only one specimen of each!
www.usd.edu /~theaton/pub/kuchta.html   (858 words)

  
 "Speciation and Biodiversity" Interview with Edward O. Wilson, Ph.D.
It's also difficult to apply the biological species concept to ancestral species.
Wilson: A chronospecies is simply a necessity of science because we have to distinguish between populations that live today and populations that are ancestral to them.
They lived so long ago that they are very different.
www.actionbioscience.org /biodiversity/wilson.html#Primer   (3306 words)

Try your search on: Qwika (all wikis)

Factbites
  About us   |   Why use us?   |   Reviews   |   Press   |   Contact us  
Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.