skistodiaptomus is a genus of freshwater copepods in the family diaptomidae , found across north america .

the genus contains eight species , three of which are endemic to the united states and are listed on the iucn red list as vulnerable species ( vu ) or data deficient ( dd ) .

skistodiaptomus bogalusensis ( m. s. wilson & moore , 1953 ) skistodiaptomus carolinensis yeatman , 1986 skistodiaptomus mississippiensis ( marsh , 1894 ) skistodiaptomus oregonensis ( lilljeborg , 1889 ) skistodiaptomus pallidus ( herrick , 1879 ) skistodiaptomus pygmaeus ( pearse , 1906 ) skistodiaptomus reighardi ( marsh , 1895 ) skistodiaptomus sinuatus ( kincaid , 1953 )

skistodiaptomus

dowell , k . m . 1997 . evidence for diapause in the freshwater copepod skistodiaptomus pallidus . american midland naturalist 137 ( 2 ) : 362 - 368 .
thum , r . a . and r . s . stemberger . 2006 . pure spatial and spatially structured environmental variables explain skistodiaptomus copepod range limits in the northeastern usa . canadian journal of fisheries and aquatic sciences 63 ( 6 ) : 1397 - 1404 .
table 1 . states with nonindigenous occurrences , the earliest and latest observations in each state , and the tally and names of hucs with observations† . names and dates are hyperlinked to their relevant specimen records . the list of references for all nonindigenous occurrences of skistodiaptomus pallidus are found here .
ghan , d . , j . d . mcphail , and k . d . hyatt . 1998 . the temporal - spatial pattern of vertical migration by the freshwater copepod skistodiaptomus oregonensis relative to predation risk . canadian j . of fisheries and aquatic sci . 55 : 1350 - 1363 .
chapman , m . a . , j . d . green , and t . g . northcote . 1985 . seasonal dynamics of skistodiaptomus pallidus herrick and other zooplankton populations in deer lake , s . w . british columbia . journal of plankton research 7 ( 6 ) : 867 - 876 .
duggan , i . c . , j . d . green , and d . f . burger . 2006 . first new zealand records of three non - indigenous zooplankton species : skistodiaptomus pallidus , sinodiaptomus valkanovi , and daphnia dentifera . new zealand journal of marine and freshwater research 40 : 561 - 569 .
potential : skistodiaptomus pallidus is an efficient omnivorous predator , with the ability to prey on preferred rotifers and microzooplankton from large distances . it also consumes algae and practices cannibalism , which may allow populations to persist when resource availability is low ( williamson and butler 1986 ; williamson and vanderploeg 1988 ) . it has also been known to attain very high densities in suitable habitats , reaching 10 , 000 per m3 in a lake erie marsh to unknown consequences ( krieger and klarer 1991 ) . skistodiaptomus pallidus became the primary calanoid copepod in a particularly eutrophic portion of lake tahoe , dominating two previously common species , leptodiaptomus tyrrelli and epischura nevadensis ( byron and saunders 1981 ) .
kipp , r . m . , a . j . benson , j . larson , t . h . makled , and a . fusaro , 2018 , skistodiaptomus pallidus herrick , 1879 : u . s . geological survey , nonindigenous aquatic species database , gainesville , fl , urltoken revision date : 5 / 2 / 2018 , access date : 7 / 9 / 2018
duggan , i . c . , neale , m . , robinson , k . v . , verburg , p . , & watson , n . t . n . ( 2014 ) . skistodiaptomus pallidus ( copepoda : diaptomidae ) establishment in new zealand natural lakes , and its effects on zooplankton community composition . aquatic invasions , 9 ( 2 ) , 195–202 . urltoken
after s . oregonensis molts to the first copepodid stage , it can filter feed on the same size class of particles ( 100 - 800ám│ ) as the adults ( mcqueen , 1970 ; comita and mcnett 1976 ) . the copepod prefers larger phytoplankon ( mcqueen , 1970 ) . richman ( 1966 ) showed that s . oregonensis exhibited it maximum ingestion rate in food concentrations of 25 000 - 50 000 cells ml‾╣ , ingestion rate declined dramatically . skistodiaptomus oregonensis may be adaped to feeding on large cells in high concentration , and would be at a feedin disadvange in lakes of very low productivity .
the north american calanoid copepod skistodiaptomus pallidus is an emerging invader globally , with non - indigenous populations recorded from constructed waters in new zealand , germany and mexico since 2000 . we examined the effects of s . pallidus establishment on the zooplankton community of a natural lake , lake kereta , where it was first recorded in late - 2008 , coincident with releases of domestically cultured grass carp ( ctenopharyngodon idella ) . although not present in any of our samples prior to august 2008 , s . pallidus was found in all samples collected in the subsequent five years . anosim indicated zooplankton community composition significantly differed between samples collected before and after s . pallidus invasion , whether the invader was included in the analysis or not . zooplankton species affected most greatly were the copepods calamoecia lucasi and mesocyclops sp . , which decreased in their relative importance , and the cladocerans bosmina meridionalis and daphnia galeata , which increased . rotifer species were relatively unaffected . as the length of grass carp released were > 6 . 5 cm , direct predatory effects by this species on the zooplankton community are unlikely . associated reductions in macrophyte biomass could explain increases in the relative abundances of planktonic cladocerans ( b . meridionalis and d . galeata ) . however , the effect of macrophyte reduction by grass carp on zooplankton communities is considered to be limited elsewhere , while the reduced macrophyte biomass cannot explain the decrease in relative abundance of the native planktonic calanoid copepod c . lucasi . competition between c . lucasi and s . pallidus is the most compelling explanation for the reduction in importance of the native calanoid copepod species . skistodiaptomus pallidus appears to have undergone a “boom - and - bust” cycle in lake kereta , increasing in relative abundance in the first three years following establishment , before declining in importance .
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first described in 1986 from lake ravenel , highlands , macon county , north carolina ( in the upper little tennessee watershed ) . has since also been found in ponds bordering the great smoky mountains national park .
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in the great lakes zooplankton literature , this sepcies was consistently referred to as diaptomus oregonensis until the subgenus name skisodiaptomus was elevated to genetric level .
in lake superior the females range from 1 . 2 - 1 . 4mm and average 1 . 33mm . males were somewhat smaller , ranging from 1 . 1 - 1 . 3mm and averaging 1 . 19mm .
the right antennule of adult male calanoids is geniculate and may possess a lateral projection on the antepenultimate segment . lateral spine on terminal segment of exopode of right 5th leg is subterminal in position .
s . oregonensis is present year round in the great lakes ( jahoda 1948 ; carter 1969 ; wilson and roff 1973 ; gannon 1975 ) . it is most abundant in the summer and fall but peaks have been observed from april to december . gannon ( 1972a , 1974 ) reported abundance peaks as early as february in green bay .
this species produces two generations each year in lake michigan . adults overwinter and produce a slow - growing spring generation that coincides with the phytoplankton maximum . this generation reproduces in the summer , and the offspring grow rapidly , maturing by fall overturn . most animals wait until spring to reproduce although gannon ( 1972a ) reported some winter reproduction in green bay . in lake superior , where abundance is low , s . oregonensis only produces one generation each year and overwinters as resting eggs ( selgeby 1974 )
sex rations of 1 : 1 are most common ( jahoda 1984 ; davis 1962 , 1968 ; torke 1975 ) , but females may outnumber males ( stewart 1974 ) . clutch size appears to be positively correlated with size of the females ( davis 1961 )
reproduction in the s . oregonensis is sexual . the male clasps the female with his modified first antennae and / or fifth legs , then transfers a packet of sperm , the spermatophore , from his genital pore to her genital segment . the sperms are stored in a seminal receptacle located in the female ' s genital segment . when the female releases eggs from her genital tract , they are fertilized by the stored sperm . female brood the eggs in one egg sac attached to the genital segment . after the first clutch of eggs has hatched , some females fertilize a second and third clutch utilizing more of the sperm stored from their first mating .
its egg hatch into small , active larva known as nauplii . the first nauplius stage ( ni ) is characterized by three pairs of appendages . the animals grow rapidly and molt to the second nauplius stage ( nii ) , which is slightly longer . the animals continue to grow and add appendages as they pass through six naupliar stages . the next molt is to the first copepodid stage ( ci ) . at this period the young species have the general body shape of the adult but are smaller and lack several of the swimming legs . growth , addition of swimming legs , and modification of the limbs continue at each molt until the adult ( cvi ) stage is reached . the animals then mate and produce the next
is one of the most widely distributed diaptomid species , occuring throughout the northern united states and southern ontario , canada ( marsh 1893 , 1929 ; carl 1940 ) . this species has been reported in all the great lakes , especially abundant in the warmer , southerly portions of the
and is of decreasing importance in the cooler , northerly regions ( robertson 1966 ) . now this species is rare in lake superior ( selgeby , 1975 ) and lake ontario , only appearing in fall and most common in lake erie ( davis 1961 , wright 1955 ) which peaks in abundance occur in september .
s . oregonensis always inhabits permanent water bodies , but occurs in lakes of different morphometric and tropic characteristics . it is common in lake michigan , but also occurs in quite shallow inland lakes and ponds . it frequently occurs with other calanoids , leptodiaptomus minutusis , l . ashlandi and l . sicilis , and occasionally with s . pallidus .
s . oregonensis is more abundant offshore than in the littoral zone ( stewart 1974 ) . during periods of thermal stratification , this species is usually found in the meta - and epilimnia , migrating toward the surface at night , but most densely concentrated near the thermocline during the day ( juday , 1903 ; langford , 1938 ; wells 1960 ) . in unstratified water masses and upwelling areas , distribution throughout the water column is more uniform ( wilson and roff 1973 ) . in teapot lake , ontario , cooley ( 1970 ) found that day - night differences in mean depth distribution were not significant for naupliar stages , but were significant for copepodid and adult stage , although these day - night distribution means only involved a depth difference of 1m or less , and some animals apparently did not migrate . birge ( 1895 ) observed no vertical movement for this species in lake mendota , dane co . diurnal migratory behavior is apparently weakly developed in this species , and the extent of migration may be influenced by age and individual behavior , and perhaps by temperature , light level , time of year and thermocline depth
s . oregonensis has been found in the stomach of severl species of fish including ass , crappie , carp , suckers , freshwater drum , trout - perch , yellow perch , and whitefish ( ewers 1933 ; wilson 1960 ) . comparing only a small percentage of the diet of some fish , it was found to be an important food item for small bloater ( wells and beeton 1963 ) .
balcer , korda , and dodson . 1984 . zooplankton of the great lakes : general morphology and ecology of the crustacean zooplankton , p . 8 - 11 . university of wisconsin pres . madison , wisconsin .
balcer , korda , and dodson . 1984 . zooplankton of the great lakes : life history and ecology of the major crustacean species , p . 91 - 93 . university of wisconsin pres . madison , wisconsin .
byron torke . 2001 . the distribution of calanoid copepods in the plankton of wisconsin lakes . hydrobiologia 453 / 454 : 351 - 365 , 2001 .
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the nonindigenous occurrences section of the nas species profiles has a new structure . the section is now dynamically updated from the nas database to ensure that it contains the most current and accurate information . occurrences are summarized in table 1 , alphabetically by state , with years of earliest and most recent observations , and the tally and names of drainages where the species was observed . the table contains hyperlinks to collections tables of specimens based on the states , years , and drainages selected . references to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the table 1 caption or through the individual specimens linked in the collections tables .
the endopod of the 1st leg of this copepod species is bifurcate . unlike some other diaptomids , the antepenultimate segment of the right 1st antenna has no distinct appendage and is not produced into a blunt point in males . the male left 5th leg is shorter than the right , reaching to the end of or slightly past the 1st segment of the right exopod . there is a scythe - like inner process on the terminal exopod segment of the male left 5th leg . females have 3 urosomal segments , rounded metasomal wings with small sensilla , and a somewhat expanded genital segment ( pennak 1989 ; lesko et al . 2003 ) .
females are around 0 . 8–1 . 2 mm long while males are around 0 . 7–1 mm long ( geddes and cole 1981 ; torke 2001 ; lesko et al . 2003 ) .
is native to the north central plain states , northeast to new york , southern united states in the mississippi river basin , texas , and west to colorado ( pennak 1989 ; mills et al . 1993 ; torke 2001 ; thum and sternberger 2006 ) .
was first recorded from lake ontario in 1967 . in the 1970s , it was recorded from lake erie , lake st . clair , lake huron and the saginaw river . the occurrences in the lake huron drainage were discovered upon re - examining archived specimens from 1974 and 1975 ( mills et al . 1993 ; torke 2001 ; lesko et al . 2003 ) . unspecified locations in
( mclaughlin et al . , 2005 ) . collected from lake tahoe , on the
border in 1979 and several other california locations ( byron and saunders 1981 ) .
has expanded its range in north america westward ( duggan et al . 2006 ) . it has been introduced outside of north america , possibly via the aquarium trade .
* hucs are not listed for states where the observation ( s ) cannot be approximated to a huc ( e . g . state centroids or canadian provinces ) .
is typically found in waters with a ph range of 7 . 5–8 . 6 and a conductivity range of 77–660 μs cm
. this species prefers to dwell in cool waters < 12ºc and was found at 10 m in june and below 16 m in july , underneath the thermocline in belews lake , north carolina ( chapman et al . 1985 ; marcogliese and esch 1992 ; torke 2001 ; thum and stemberger 2006 ) .
produces some eggs that go through a diapause stage before they hatch and some that do not . breeding in general takes place from around march to november and females can produce up to around 20 eggs per brood . diapausing eggs produced between june and october hatch from december to june of the following year . when production of diapausing eggs occurs in the summer it may aid populations to avoid fish predation . these eggs have been known to reach densities of 105 per m
in the sediments of some habitats . such high densities may help mitigate the effects of a poor year in reproduction and recruitment . it may take around 7 weeks for resting stages to hatch . one study found that it takes around 66 days at 10ºc and 15 days at 25ºc for development to the adult stage . there are 2–5 generations per year in different parts of this species’ range ( geiling and campbell 1972 ; chapman et al . 1985 ; dowell 1997 ; torke 2001 ; lesko et al . 2003 ; wonham et al . 2005 ) .
feeds on phytoplankton , especially individual algae > 53 μm in size . it can also selectively and intensely prey on some rotifer species ( geiling and campbell 1972 ; williamson and butler 1986 ; torke 2001 ) .
could have been introduced accidentally in bait buckets , in fishing equipment , by recreational boaters , with hatchery stock from the mississippi river basin , or through dispersal ( mills et al . 1993 ; lesko et al . 2003 ; reid and hudson 2008 ) .
additionally , based on evidence from an ohio lake , it has been suggested that s . pallidus is an intermediate host for the parasitic worm tanaorhamphus longirostris , although study of this occurrence has been limited ( hubschman 1983 ) . documented evidence combined with its record of spread across the u . s . ( byron and saunders 1981 ) have led some recently colonized areas , like new zealand , to express concern over the potential effects of s . pallidus on native ecosystems ( duggan et al . 2006 ) .
there have been no recent records of this species in the great lakes . persistent populations of
may be lacking in the main water bodies of the great lakes , although individuals are probably washed into the lakes during floods . its native range could extend into tributaries and coastal wetlands within the basin ( mills et al . 1993 ; lesko et al . 2003 ; reid and hudson 2008 ) .
geddes , m . c . , and g . a . cole . 1981 . variation in sexual size differentiation in north american diaptomids ( copepoda : calanoida ) : does variation in the degree of dimorphism have ecological significance ? limnology and oceanography 26 ( 2 ) : 367 - 374 .
geiling , w . t . , and r . s . campbell . 1972 . the effect of temperature on the development rate of the major life stages of diaptomus pallidus herrick . limnology and oceanography 17 : 304 - 307 .
glmris . 2012 . appendix c : inventory of available controls for aquatic nuisance species of concern , chicago area waterway system . u . s . army corps of engineers .
hubschman , j . h . 1983 . diaptomus pallidus herrick , 1879 ( crustacea : copepoda ) as an intermediate host for tanaorhamphus longirostris ( van cleave , 1913 ) ( acanthocephala : neoechinorhynchidae ) . journal of parasitology 69 ( 5 ) : 930 - 932 .
krieger , k . a . , and d . m . klarer . 1991 . zooplankton dynamics in a great lakes coastal marsh . journal of great lakes research 17 : 255 - 269 .
lesko , l . t . , p . l . hudson , and m . a . chriscinske . 2003 . calanoid copepods of the laurentian great lakes . ann arbor , mi , online at urltoken
mclaughlin , p . l . , and 39 others . 2005 . common and scientific names of aquatic invertebrates from the united states and canada—crustaceans . american fisheries society special publication 31 , bethesda , maryland , american fisheries society , 545 p .
marcogliese , d . j . , and g . w . esch . 1992 . alterations of vertical distribution and migration of zooplankton in relation to temperature . american midland naturalist 128 ( 1 ) : 139 - 155 .
mills , e . l . , j . h . leach , j . t . carlton , and c . l . secor . 1993 . exotic species in the great lakes : a history of biotic crises and anthropogenic introductions . journal of great lakes research 19 ( 1 ) : 1 - 54 .
pennak , r . 1989 . fresh - water invertebrates of the unites states , 3rd ed . protozoa to mollusca . john wiley & sons , inc . , new york , new york state . 628 pp .
reid , j . w . , and p . l . hudson . 2008 . comment on “rate of species introductions in the great lakes via ship’s ballast water and sediments . canadian journal of fisheries and aquatic sciences 65 ( 3 ) : 549 - 553 .
torke , b . 2001 . the distribution of calanoid copepods in the plankton of wisconsin lakes . hydrobiologia 453 - 454 : 351 - 365 .
williamson , c . e . , and n . m . butler . 1986 . predation on rotifers by the suspension - feeding calanoid copepod diaptomus pallidus . limnology and oceanography 31 : 393 - 402 .
williamson , c . e . , and h . a . vanderploeg . 1988 . predatory suspension - feeding in diaptomus : prey defenses and the avoidance of cannibalism . bulletin of marine science 43 ( 3 ) : 561 - 572 .
wonham , m . j . , s . a . bailey , h . j . macisaac , and m . a . lewis . 2005 . modelling the invasion risk of diapausing organisms transported in ballast sediments . canadian journal of fisheries and aquatic sciences 62 : 2386 - 2398 .
kipp , r . m . , a . j . benson , j . larson , t . h . makled , and a . fusaro
this information is preliminary or provisional and is subject to revision . it is being provided to meet the need for timely best science . the information has not received final approval by the u . s . geological survey ( usgs ) and is provided on the condition that neither the usgs nor the u . s . government shall be held liable for any damages resulting from the authorized or unauthorized use of the information .
the data represented on this site vary in accuracy , scale , completeness , extent of coverage and origin . it is the user ' s responsibility to use these data consistent with their intended purpose and within stated limitations . we highly recommend reviewing metadata files prior to interpreting these data .
citation information : u . s . geological survey . [ 2018 ] . nonindigenous aquatic species database . gainesville , florida . accessed [ 7 / 9 / 2018 ] .
contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co - authorship if warranted . for queries involving fish , please contact pam fuller . for queries involving invertebrates , contact amy benson .
walter , t . c . & boxshall , g . ( 2018 ) . world of copepods database .
walter , chad . the world of copepods . , available online at urltoken [ details ]
webber , w . r . ; fenwick , g . d . ; bradford - grieve , j . m . ; eagar s . g . ; buckeridge , j . s . ; poore , g . c . b . ; dawson , e . w . ; watling , l . ; jones , j . b . ; wells , j . b . j . ; bruce , n . l . ; ahyong , s . t . ; larsen , k . ; chapman , m . a . ; olesen , j . ; ho , j . ; green , j . d . ; shiel , r . j . ; rocha , c . e . f . ; lörz , a . ; bird , g . j . ; charleston , w . a . ( 2010 ) . phylum arthropoda subphylum crustacea : shrimps , crabs , lobsters , barnacles , slaters , and kin , in : gordon , d . p . ( ed . ) ( 2010 ) . new zealand inventory of biodiversity : 2 . kingdom animalia : chaetognatha , ecdysozoa , ichnofossils . pp . 98 - 232 . [ details ]
( of leptodiaptomus pallidus ( light , 1938 ) ) walter , chad . the world of copepods . , available online at urltoken [ details ]
( of diaptomus pallidus herrick , 1879 ) walter , chad . the world of copepods . , available online at urltoken [ details ]
( of diaptomus reighardi marsh , 1895 ) walter , chad . the world of copepods . , available online at urltoken [ details ]
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s _ pygmaeus _ 5th _ leg . mov - virtual focus of the 5th leg ( 1 . 71 mb )
torke , b . 2001 . the distribution of calanoid copepods in the plankton of wisconsin lakes . hydrobiologia . 453 - 454 : 351 - 365 .
chow - fraser , p . and e . j . maly . 1988 . aspects of mating reproduction and co - occurrence in three freshwater calanoid copepods . freshwater biol . 19 : 95 - 108 .
havens , k . e . , n . d . yan , and w . keller . 1993 . lake acidification : effects on crustacean zooplanktonic populations . environ . sci . and technology . 27 : 1621 - 1624 .
hairston , n . g . and r . a . vanbrunt . 1994 . diapause dynamics of two diaptomid copepod species in a large lake . hydrobiologia . 292 - 293 : 209 - 218 .
bundy , m . h . and h . a . vanderploeg . 2002 . detection and capture of inert particles by calanoid copepods : the role of the feeding current . j . of plankton research . 24 : 215 - 223 .
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to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .
disclaimer : the animal diversity web is an educational resource written largely by and for college students . adw doesn ' t cover all species in the world , nor does it include all the latest scientific information about organisms we describe . though we edit our accounts for accuracy , we cannot guarantee all information in those accounts . while adw staff and contributors provide references to books and websites that we believe are reputable , we cannot necessarily endorse the contents of references beyond our control .
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utegenia is a genus of early tetrapod .

it is usually regarded as a basal seymouriamorph , but sometimes included in the discosauriscidae or as a sister taxon of the latter .

only one species , utegenia shpinari , found from kazakhstan , is known .

urumqia , another basal seymouriamorph , from urumqi , xinjiang of china is probably a junior synonym of utegenia .

utegenia

urumqia was originally associated with utegenia , but actually urumqia is a basal lepidosauromorph reptile .
figure 1 . skull of a postmetamorphic specimen of utegenia shpinari . notice the contact between the postorbital ( po ) and the supratemporal ( st ) .
according to the present family tree , the rise of the living amphibians occurs in this lineage beginning with utegenia . this is where living amphibians depart from living reptiles .
overall much smaller than kotlassia , the skull of utegenia was relatively larger , lower and wider . the interpterygoid space expanded ( narrower pterygoid ) . the parasphenoid and basisphenoid were enlarged .
laurin , m . in press . a reappraisal of utegenia , a permo - carboniferous seymouriamorph ( tetrapoda : batrachosauria ) from kazakhstan . journal of vertebrate paleontology 29 pages , 6 figures .
laurin m 1996 . a reappraisal of utegenia , a permo - carboniferous seymouriamorph ( tetrapoda : batrachosauria ) from kazakhstan . journal of vertebrate paleontology 16 ( 3 ) : 374 - 383 .
utegenia shpinari kuznetsov and ivakhnenko , 1981 ( batrachosauria : seymouriamorpha ) . kurty locality . latest carboniferous - early permian of kazakhstan . two postmetamorphic specimens and larvae with leaves of pecopteris , taeniopteris and kerpia .
of course they are not an ancestors of axolotl despite some morphological similarities utegenia much closer to ancestors of reptiles in a broad sense . but you are correct , this small - sized specimens which are larvae , really looks similar to modern axolotls .
utegenia had a moderately long trunk , with 28 presacral vertebrae ( three of four more than in other seymouriamorphs ) . the neural arches are paired and disarticulated from the pleurocentra even in the largest known specimen , but this is probably a juvenile character ( neural arch fusion occurred relatively late in the ontogeny of early terrestrial vertebrates ) .
utegenia had circular scales over most of its body , like discosauriscus . it retained rhomboidal ventral scales ( fig . 2 ) arranged in a chevron pattern ( gastralia ) and a contact between the postorbital and the supratemporal ( fig . 1 ) . both of these characters suggest that it is not closely related to discosauriscus , ariekanerpeton , or seymouria ( none of these seymouriamorphs appear to have had rhomboidal gastralia , although circular ventral scales were present in discosauriscus , and the presence of gastralia cannot be determined in seymouria ) . the contact between the supratemporal and the postorbital is rarely present in discosauriscus and ariekanerpeton , and it is not found in seymouria , but it is present in most postmetamorphic specimens of utegenia .
the first published reconstructions of utegenia shpinari showed a very broad skull ( kuznetsov and ivakhnenko , 1981 ) , but recent work suggests that kuznetsov and ivakhnenko did not take the extensive crushing into consideration ( fig . 1 ) , and that the skull was somewhat more narrow ( laurin , in press ) . the braincase is virtually unknown because its endochondral elements were cartilaginous . however , the parasphenoid was broad , triangular , and covered in a shagreen of denticles .
utegenia shpinari was found in the upper pennsylvanian or lower permian of kazakhstan ( the stratigraphy of this area is problematic ) . it is represented by more than four hundred flattened but well preserved specimens . these specimens document a growth series ranging from small larvae to small post - metamorphic specimens . this growth series shows that the neural arches ossify before the centra , and the external gills disappear when the skull reaches a length of about 1 . 5 cm ( kuznetsoz and ivakhnenko , 1981 ) . however , the poor ossification of most endochondral elements suggests that no fully mature specimen was found . the cranial length of the known specimens ranges from 1 cm to 3 . 5 cm ( kuznetsov and ivakhnenko , 1981 ) .
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the appendicular skeleton is poorly known because of its poor ossification . the scapula and coracoid are discrete elements , and the scapula is approximately circular . the ends of the limb bones are unossified . the carpus and tarsus are usually not ossified .
kuznetsov , v . v . , and m . f . ivakhnenko . 1981 . discosauriscids from the upper paleozoic in southern kazakhstan . paleontological journal 1981 : 101 - 108 .
skeleton of a postmetamorphic specimen . this specimen is one of more than four hundred skeletons recently collected in kazakhstan . impressions of ventral scales are preserved on the right side of the abdomen .
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in the lineage of microsaurs . it also phylogenetically preceded the amniota , and its basalmost taxon ,
the cervicals and caudals are not known . the dorsal ribs were wide , producing a flattened torso .
the scapula and coracoid were reduced to two unfused discs . the extremely robust humerus was enlarged proximally , removing any trace of the former l shape . the radius and ulna were more robust . the manus and pes were not documented .
kuznetzov vv and ivakhnenko mf 1981 . discosauriscids from the upper paleozoic in southern kazakhstan . paleontological journal 1981 : 101 - 108 .
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full reference : v . v . kuznetsov and m . f . ivakhnenko . 1981 . discosauriscids from the upper paleozoic in southern kazakhstan . paleontological journal 1981 : 101 - 108
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southern halo ( 1983 – 2009 ) was an american-bred thoroughbred racehorse and sire .

in his racing career he ran twenty-four times winning five races and finishing second in the grade i swaps stakes and super derby .

he is chiefly notable for his remarkable career at stud where he was leading sire in argentina on ten occasions and the sire of 170 stakes winners , 56 of them group/grade i winners , and 16 of them were champions .

southern halo

original southern halo song co - written by natalia morris of southern halo and melissa bollea rowe .
it all started when . . . | we are halo | southern halo season 1 preview
official twitter page for sister trio country pop band southern halo . new album # justlikeinthemovies available now !
nineteen - year - old southern halo ( halo - - northern sea , by northern dancer ) stands for $ 15 , 000 .
take a look at the official music video for
rewind
by southern halo directed by : james & heather mathews written by : c . neal , g ' . o ' brien and c . gravitt copyright 2016 - southern halo
take a look at the official music video for
rewind
by southern halo directed by : james & heather mathews written by : c . neal , g ' . o ' brien and c . gravitt copyright 2016 - southern halo show less
the latter , like former equus champion entisaar , is a son of outstanding shuttle sire more than ready ( himself a son of the halo stallion southern halo ) .
leading sire kantharos ( lion heart–contessa halo , by southern halo ) is moving from ocala stud in florida to hill ‘n’ dale farms in lexington , kentucky , stonestreet stables announced thursday .
we are proud to introduce our music video for
little white dress
our debut single off the self titled album southern halo ! take a look and be sure to check back each week for new videos and don ' t forget to subscribe ! published on august 25 , 2015 . music video by southern halo performing little white dress . produced by james matthews films . ( c ) 2015 southern halo publishing .
cangon stud farm owner jamie mackay has announced that snapy halo , a group 1 winning son of southern halo , has been retired to stand at his hunter valley based property in 2011 .
“i think it ' s pretty fair to say that snapy halo is the best bred son of southern halo to ever stand in australasia which certainly bodes well for his chances , ” said mackay .
southern halo also stood at john magnier and partners’ ashford stud near versailles , ky . , and in japan . his kentucky - bred stakes winners include millionaire
southern halo won or placed in 15 of 22 races and earned $ 344 , 875 in north america for owner stavros niarchos while trained by d . wayne lukas . southern halo’s five stakes - placings included runner - up efforts in the super derby ( gr . i ) and the swaps stakes ( gr . i ) .
halo became a sire - of - sires which besides sunday silence , included saint ballado and southern halo who died aged 26 after a very successful career at stud in argentina - being a leading sire for eight years .
the most influential and successful argentine stallion of the past generation , southern halo was a son of halo and the northern dancer mare northern sea . bred by e . p . taylor , southern halo sold for $ 600 , 000 as a yearling to stavros niarchos , who raced him in the u . s . second in both the g1 super derby and swaps stakes as a 3 - year - old in 1986 but not a stakes winner during his racing career , southern halo had to sail afar to find stallion success when niarchos sold him for export as a stallion prospect .
it’s hard , it’s between kitchen notes at the omni , they have the best buffet , but then there’s the southern .
markedly back at the knee , upright in the pasterns and a non - stakes winner to boot , southern halo was always going to be a marginal stud prospect in kentucky . however , prominent argentine stud farm haras la quebrada gave recognition to his impeccable breeding and southern halo was despatched to a stallion career in argentina , where he would rewrite the record books .
halo surface brightnesses that are generally in reasonable agreement with those inferred from the best - fit halo models in this paper . however , the halo temperatures inferred from the o
, we showed that the halo emission measure tends to increase from the outer to the inner galaxy , at least in the southern galactic hemisphere . we previously noted a similar trend for the
southern halo will be buried at haras la quebrada near another north american - bred stallion , solazo , sire of the second dam of north america’s two - time horse of the year cigar .
central kentucky stallion southern halo entered into the history books by becoming the 14th stallion to top the 100 mark by number of stakes winners among those stallions who stood at least one season in north america . southern halo , who began his stallion career in south america and now has 102 stakes winners , has held court at ashford stud near versailles , ky . , starting in 1996 .
not so long afterward , southern halo was restricted solely to covering in the southern hemisphere , and his production of top racers in argentina has continued . the stallion ' s influence in the northern hemisphere has enjoyed a renewal of success as more than ready has steadily earned respect as one of the best stallions in the world .
none of the estrellas is so closely linked to the giant reputation of southern halo than the sprint , which went to offspring of the stallion six times in seven year from 1995 through 2001 . three of those were , however , the years that the wonderful wally dominated speed in the southern hemisphere to a degree that is unrivaled . the extraordinary daughter of southern halo out of the logical mare welcome won the sprint in 1995 through 1997 , when she was pretty much the fastest thing to wear plates in the racing world .
this entry was posted in bloodlines archive and tagged buster ' s ready , estrellas classic , more than ready , mother goose stakes , southern halo , star runner by frank mitchell . bookmark the permalink .
watch southern halo’s “little white dress” video and let us know what you think of country music’s emerging sibling trio . also , make sure to follow the girls on twitter , facebook , and by checking out their website !
halo’s close relationship to northern dancer offered breeders many opportunities to inbreed to their shared grandam , almahmoud , a combination that has resulted in innumerable top horses , including champions serena’s song , fantastic light , ashado , daiwa major , and singspiel , but one of the best racehorses to emerge from the direct cross of halo and a northern dancer mare was southern halo .
today , other sons of halo , including saint ballado and southern halo , are commanding prestige in the breeding sheds as well . as a broodmare sire , halo is equally sensational , with daughters or granddaughters producing champions victory gallop , machiavellian , singspiel , and coup de genie ; classic winners fusaichi pegasus and pine bluff ; and sires such as rahy and silver ghost .
that disappointment , added to the rather academic attitude of sales buyers ' rejecting some of southern halo ' s stock as imperfect , produced a cooling off of the love affair with kentucky breeders that had so quickly sprung around the stallion .
snapy halo is by one of the best sire of sires in the world , southern halo , who was argentina ' s leading sire from 1994 to 2000 , and in 2004 and 2007 . he sired more than 100 stakes winners including 50 winners at the group 1 level , 16 of which were champions .
more than ready’s flying start proved a perfect catalyst for collingrove stud in victoria to import another us - bred sprinting son of southern halo . halo homewrecker hadn’t been as good as sprinter as more than ready , but don’t say halo and more than ready had paved the way for his importation , and the timing was excellent for his arrival at collingrove in advance of the 2005 stud season .
that résumé omission , combined with the fact that he was markedly back at the knee and upright in his pasterns , made him a marginal stud prospect in kentucky , so southern halo was sold to haras la quebrada near buenos aires , argentina . southern halo quickly proved himself the most successful sire of the modern era in argentina , winning seven sire championships and siring 18 argentine champions among his career total of 175 stakes winners from 1 , 828 foals ( 9 . 6 percent ) .
in summary , our observations suggest that the halo is concentrated toward the galactic center . other than that , the morphology of the hot halo remains uncertain . however , our observed emission measures do not vary with latitude in the way expected for a disk - like halo morphology . the patchiness of the halo emission makes it difficult to determine the halo ' s underlying global morphology .
column densities when calculating the attenuation of the halo emission . the details of the morphology of the halo remain uncertain , but the variation of the emission measure with longitude suggests that the halo is concentrated toward the galactic center ( section
in part due to the massive impression that wally made , along with a series of champion juveniles , southern halo became associated with the speed to an inordinate degree . but as star runner and numerous other fine athletes like el compinche and miss linda ( spinster stakes ) have shown , speed was a benefit of breeding to southern halo , not a limitation . many of the stallions ' offspring have excelled at eight , nine , or 10 furlongs , as well as many at the shorter distances .
southern halo , the most successful sire in argentine history , died in his paddock at haras la quebrada near buenos aires from complications from the infirmities of old age , according to gustavo gonzalez . the 24 - year - old maryland - bred son of halo out of the northern dancer mare northern sea had been pensioned this year .
“i ( told ) him goodbye the last weekend . he didn’t suffer or feel pain” , said hernan ceriani cernadas iii , son of the late hernan ceriani cernadas and owner of la quebrada with his family . “a few days ago , when someone said that southern halo was the sadler’s wells of argentina , john magnier said , ‘southern halo has joined around him people of the class of robert sangster ( of coolmore ) , e . p . taylor , d . wayne lukas , hernán ceriani cernadas . ’ ”
( b ) , in which the halo temperature was fixed at 2 . 5
intensity , it may also be due to the fact that the halo likely has a complicated temperature and ionization structure , so different methods of characterizing the halo emission may yield different temperatures . despite this , such temperature measurements are still useful for testing halo models , provided the predicted halo emission is treated like the true halo emission . this involves creating synthetic observations from the predicted halo spectra , which are then analyzed with the same sxrb model as the real observations ( hskjm ) .
halo - a horse with the reputation for being anything but angelic . . .
southern halo was argentina’s leading sire from 1994 to 2000 , and in 2004 and 2007 . he topped the broodmare sire’s list from 2004 to 2008 and ranks as the current leader . his 167 stakes winners include 56 group / grade i winners and 16 champions .
we are southern halo ! welcome to our channel ! here you will see our latest interviews , music videos , and . . . . coming in may our new series where we let cameras into our life and show you guys , what h . . .
buenos aires — the victor in the group 1 estrellas classic on saturday at san isidro racecourse in buenos aires was the bay colt star runner , a son of the great us - bred and argentine - based stallion southern halo , who died in november 2009 .
the combination of the stallion ' s immediate success in argentina , internationally recognizable pedigree , and the versatility in his offspring made coolmore reach out and acquire southern halo as a reverse shuttle horse for their burgeoning operation in kentucky at ashford stud in the early 1990s .
as a premium stallion in the argentine , southern halo made his mark from the beginning , and the carreras de las estrellas , renewed for the 21st time this weekend , have proven to be a showcase for the talents and versatility of the stallion and his offspring .
besides snapy halo , esnaola is also the dam of exciting young group 1 winning stallion sebi halo and the champion older mare , halo ola . she has also produced a further three black type placed runners and all this has come from just nine foals .
bred by e . p . taylor , southern halo went through the 1984 keeneland july yearling sale , where he was purchased for $ 600 , 000 by the irish branch of the british bloodstock agency . he initially raced in ireland , where he was unplaced in two starts .
southern halo , who has shuttled back and forth between ashford and argentine the last several years , is represented by several stakes winners from his u . s . crops . the group is led by grade i winner more than ready , who stands at stud at vinery near lexington .
intensity , thus biasing the halo measurements . alternatively , the discrepancy may be due to the halo having a complex multitemperature , multi - ionization - state structure , meaning that the o
despite being a gr1 winner on turf , however , it was through his top class dirt performers sunday silence , devil’s bag , sunny’s halo and glorious song , that halo largely made his mark –a mark potent enough to score halo a pair of us sires titles ( in 1983 and 1989 ) and both sunny’s halo and sunday silence won the gr1 kentucky derby .
a full brother to snapy halo , sebi halo has kicked off his stallion career in great order having produced a group 2 winner among 8 stakes winners in his first two crops .
southern halo ( usa ) b . h , 1983 { 16 - g } dp = 18 - 5 - 23 - 4 - 0 ( 50 ) di = 2 . 23 cd = 0 . 74 - 24 starts , 5 wins , 7 places , 3 shows career earnings : $ 344 , 875
the halo and extragalactic components were both subject to absorption . for this purpose we used the xspec
kzn breeders : halo - a horse with the reputation for being anything but angelic . . .
sadly , halo homewrecker died after only one season at collingrove , but time has shown that he would have had enough potential to write his own ( admittedly small ) chapter in halo’s story .
southern halo also was represented by major north american winners miss linda and edenwold . an argentine - bred champion , miss linda won the 2001 overbrook spinster stakes ( gr . i ) at keeneland . edenwold was voted canada’s 2005 champion 2 - year - old male . he won the following year’s classic queen’s plate stakes .
) . similarly , column 13 contains the best - fit halo emission measure . as noted in section
bred by northern dancer’s breeder , e . p . taylor , out of 1977 grade 3 test stakes winner northern sea from the great family of lea lark , southern halo clearly possessed plenty of racing ability . purchased for $ 600 , 000 at the 1984 keeneland july sale by stavros niarchos , he failed to place at 2 in ireland but won 5 of 22 starts for trainer d . wayne lukas over the next two years in america . southern halo was beaten only a head by clear choice in the 1986 grade 1 swaps stakes and finished second in the grade 1 super derby to wise times , but he never managed to win a stakes race .
column density used to attenuate the halo and extragalactic components . column 12 contains the best - fit halo temperature , along with the statistical error ( 90 % confidence interval for one interesting parameter ; lampton et al .
measurements suggests that , in fact , our choice of foreground model is not adversely affecting our halo measurements .
southern halo , made up of natalia ( pronounced natalie - uh ) , christina , and hannah , a trio of sisters from the mississippi delta , recently released its debut single , “ little white dress , ” to radio . the track marks the lead single off the group’s self - titled debut album and is already receiving spins across the country .
glorious song was by no means the only daughter of halo to leave behind a top sire son –halo matriarch coup de folies produced three gr1 winners , including champion 2yo colt and outstanding sire machiavellian ( mr prospector ) .
as a stallion , halo’s image ( halo - - sugar’s image , by valid appeal ) is represented by 39 stakes horses and the earners of $ 20 . 5 million . the best of his 17 stakes winners ,
) , we find that this leads to an uncertainty in the halo surface brightness typically of only ±0 . 3
to say that the halo male line has enjoyed its most success outside the states , would be an understatement .
emission from the outer to the inner galaxy , in agreement with the halo measurements presented here . these results argue against the hot halo having a simple plane - parallel disk - like morphology , in which case the emission measure would be independent of galactic longitude . instead , these results suggest a halo that is concentrated toward the galactic center .
the majority of southern halo ' s stakes winners have come from his argentine crops . he is represented by some 35 argentine group i winners , including miss linda . a champion in argentina who was imported to the u . s . in 2000 , miss linda won a u . s . grade i stakes last year and is a grade iii winner this year .
an xmm - newton survey of the soft x - ray background . iii . the galactic halo x - ray emission
pensioned from stud duty at stone farm in 1997 , halo passed away at the age of 31 late in 2000 .
our halo emission measures do not decrease with increasing galactic latitude , contrary to what is expected for a plane - parallel disk - like halo morphology . this result appears not to be an artifact of soft proton contamination , nor of our using h
halo spent most of his career at stone farm and produced a number of champions , amongst them devil ' s bag - who happens to be a full brother to glorious song and sunny ' s halo - winner of the 1983 kentucky derby .
figure 7 . 0 . 5–2 . 0 kev halo surface brightnesses against halo temperatures . sight lines on which the original target of the xmm - newton observation was a galaxy cluster are colored orange . the triangles indicate upper limits on the surface brightnesses .
the halo male line in america suffered another serious blow seven years ago when 2005 horse of the year saint liam , the best son of halo’s leading sire son saint ballado , died after only one season at stud without leaving an obvious male heir .
2nd super derby invitational ( g1 ) , swaps s ( g1 ) , silver screen h . ( g2 ) , el cajon s . ; 3rd kensington h . leading sire in argentina 8 times . southern halo is the sire of 120 stakes winners , including 88 graded / group winners , and 12 champions , according to jockey club records . he currently stands exclusively at haras la quebrada , argentina .
figure 5 . halo emission measure against ( a ) b for the northern galactic hemisphere , ( b ) b for the southern galactic hemisphere , ( c ) | l | for the northern galactic hemisphere ( see equation ( 2 ) ) , and ( d ) | l | for the southern galactic hemisphere . panels ( a ) and ( d ) show the only two examples of statistically significant correlations in table 3 ; the other two panels are shown for comparison . detections are shown with crosses and error bars ; upper limits are shown with triangles . the red data points indicate emission measures from sight lines for which the temperature was fixed at 2 . 1 × 10 6 k .
an xmm - newton survey of the soft x - ray background . iii . the galactic halo x - ray emission - iopscience
, respectively . they subsequently used a foreground model with these oxygen intensities to obtain their halo measurements . gupta et al . (
halo’s image stood this season for a fee of $ 4 , 000 . his 10 - year - old half - brother ,
, won the 2004 santa anita handicap ( gr . i ) and pimlico special ( gr . i ) and the $ 1 million barretts / ctba classic stakes the year he was florida’s horse of the year . southern image earned a career total of $ 1 , 843 , 750 .
halo sired seven champions and 62 stakes winners , and led the leading sire list twice . standout runners sired by halo included goodbye halo , who counted the kentucky oaks among her seven gr 1 victories , strodes creek , who was second in the 1994 kentucky derby and third in the belmont stakes gr 1 , and millionaire lively one , whose long list of accomplishments included the swaps stakes gr 1 . halo ' s progeny earned over $ 44 million on the racetrack and have netted far more in the breeding shed .
in only two cases is the correlation statistically significant at the 5 % level . the halo emission measure is positively correlated with | b | in the northern hemisphere ( i . e . , the emission measure tends to increase from low latitudes to the pole ; see figure 5 ( a ) ) . there is no correlation between emission measure and | b | in the southern hemisphere ( see figure 5 ( b ) ) . however , the emission measure is negatively correlated with | l | in the southern hemisphere ( i . e . , the emission measure tends to increase from the outer galaxy to the inner galaxy , as noted in the previous section ; see figure 5 ( d ) ) .
today , the late sunday silence is immortalized as the greatest sire and sire of sires in japanese history , a horse so good that even less - accomplished sons like silent name and hat trick are making a positive contribution in the land of their father’s birth . another unheralded son of halo , the beautifully bred southern halo , became one of the greatest sires in argentine history , and his best american son , more than ready , is the sire of current kentucky derby favorite verrazano , who is exactly the type of horse that will make breeders salivate .
and the number of degrees of freedom . column 15 contains the intrinsic 0 . 5–2 . 0 kev surface brightness of the halo ,
halo developed into a good grass horse at 3 , winning the lawrence realization , which attracted a bid from english breeder irving allen . when allen’s representatives discovered that halo was a cribber ( a horse that clings to objects with his teeth and sucks air into his stomach ) – then considered a disqualifying flaw by old - fashioned english breeders – the sale was rescinded and halo returned to the barn of trainer mackenzie miller . halo improved further as a 5 - year - old , winning the grade 1 united nations handicap and grade 2 tidal handicap , earning a place at windfields farm alongside his “cousin” northern dancer , a son of a half - sister to halo’s dam .
although a stallion ' s success at stud is usually defined by statistics , his true legacy carries far deeper than mere numbers . halo , one of only 18 stallions in history to sire more than one derby winner , certainly has impressive statistics , but to stone farm , halo represents more than sheer numbers . halo meant the world to stone farm , partly because he gave stone farm 1989 horse of the year sunday silence .
while roberto horses ended up excelling all around the world , the influence of hail to reason’s other extremely influential son , halo , has largely been much more localized . halo wasn’t as good a racehorse as roberto ( whose derby victory was only his second greatest triumph , as his defeat of
the latest chapter in the halo success story can be seen in south africa –thanks to the exploits of last season’s leading first crop sire gimmethegreenlight .
that overwhelming success led to ashford stud re - importing him as a shuttle sire in 1996 , but he did not meet the same success in the land of his birth . southern halo sired canadian champion edenwold , but by far his most important north american - conceived offspring was more than ready . out of the woodman mare woodman’s girl , more than ready was bred by woodlynn farm and sold for $ 187 , 000 to edward rosen as agent for james scatuorchio .
intensity in our spectral fitting , and thus overestimating the halo temperature . however , d . b . henley & r . l . shelton ( in preparation ) also point out that the halo emission likely originates from plasma with a range of temperatures and in a range of ionization states . if this is the case , the spectral fitting described here will not necessarily arrive at the same best - fit halo temperature as that inferred from the o
column densities to attenuate the halo emission . by using such column densities , we could potentially be neglecting the contributions to the absorption from regions containing h
we defer a detailed comparison of our observations to models of the hot halo to a follow - up paper ( d . b . henley et al . , in preparation ) . however , here we make some general comments on the implications of our results for the origin of the hot halo .
in the spring of 1983 , the northern dancer mare northern sea foaled a halo colt at windfields whose pedigree featured a coupling of the half - sisters cosmah and natalma ( the dam of northern dancer ) . sent to the keeneland yearling sale , he was purchased by the bba on behalf of stavros niarchos for $ 600 , 000 . unplaced in two starts in europe , the colt , now named southern halo , returned to the states to join the american stable of master trainer d wayne lukas , for whom he won five times and ran second in both the gr . 1 swaps stakes and the gr . 1 super derby .
we are unable to distinguish between extragalactic accretion and outflows from the disk as the source of the ~ ( 2–3 ) × 10 6 k halo plasma . both processes have more than enough energy to maintain the halo ' s surface brightness , and other aspects of the halo emission ( such as the increase in emission measure toward the inner galaxy and the general patchiness of the emission ) could plausibly be explained by either scenario ( section 5 . 5 ) . a detailed comparison of our measurements with the predictions of hydrodynamical models of the halo is needed to distinguish between different scenarios for the heating of the halo . we will carry out such a comparison in a follow - up paper ( d . b . henley et al . , in preparation ) .
; d . b . henley & r . l . shelton , in preparation ) , we conclude that our choice of foreground model is not seriously biasing our measurements of the halo surface brightness . similarly , our halo temperatures agree with those from other studies that use spectral fitting ( yoshino et al .
spectra , which requires us to fix the normalization of the extragalactic background , potentially introduces some uncertainty in the normalization of the halo x - ray emission .
now , with the emergence of potent young sire gimmethegreenlight , the spotlight has fallen on a lesser known son of hail to reason , the fiery halo .
in the following subsections , we compare our measurements with those from previous studies , we discuss the effect of our assumed foreground model on our halo measurements , and we consider sources of contamination that could be affecting our halo measurements ( sections 5 . 1 – 5 . 3 , respectively ) . we conclude that contamination and our choice of foreground model are , in general , not adversely affecting our halo measurements . then , in section 5 . 4 , we discuss the morphology of the hot halo . finally , in section 5 . 5 , we comment on the implications of our measurements for the origin of the hot halo ( deferring a more detailed study of this issue to a follow - up paper ; d . b . henley et al . , in preparation ) .
as noted in section 2 . 1 , our sample of xmm - newton observations includes 20 that were analyzed in the hskjm . the halo temperatures that we have measured for these sight lines are generally in good agreement with those measured in hskjm , and there is no systematic difference in the halo temperatures ( although it should be noted that for five of these sight lines we had to fix the halo temperature at 2 . 1 × 10 6 k for the current analysis ) .
in 1984 , texas oilman tom tatham purchased 25 of the 40 shares in halo ' s syndicate and moved the stallion to kentucky to stand at stone farm .
although most of his stallion career was spent at stone farm , halo originally entered stud in 1975 at windfields in maryland where his first crop yielded glorious song , the canadian horse of the year . subsequent champions included devil ' s bag ( full brother to glorious song ) , sunny ' s halo ( winner of the 1983 kentucky derby - g1 ) , and of course , sunday silence ( derby , preakness s . - g1 , and breeders ' cup classic - g1 winner ) , who was conceived during halo ' s second breeding season at stone farm . in all , halo sired seven champions , 62 stakes winners , and led the leading sire list twice in the 1980s . standout runners sired by halo included goodbye halo , who counted the kentucky oaks among her seven g1 victories , strodes creek , who was second in the 1994 kentucky derby and third in the belmont s . - g1 , and millionaire lively one , whose long list of accomplishments included the swaps s . - g1 . halo ' s progeny earned over $ 44 million on the racetrack and have netted far more in the breeding shed .
and just as he had with his initial mares in argentina , southern halo scored a big hit early in the bluegrass . the star he sired in kentucky is one of lasting brilliance : more than ready . as a high - class 2 - year - old , more than ready won five of his seven starts , including the flash , tremont , and sanford . the dark brown colt added victories in the g1 king ' s bishop and g2 hutcheson the following year but was not a star for the triple crown .
uniformly better regarded at his southern hemisphere shuttle base in australia than in kentucky , more than ready has done his part to make believers of northern hemisphere breeders too . in last year ' s breeders ' cup , the stallion had both the juvenile turf winners , and this weekend , his daughter buster ' s ready won the g1 mother goose stakes at belmont .
, whose excellent season in 1990 / ’91 ( in which he won the blue diamond and finished second in the golden slipper ) saw don’t say halo crowned the country’s leading sire of two - year - olds . ultimately , don’t say halo became a very good broodmare sire , his daughters breeding the likes of ajc derby winner
alter added : “the combination of his racing career and his breeding career put him into a select group of florida horses . i trained his mother , sugar’s image , who was the winningest valid appeal mare , and we chose to breed her to halo . all my expectations became true when halo’s image hit the racetrack . ”
star winner earned the fifth estrellas classic trophy for his sire , who also won with el compinche ( 1996 and 1998 ) , manpower ( 2003 ) , and fairy magic ( 2007 ) . over the years , offspring of southern halo have won 17 of the previous grand premios that make up the estrellas program , and the stallion has had a winner of each of the seven races that make up the bulk of the card : the classic , distaff , sprint , junior sprint , mile , juvenile , and juvenile fillies .
observation . they then combine this prior with oxygen intensities from other directions to constrain the posterior probability distribution for the intrinsic halo emission . this new technique yields combined o
and the number of degrees of freedom . column 15 contains the intrinsic 0 . 5–2 . 0 kev surface brightness of the halo , calculated using the best - fit 1
halo sired sunday silence , the defining horse who has continued his legacy . sunday silence was exported to japan and has become the top sire in history in that country .
snapy halo will stand his first season at a fee of $ 6 , 500 plus gst . a lifetime breeding right is priced at $ 10 , 000 plus gst .
pensioned from stud duty in 1997 , halo passed away at the age of 31 late in 2000 .
you have to rejoice that halo lived to be almost 32 ,
arthur b . hancock iii , owner of stone farm , told the blood - horse at the time .
we were so grateful to have had him .
we typically used a 1 t raymond & smith ( 1977 and updates ) model to model the galactic halo emission , assuming that the halo plasma is in collisional ionization equilibrium , and assuming anders & grevesse ( 1989 ) solar abundances . although the true halo emission is likely from plasma at a range of temperatures ( yao & wang 2007 ; shelton et al . 2007 ; lei et al . 2009 ; yao et al . 2009 ) , a 1 t model is generally adequate to characterize the x - ray emission in the xmm - newton band . we used a raymond & smith model in order to match the code used to calculate x - ray emission from hydrodynamical models of the halo ( hskjm ; d . b . henley et al . , in preparation ) . in general , the temperature and emission measure of this component were free parameters in the fitting . in some cases , typically when the halo emission was faint , xspec ' s error command was unable to determine the statistical error on the halo temperature . in a few additional cases , the best - fit temperature was > 5 × 10 6 k , but very poorly constrained . in such cases , we fixed the halo temperature at 2 . 1 × 10 6 k , and redid the fit . this temperature was chosen as it was the median halo temperature resulting from our preliminary analysis of our data set .
in the breeders’ cup sprint over six furlongs at churchill downs . retiring to vinery stud in kentucky in 2001 , more than ready was an obvious candidate to be shuttled to vinery’s southern hemisphere outpost , the former segenhoe stud at scone in new south wales , so that was what he did later that year – and such has been his success there ( most notably with the golden slipper winners
the distinct talents and personalities of the sisters of southern halo blend together on its debut effort , “little white dress , ” providing country music fans with an energetic , beautifully performed piece of art . though the title of the track gives the impression that a love song is ahead , the tune is actually about putting the brakes on a relationship before it gets too far too fast . considering the girls are eighteen , sixteen , and fifteen , respectively , the lyrics are age appropriate , while also speaking to anybody who isn’t necessarily ready for that next big step .
were not contaminating the hskjm halo measurements ) . instead , the difference is most likely due to our using a lower normalization for the extragalactic background ( the extragalactic normalization used in
the variation ( or lack thereof ) of the halo emission measure with latitude is also different from that expected for a plane - parallel disk - like halo morphology . in such a morphology , the emission measure is expected to decrease with latitude as 1 / sin | b | . instead , we find the halo emission measure to weakly increase with latitude in the north , and to be uncorrelated with latitude in the south ( see table 3 , and figures 5 ( a ) and ( b ) ) . similarly , we previously found that our sxrb oxygen intensity measurements argued against a plane - parallel halo model in the northern galactic hemisphere ( see hs12 , section 4 . 3 . 3 ) .
column densities is unlikely to be responsible for our emission measure measurements not following the trend expected for a disk - like halo morphology . note also that yoshino et al . (
. somewhat surprisingly , increasing the brightness of the extragalactic background from its nominal value generally leads to an increase in the halo surface brightness . this is because increasing the brightness of the extragalactic background causes the soft proton component to decrease in brightness to compensate , and the combination of these effects leads to more flux being attributed to the halo emission ( see section
in the grade two woody stephens handicap at belmont the following month . unfortunately , he failed to progress from this , although he did finish second in a six - furlong listed race at colonial downs the following year . by the end of 2004 , though , he hadn’t really done enough to make him particularly appealing to the american stallion market – but the success of more than ready meant that by 2005 the time was right for another fast son of southern halo to be imported into australia . halo homewrecker was fast , had won three of his 15 starts including one graded stake , and was closely related to several very good horses , so collingrove stud in victoria snapped him up , offering his services to breeders in 2005 for $ 6 , 600 ( inc . gst ) .
it should be noted that our best - fit halo models attribute somewhat less r45 ( 3 / 4 kev ) emission to the galactic halo than kuntz & snowden ' s ( 2000 ) analysis of the rosat all - sky survey . for sight lines on which emission is detected , our best - fit models typically imply observed halo r45 count rates of ( 18–49 ) × 10 −6 counts s −1 arcmin −2 ( median = 27 × 10 −6 counts s −1 arcmin −2 ) . in contrast , kuntz & snowden ( 2000 ) inferred an observed halo r45 count rate of 38 . 6 × 10 −6 counts s −1 arcmin −2 in the vicinity of the northern galactic pole ( their table 2 :
remainder
−
stars
) . however , the uncertainty on the kuntz & snowden ( 2000 ) halo r45 count rate is not stated , so we are unable to determine whether or not this discrepancy is significant .
halo’s 60 plus stakes winners included a string of champions , and his son sunday silence was named us horse of the year in 1989 . other champions sired by him included devil’s bag and glorious song , while his daughter goodbye halo surely rates as one of the best horses never named a champion –she won 11 races , with her 7 gr1 victories including the kentucky oaks .
figure 4 shows maps of the measured halo temperatures and emission measures . from a visual inspection of figures 4 ( a ) and ( c ) , it appears that the halo temperature is in general rather uniform . figures 4 ( b ) and ( d ) , meanwhile , show that there is considerable variation in the emission measure of the halo plasma . in the northern hemisphere , no clear trends are apparent from figure 4 ( b ) ( although see section 4 . 1 ) . from figure 4 ( d ) , it appears that the halo emission measure in the south tends to increase from the outer galaxy ( l = 180° ) to the inner galaxy ( l = 0° ) , a trend which we will confirm in the following section .
we noted in section 4 that the halo emission measure and intrinsic surface brightness vary by an order of magnitude over the sky , while the temperature is fairly uniform ( see figure 3 ) . figures 4 ( b ) and ( d ) show that the halo emission is patchy ( yoshino et al . 2009 ; hs10 ; hskjm ) . such patchiness may favor a stochastic , inhomogeneous energy source , such as sne , as the source of the hot halo ( hskjm ) . however , if accreting extragalactic material fragments as it accretes , it too could lead to patchy emission .
in 1984 , texas oilman tom tatham purchased 25 of the 40 shares in halo ' s syndicate and moved the stallion to kentucky to stand at stone farm . while at stone farm , halo sired sunday silence , the defining horse who will carry on his legacy . sunday silence is known as the
northern dancer of japan
and has become the top sire in history in that country .
to estimate the systematic errors due to our fixing the foreground normalization , we reanalyzed each sight line with a foreground normalization corresponding to an r12 count rate of 610 counts s −1 arcmin −2 ( this is the median of the values in column 10 of table 1 ) . we then used the median differences between the original halo parameters and these new halo parameters to estimate the systematic errors due to our fixing the foreground normalization , yielding ±0 . 046 × 10 6 k and ±0 . 027 dex for the halo temperature and emission measure , respectively . we applied these systematic errors to all sight lines .
halo raced for four years and in 1974 , at age five , won the grade i united nations handicap . he achieved nine wins from 31 starts and earned over a quarter of a million dollars .
of all the numerous high class athletes and sires descended from the great tap root mare almahmoud ( mahmoud ) , few have enjoyed more influence worldwide than the famously evil tempered halo , writes sarah whitelaw .
above , we noted that the presence of the soft proton contamination in the xmm - newton spectra potentially introduces some uncertainty in the normalization of the halo x - ray emission . in general , our halo measurements and those obtained with suzaku ( which does not suffer from soft proton contamination ) are in reasonable agreement . this suggests that , in practice , soft proton contamination is not a major source of bias .
we detected emission from ~ ( 2–3 ) × 10 6 k plasma on 87 of our sight lines ( 79 % ) , with typical emission measures of ( 1 . 4–3 . 0 ) × 10 −3 cm −6 pc , and typical intrinsic 0 . 5–2 . 0 kev surface brightnesses of ( 1 . 1–2 . 3 ) × 10 −12 erg cm −2 s −1 deg −2 ( section 4 ) . the halo emission measure tends to increase from the outer to the inner galaxy in the southern galactic hemisphere ( section 4 . 1 ) . there is some evidence that the halo is hotter and has a larger emission measure in the southern hemisphere than in the north ( section 4 . 2 ) . however , the differences may be partly due to the fact that we are not comparing equivalent regions in both hemispheres . because of the presence of the sco - cen superbubble , we excluded the region toward the inner galaxy in the northern hemisphere but not in the south , and , as noted above , the emission measure increases toward the inner galaxy in the south . in addition , it should be noted that the difference in the median temperature between the hemispheres ( ~ 0 . 2 × 10 6 k ) is less than the typical error on the temperature ( ~ ± 0 . 4 × 10 6 k ) .
the winner of 6 races from 19 starts , snapy halo was an exceptionally fast horse , winning races from 1000m to 1600m in the sort of times that stamp him as a horse of the highest calibre .
swcx emission is also unlikely to be adversely affecting our halo measurements : our observations were selected from hs12 ' s catalog as they were expected to be the least contaminated by swcx emission ( section 2 . 1 ) , and in section 5 . 2 we argued that our choice of foreground model is not seriously biasing our measurements of the halo surface brightness . in this subsection , we consider other potential sources of contamination .
we have presented measurements of the galactic halo ' s x - ray emission on 110 xmm - newton sight lines . this is an approximately fourfold increase in the number of sight lines over the previous largest study of the galactic halo with ccd - resolution x - ray spectra ( hskjm ) . our sample of observations is drawn from an xmm - newton survey of the sxrb ( hs12 ) . we selected these observations as they should be the least contaminated by charge exchange emission from within the solar system . we analyzed the spectra with a standard sxrb model , with components representing the foreground , galactic halo , and extragalactic background emission .
figure 3 . ( a ) halo emission measure and ( b ) intrinsic 0 . 5–2 . 0 kev halo surface brightness against halo temperature , from our spectral modeling . black : the temperature was free to vary , and is well constrained . gray : the temperature was free to vary , but is poorly constrained ( combined statistical and systematic confidence interval spans more than 4 × 10 6 k ) . red : the temperature was fixed at t = 2 . 1 × 10 6 k ( see section 3 . 1 . 2 ) . the red triangles indicate upper limits on the emission measures and surface brightnesses . note that to avoid clutter , the red data points have been randomly displaced by small amounts in the horizontal direction from t = 2 . 1 × 10 6 k . top panel : histogram of halo temperatures . the sight lines on which the temperature was fixed have been omitted . side panels : histograms of halo emission measures ( upper panel ) and intrinsic surface brightnesses ( lower panel ) . black : detections ; red : upper limits .
halo was no northern dancer as a stallion , but he developed into a terrific sire , with six champions and seven grade 1 winners among his 63 stakes winners from 749 foals ( 8 . 4 percent ) .
in summary , there is some evidence that the halo temperature and emission measure tend to be somewhat higher in the south than in the north . however , these differences may in part be due to the fact that we do not have data from equivalent regions of the halo in the two hemispheres , as the region toward the inner galaxy is excluded in the north ( because of the presence of the sco - cen superbubble ) .
henley et al . ( 2010 , hereafter hskjm ) tested models of the hot halo gas using a sample of 26 sxrb spectra extracted from archival xmm - newton observations between l = 120° and 240° ( henley & shelton 2010 , hereafter hs10 ) . they compared the observed x - ray temperatures and emission measures of the hot halo with the distributions expected from different physical models . hskjm ' s analysis favored fountains of hot gas ( joung & mac low 2006 ) as a major , possibly dominant , contributor to the halo x - ray emission in the xmm - newton band over extraplanar sn remnants ( shelton 2006 ) . however , in the absence of x - ray surface brightness predictions from disk galaxy formation models , they were unable to rule out the possibility that an extended halo of accreted material also contributed to the observed emission ( crain et al . 2010 ) .
yoshino et al . ( 2009 ) did find that the halo emission measure decreased with latitude . however , the decrease with latitude is steeper than that expected for a plane - parallel model ( see their figure 7 ; em × sin | b | is expected to be constant for a plane - parallel model ) . note also that the yoshino et al . ( 2009 ) data set contains far fewer sight lines than ours . the fact that our halo emission measures do not decrease with increasing latitude , contrary to what is expected for a disk - like halo morphology , and contrary to the yoshino et al . ( 2009 ) suzaku results , is unlikely to be due to soft proton contamination ( a problem from which suzaku does not suffer ) . we argued in sections 5 . 1 and 5 . 3 that such contamination does not seriously bias our halo emission measures .


beerichthys ingens is an extinct prehistoric bony fish that was a member of the ypresian london clay fauna of lower eocene england .

it is known only from a series of incomplete skulls .

when originally described in 1966 , b. ingens was placed in a monotypic family , " beerichthyidae , " within iniomi .

later , more ( also incomplete ) skulls were studied by colin patterson , who determined that the fish was a louvar .

beerichthys

this is the place for beerichthys definition . you find here beerichthys meaning , synonyms of beerichthys and images for beerichthys copyright 2017 © urltoken
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reconstruction of the extinct louvar , beerichthys ingens , from the ypresian - aged london clay fauna .
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full reference : r . a . stirton . 1953 . vertebrate paleontology and continental stratigraphy in colombia . geological society of america bulletin 64 : 603 - 622
parent taxon : percomorpharia according to r . betancur - r et al . 2013
see also bannikov 2014 , bannikov and carnevale 2009 , böhme 2010 , carnevale et al . 2011 , carnevale et al . 2003 , cvancara and hoganson 1993 , day 2002 , estes 1964 , fierstine 1998 , fierstine 1999 , fierstine 2001 , fierstine 2005 , fierstine and starnes 2005 , friedman and johnson 2005 , gottfried et al . 2012 , long 2011 , malabarba et al . 2006 , murray and attia 2004 , nelson 2006 , nolf and dockery 1990 , purdy et al . 2001 , sepkoski 2002 , shoshani et al . 1989 , thurmond and jones 1981 and weems 1999
natural history museum ( 2014 ) . dataset : collection specimens . resource : specimens . natural history museum data portal ( data . nhm . ac . uk ) . urltoken
an open source project by the natural history museum ' s biodiversity informatics group .
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