the arizona night lizard ( xantusia arizonae ) is a small smooth-skinned gray-brown lizard with dark spots that sometimes form partial lines down the back .

the lizard has a slightly flattened head .

the scales of the underside and tail are larger than those of the upper side .

the lizard grows to a length of 6 to 10 cm .

despite its name , the arizona night lizard is primarily active during the day .

the lizard 's range extends across west-central arizona .

it is usually found in rock crevices or under plant debris .

its diet consists of insects and spiders .

the young of the lizard are born live , usually one or two around august or september .

as the lizard tends not to move about and generally avoids humans , not much is known about it .

arizona night lizard

arizona night lizard <EOT> x . henshawi - granite night lizard x . gracilis - sandstone night lizard x . vigilis - desert night lizard x . r . reticulata - san clemente night lizard

x . henshawi - granite night lizard x . gracilis - sandstone night lizard x . sierrae - sierra night lizard x . r . reticulata - san clemente night lizard x . wigginsi - baja california night lizard

welcome to our desert night lizard webpage for owners and desert night lizard enthusiasts . desert night lizard information - it is a secretive lizard of arid and semi - arid locales . more

arizona night lizard by lambert m . surhone , mariam t . tennoe , susan f . henssonow

arizona night lizard ( xantusia arizonae ) arizona | united states of america , ( usa or u . s . a . ) | pinterest | lizards and reptiles

the desert night lizard xantusia vigilis is a night lizard native to southern california east of the sierras and san gabriel mountains into baja california , southern nevada , southwestern utah and extreme western arizona . more

the desert night lizard , xantusia vigilis , is a night lizard native to southern california east of the sierras and san gabriel mountains into baja california , southern nevada , southwestern utah and extreme western arizona .

usa ( w / c arizona ) type locality : yarnell , yavapai county , arizona .

this desert night lizard is diligently looking for food . page 1 subscribe to the lizard lounge rss feed subscribe bookmark and share more

a funny thing about me is that i love to be out and about during the day even though i am called the arizona night lizard .

the desert night lizard is rarely found outside cover . feeding ecology and diet the desert night lizard is insectivorous , feeding primarily on ants and beetles within the confines of yucca logs and agaves . more

the durango night lizard is a diminutive lizard found in the mexican state of durango . it is usually found in niches of agave and yucca plants .

hi , i ' m the arizona night lizard or sometimes i am called xantusia arizonae . i am commonly found in yavapai county in arizona . i love to explore rocky terrain and hide under boulders or dead dry plants .

goldberg , stephen r . and robert l . bezy . 2014 . xantusia arizonae ( arizona night lizard ) reproduction . herpetological review 45 ( 3 ) : 508 - 509

the desert night lizard feeds on ants , flies , beetles , a variety of other insects , and spiders .

bezy , r . l . 1967 . variation , distribution , and taxonomic status of the arizona night lizard ( xantusia arizonae ) . copeia 1967 ( 3 ) : 653 - 661 - get paper here

some of the endemic reptiles are the southern alligator lizard ( elgaria multicarinata ) and the yucca night lizard ( xantusia vigilis ) . other reptilian taxa found in the sierra de la laguna pine - oak forests include the baja california rock lizard ( petrosaurus thalassinus ) , baja california rattlesnake ( crotalus enyo ) and the baja california brush lizard ( urosaurus nigricaudus ) .

bezy , r . l . , 2005 . the night lizards ( xantusia ) of arizona . sonoran herpetologist . 18 ( 2 ) 14 - 19 .

the vertical pupil of desert night lizards , like cat ' s eyes , give them away as creatures of the night and dark places . night lizards are live - bearing , with one to three young per brood . more

the desert night lizard is classified as least concern . does not qualify for a more at risk category . widespread and abundant taxa are included in this category .

bezy , r . l . 2005 . the night lizards ( xantusia ) of arizona . sonoran herpetologist 18 ( 2 ) : 14 - 19 . - get paper here

the desert night lizard is small ( maximum snout - vent length , 1 . 5 in ) and has vertically elliptical pupils lacking eyelids . the lizard is covered with small , granular dorsal scales and 12 longitudinal rows of ventral scales . more

desert night lizard elsewhere on the web * wikipedia edit and show details add or delete facts , download data in json or rdf formats , and explore topic metadata . more

nabhan , gary p . gathering the desert . tucson : university of arizona press , 1985 .

desert night lizard xantusia vigilis description : a small ( up to 57 mm or 2 . 25 " from snout to vent ) , soft - skinned lizard with small , dark spots or flecks on a light tan , gray - brown , olive gray , or dark gray background . more

comments : inactive in cold temperatures and extreme heat . may be active at night during the summer .

hanson , roseann beggy and jonathan hanson . southern arizona nature almanac . boulder : pruett publishing co , 1996 .

like all night lizards , the desert night lizard is viviparous , giving birth to live young and producing 1 to 3 young from august to december . the desert night lizard attains a snout - to - vent length ( svl ) of 1 . 5 to 2 . 75 in ( 3 . 8 to 7 . 0 cm ) with a tail roughly the same length . the lizard ' s coloring is usually gray , yellow - brownish , or olive . despite their name , night lizards are active during the day . they are known to easily to change their color , from light olive ( usually during the evening ) to dark brown during the day . it is a good climber and usually eats termites , small insects , spiders and other arthropods .

the night lizards , genus xantusia , have small granular scales on soft skin . xantusia henshawi is shown here .

helminths of night lizards in the genus xantusia ( squamata : xantusiidae ) and the effects of host eco . . .

the desert night lizard is from the order squamata . species from this order are amphisbaenians , lizards or snakes . there are over 6 , 000 living species belonging to the squamata order - it is the largest order of all reptiles . more

a view of some desert night lizards , discovered underneath dead joshua tree branches in the desert , close up and in motion .

the tail breaks off easily and continues wriggling to distract would - be predators long enough for the lizard to run away .

papenfuss , t . j . , macey , j . r . & schulte ii , j . a . 2001 . a new lizard in the genus xantusia from arizona . scientific papers of the natural history museum , university of kansas ( 23 ) : 1 - 9

several subspecies of xantusia vigilis are traditionally recognized , including two in california - x . v . vigilis , and x . v . sierrae . using nuclear dna studies , leavitt et al , 2007 , provide support for the recognition of new species within the x . vigilis complex , including x . wigginsi in california , but they continue to recognize the subspecies x . v . vigilis and x . v . sierrae . in addition , they identify several major clades , four of which occur in california - x . vigilis , x . wigginsi ( now a full species ) , a yucca valley clade , and a san jacinto clade . the 2008 society for the study of amphibians and reptiles standard names list uses x . vigilis based on sinclair et . al ( 2004 , am . nat . 164 : 396 - 141 ) . alternate and previous names ( synonyms ) xantusia vigilis vigilis - yucca night lizard ( stebbins 2003 ) xantusia vigilis vigilis - common night lizard ( stebbins 1985 ) xantusia vigilis vigilis - desert night lizard ( stebbins 1966 ) xantusia vigilis - yucca night lizard ( stebbins 1954 )

the detached tail of a desert night lizard wriggles on the ground . ( it kept wriggling for almost 4 minutes . ) many species of lizards release their tail when they want to escape from a potential predator . the tail then continues to wriggle like a living creature . more

bowers , janice e . a full life in a small place and other essays from a desert garden . tucson , university of arizona press , 1993 .

the following status listings are copied from the april 2018 special animals list and the 2017 endangered and threatened animals list , both of which are published by the california department of fish and wildlife . if no status is listed here , the animal is not included on either cdfw list . this most likely indicates that there are no serious conservation concerns for the animal . to find out more about an animal ' s status , you can go to the natureserve and iucn websites to check their rankings . check here to see the most current complete lists . formerly listed as the subspecies xantusia vigilis sierrae - sierra night lizard , this lizard is now listed as the full species xantusia sierrae - sierra night lizard .

northwestern border , up the western grand canyon to the vicinity of powell plateau , and down into several mountain ranges in southwestern arizona . it occurs at elevations ranging from about 150 m ( 500 ' ) in southwestern arizona to nearly 2 , 000 m ( 7 , 000 ' ) on the peaks of our northwestern ranges .

this adult lizard dropped its tail as a defesive measure . ( you can see the tail wriggling after it was dropped off in the video below . )

the detached tail of a desert night lizard wriggles on the ground . ( it kept wriggling for almost 4 minutes . ) many species of lizards release their tail when they want to escape from a potential predator . the tail then continues to wriggle like a living creature . the aim is to momentarily distract the predator away from the lizard ' s vulnerable body , allowing it to escape , while the predator is left holding or trying to catch the expendable tail . this tail dropping is called " autotomy . " losing the tail does not seriously harm the lizard , and may save its life , but the loss of a tail might have a negative effect on the lizard ' s social standing . dropped tails do grow back , but these regenerated tails are often not as long or as perfect as the original .

due to its small range , the sierra night lizard is very suceptible to any habitat alteration . this lizard needs exfoliated and fissured granite outcrops to survive . it takes thousands of years for this exfoliation and fissuring to occur , so this habitat will not be replaced for many centuries . when flakes and slabs are torn off rock outcrops by someone searching for this lizard or other reptiles , the habitat is irreparably damaged . such rock destruction is illegal in california : " it is unlawful to use any method or means of collecting that involves breaking apart of rocks , granite flakes , logs or other shelters in or under which reptiles may be found . " ( 2007 regulations 5 . 60 . 4 . ) however , this does not protect the lizard from other sources of rock destruction including human development of its habitat .

leavitt , dean h . ; robert l . bezy , keith a . crandall and jack w . sites jr 2007 . multi - locus dna sequence data reveal a history of deep cryptic vicariance and habitat - driven convergence in the desert night lizard xantusia vigilis species complex ( squamata : xantusiidae ) . molecular ecology 16 : 4455–4481 - get paper here

there is a smaller group of annual species that grow only in response to summer rains . annual devil’s claw ( proboscidea parviflora ) and arizona poppy ( kallstroemia grandiflora ) are among the few showy ones .

little is known about this lizard ' s reproduction . related california xantusiids breed in late spring and the young are born live , 1 - 3 per brood , from august to october .

jones , k . b . ; abbas , d . r . & bergstedt , t . 1981 . herpetological records from central and northeastern arizona . herpetological review 12 ( 1 ) : 16 - get paper here

is found in several mountain ranges within sonoran desertscrub . it inhabits rugged slopes and boulder fields and shelters under dead plants such as agave , yucca , and prickly pear and , in northwestern arizona , in rock crevices .

a small thin lizard with soft skin with fine granular scales on most of the body , a head covered with large plates , lidless eyes with vertical pupils , a gular fold , and a detachable tail . the head and body tend to be flattened , an adaptation to this lizard ' s rock - crevice habitat . dorsal scales in 40 - 44 lengthwise rows at mid - body .

klauber , laurence m . 1931 . a new species of xantusia from arizona , with a synopsis of the genus . transactions of the san diego society of natural history 7 ( 1 ) : 1 - 16 - get paper here

little is known about the diet of this lizard . presumably it is similar to other related california xantusiids , which eat small invertebrates such as ants , termites , beetles , caterpillars , crickets , and spiders .

i am commonly found in the yavapai county of arizona . i love rocky terrain with big boulders to build my home under . i also can find shelter in small crevices between rocks or under dead plants like a prickly pear or yucca .

unusually for a lizard it forms family social groups with a father - mother pair and offspring , which may delay dispersing for years . the young are capable of feeding themselves but will huddle together with their relatives .

this species is endemic to the southwestern united states . the range includes only a small area in arizona ; a recent taxonomic change that recognized x . arizonae as a distinct species and that described a new species ( x . bezyi ) in arizona ( papenfuss et al . 2001 ) did not precisely define the range of x . arizonae . a phylogeographic analysis of xantusia by sinclair et al . ( 2004 ) determined that x . arizonae has a smaller range than depicted by stebbins ( 2003 ) .

when frightened , runs away quickly and dashes under cover . the tail breaks off easily and continues wriggling to distract would - be predators as the lizard runs away as you can see in this video . this does not hurt the lizard , although it might suffer from the stress of attempted predation , the loss of fatty energy that is stored in the tail , and have difficulties finding a mate during breeding season due to a less healthy appearance .

the range extends from southern utah , western and central arizona , southern nevada , and southern california south to southwestern sonora and throughout most of baja california , mexico ( grismer 2002 , stebbins 2003 ) . some arizona populations formerly included in this species are now regarded as x . arizonae and x . bezyi ( papenfuss et al . 2001 ) . a population in northern durango is now recognized as x . extorrus . see feldman et al . ( 2003 ) for discussion of distribution in the southern sierra nevada region of california .

in the spring it is time for me to think about having new little night lizards . i will mate in the spring and then in the late summer i will have one or maybe two babies . wow , they can keep me busy !

vicario , saverio ; adalgisa caccone and jacques gauthier 2003 . xantusiid " night " lizards : a puzzling phylogenetic problem revisited using likelihood - based bayesian methods on mtdna sequences . molecular phylogenetics and evolution 26 ( 2 ) : 243 - 261 - get paper here

desert night lizards have a lot of personality , and stalk their insect prey with a cat - like twitching tail . take care if you must handle them , for they may try to escape your grasp , and can be very wiggly . . . more

p rotection stored water in an arid environment requires protection from thirsty animals . most succulent plants are spiny , bitter , or toxic , and often all three . some unarmed , nontoxic species are restricted to inaccessible locations . smooth prickly pear ( opuntia phaeacantha var . laevis ) and live - forever ( dudleya spp . ) grow on vertical cliffs or within the canopies of armored plants . still others rely on camouflage ; arizona night - blooming cereus ( peniocereus greggii ) closely resembles the dry stems of the shrubs in which it grows .

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first locality records for mono county were published in 2016 ( herpetological review 47 ( 3 ) , 2016 ) extending the range to the northernmost localities for the species west of utah . the range extends east of california into nevada , arizona , and extreme southwest utah and south barely into mexico .

i am a petite lizard that can fit in the palm of your hand . i spend my days sunbathing on rocks very close to dwelling to keep warm throughout the day . i will hide under rocks to keep my safe from predators that want to eat me .

a small thin lizard with soft skin with fine granular scales on most of the body , a head covered with large plates , lidless eyes with vertical pupils , a gular fold , and a detachable tail . dorsal scales in 30 - 50 lengthwise rows at mid - body .

it is a secretive lizard of arid and semi - arid locales . during the day it may be found under fallen debris of desert plants and in rock crevices . it is usually associated with varieties of yucca such as the joshua tree , spanish dagger , and spanish bayonet .

xantusia vigilis - baird , 1858 - proc . acad . nat . sci . philadelphia , vol . 10 , p . 255 xantusia vigilis sierrae - bezy , 1967 - journ . arizona acad . sci . , vol . 4 , p . 163 from original description citations for the reptiles and amphibians of north america © ellin beltz

continent : middle - america north - america distribution : usa ( s california , s nevada , s utah , w / c arizona ) , mexico ( e durango , baja california ) extorris : durango , zacatecas gilberti : mexico ( baja california sur ) ; type locality : san francisquito , sierra laguna , lower california . type locality : fort tejon , california .

this lizard lives in arid and semi - arid habitats among fallen leaves and trunks of yuccas , agaves , cacti , and other large plants , also in crevices of rock outcroppings and under logs and bark of foothill pines ; it ranges locally into pinyon - juniper , sagebrush - blackbrush , and chaparral - oak ( stebbins 2003 ) .

comments : this lizard lives in arid and semiarid habitats among fallen leaves and trunks of yuccas , agaves , cacti , and other large plants , also in crevices of rock outcroppings and under logs and bark of foothill pines ; it ranges locally into pinyon - juniper , sagebrush - blackbrush , and chaparral - oak ( stebbins 2003 ) .

global range : ( 20 , 000 - 2 , 500 , 000 square km ( about 8000 - 1 , 000 , 000 square miles ) ) the range extends from southern utah , western arizona , southern nevada , and southern california south to southwestern sonora and baja california ( grismer 2002 , stebbins 2003 ) . some arizona populations formerly included in this species are now regarded as x . arizonae , x . bezyi , and x . wigginsi ( papenfuss et al . 2001 , sinclair et al . 2004 , leavitt et al . 2007 ) . a population in northern durango is of uncertain taxonomic status ( bezy and flores villela 1999 ) . see feldman et al . ( 2003 , herpetol . rev . 34 : 167 ) for discussion of distribution in the southern sierra nevada region of california .

little is known about this lizard . presumably it is similar to other california xantusiids , being diurnal ( contrary to the common name ) and crepuscular . it is certainly secretive - spending most of its life undercover , and a specialized rock - crevice dweller , living under flakes of granite on rocky outcrops and in rock crevices . it is not typically active on the surface away from cover .

noonan , brice p . ; jennifer b . pramuk , robert l . bezy , elizabeth a . sinclair , kevin de queiroz , jack w . sites jr . 2013 . phylogenetic relationships within the lizard clade xantusiidae : using trees and divergence times to address evolutionary questions at multiple levels . molecular phylogenetics and evolution , volume 69 , issue 1 , october 2013 , pages 109–122 - get paper here

water scarcity is the most important—but not the only—environmental challenge to desert organisms . the aridity allows the sun to shine unfiltered through the clear atmosphere continuously from sunrise to sunset . this intense solar radiation produces very high summer temperatures which are lethal to nonadapted plants . at night much of the accumulated heat radiates through the same clear atmosphere and the temperature drops dramatically . daily fluctuations of 40°f ( 22°c ) are not uncommon when the humidity is very low .

i am a petite lizard that can fit in the palm of your hand . i have little rectangular scales that cover my body . i have small blotches on soft light olive or yellow skin . i enjoy sunbathing on the rocks very close to my shelter to keep warm during the day . my diet includes a variety of spiders and insects . in the late summer i will have one or two babies to keep me busy .

described by bezy in 1967 . several subspecies of xantusia vigilis are traditionally recognized , including two in california - x . v . vigilis x . v . sierrae using nuclear dna studies , leavitt et al , 2007 , provide support for the recognition of new species within the x . vigilis complex , including x . wigginsi in california , but they continue to recognize the subspecies x . v . vigilis and x . v . sierrae . in addition , they identify several major clades , four of which occur in california - x . vigilis , x . wigginsi ( now a full species ) , a yucca valley clade , and a san jacinto clade . the 2008 society for the study of amphibians and reptiles standard names list uses x . sierrae based on sinclair et . al ( 2004 , am . nat . 164 : 396 - 141 ) . alternate and previous names ( synonyms ) xantusia vigilis sierrae - sierra night lizard ( stebbins 1985 , 2003 )

many succulents possess a water - efficient variant of photosynthesis called cam , an acronym for crassulacean acid metabolism . the first word refers to the stonecrop family ( crassulaceae ) in which the phenomenon was first discovered . ( dudleya is in this family , as are hen - and - chickens and jade plant . ) cam plants open their stomates for gas exchange at night and store carbon dioxide in the form of an organic acid . during the day the stomates are closed and the plants are nearly completely sealed against water loss ; photosynthesis is conducted using the stored carbon dioxide . at night the temperatures are lower and humidity higher than during the day , so less water is lost through transpiration . plants using cam lose about one - tenth as much water per unit of carbohydrate synthesized as do those using standard c3 photosynthesis . but there is a trade - off : the overall rate of photosynthesis is slower , so cam plants grow more slowly than most c3 plants . ( an additional limitation is the reduced photosynthetic surface area of most succulents compared with “ordinary” plants . )

wildflower spectacles like the one described above are rare events . mass germination and prolific growth depend on rains that are both earlier and more plentiful than normal . the dazzling displays featured in photographic journals and on postcards occur about once a decade in a given place . in the six decades between 1940 and 1998 there have been only four documented drop - everything - and - go - see - it displays in southern arizona : 1941 , 1978 , 1979 , and 1998 . during that period only the displays of 1978 and 1998 were widespread throughout both the sonoran and mohave deserts .

winter annuals provide most of the color for our famous wildflower shows . woody perennials and succulents can be individually beautiful , but their adaptive strategies require them to be widely - spaced , so they usually don’t create masses of color . a couple of exceptions are brittlebush when it occurs in pure stands , and exten sive woodlands of foothill palo verde ( cercidium microphyllum ) . the most common of the showy winter annuals that contribute to these displays in southern arizona are mexican gold poppy ( eschscholtzia mexicana ) , lupine ( lupinus sparsiflorus ) , and owl - clover ( castilleja exserta , formerly orthocarpus purpurascens ) .

i conducted a wildlife survey in the lower colorado river valley in the 1970s . the site had received almost no biologically effective rainfall for three years . creosote bushes were almost the only plants present ; they were widely - spaced and had shed most of their leaves . yet in the kilometer ( 6 / 10 mile ) long by fifty meter ( 150 foot ) wide transect i trapped one pocket mouse overnight , and in the morning observed a whiptail lizard , a rock wren , and two black - throated sparrows . these are all resident species ; not transitory migrants . what were they living on ?

t rees and large shrubs are fairly dependable bloomers , though flowers will be sparse in dry years . creosote bush ( larrea tridentata ) and whitethorn acacia ( acacia constricta , shown here ) both bloom mainly in spring and sometimes again in summer . blue palo verde ( cercidium floridum ) turns bright yellow in late april , followed two weeks later by the much more abundant but paler yellow foothills palo verde ( c . microphyllum ) . desert ironwood trees ( olneya tesota ) bloom heavily about every other year with masses of lavender flowers , usually in late may . the abundant ocotillo reliably produces spikes of red flowers throughout april . these species bloom about two weeks earlier in western arizona .

the spring flowering season in the arizona upland subdivision spans from mid february to mid june with a peak from mid march to late april depending on rainfall and temperatures during the growing season . in the warmest areas of the lower colorado river valley subdivision it is normally a couple of weeks earlier , though it sometimes starts as early as november . the different life forms which dominate at different times vary in their showyness and reliability . the early - blooming winter annuals can create an incredible display , but do so only rarely . later - blooming species bloom more dependably , but mostly not in great masses of color . the progression of spring bloom described below is for average years near tucson . it may be three weeks earlier or later depending on weather , elevation , and latitude .

papenfuss et al . ( 2001 ) examined genetic and morphological variation of xantusia and reviewed allozyme data from bezy and sites ( 1987 ) . they concluded that three species are represented in arizona : xantusia vigilis , a yucca - dwelling species ; x . arizonae , a granite - adapted species ; and x . bezyi ( newly described ) , another granite - associated species . crother et al . ( 2003 ) listed x . bezyi and x . vigilis as distinct species but included arizonae as a subspecies of x . vigilis . stebbins ( 2003 ) mentioned the taxonomic changes proposed by papenfuss et al . but did not adopt them . sinclair et al . ( 2004 ) examined phylogeographic patterns in xantusia and concluded that x . bezyi is a valid species ( but more widely distributed than previously known ) and that x . arizonae has a smaller range than previously understood .

another diversity - promoting phenomenon is temporal niche separation : the mix of species at the same location changes from year to year . seeds of the various species have different germination requirements . the time of the season ( which influences temperature ) and quantity of the first germination - triggering rain determines which species will dominate , or even be present at all in that year . of the three most common annuals of southern arizona listed above , any one may occur in a nearly pure stand on a given hillside in different years , and occasionally all three are nearly equally abundant . this interpretation of the cause of these year - to - year variations is a hypothesis based on decades of empirical observation . much more research is needed to discover the ecological requirements of most species of desert annuals . and of course the sonoran desert’s two rainy seasons provide two major temporal niches . summer and winter annuals almost never overlap .

the annual habit is a very successful strategy for warm - arid climates . there are no annual plants in the polar regions or the wet tropics . in the polar zones the growing season is too short to complete a life cycle . in both habitats the intense competition for suitable growing sites favors longevity . ( once you’ve got it , you should hang onto it . ) annuals become common only in communities that have dry seasons , where the perennials are widely spaced because they must command a large soil area to survive the drier years . in the occasional wetter years , both open space and moisture are available to be exploited by plants that can do so rapidly . the more arid the habitat , the greater the proportion of annual species in north america . ( the percentage decreases in the extremely arid parts of the saharan - arabian region . ) half of the sonoran desert’s flora is comprised of annual species . in the driest habitats , such as the sandy flats near yuma , arizona , up to ninety percent of the plants are annuals .

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justification : listed as least concern because it is unlikely to be declining fast enough to qualify for listing in a more threatened category ( its populations are probably stable ) .

this species is represented by at least several distinct occuurrences or subpopulations . sinclair et al . ( 2004 ) mapped six collection sites . the total adult population size is unknown . population trends have not been documented but presumably are relatively stable .

this species is found under exfoliating rock in granite outcrops ( pappenfuss et al . 2001 ) .

the level of protection is uncertain , but the rocky habitat is not readily convertible to destructive human uses . better information is needed on the current conservation status of this species .

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daytime activity takes place under the cover of rocks or plant debris . crevice - dwelling individuals thermoregulate by basking near the sun - warmed edge of the crevice or under sun - warmed rocks .

live bearing . mating presumably takes place in spring and a brood of 1–3 young is born in summer .

stebbins , r . c . 2003 . a field guide to western reptiles and amphibians , third edition . houghton mifflin company , boston , ma .

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my favorite things to eat are spiders and insects . my diet includes juicy beetles , ants and flies if i can catch them . yum ! ! !

i have small blotches that cover my body like tiny freckles . my skin is soft to the touch and is usually a light olive or yellow background . this helps me to blend in with the rocks and helps me hide from predators . i can grow anywhere between 6 and 10 cm in length . my head is slightly flat and wide and it almost looks like a plate . my eyes do not have lids and my pupils are vertical .

you did a great job working on this lesson today . i hope that you had a wonderful time learning about me . so , let’s have fun doing an activity about me . you can work with your friends , parents or teacher . i want you to create a clay model of me . try to include as many of my features that you learned about in the model . after you let your model dry you may paint it too . have fun ! ! !

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xantusia arizonae klauber 1931 xantusia arizonae — klauber 1938 xantusia vigilis arizonae — bezy 1967 xantusia vigilis arizonae — stebbins 1985 xantusia arizonae — papenfuss et al . 2001 xantusia arizonae — vicario et al . 2003 xantusia arizonae — sinclair et al . 2004 xantusia arizonae — leavitt et al . 2007

crother , b . i . ( ed . ) 2012 . standard common and current scientific names for north american amphibians , turtles , reptiles , and crocodilians , seventh edition . herpetological circular 39 : 1 - 92

jones , l . l . & lovich , r . e . 2009 . lizards of the american southwest . a photographic field guide . rio nuevo publishers , tucson , az , 568 pp . [ review in reptilia 86 : 84 ] - get paper here

klauber , laurence m . 1938 . notes from a herpetological diary , i . copeia 1938 ( 4 ) : 191 - 197 - get paper here

klauber , laurence m . 1940 . notes from a herpetological diary , ii . copeia 1940 ( 1 ) : 15 - 18 - get paper here

sinclair , elizabeth a . ; robert l . bezy ; kathryn bolles ; jose l . camarillo r . ; keith a . crandall and < br / > jack w . sites , jr . 2004 . testing species boundaries in an ancient species complex with deep phylogeographic history : genus xantusia ( squamata : xantusiidae ) . american naturalist 164 ( 3 ) : 396 - 414 - get paper here

stebbins , r . c . 1985 . a field guide to western reptiles and amphibians , 2nd ed . houghton mifflin , boston

this database is maintained by peter uetz ( database content ) and jakob hallermann , zoological museum hamburg ( new species and updates ) .

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for additional information on this species , please see the following volumes and pages in the sonoran herpetologist : 2003 apr : 26 - 29 ; 2005 february : 14 - 19 ; 2008 may : 50 - 53 ; 2009 dec : 132 - 133 .

adult , scissors crossing , san diego county © jeff nordland ( xantusia wigginsi has been found at scissors crossing and since appearance alone cannot determine the species , so this could be x . wigginsi . )

1 . 5 - 2 . 75 inches long from snout to vent ( 3 . 8 - 7 cm ) . ( stebbins 2003 )

color is olive , grayish , or brown with light brown or black spots , sometimes forming narrow stripes . a narrow beige stripe , edged in black , extends from the eye to the shoulder . the underside is whitish and made up of large square scales , usually in 12 rows .

eats small invertebrates inhabiting the decaying vegetation in which it lives including ants , termites , beetles , caterpillars , crickets , and spiders .

breeds in late spring . bears live young , 1 - 3 per brood , from august to october .

utilizes a variety of habitats in arid and semi - arid areas , including those grown with joshua tree , desert scrub , pinon - juniper , basin sagebrush , chaparral , pine - oak woodland , and yucca .

found on the desert slopes of the peninsular ranges , throughout the mojave desert , along the east slopes of the sierra nevada mountains north to west of bishop , the inyo and panamint mountains , the greenhorn and piute mountains and upper kern river canyon in the southern sierra nevada mountains , the coastal side of the mountains in upper santa clara river drainage , the headwaters of big tujunga and the upper san gabriel river drainage , and the inner coast ranges at the panoche hills and pinnacles national monument .

from sea level to 9 , 300 ft . ( 2 , 830 m ) . ( stebbins 2003 )

xantusia vigilis - baird , 1858 - proc . acad . nat . sci . philadelphia , vol . 10 , p . 255 from original description citations for the reptiles and amphibians of north america © ellin beltz

the following status listings are copied from the april 2018 special animals list and the 2017 endangered and threatened animals list , both of which are published by the california department of fish and wildlife . if no status is listed here , the animal is not included on either cdfw list . this most likely indicates that there are no serious conservation concerns for the animal . to find out more about an animal ' s status , you can go to the natureserve and iucn websites to check their rankings . check here to see the most current complete lists . this animal is not included on the special animals list , which indicates that there are no significant conservation concerns for it in california .

color is olive , grayish , or brown with light brown or black spots which tend to be interconnected , forming a dark net - like pattern . a broad and conspicuous stripe extends from the eye to the shoulder . the underside is whitish and made up of large square scales , usually in 12 rows .

inhabits rocky outcrops around granite station in open grassland with scattered oak woodland and low shrubs .

endemic to california . found only in the southwestern foothills of the sierra nevada mountains along the western edge of the greenhorn mountains around granite station , in kern co .

california department of fish and wildlife stebbins , robert c . , and mcginnis , samuel m . field guide to amphibians and reptiles of california : revised edition ( california natural history guides ) university of california press , 2012 . stebbins , robert c . california amphibians and reptiles . the university of california press , 1972 . stebbins , robert c . a field guide to western reptiles and amphibians . 3rd edition . houghton mifflin company , 2003 . behler , john l . , and f . wayne king . the audubon society field guide to north american reptiles and amphibians . alfred a . knopf , 1992 . powell , robert . , joseph t . collins , and errol d . hooper jr . a key to amphibians and reptiles of the continental united states and canada . the university press of kansas , 1998 . bartlett , r . d . & patricia p . bartlett . guide and reference to the turtles and lizards of western north america ( north of mexico ) and hawaii . university press of florida , 2009 . jones , lawrence , rob lovich , editors . lizards of the american southwest : a photographic field guide . rio nuevo publishers , 2009 . smith , hobart m . handbook of lizards , lizards of the united states and of canada . cornell university press , 1946 .

secure—common ; widespread and abundant . [ this ranking apparently refers to the full species that this taxa formerly belonged to , xantusia vigilis , and indicates that the status of the species is secure , not the subspecies . ]

critically imperiled in the state because of extreme rarity ( often 5 or fewer populations ) orbecause of factor ( s ) such as very steep declines making it especially vulnerable to extirpation from the state .

syntype : baird , s . f . 1858 . proc . acad . nat . sci . philadelphia . 10 : 254 .

this taxon is found in the sierra de la laguna pine - oak forest , a mountainous ecoregion which rises from the arid baja california sur , creating islands of unique vegetative communities . there are approximately 694 plant species , approximately 85 of which are endemic to this ecoregion . overall species richness is low to moderate , with a total of only 231 vertebrate taxa . the ecoregion is classified in the tropical and subtropical coniferous forests biome . much of the pine - oak association remains intact due to the inaccessibility of the rugged and inaccessible terrain .

the topographical features and geological events that gave rise to this particular region are responsible for the diversity of climates and vegetation in the same area . the highest strata of mountains , situated at 1600 to 2000 metres ( m ) in elevation , are composed of pine - oak forests that transform into oak - pine forests ( 1200 m ) and oak forests ( 800 m ) as elevation decreases . the climate is temperate sub - humid with summer rains and occasional winter rains .

these pine - oak forests constitute the wettest portions in the state of baja california sur ( 760 millimetres of precipitation annually ) . slight variations in climatic conditions make up three different vegetation assemblages in the temperate forest . pine forests at the highest elevations are dominated by pinus cembroides ssp . lagunae , and understory taxa such as muhlenbergia spp . and festuca spp . pine - oak forests dominated by associations of pinus cembroides subsp . lagunae with quercus devia , arbutus peninsularis , and quercus tuberculata , and a variety of trees of smaller stature such as calliandra peninsularis and mimosa tricephala , with associated shrubs to complement the landscape .

only two amphibian taxa are found in the sierra de la laguna pine - oak forests . the red - spotted toad ( anaxyrus punctatus ) is one anuran found here . the widely distributed california chorus frog ( pseudacris cadaverina ) is another resident of the ecoregion . one other anuran , pseudacris regilla , was previously recognized in the ecoregion , but erecent dna analysis has rendered this taxon of unclear distribution .

of the approximately 30 mammalian species of mammals present , one of them ( an endemic bat ) lives only in pine - oak forests . the level of endemism is high , and this is well demonstrated by the proportion of endemic species with respect to total recorded species . more than ten percent of the mammalian species found at sierra de la laguna are endemic . one notable mammal found along the far west coast , including california and baja , is the ornate shrew ( sorex ornatus ) . there are several threatened mammals found in the sierra de la laguna pine - oak forests , including : the mexican long - tongued bat ( choeronycteris mexicana nt ) . the isolation of this region has contributed to the scarcity of predators , and to the poor competitive ability of some animals . rodents and lagomorphs are virtually absent from the region

the avifauna inhabiting these pine - oak forests is important because half of the bird species breeding at sierra de la laguna only utilize pine - oak forests as breeding habitat . the endemic baja pygmy owl ( glaucidium gnoma hoskinsii ) , along with the white - winged dove ( zenaida asiatica ) and golden eagle ( aquila chrysaetos ) are only a few of the avian species found in this ecoregion . other notable birds in this and the gulf of california xeric scrub ecoregion include the xantus ' s hummingbird ( hylocharis xantusii ) and the endangered peninsular yellowthroat ( geothlypis beldingi en ) . .

non - migrant : yes . at least some populations of this species do not make significant seasonal migrations . juvenile dispersal is not considered a migration .

locally migrant : no . no populations of this species make local extended movements ( generally less than 200 km ) at particular times of the year ( e . g . , to breeding or wintering grounds , to hibernation sites ) .

locally migrant : no . no populations of this species make annual migrations of over 200 km .

comments : eats insects ( e . g . , termites , ants , beetles , and flies ) , spiders , and other arthropods ( behler and king 1979 ; stebbins 1985 ) .

note : for many non - migratory species , occurrences are roughly equivalent to populations .

comments : this species is represented by many occurrences or subpopulations ( e . g . , see map in bezy 1982 ) .

comments : total adult population size is unknown but surely exceeds 10 , 000 and probably exceeds 100 , 000 .

breeding occurs may to june ( behler and king 1979 ) . female gives birth to 1 - 3 young / brood , august - october ( stebbins 1985 ) .

hammerson , g . a . , frost , d . r . & santos - barrera , g .

listed as least concern in view of the probably relatively stable extent of occurrence , area of occupancy , number of subpopulations , and population size . no major threats are known .

this species is represented by many occurrences or subpopulations ( e . g . , see map in bezy 1982 ) . the total adult population size is unknown but surely exceeds 10 , 000 and probably exceeds 100 , 000 . no evidence of a significant overall decline has been reported . the species is common in mexico .

no major threats have been identified , but locally the species likely is locally declining where its habitat has been degraded by commercial and residential development .

comments : no major threats have been identified , but locally the species likely is declining where its habitat has been degraded by commerical and residential development .

at least several occurrences are in national parks . other than some general research activities , no direct conservation measures are needed for this species as a whole .

they do not receive any direct care from their parents and older siblings and it is not yet known what the advantages of staying with their parents are .

the baby lizards are well - camouflaged and are not much bigger than a toothpick .

baird sf . 1859 . description of new genera and species of north american lizards in the museum of the smithsonian institution . proc . acad . nat . sci . phildelphia 10 : 253 - 256 . ( xantusia vigilis , new species , p . 255 ) .

behler jl , king fw . 1979 . the audubon society field guide to north american reptiles and amphibians . new york : alfred a . knopf . 743 pp . isbn 0 - 394 - 50824 - 6 . ( xantusia vigilis , pp . 551 - 552 + plate 406 ) .

boulenger ga . 1885 . catalogue of the lizards in the british museum ( natural history ) . second edition . volume ii . . . . xantusiidæ . london : trustees of the british museum ( natural history ) . ( taylor and francis , printers ) . xiii + 497 pp . + plates i - xxiv . ( xantusia vigilis , pp . 327 - 328 ) .

goin cj , goin ob , zug gr . 1978 . introduction to herpetology , third edition . san francisco : w . h . freeman and company . xi + 378 pp . isbn 0 - 7167 - 0020 - 4 . ( xantusia vigilis , pp . 129 , 132 , 148 , 286 ) .

smith hm , brodie ed jr . 1982 . reptiles of north america : a guide to field identification . new york : golden press . 240 pp . isbn 0 - 307 - 13666 - 3 . ( xantusia vigilis , pp . 84 - 85 ) .

stebbins rc . a field guide to western reptiles and amphibians , third edition . the peterson field guide series ® . boston and new york : houghton mifflin company . xiii + 533 pp . isbn 978 - 0 - 395 - 98272 - 3 . ( xantusia vigilis , pp . 307 - 309 + plate 35 + map 76 ) .

gadsden . h . & santos - barrera , g . ( 2007 ) .

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attercopus is an extinct genus of arachnids , containing one species attercopus fimbriunguis , known from a devonian-aged fossil .

it is placed in the extinct order uraraneida , spider-like animals able to produce silk , but which lacked true spinnerets and retained a segmented abdomen bearing a flagellum-like tail resembling that of a whip scorpion .

they are thought to be close to the origins of spiders .

an important early devonian ( about 390 million years ago ) fossil example from gilboa , new york , was originally described as a member of the extinct order trigonotarbida and named gelasinotarbus ? fimbriunguis .

it was later assigned to a new genus attercopus and reinterpreted as the oldest , and most primitive , example of a true spider ( araneae ) .

this hypothesis was based on the supposed presence of unique spider features such as silk-producing spinnerets and the opening of a venom gland on the fang of the chelicera .

further study – based on new fossils from a comparable devonian locality called south mountain – and comparison with other material from the permian of russia , i.e. , of permarachne , indicates that attercopus does not actually have spinnerets .

the feature which looked like a tubular spinneret is actually a folded sheet of cuticle .

it would , however , have produced silk from a series of silk gland openings , or spigots , located across plates on the underside of the abdomen .

the opening for the venom gland is also a misinterpretation .

a segmented tail , or flagellum , also belonged to this animal .

it seems unlikely that attercopus spun webs , but it may have used its silk to wrap eggs , lay draglines or construct burrow walls .

attercopus fimbriunguis is not a spider , but it is probably close to the type of animals which did give rise to modern spiders today .

its name is taken from the english dialect word attercop ( " spider " ) , which came from old english attorcoppa ( " poison-head " ) , from ator ( " poison " ) , itself drawn from the proto-germanic * aitra - ( " poisonous ulcer " ) and kopp - ( " head " ) .

attercopus

attercopus <EOT> attercopus was spider - like ,  but was not a true spider .  attercopus had a segmented tail and silk producing organs ,  but probably only used silk for constructing shelters and wrapping eggs ,  rather than constructing elaborate webs .

in the original description of attercopus , several chelicerae were illustrated and described . in at least one of these specimens ( 329 . 22 . ar9 ; fig . 1 f ) , a hole near the tip of the fang was interpreted as a poison gland pore . revisiting this specimen raises uncertainty because other apparent holes on the same fang appear to be artefacts of preservation and none of the chelicera specimens show this pore clearly . mesothele spiders lack poison glands ( 16 ) , and to infer their existence in attercopus would require their loss and reacquisition ( by opithotheles ) in araneae . because the preponderance of the evidence now suggests that poison glands were also absent in attercopus , it is more parsimonious to assume that they were acquired only once , in the spider suborder opisthothelae , and are synapomorphic for that taxon , not for spiders as a whole .

because of the different preservational styles of attercopus and permarachne , it is not clear whether the apomorphies of attercopus ( palpal femur spinules , fimbriate tarsal claws , lack of emargination at distal joint of leg patella ) are shared by permarachne . it is possible that the flagellum was uniquely derived and not homologous with that of the pedipalp orders . although we do not presently have evidence of any synapomorphies for this lineage , we wish to draw attention to its distinctiveness and so establish the ordinal name uraraneida selden & shear ord . nov . ( etymology : greek oura , tail , and latin , aranea , spider ; included taxa : attercopus and permarachne ) . uraraneida and araneae are distinguished from the pedipalp orders by 2 characters : the naked ( seta - less ) cheliceral fang and the presence of opisthosomal silk glands and spigots . the existence of permarachne alongside mesotheles in the fossil record indicates that uraraneida was a persistent lineage that only became extinct ( if , indeed , it is ) some time after the late permian .

silk production from opisthosomal glands is a defining characteristic of spiders ( araneae ) . silk emerges from spigots ( modified setae ) borne on spinnerets ( modified appendages ) . spigots from attercopus fimbriunguis , from middle devonian ( 386 ma ) strata of gilboa , new york , were described in 1989 as evidence for the oldest spider and the first use of silk by animals . slightly younger ( 374 ma ) material from south mountain , new york , conspecific with a . fimbriunguis , includes spigots and other evidence that elucidate the evolution of early araneae and the origin of spider silk . no known attercopus spigots , including the original specimen , occur on true spinnerets but are arranged along the edges of plates . spinnerets originated from biramous appendages of opisthosomal somites 4 and 5 ; although present in limulus , no other arachnids have opisthosomal appendage homologues on these segments . the spigot arrangement in attercopus shows a primitive state before the reexpression of the dormant genetic mechanism that gave rise to spinnerets in later spiders . enigmatic flagellar structures originally described as arachnida incertae sedis , are shown to be attercopus anal flagella , as found in permarachne , also originally described as a spider . an arachnid order , uraraneida , is erected for a plesion , including these two genera , based on this combination of characters . the inability of uraraneida precisely to control silk weaving suggests its original use as a wrapping , lining , or homing material .

the oldest known silk - producing spigots are from the middle devonian of gilboa , new york ( 1 ) . this specimen ( slide 334 . 1b . ar34 , fig . 1 a ) , was described as a nearly complete , fusiform spinneret , consisting of a single article , bearing ≈20 spigots arrayed along the presumed medial surface but more clustered distally . on the basis of the single , simple spigot type and the lack of tartipores ( vestigial spigots from earlier instars ) , the fossil spinneret was compared most closely with posterior median spinnerets of the primitive spider suborder mesothelae . the distinctiveness of the cuticle enabled us to associate the spinneret with remains previously referred tentatively to a trigonotarbid arachnid ( 2 ) . restudy of this material resulted in a fuller description of the animal as the oldest known spider , attercopus fimbriunguis ( 3 ) . the appendicular morphology of attercopus , but little of the body , is now known in great detail . in this article , morphological information on attercopus is described , which significantly alters these earlier interpretations , and provides insights into the evolution of the spider silk system .

specimen sm 1 . 11 . 3b ( fig . 2 b ) shows overlapping layers of undoubted attercopus cuticle with both small setal and large macrosetal follicles but no silk spigots . slightly darker and lighter bands of cuticle are interpreted , as in sm 1 . 11 . 3a , as plate edges and interplate membrane , respectively . the few macrosetal follicles are interpreted as those present at the posterior edges of plates ( and the largest of these occurs adjacent to a darker plate edge ) . the plates taper and become narrower to one side ; the widest plate is torn along most of its width and laterally , whereas the narrower ones are more complete . setae on the specimen point toward the side of the specimen with narrower plates , and ≈3 plates are present . we interpret this specimen as the posterior end of the opisthosoma where the plates narrow . both tergite and sternite remains could be present on this specimen , but the posteriormost , at least , appears to be a complete ring . the importance of this specimen is that emerging from the posterior end are two annular segments with thickened posterior collars that bear a row of ≈12 prominent setal follicles . these are clearly part of the same flagellar organ found in association , but hitherto not in direct organic connection , with attercopus ( 2 ) . despite the virtually identical cuticle pattern , including slit sensilla , between these flagella and attercopus , we described them as arachnida incertae sedis because no flagella are known from spiders . the evidence provided by specimen sm 1 . 11 . 3b shows unequivocally that attercopus did , indeed , bear a postanal flagellum of at least 12 segments . in two of the attercopus specimens ( e . g . , fig . 1 e ) , a distinctive terminal article appears that is 2–3 times as long as the more proximal articles and densely set with setal sockets .

attercopus fimbriunguis , devonian of south mountain , new york , macerated from matrix with hf and slide - mounted . ( a ) part of opisthosoma with rows of spigots , sm 1 . 11 . 3a . ( b ) two flagellar segments emerging from posterior part of opisthosoma , sm 1 . 11 . 3b . ( scale bars : 0 . 5 mm . )

spiders probably evolved about 400 million years ago from thick - waisted arachnid ancestors that were not long emerged from life in water . the first definite spiders , thin - waisted arachnids with abdominal segmentation and silk producing spinnerets , are known from fossils like attercopus fimbriungus . this spider lived 380 million years ago during the devonian period , more than 150 million years before the dinosaurs .

it seems unlikely that the spigot - bearing plates in attercopus are tergites , and much more probable that they represent ventral plates , because in spiders the spinnerets are invariably ventral . if the ventral plates are appendage - derived , the reactivation of genes ( such as distalless ) that would extend these plates once more into segmented appendages would carry along with them the spigots observed in attercopus to be distributed along the posterior margins of those plates . we suggest that developmental genetic studies to determine the homologies of the ventral plates in the pedipalp orders could provide evidence to resolve this question . further evidence that silk spigots are associated with appendages comes from the recent finding that at least one species of mygalomorph spider has silk spigots on its leg tarsi that produce threads that help the spider cling to smooth surfaces ( 10 ) .

the advantage of spigots on spinnerets is that silk production can be controlled to produce complex linear structures , rather than simple , sheet - like masses of threads . our interpretation of spigot location in attercopus suggests that the original use of silk in protospiders was to produce such sheets , perhaps used as burrow linings , to cover egg masses ( 17 ) , or as trails that would allow hunting animals to return to the safety of a retreat ( 18 ) .

name : attercopus . phonetic : at - ter - coe - pus . named by : p .  a .  selden & w .  a .  shear  -  1991 . classification : arthropoda ,  chelicerata ,  arachnida ,  uraraneida . species : a .  fimbriunguis ( type )  . diet : insectivore . size : unavailable . known locations : usa ,  new york .  time period : mid devonian . fossil representation : almost complete .

from our reevaluation of 334 . 1b . ar34 we conclude that the original description is essentially correct , but note that the specimen consists of a sheet of cuticle folded over twice ; thus , the resemblance of the piece of cuticle bearing spigots to a “semifusiform” spinneret ( 3 ) is fortuitous . in summary , the specimens of attercopus bearing spigots are plate - like in morphology , with 2 rows of spigots along the presumed posterior edge . the spigots are not borne on appendage - like spinnerets .

taking the evidence from attercopus and permarachne together , we conclude that both lacked spinnerets but possessed rows of spigots along the margins of sclerotized ventral plates , and a long , multiarticled postanal flagellum . these characters , while evidently plesiomorphic , would exclude attercopus and permarachne from the order araneae as presently defined . removal of permarachne from the mesothelae leaves only one other described mesothele in the fossil record : palaeothele montceauensis from the late carboniferous of france ( 20 ) . a number of other paleozoic fossils have been referred to araneae ; some of these are not spiders at all ( 21 ) , whereas others can be referred to mesothelae with confidence ( p . a . s . , unpublished observations ) . the external mold of the london specimen of palaeothele shows an anal tubercle , and to ascertain whether this continued into a flagellum ( which could place palaeothele as an intermediate between araneae and the order ) , an x - ray computed tomography ( ct ) scan was performed on the specimen by m . d . s . ( fig . 3 d ) . this showed without doubt that there is no flagellum , and therefore palaeothele remains the earliest and only described fossil mesothele spider to date .

a . fimbriunguis specimens were recovered from the rock matrix by digestion in concentrated hydrofluoric acid followed by washing in dilute hydrochloric acid and mounted on plain microscope slides in clearcol mountant . the specimens were studied by using a leica dm2500 m microscope and photographed with a leica dfc420 digital camera attachment . images of the attercopus specimens were captured by using leica firecam software on an apple macbook pro computer and manipulated by using adobe photoshop cs3 software . drawings were made by using a drawing tube attached to the microscope and also by tracing photographic images in adobe illustrator cs3 . all specimens are deposited in the department of invertebrates , american museum of natural history , new york .

many other characters demonstrate that both attercopus and permarachne are spider - like in their morphology , without features of other known pulmonate arachnids ( 3 , 11 ) . among pulmonate orders , only uropygids and schizomids have a postanal flagellum , and only in uropygids is the flagellum long and multisegmented . in other pulmonate orders ( amblypygids , trigonotarbids , and spiders ) , the pygidium is a 1 - to 3 - segmented preanal structure with a postanal tubercle . the multisegmented flagellum may be a plesiomorphy of pantetrapulmonata ( 13 ) that has been retained in uropygi ( where it appears to function as a sensory structure used for aiming shots of the acetic / caprylic acid repugnatorial secretion ) , and in our proposed order where the function is unknown , or it could be a homoplasy .

in permarachne , from the permian of russia , a series of 6 opisthosomal plates are clearly seen ( 11 ) ( fig . 3 a and b ) . in the original description these were interpreted as tergites ( as seen in mesotheles ) even though all other visible structures in the fossil are ventral , a fact originally accounted for by assuming that the specimen represented a molt from which the carapace had been displaced , thus revealing ventral structures in the prosoma . however , these structures are in ventral , not dorsal , view . it now seems more parsimonious to interpret the series of plates as ventral plates , conforming to the ventral view of the rest of the fossil . thus , there is a real probability that , unlike spiders , both attercopus and permarachne bore a series of ventral plates .

a flagellar structure was described in permarachne ( 11 ) , but because such a structure was previously unknown in spiders , yet all other morphological features suggested that permarachne was a mesothele , the structure was interpreted as an elongate , multiarticled spinneret . however , close examination of the specimen shows a complete absence of spigots ; the structure appears to emerge from the posterior of the opisthosoma along the median line ( fig . 3 a and b ) , not laterally as would be expected for a spinneret , and is not matched by any corresponding paired structure on the specimen . spider spinnerets are always paired , except where the anterior median spinnerets are fused into a single cribellar plate or nonfunctional colulus ( 12 ) . in permarachne the flagellum shows setal whorls ( fig . 3 c ) , but only a few segment collars are distinct , because of the poor preservation ; those preserved are similar to the segments of attercopus . extrapolation from the lengths of the more distinct segments , ≈12 articles appear to be present , but the distal end is not preserved .

sm 1 . 11 . 3a ( fig . 2 a ) consists of a subrectangular mass of overlapping layers of cuticle with ≈33 spigots arrayed in an approximate double row along one long edge and an area of unsculptured cuticle along the opposite edge . the folds have their long axes parallel to the shorter edges . these features , together with the setal arrangement , suggest that the preferred orientation is : unsculptured cuticle anterior , spigots posterior , shorter edges lateral . seven macrosetae and / or their sockets are present on sm 1 . 11 . 3a . one posterolateral corner is missing ; spigots are most numerous at the opposite posterolateral corner . because of the presence of spigots , we interpret sm 1 . 11 . 3a as part of the opisthosoma . living and fossil mesotheles have macrosetae at the rear of each large tergite ( 5 ) , and other spiders that lack tergites commonly bear large setae on the opisthosoma that reflect original segmentation ; thus , the macrosetae on attercopus sm 1 . 11 . 3a could also reflect at least 4 sclerotized plates and the transverse lines could represent plate boundaries ( note : both dorsal and ventral surfaces are present ) .

attercopus fimbriunguis , devonian of new york ( localities : g , gilboa ; sm , south mountain ) , macerated from matrix with hf and slide - mounted . ( a ) first - described “spinneret , ” g 334 . 1b . 34 ; darkness of cuticle reflects number of layers , so this fragment is folded over twice . ( b ) palpal femur , sm 1 . 11 . 12 ; arrow indicates patch of distinctive spinules . ( c ) piece of cuticle from corner of opisthosomal ventral plate showing setae , spigots , and possible silk strand , sm 1 . 11 . 4 . ( d ) close - up of e showing possible silk strand emerging from spigot shaft , sm 1 . 11 . 4 . ( e ) flagellar structure with 12 segments ( including possible distalmost ) from original gilboa locality ; segments show distal collars and setae , g 334 . 1a . 4 . ( f ) close - up of cheliceral fang showing a number of holes ( arrowed ) , the most distal of which had been interpreted as a venom - gland opening , g 329 . 22 . 9 . ( scale bars : 0 . 5 mm , except f , 0 . 25 mm . )

sm 1 . 11 . 4 ( fig . 1 c and d ) is a smaller piece of cuticle than sm 1 . 11 . 3a . the distribution of setae and spigots enables orientation of the piece . at one lateral side is an even fold that conforms to the curved outline of the posterolateral margin ; this is interpreted as a doublure along the margin of the plate . it is folded at the lateral side and bears ≈15 spigots in an approximate double row along the posterior edge ; the anterior and opposite lateral edges are torn . if sm 1 . 11 . 4 were once joined to sm 1 . 11 . 3a , then it is likely that it is the missing posterolateral corner of sm 1 . 11 . 3a , with its posterolateral concentration of spigots . of especial interest on sm 1 . 11 . 4 is the long , winding filament emerging from the distal end of one spigot ( fig . 1 e ) . detailed study shows that this is a single strand that is inseparable microscopically from the tip of the spigot , thus leading us to hypothesize that this is a strand of silk . no other silk strands have been seen in attercopus material , but silk from modern spiders is identical in size and appearance under the light microscope .

amptes & attircoppes & suche oþer þat ben euere bisy ben maide to schewe man ensaumple of stodye & labour . [ elucidarium of honorius of autun ( wycliffite version ) c . 1400 ]

it lingered in northern england dialect in the sense " peevish , ill - natured person " ( c . 1500 ) .

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further reading -  new terrestrial arachnids from the devonian of gilboa ,  new york .   -  american museum novitates 2901 :  1–74 .   -  william a .  shear ,  paul a .  selden ,  w .  d .  i .  rolfe ,  patricia m .  bonamo & james d .  grierson  -  1987 . -  a spider and other arachnids from the devonian of new york ,  and reinterpretations of devonian araneae .   -  palaeontology 34 :  241–281 .   -  paul a .  selden ,  william a .  shear & patricia m .  bonamo  -  1991 . -  taxonomic names ,  in a spider and other arachnids from the devonian of new york ,  and reinterpretations of devonian araneae .   -  palaeontology 34 : 241 - 281 .   -  p .  a .  selden & w .  a .  shear  -  1991 .

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full reference : w . a . shear , p . a . selden , and w . d . i . rolfe . 1987 . systematic paleontology , in new terrestrial arachnids from the devonian of gilboa , new york ( arachnida , trigonotarbida ) . american museum novitates 2901 : 1 - 74

edited by may r . berenbaum , university of illinois at urbana–champaign , urbana , il , and approved november 14 , 2008 ( received for review september 14 , 2008 )

the defining adaptation of spiders is the production of silk from highly modified appendages called spinnerets , located on the posterior division of the body ( opisthosoma ) . silk emerges from spigots ( modified setae ) arrayed on the spinnerets and connected to internal silk glands capable of producing , in the most advanced spiders , several kinds of chemically and physically distinct fibers . silk is used not only to create webs of various types , but also to produce egg - sac material , for prey wrapping , lining burrows , and to aid in navigation and communication , among other uses . because of the importance of silk and spinnerets in the lives of spiders , clues to the origins of the spinning apparatus are of great importance in understanding the evolution of the group . although silk is important in other animals ( e . g . , moth cocoons ) , no other arthropod group relies so heavily on its use in so many ways . here , we reinterpret old and assess recent fossil evidence , and combine our analysis with developmental genetic studies , to clarify how silk use may have evolved . an unexpected result of the study was the discovery that some paleozoic fossils thought to be spiders represent a hitherto undiagnosed order of arachnida .

collections made in 1993 and 1996 in middle devonian strata [ lower frasnian , lowermost onteora formation , 374 ma ( 4 ) ] at south mountain , schoharie county , new york ( 74°16′30″e / 42°23′55″n ) yielded material that is indistinguishable from a . fimbriunguis from gilboa , and thus presumed to be conspecific . this material includes 3 pairs of chelicerae ( therefore , at least 3 individuals ) , numerous podomeres including a palpal femur showing the distinctive patch of spinules on the inferoanterior surface ( fig . 1 b ) , and two slides with specimens showing spigots . the last are numbered sequentially ( sm 1 . 11 . 3 and sm 1 . 11 . 4 ) , which means they were extracted from the same acid - macerate residue and slide - mounted one after another , and so could be parts of the same animal .

although mesothele spiders and a few mygalomorphs have opisthosomal tergites that can be attributed to the original segmentation of the opisthosoma , no spiders living or fossil have ventral opisthosomal plates . however , these plates are present in all other arachnid orders , including the pedipalpi ( orders amblypygi , uropygi , and schizomida ) , sister group to spiders . there is no evidence for the origin of these plates from genetic studies ; the patterns of expression of hox genes has only been studied in some spiders and mites [ in the latter , with focus on head segmentation , not expression of appendage - determining genes ( 6 ) ] . it has been suggested , on the basis of paleontological and developmental evidence ( 7 ) , that , in scorpions , these plates are not true sternites but are the fused remnants of paired opisthosomal appendages , as indeed seems to be the case for the epigastric plate and book - lung covers of spiders , and the homologous anterior opisthosomal opercula in uropygi ( 8 ) and amblypygi ( 9 ) . in mesotheles the first 2 pairs of book - lung covers are part of continuous sclerotization across the opisthosoma , with distinct posterior margins .

paleozoic araneae and uraraneida . ( a–c ) permarachne novokshonovi , permian of russia , pin 4909 / 12 . ( a ) holotype part in rock matrix . ( b ) explanatory drawing of a . ( c ) close - up of flagellum showing whorls of setae . ch , chelicera ; cx , coxa ; fe , femur ; mt , metatarsus ; pa , patella ; pl , ventral plate ; st , sternum ; ta , tarsus ; ti , tibia . ( d ) palaeothele montceauensis , carboniferous of france , in 62050a , x - ray ct scan showing appendages buried in the rock matrix ; note , anal tubercle ( arrowed ) is not a flagellum . ( scale bars : b , 1 mm ; c and d , 0 . 1 mm . )

spider spinnerets are homologs of biramous opisthosomal appendages , still present in the primitive chelicerate limulus , as demonstrated by expression of the developmental genes pdm / nubbin and apterous in embryos of spiders and limulus ( 14 ) . in limulus these appendages consist of a segmented median branch and a lateral branch with a plate covering lamellate gills . in spider embryos , distalless gene expression shows 4 pairs of spinnerets ( anterior and posterior median and lateral pairs ) represented by 2 pairs of appendage buds on opisthosomal somites 4 and 5 ( 15 ) . the appendage buds each later divide in 2 to produce potentially 4 pairs of spinnerets , although in nearly all spiders some of these buds do not develop into functional postembryonic spinnerets . the full complement of 8 spinnerets is today seen only in the primitive mesotheles liphistius and heptathela ( even in these animals the anterior median pair bears no silk - producing spigots ) ( 16 ) . other homologs of opisthosomal appendages in spiders are the book - lung opercula ( 2 pairs in mesotheles and mygalomorphs , on somites 2 and 3 ) and tracheae derived from appendage apodemes in araneomorph spiders on somite 3 . in other arachnids , homologs of opisthosomal appendages can be seen in the gonopods , book - lung opercula , and ventral sacs of pantetrapulmonates , and other organs in diverse groups ( 13 ) . only spiders show expression of appendage homologs on somites 4 and 5 [ although structures in other orders could be silk gland homologs , such as the fusules in female palpigrades ( 17 ) ] . silk glands also occur in many adult male spiders along the anterior edge of the epigastric furrow ( somite 2 ) . these are termed epiandrous or epigastric glands ( 12 ) , and open through simple spigots ( fusules ) . because of their medial position in relation to the more lateral book - lung opercula , epigastric fusules could be serial homologs of the median spinnerets of somites 4 and 5 .

loss and reappearance of wings in stick insects suggests that genes for appendage development can be suppressed , perhaps by a single disabling mutation , and later reactivated , again perhaps by a reversal of the original mutation or an offsetting mutation that restores gene function ( 19 ) . once these genes were reactivated in the ancestors of spiders , it would be a clear advantage to have the spigots on them as this would confer significantly more control over the use and distribution of silk , as seen in the orb - weaving orbiculariae of today in the construction of their architecturally precise webs .

the holotype and only known specimen of permarachne novokshonovi , pin 4909 / 12 , part and counterpart , comes from the koshelevka formation , kungurian stage , cisuralian series ( permian ) , at the krutaya katushka outcrop , left bank of the barda river , upstream of matveyevka , russia , and is deposited in the palaeontological institute of the russian academy of sciences , moscow . the specimen was studied , under ethanol to enhance contrast , by using a wild m7s stereomicroscope , drawn by using a drawing tube , and photographed with a nikon d1x digital camera attached to the microscope .

a specimen of palaeothele montceauensis , in 62050a housed in the natural history museum , london , was submitted to x - ray ct analyses . these were performed on a phoenix v | tome | x “s” x - ray tomography system in the engineering faculty , imperial college , london . x - ray source energy was 160 kv ; the detector was a 16 - bit flat panel 512 × 512 pixel - direct digital detector using a stepping mode to double initial resolution . analysis and reconstruction of tomographic slices was performed by using the custom spiers software suite ; visualizations are ray - traced isosurfaces of data , manually prepared to remove artefacts and extraneous material .

we thank linda hernick ( new york state museum ) and the new york department of forestry for help in field work at south mountain , and kirill eskov ( paleontological institute , moscow ) for discussions on permarachne .

author contributions : p . a . s . and w . a . s . designed research ; p . a . s . and w . a . s . performed research ; m . d . s . contributed new reagents / analytic tools ; p . a . s . and w . a . s . analyzed data ; and p . a . s . and w . a . s . wrote the paper .

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first report of amber with spider webs and microbial inclusions from the earliest cretaceous ( c . 140 ma ) of hastings , sussex

researchers used field data from 2012 to 2015 to study mortality and allele frequency changes in the sea star pisaster ochraceus during a mass mortality event in northcentral california , and found that surviving adult and juvenile sea stars experienced 81 % mortality and allele shifts , according to the authors .

a survey of more than 4 , 600 american adults conducted in 1995 - 1996 and in 2011 - 2014 suggests that among individuals of low socioeconomic status , negative affect increased significantly between the two survey waves , whereas life satisfaction and psychological well - being decreased .

a study of cognitive ability in norwegian males born from 1962 to 1991 suggests that environmental factors rather than changing genetic composition of families likely account for most of the change in norwegian population iq .

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spiders were among the earliest animals to live on land , probably evolving about 400 million years ago .

most of the early segmented fossil spiders belonged to the mesothelae , a group of primitive spiders with the spinnerets placed underneath the middle of the abdomen ( rather than at the end as in ' modern ' spiders ) . they were probably ground dwelling predators , living in the giant clubmoss and fern forests of the mid - late palaeozoic , where they were presumably predators of other primitive arthropods ( like cockroaches , giant silverfish , slaters and millipedes ) . silk may have been used simply as a protective covering for the eggs , a lining for a retreat hole , and later perhaps for simple ground sheet web and trapdoor construction .

as plant and insect life diversified so also did the spider ' s use of silk . spiders with spinnerets at the end of the abdomen ( opisthothelae ) appeared more than 250 million years ago , presumably promoting the development of more elaborate sheet and maze webs for prey capture both on ground and foliage , as well as the development of the safety dragline .

by the jurassic period ( 191 - 136 million years ago ) , when dinosaurs roamed the earth , the sophisticated aerial webs of the orb weaving spiders had developed to trap the rapidly diversifying hordes of flying insects . similarly , the diversification of hunting spiders in litter , bark and foliage niches would have progressed in response to new prey - capture and habitat opportunities .

despite this the spider fossil record is relatively poor . during the tertiary period the rich record of amber spider fossils - complete spiders trapped in clear , sticky , tree resins - show us that a spider fauna basically similar to that of the present day existed more than 30 million years ago .

amazingly , segmented mesothelid spiders have survived in eastern asia ( china to indonesia ) from late palaeozoic times to the present day . these large , impressive spiders live in soil burrows with trapdoors in forested areas and caves . segmented spiders are very similar to their ancestors and have virtually remained unchanged . they are not found in australia .

a 300 million year old , half metre long , fossil arachnid , megarachne servinei , was originally described as a spider , but is now thought more likely to represent another type of spider - like ancient arachnid . its unique features include the enormous size , massive shovel - like jaws and ribbed , shield - like covering over the abdomen . an arachnid of this size must have fed on large prey like cockroaches and giant millipedes . but why did this massive predator need such an impressively armoured body - were there even bigger arachnid predators about ?

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