जीवाश्म
[[chitr:Fish-Fossil.jpg|thumb|250px|machhali ka jivashm]] kisi samay prithvi par jivit rahane vale ati prachin sajivoan ke parirakshit avasheshoan ko jo prithvi ki satahoan ya chattanoan ki paratoan mean surakshit paye jate haian, unhean jivashm (aangrezi: Fossil) kahate haian. inake adhyayan ko 'jivashm vijnan' ya pailentol aauji kahate haian. vibhinn prakar ke jivashmoan ke nirikshan se pata chalata hai ki prithvi par alag-alag kaloan mean bhinn-bhinn prakar ke jantu hue haian. jivashmoan ki sahayata se ham yah pata laga sakate haian ki kis sthan par delta, parvat, nadi, samudratat, chhichhale athava gahare samudr the. jivashm ki upasthiti ke karan mrida mean urvara shakti hoti hai. jis mrida mean jivashm paryapt matra mean hote haian, vah adhik upajaoo hoti hai.
arth
- jivashm shabd do shabdoan se milakar bana hai, ‘jiv’ tatha ‘ashm’. ashm ka arth hota hai- patthar. is prakar jivashm ka arth hua 'vah jiv jo patthar ban gaya'. aangrezi mean jivashm ko ph aausil kaha jata hai. ‘ph aausil’ laitin bhasha ka shabd hai jisaka arth hai- 'jamin khodakar nikala gaya padarth'.
- shuruat mean jivashm shabd un sabhi padarthoan ke lie upayog mean laya jata tha jo bhoo-satah ko khodakar nikale jate the. inamean shamil the khanij, manav nirmit puratan aujar, patthar tatha prachin paudhoan evan jantuoan ke avashesh. lekin dhire-dhire jivashm shabd sirph paudhoan evan jantuoan ke puravasheshoan ke lie hi simit rah gaya. ye avashesh talachhati chattanoan mean hi pae jate haian lekin kabhi-kabhi ye daladal, baloo tatha barph mean bhi milate haian.
- bhoo-satah ke niche asankhy jivashm dabe p de haian. kuchh chattanean jaise- choona patthar tatha kh diya pray: asankhy chhote-chhote jivashmoan se nirmit rahati haian. khanij koyala jivashmit vanaspatiyoan ka sangathit roop hai. isi prakar se khanij tel purane mrit sookshmajiviyoan ka parivartit roop hai. isilie inhean jivashm eeandhan kahate haian.
soochak jivashm
jivashm vaijnanikoan ke matanusar pratyek bhoogarbhiy kal ke dauran kuchh vishisht prakar ke jantu ya paudhe pae jate haian aur inake jivashm ek bhoogarbh stanbh mean kisi bhi shail star ke kal ka jnan karate haian. is prakar ke jivashm jo kisi vishesh kal ki chattan mean hi pae jate haian soochak jivashm kahe jate haian.
kisi bhi jiv par usake paryavaran ki chhap avashy paee jati hai. at: jivashmoan se us kal ke paryavaran ka anuman asani se lagaya ja sakata hai. kuchh jivashmoan ke vitaran ke adhyayan se atit mean thal tatha samudr ke vitaran, dharaoan ki disha, tatha prachin jivoan ke prajanan vagairah ka anuman lagaya ja sakata hai. at: jivashm prachin kal ke bhoogol ki upayogi janakari bhi pradan kar sakate haian.
nirman
ek mahatvapoorn prashn yah uthata hai ki, jivashm nirmit kaise hote haian? mrit jiv s dakar pray: nasht ho jate haian. lekin jivashm kisi mrit jiv ka aisa avashesh hai jo s dakar nasht nahian ho saka. s dane ki kriya kee karanoan se dhimi ho sakati hai ya bilakul ruk bhi sakati hai. jivashm ke nirman ya parirakshan ki vidhi jantu ya vanaspati ki prakriti, usaki jivan shaili, tatha usake marane tatha s dane ki paristhiti par nirbhar karati hai. jivashm-nirman ke lie do batean avashyak haian-
- jiv ke sharir mean k de aansh ki upasthiti
- maranoparaant avilamb talachhat se dhank jana
k de kavach vale jivoan ke jivashmit hone ki sanbhavana kavach vihin ya kankal vihin jivoan ki apeksha adhik hai. isi prakar jo jiv daladal mean dab jata hai usake jivashmit hone ki sanbhavana khule maidan mean marane vale jiv se adhik hai. isaka karan yah hai ki khule maidan mean baiktiriya dvara mrit jiv ke sharir ka nasht hona nishchit hai. chooanki jivashm talachhat ke aandar banate haian, isalie adhikaansh jivashmoan ka nirman chhichhale pani ke niche hota hai, jahaan talachhat shighratapoorvak tatha lanbe samay tak lagatar jama hoti rahati hai.
prapti sthan
jivashm pray: samudr ke niche jamin se sate hue sthanoan ya nadiyoan ke muhanoan par banate haian. yahaan jivoan ke avashesh ya to pani ke sath bahakar ate haian ya phir usi sthan par jivoan ke marane se prapt hote haian. thalachar jivoan ke avashesh pray: nadiyaan ya jhiloan mean nirmit talachhati chattanoan mean pae jate haian. akasheruki jivoan ke khol jnat jivashmoan mean sabase achchhi sthiti mean mile haian. inake jivashmit hone ki vidhi ek hi tarah ki hai. in jivoan ka talachhat mean daba hua khol us samay kee prakar ke parivartanoan ke daur se gujarata hai jab usake charoan or ka saancha patthar ke roop mean jamata jata hai. dhire-dhire bahata hua bhoomigat jal jivan ke khol ko poori tarah ghol deta hai tatha usake sthan par ek rikt sthan ya saancha bana rah jata hai. yah saancha mool khol ke akar tatha usaki satah ke chihnoan ko poornat: surakshit roop se darshata hai. yadi kuchh samay ke bad saanche ka yah rikt sthan khanijoan se bhar jata hai to mool khol ka dhaancha ban jata hai.
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