{"id":37393,"date":"2019-10-31T22:17:23","date_gmt":"2019-10-31T19:17:23","guid":{"rendered":"https:\/\/prohoster.info\/blog\/zubnaya-feya-tut-ne-rabotaet-struktura-emali-zubov-krokodilov-i-ih-doistoricheskih-predkov\/"},"modified":"2019-10-31T22:17:23","modified_gmt":"2019-10-31T19:17:23","slug":"zubnaya-feya-tut-ne-rabotaet-struktura-emali-zubov-krokodilov-i-ih-doistoricheskih-predkov","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/news\/zubnaya-feya-tut-ne-rabotaet-struktura-emali-zubov-krokodilov-i-ih-doistoricheskih-predkov","title":{"rendered":"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/377dfa395dc5ecd0aac8ed2ccdc12d61.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nIntra\u021bi \u00eentr-un coridor cu lumin\u0103 slab\u0103, unde \u00eent\u00e2lni\u021bi suflete neajutorate, chinuite de durere \u0219i suferin\u021b\u0103. Dar nu vor g\u0103si lini\u0219te aici, c\u0103ci \u00een spatele fiec\u0103rei u\u0219i \u00eei a\u0219teapt\u0103 \u0219i mai multe chinuri \u0219i frici, umpl\u00e2nd fiecare celul\u0103 a corpului \u0219i umple toate g\u00e2ndurile. V\u0103 apropia\u021bi de una dintre u\u0219i, din spatele c\u0103reia se aude un zgomot infernal \u0219i un zumzet care p\u0103trunde p\u00e2n\u0103 \u00een oase. Adun\u00e2nd ultimele r\u0103m\u0103\u0219i\u021be de curaj, \u00eentinde\u021bi m\u00e2na rece de fric\u0103 spre clan\u021ba u\u0219ii, c\u00e2nd dintr-o dat\u0103 cineva v\u0103 atinge um\u0103rul din spate, \u0219i, zgribulind de surpriz\u0103, v\u0103 \u00eentoarce\u021bi. \u201eDoctorul se va elibera \u00een c\u00e2teva minute. \u00centre timp, v\u0103 rog s\u0103 lua\u021bi loc, v\u0103 vom chema\u201d, v\u0103 spune o voce bl\u00e2nd\u0103 a asistentei. Se pare c\u0103 a\u0219a \u00ee\u0219i \u00eenchipuie unele persoane vizita la dentist, care au o p\u0103rere extrem de negativ\u0103 despre ace\u0219ti \u201esadici\u201d \u00een halate albe. Dar ast\u0103zi nu vom vorbi despre dentofobie, ci despre crocodili. Da, da, exact despre ei, \u0219i mai precis despre din\u021bii lor, care nu necesit\u0103 tratament stomatologic. <\/p>\n<p>Cercet\u0103torii de la Universitatea din Missouri (SUA) au realizat un studiu asupra din\u021bilor crocodililor, care a ar\u0103tat caracteristici interesante ale smal\u021bului acestor v\u00e2n\u0103tori irepro\u0219abili, care se bazeaz\u0103 tocmai pe maxilarele lor. Ce au descoperit cercet\u0103torii, cum difer\u0103 din\u021bii crocodililor moderni de cei preistorici \u0219i ce beneficii aduce acest studiu? Aici vom afla din raportul echipei de cercetare.<noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><\/p>\n<h3>Baza cercet\u0103rii<\/h3>\n<p>\nPentru majoritatea vertebratelor, din\u021bii sunt un atribut indispensabil pentru ob\u021binerea \u0219i consumul hranei (anteaterii nu sunt inclu\u0219i). Unii dintre pr\u0103d\u0103tori se bazeaz\u0103 pe vitez\u0103 \u00een timpul v\u00e2n\u0103torii (ghepardele), al\u021bii \u2013 pe cooperare (lei), iar pentru al\u021bii, o mare influen\u021b\u0103 o are puterea mu\u0219c\u0103turii lor. Acest lucru se aplic\u0103 \u0219i crocodililor, care se apropie sinistru de victimele lor \u00een ap\u0103 \u0219i le prind cu maxilarele lor puternice. Pentru ca victima s\u0103 nu poat\u0103 sc\u0103pa, prinderea trebuie s\u0103 fie puternic\u0103, ceea ce se traduce prin \u00eenc\u0103rc\u0103ri mari asupra structurii osoase. Pentru a compensa efectul negativ al mu\u0219c\u0103turilor lor puternice, crocodilii au palate secundare osoase, care sunt conectate rigid la craniu. <\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/de663bdf4f39a7454d23fb6be395c38c.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>O demonstra\u021bie vizual\u0103 a \u00eenchiderii \u0219i deschiderii maxilarului crocodilului.<\/i><\/p>\n<p>Una dintre principalele caracteristici ale din\u021bilor de crocodil este \u00eenlocuirea continu\u0103 a acestora cu altele noi, pe m\u0103sur\u0103 ce cele vechi se uzeaz\u0103. Este vorba c\u0103 din\u021bii crocodililor seam\u0103n\u0103 cu o matri\u021b\u0103, \u00een interiorul c\u0103reia se dezvolt\u0103 din\u021bi noi. Aproximativ o dat\u0103 la 2 ani, fiecare dinte din maxilar este \u00eenlocuit cu unul nou.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/49e8268bd90f0105cc608cc10cabe7c0.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Observa\u021bi c\u00e2t de bine se \u00eenchide aceast\u0103 \"capcan\u0103 dentar\u0103\".<\/i><\/p>\n<p>Din\u021bii crocodililor sunt \u00eemp\u0103r\u021bi\u021bi \u00een mai multe categorii, \u00een func\u021bie de form\u0103 \u0219i func\u021bionalitate. La \u00eenceputul maxilarului se afl\u0103 4 col\u021bi mari, necesari pentru capturarea eficient\u0103 a pr\u0103zii. \u00cen mijloc se afl\u0103 din\u021bi mai gro\u0219i, care se m\u0103resc pe parcursul maxilarului. Aceast\u0103 parte este destinat\u0103 t\u0103ierii pr\u0103zii. La baza, din\u021bii se l\u0103rgesc \u0219i devin mai pla\u021bi, ceea ce le permite crocodililor s\u0103 sparg\u0103 cochiliile melcilor \u0219i carapacele \u021bestoaselor, ca pe semin\u021be. <\/p>\n<p>C\u00e2t de puternic\u0103 este maxilarul unui crocodil? Evident, aceasta depinde de dimensiunile \u0219i speciile sale. De exemplu, \u00een 2003 s-a descoperit c\u0103 un alligator din Mississippi, cu o greutate de 272 de kilograme, mu\u0219c\u0103 cu o for\u021b\u0103 de aproximativ 9500 N (N \u2013 Newton, 1 N = 1 kg\u00b7m\/s2). Pe de alt\u0103 parte, un crocodil de 1308 kilograme a demonstrat o for\u021b\u0103 impresionant\u0103 de aproximativ 34500 N. Ca un termen de compara\u021bie, for\u021ba absolut\u0103 de mu\u0219c\u0103tur\u0103 a unui om este de aproximativ 1498 N.<\/p>\n<p>For\u021ba mu\u0219c\u0103turii depinde mai mult de mu\u0219chii maxilarului dec\u00e2t de din\u021bi. La crocodili, ace\u0219ti mu\u0219chi sunt foarte densi \u0219i numero\u0219i. Totu\u0219i, exist\u0103 o diferen\u021b\u0103 semnificativ\u0103 \u00eentre mu\u0219chii foarte dezvolta\u021bi, care sunt responsabili de \u00eenchiderea maxilarului (ceea ce ofer\u0103 acea for\u021b\u0103 de mu\u0219c\u0103tur\u0103), \u0219i mu\u0219chii slabi, care sunt responsabili de deschiderea maxilarului. Acesta este motivul pentru care maxilarul \u00eenchis al unui crocodil poate fi \u021binut cu ajutorul unei simple benzi adezive.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/281c595d45d92f12b47466a8018f191f.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Hai s\u0103 vedem cine te-a numit \u201eb\u0103ie\u021bandru\u201d.<\/i><\/p>\n<p>Dar maxilarul crocodililor nu este necesar doar pentru ucideri f\u0103r\u0103 mil\u0103 \u00een c\u0103utarea hranei, ci \u0219i pentru \u00eengrijirea puilor. Femelele de crocodil adesea \u00ee\u0219i transport\u0103 puii tocmai \u00een maxilar (este greu s\u0103 g\u0103se\u0219ti un loc mai sigur pentru ei, deoarece cine ar avea curajul s\u0103 se apropie). Maxilarele crocodililor sunt echipate cu receptori foarte sensibili, care le permit s\u0103 regleze for\u021ba mu\u0219c\u0103turii, ceea ce le permite s\u0103 \u021bin\u0103 mai bine prada sau s\u0103 transporte delicat puii.<\/p>\n<p>Din\u021bii oamenilor, din p\u0103cate, nu cresc \u00eenapoi dup\u0103 ce cei vechi cad, dar au ceva \u00een comun cu crocodilii \u2013 smal\u021bul.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/3e1bdf40afaccbced0f824410b237372.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginile nr. 1: dintele caudal al aligatorului din Mississippi (Alligator mississippiensis).<\/i><\/p>\n<p>Emailul este \u00eenveli\u0219ul extern al p\u0103r\u021bii coronare a dintelui. Este cea mai rezistent\u0103 parte a corpului uman, la fel ca \u0219i la multe alte vertebrate. Totu\u0219i, dup\u0103 cum \u0219tim, din\u021bii no\u0219tri nu se schimb\u0103 cu al\u021bii noi, astfel c\u0103 emailul nostru trebuie s\u0103 fie mai gros. \u00cen schimb, crocodilii \u00ee\u0219i \u00eenlocuiesc din\u021bii uzati cu unii noi, a\u0219a c\u0103 nu este necesar s\u0103 aib\u0103 un email at\u00e2t de gros. Se pare c\u0103 are sens, dar este totu\u0219i adev\u0103rat?<\/p>\n<p>Oamenii de \u0219tiin\u021b\u0103 spun c\u0103 \u00een\u021belegerea modific\u0103rilor emailului \u00een cadrul unei taxa ne va permite s\u0103 ne amintim mai bine cum se schimb\u0103 structura emailului \u00een func\u021bie de biomecanica \u0219i dieta animalului. <\/p>\n<p>Crocodilii, mai exact <i>Alligator mississippiensis<\/i>, sunt foarte potrivi\u021bi pentru aceast\u0103 cercetare din mai multe motive. \u00cen primul r\u00e2nd, din\u021bii lor, for\u021ba mu\u0219c\u0103turii \u0219i structura emailului se schimb\u0103 \u00een func\u021bie de v\u00e2rst\u0103 \u0219i dimensiunea individului, ceea ce este influen\u021bat \u0219i de schimbarea dietei. \u00cen al doilea r\u00e2nd, din\u021bii crocodililor au o morfologie diferit\u0103 \u00een func\u021bie de pozi\u021bia din maxilar. <\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/013855cf61d1f20b442e4f223ecd8202.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginile nr. 2: a \u0219i b arat\u0103 diferen\u021ba dintre din\u021bii indivizilor mari \u0219i mici, c \u0219i e arat\u0103 din\u021bii fossililor str\u0103mo\u0219i ai crocodililor moderni.<\/i><\/p>\n<p>Din\u021bii rostali sunt sub\u021biri \u0219i sunt utiliza\u021bi pentru a prinde prada, \u00een timp ce din\u021bii caudali sunt obtuzi \u0219i sunt utiliza\u021bi pentru a zdrobi cu o for\u021b\u0103 de mu\u0219c\u0103tur\u0103 mai mare. Cu alte cuvinte, sarcina asupra dintelui depinde de pozi\u021bia sa \u00een maxilar \u0219i de dimensiunile proprietarului acestui maxilar.<\/p>\n<p>\u00cen aceast\u0103 cercetare sunt prezentate rezultatele analizei \u0219i m\u0103sur\u0103rilor grosimii absolute a emailului (AET) \u0219i grosimii relative standardizate (RET) a din\u021bilor crocodilului.<\/p>\n<p>AET reprezint\u0103 o estimare a distan\u021bei medii de la tranzi\u021bia email-dentin\u0103 p\u00e2n\u0103 la suprafa\u021ba exterioar\u0103 a emailului \u0219i reprezint\u0103 o m\u0103surare liniar\u0103. RET este o m\u0103rime adimensional\u0103 care permite compararea grosimii relative a emailului la diferite scale.<\/p>\n<p>Oamenii de \u0219tiin\u021b\u0103 au evaluat AET \u0219i RET a din\u021bilor rostali (\u00een \u00abnasul\u00bb maxilarului), intermediari (\u00een mijlocul r\u00e2ndului) \u0219i caudali (la baza maxilarului) la \u0219apte indivizi ai speciei. <i>Alligator mississippiensis<\/i>.<\/p>\n<p>Este important de asemenea de men\u021bionat c\u0103 structura smal\u021bului poate depinde de dieta individului \u0219i de \u00eentreaga specie \u00een general. Crocodilele au o diet\u0103 destul de diversificat\u0103 (ce prind, aceea va fi pr\u00e2nzul), dar aceasta difer\u0103 de cea a rudelor lor care au disp\u0103rut de mult. Pentru a verifica acest lucru din perspectiva smal\u021bului, oamenii de \u0219tiin\u021b\u0103 au realizat analize AET \u0219i RET ale fosilelor. <i>Protosuchidae<\/i> (UCMP 97638), <i>Iharkutosuchus<\/i> (MTM VER 2018.837) \u0219i <i>Allognathosuchus<\/i> (YPM-PU 16989). <i>Protosuchidae<\/i> este reprezentant al perioadei jurasice, <i>Iharkutosuchus<\/i> \u2014 perioadei cretacice, iar <i>Allognathosuchus<\/i> din eocen.<\/p>\n<p>\u00cenainte de a \u00eencepe m\u0103sur\u0103torile efective, cercet\u0103torii au realizat o sesiune de brainstorming \u0219i au propus c\u00e2teva ipoteze teoretice:<\/p>\n<ul>\n<li>ipoteza 1a \u2014 deoarece AET este o m\u0103sur\u0103 liniar\u0103 \u0219i ar trebui s\u0103 depind\u0103 de dimensiune, se presupune c\u0103 dispersia \u00een AET va fi explicat\u0103 cel mai bine de dimensiunea craniului;<\/li>\n<li>ipoteza 1b \u2014 deoarece RET este standardizat \u00een func\u021bie de dimensiune, se presupune c\u0103 dispersia \u00een RET va fi explicat\u0103 cel mai bine de pozi\u021bia din\u021bilor;<\/li>\n<li>ipoteza 2a \u2014 deoarece AET \u0219i lungimea craniului sunt m\u0103suri liniare ale dimensiunii, acestea ar trebui s\u0103 se scaleze cu \u00eenclina\u021bie izometric\u0103;<\/li>\n<li>ipoteza 2b \u2014 deoarece din\u021bii caudali suport\u0103 cele mai mari for\u021be de mu\u0219c\u0103tur\u0103 \u00een r\u00e2ndul din\u021bilor, prin urmare RET va fi mai mare la din\u021bii caudali.<\/li>\n<\/ul>\n<p>\u00cen tabelele de mai jos sunt prezentate datele mostrelor (craniile crocodililor din specia <i>Alligator mississippiensis<\/i>, prelevate din rezerva\u021bia Rockefeller din Grand Chenier, Louisiana, \u0219i fosile).<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/cf7306548a2f0e488c4fa354ffdc6fe7.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Tabelul nr. 1: datele de scanare a din\u021bilor de crocodil (rostale, intermediare \u0219i caudale).<\/i><\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/bebcdd3f91785efcd55077945a4e98d9.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Tabelul nr. 2: datele din\u021bilor (LSkull \u2014 lungimea craniului, hCrown \u2014 \u00een\u0103l\u021bimea coroanei, VE \u2014 volumul smal\u021bului, VD \u2014 volumul dentinei, SAEDJ \u2014 suprafa\u021ba interfe\u021bei smal\u021b-dentin\u0103, AET \u2014 grosimea absolut\u0103 a smal\u021bului, RET \u2014 grosimea relativ\u0103 a smal\u021bului).<\/i><\/p>\n<h3>Rezultatele cercet\u0103rii<\/h3>\n<p>\nConform datelor dentare prezentate \u00een tabelul nr. 2, cercet\u0103torii au concluzionat c\u0103 grosimea smal\u021bului se scaleaz\u0103 izometric cu lungimea craniului, indiferent de pozi\u021bia din\u021bilor.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/5cd51ee8c3209f309da0800fce1d5371.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Tabelul nr. 3: valorile AET \u0219i RET \u00een func\u021bie de variabile.<\/i><\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/402465590a3d79a24f6841324a662077.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea nr. 3: scalarea AET\/RET \u00een raport cu lungimea craniului.<\/i><\/p>\n<p>\u00cen acela\u0219i timp, grosimea smal\u021bului pe din\u021bii caudali este semnificativ mai mare dec\u00e2t pe ceilal\u021bi, dar aceasta nu depinde nici de lungimea craniului.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/3a8bac56514674cfc2d3c3d54105bdba.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Tabelul Nr. 4: valorile medii ale grosimii smal\u021bului la vertebrate superioare (Crocodyliform \u2014 grup taxonomic de crocodili, Dinosaur \u2014 dinozauri, Artiodactyl \u2014 paranocoprieni, Odontocete \u2014 subordonarea cetaceelor, Perissodactyl \u2014 nep\u0103rcoprin, Primate \u2014 primate, Rodent \u2014 roz\u0103toare).<\/i><\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/6fa09d71c0ed5e30976c56048c4dd011.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea Nr. 4: grosimea smal\u021bului din\u021bilor caudali este mai mare dec\u00e2t la ceilal\u021bi.<\/i><\/p>\n<p>Datele referitoare la scalare (tabelul Nr. 3) au confirmat ipoteza 1a, care explic\u0103 dependen\u021ba valorii AET de lungimea craniului, nu de pozi\u021bia din\u021bilor. \u00cen schimb, valorile RET depind de pozi\u021bia din\u021bilor \u00een r\u00e2nd, nu de lungimea craniului, ceea ce confirm\u0103 ipoteza 1b.<\/p>\n<p>Celelalte ipoteze (2a \u0219i 2b) au fost, de asemenea, confirmate, conform datelor analizei grosimii medii a smal\u021bului din\u021bilor cu diferite pozi\u021bii \u00een r\u00e2nd.<\/p>\n<p>Compararea grosimii smal\u021bului la alligatorul modern din Mississippi \u0219i str\u0103mo\u0219ii s\u0103i antici a ar\u0103tat multe asem\u0103n\u0103ri, dar \u0219i diferen\u021be. Astfel, la Allognathosuchus grosimea smal\u021bului este cu aproximativ 33% mai mare dec\u00e2t la crocodilii moderni (imaginea de mai jos).<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/7963e687b9e86090021b26033ea50135.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea Nr. 5: compararea grosimii medii a smal\u021bului la aligator \u0219i la crocodilii fosili \u00een func\u021bie de \u00een\u0103l\u021bimea coronarei dentare.<\/i><\/p>\n<p>Sumariz\u00e2nd toate datele de mai sus, cercet\u0103torii au concluzionat c\u0103 grosimea smal\u021bului depinde direct de rolul din\u021bilor. Dac\u0103 ace\u0219ti din\u021bi sunt necesari pentru zdrobire, atunci smal\u021bul lor va fi semnificativ mai gros. S-a stabilit anterior c\u0103 presiunea (for\u021ba de comprimare) din\u021bilor caudali este mai mare dec\u00e2t la cei rostrali. Aceasta se leag\u0103 de rolul lor \u2014 de a prinde prada \u0219i de a zdrobi oasele. A\u0219adar, smal\u021bul mai gros previne deteriorarea din\u021bilor care sunt supu\u0219i unei sarcini maxime \u00een timpul hr\u0103nirii. \u0218i \u00eentr-adev\u0103r, datele sugereaz\u0103 c\u0103 din\u021bii caudali la crocodili se rup semnificativ mai rar, \u00een ciuda sarcinilor serioase.<\/p>\n<p>\u00cen plus, s-a descoperit c\u0103 din\u021bii <i>Allognathosuchus<\/i> au smal\u021b semnificativ mai gros dec\u00e2t al celorlalte crocodile studiate. Se consider\u0103 c\u0103 aceast\u0103 specie fosil\u0103 prefera s\u0103 se hr\u0103neasc\u0103 cu \u021bestoase, iar pentru zdrobirea carapacei lor sunt necesari din\u021bi puternici \u0219i smal\u021b gros. <\/p>\n<p>Cercet\u0103torii au efectuat, de asemenea, o compara\u021bie a grosimii smal\u021bului crocodilelor \u0219i unor dinozauri, corespunz\u0103tor greut\u0103\u021bii \u0219i dimensiunii presupuse. Aceast\u0103 analiz\u0103 a ar\u0103tat c\u0103 smal\u021bul la crocodili a fost mai gros (diagram\u0103 de mai jos).<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/4002b03317556599a448aed9616af1a1.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea nr. 6: compara\u021bia grosimii smal\u021bului crocodililor \u0219i dinozaurilor.<\/i><\/p>\n<p>Este curios c\u0103 smal\u021bul la tiranosaurus a fost aproape la fel de gros ca \u0219i la considerably mai micul Allognathosuchus \u0219i chiar la crocodilii moderni. Este logic c\u0103 structura din\u021bilor crocodililor este explicat\u0103 prin comportamentele lor \u00een aspectele v\u00e2n\u0103torii \u0219i dietei.<\/p>\n<p>Cu toate acestea, \u00een ciuda recordurilor sale, smal\u021bul arcosaurilor (crocodili, dinozauri, pterosauri etc.) este mai sub\u021bire dec\u00e2t la mamifere.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/782281ee37da90136d3f58922e8e9f4e.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea nr. 7: compara\u021bia grosimii smal\u021bului (AET) crocodililor \u0219i a unor specii de mamifere.<\/i><\/p>\n<p>De ce are smal\u021bul v\u00e2n\u0103torilor, care se bazeaz\u0103 at\u00e2t de mult pe f\u0103lci, o grosime mai mic\u0103 dec\u00e2t la mamifere? R\u0103spunsul la aceast\u0103 \u00eentrebare a fost prezentat la \u00eenceput \u2014 \u00eenlocuirea din\u021bilor uza\u021bi cu unii noi. De\u0219i crocodilii au din\u021bi rezisten\u021bi, nu au nevoie de din\u021bi extrem de duri, av\u00e2nd \u00een vedere c\u0103 un dinte nou va veni \u00eentotdeauna s\u0103-l \u00eenlocuiasc\u0103 pe cel rupt. Mamiferele (\u00een mare parte) nu au acest talent.<\/p>\n<p><img decoding=\"async\" alt=\"Vise cu z\u00e2mbet: structura smal\u021bului din\u021bilor crocodililor \u0219i str\u0103mo\u0219ilor lor preistorici\" src=\"\/wp-content\/uploads\/2019\/08\/9b0a14642c99f16360d6d8f82f9e8294.jpeg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Imaginea nr. 8: compara\u021bia grosimii smal\u021bului (RET) crocodililor \u0219i a unor specii de mamifere.<\/i><\/p>\n<p>Mai exact, grosimea smal\u021bului la arcosauri variaz\u0103 \u00eentre 0,01 \u0219i 0,314 mm, iar la mamifere \u00eentre 0,08 \u0219i 2,3 mm. Diferen\u021ba, a\u0219a cum se spune, este evident\u0103.<\/p>\n<p>Pentru o mai bun\u0103 \u00een\u021belegere a detaliilor studiului, v\u0103 recomand s\u0103 consulta\u021bi <noindex><a rel=\"nofollow\" href=\"https:\/\/www.researchgate.net\/publication\/334150418_The_significance_of_enamel_thickness_in_the_teeth_of_Alligator_mississippiensis_and_its_diversity_among_crocodyliforms_Enamel_thickness_in_crocodyliforms\">raportul cercet\u0103torilor.<\/a><\/noindex><\/p>\n<h3>Epilog<\/h3>\n<p>\nDin\u021bii, oric\u00e2t de ciudat ar suna, sunt un instrument extrem de important \u00een ob\u021binerea hranei. Da, omul modern poate \u00eentotdeauna s\u0103 corecteze orice defect legat de din\u021bi, dar \u00een r\u00e2ndul animalelor s\u0103lbatice nu exist\u0103 stomatologi. Chiar \u0219i omul nu a \u0219tiut \u00eentotdeauna ce \u00eenseamn\u0103 tratamentul din\u021bilor. De aceea unele specii aleg din\u021bi puternici \u0219i durabili, \u00een timp ce altele prefer\u0103 s\u0103-i schimbe, ca pe m\u0103nu\u0219i. Crocodilii \u0219i rudele lor \u00eendep\u0103rtate pot fi incluse \u00een ambele grupuri. Smal\u021bul din\u021bilor, care sunt esen\u021biali pentru prinderea eficient\u0103 a pr\u0103zii \u0219i zdrobirea oaselor, la crocodili este destul de gros, dar, av\u00e2nd \u00een vedere sarcinile serioase, din\u021bii lor se uzeaz\u0103 \u0219i uneori se rup. \u00cen astfel de cazuri, un nou dinte vine s\u0103 \u00eenlocuiasc\u0103 pe cel vechi. <\/p>\n<p>Pentru oameni, una dintre tr\u0103s\u0103turile distinctive este degetul mare opus, care ne-a ajutat enorm \u00een multe \u00eenceputuri, de la \"a lua o b\u00e2t\u0103 \u0219i a lovi vecinul enervant de pe crac\u0103\" p\u00e2n\u0103 la \"a lua o pan\u0103 \u0219i a scrie un sonet\". Pentru crocodili, \u00eens\u0103, acest instrument sunt maxilarele lor, \u00een special din\u021bii. Aceast\u0103 parte a corpului \u00eei face pe crocodili v\u00e2n\u0103tori at\u00e2t de periculo\u0219i \u0219i mortali, de care ar trebui s\u0103 ne ferim.<\/p>\n<p><b class=\"spoiler_title\">Off-topic de vineri:<\/b><center><div class=\"youtube-placeholder\" data-id=\"2xp22IYL2uU\" onclick=\"loadVideo(this)\">\r\n        <img decoding=\"async\" src=\"https:\/\/img.youtube.com\/vi\/2xp22IYL2uU\/hqdefault.jpg\" alt=\"Reda\u021bi video\" loading=\"lazy\" width=\"480\" height=\"360\" style=\"width:100%;height:auto;\">\r\n        <div class=\"play-button\"><\/div>\r\n    <\/div><\/center><br \/>\n<i>Un scurtmetraj foarte curios \u0219i estetic frumos, \u00een care crocodilul nu este chiar un crocodil. <\/i><\/p>\n<p><center><div class=\"youtube-placeholder\" data-id=\"JMJXvsCLu6s\" onclick=\"loadVideo(this)\">\r\n        <img decoding=\"async\" src=\"https:\/\/img.youtube.com\/vi\/JMJXvsCLu6s\/hqdefault.jpg\" alt=\"Reda\u021bi video\" loading=\"lazy\" width=\"480\" height=\"360\" style=\"width:100%;height:auto;\">\r\n        <div class=\"play-button\"><\/div>\r\n    <\/div><\/center><br \/>\n<i>Un desen animat despre cum s\u0103 nu ai \u00eencredere \u00een \"b\u00e2rnele\" suspecte din ap\u0103, mai ales dac\u0103 e\u0219ti o antilop\u0103 gnu.<\/i><\/p>\n<p>Mul\u021bumesc pentru aten\u021bie, r\u0103m\u00e2ne\u021bi curio\u0219i \u0219i s\u0103 ave\u021bi un weekend minunat, b\u0103ie\u021bi! \ud83d\ude42<\/p>\n<p>\nV\u0103 mul\u021bumim c\u0103 r\u0103m\u00e2ne\u021bi cu noi. V\u0103 plac articolele noastre? Dori\u021bi s\u0103 vede\u021bi mai multe materiale interesante? Sus\u021bine\u021bi-ne f\u0103c\u00e2nd o comand\u0103 sau recomand\u00e2ndu-ne prietenilor. <b>30% reducere pentru utilizatorii Habr pentru un server entry-level unic, creat special pentru tine:<\/b> <noindex><a rel=\"nofollow\" href=\"https:\/\/habr.com\/company\/ua-hosting\/blog\/347386\/\">Adev\u0103rul despre VPS (KVM) E5-2650 v4 (6 nuclee) 10GB DDR4 240GB SSD 1Gbps de la 20$ sau cum s\u0103 \u00eemp\u0103r\u021bim corect un server?<\/a><\/noindex> (sunt disponibile op\u021biuni cu RAID1 \u0219i RAID10, p\u00e2n\u0103 la 24 nuclee \u0219i p\u00e2n\u0103 la 40GB DDR4).<\/p>\n<p><b>Dell R730xd la jum\u0103tate de pre\u021b?<\/b> Numai la noi <b><noindex><a rel=\"nofollow\" href=\"https:\/\/ua-hosting.company\/serversnl\">2 x Intel TetraDeca-Core Xeon 2x E5-2697v3 2.6GHz 14C 64GB DDR4 4x960GB SSD 1Gbps 100 TB de la 199 $<\/a><\/noindex> \u00een Olanda! <b>Dell R420 \u2014 2x E5-2430 2.2Ghz 6C 128GB DDR3 2x960GB SSD 1Gbps 100TB \u2014 de la 99 $!<\/b><\/b> Citi\u021bi despre <noindex><a rel=\"nofollow\" href=\"https:\/\/habr.com\/company\/ua-hosting\/blog\/329618\/\">Cum s\u0103 construi\u021bi o infrastructur\u0103 de clas\u0103 enterprise folosind servere Dell R730xd E5-2650 v4 la pre\u021buri foarte mici de 9000 \u20ac?<\/a><\/noindex><br \/>\n<br \/>Sursa: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/company\/ua-hosting\/blog\/464711\/\">habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0412\u044b \u0437\u0430\u0445\u043e\u0434\u0438\u0442\u0435 \u0432 \u043a\u043e\u0440\u0438\u0434\u043e\u0440 \u0441 \u043f\u0440\u0438\u0433\u043b\u0443\u0448\u0435\u043d\u043d\u044b\u043c \u0441\u0432\u0435\u0442\u043e\u043c, \u0432 \u043d\u0435\u043c \u0432\u0430\u043c \u0432\u0441\u0442\u0440\u0435\u0447\u0430\u044e\u0442\u0441\u044f \u043e\u0431\u0435\u0437\u0434\u043e\u043b\u0435\u043d\u043d\u044b\u0435 \u0434\u0443\u0448\u0438, \u0442\u0435\u0440\u0437\u0430\u0435\u043c\u044b\u0435 \u0431\u043e\u043b\u044c\u044e \u0438 \u0441\u0442\u0440\u0430\u0434\u0430\u043d\u0438\u044f\u043c\u0438. \u041d\u043e \u0438\u043c \u043d\u0435 \u0431\u0443\u0434\u0435\u0442 \u0442\u0443\u0442 \u043f\u043e\u043a\u043e\u044f, \u0438\u0431\u043e \u0437\u0430 \u043a\u0430\u0436\u0434\u043e\u0439 \u0438\u0437 \u0434\u0432\u0435\u0440\u0435\u0439 \u0438\u0445 \u0436\u0434\u0435\u0442 \u0435\u0449\u0435 \u0431\u043e\u043b\u044c\u0448\u0435 \u043c\u0443\u043a \u0438 \u0441\u0442\u0440\u0430\u0445\u0430, \u043d\u0430\u043f\u043e\u043b\u043d\u044f\u044e\u0449\u0438\u0435 \u0432\u0441\u0435 \u043a\u043b\u0435\u0442\u043e\u0447\u043a\u0438 \u0442\u0435\u043b\u0430 \u0438 \u0437\u0430\u043f\u043e\u043b\u043e\u043d\u044f\u044e\u0449\u0438\u0435 \u0432\u0441\u0435 \u043c\u044b\u0441\u043b\u0438. \u0412\u044b \u043f\u043e\u0434\u0445\u043e\u0434\u0438\u0442\u0435 \u043a \u043e\u0434\u043d\u043e\u0439 \u0438\u0437 \u0434\u0432\u0435\u0440\u0435\u0439, \u0437\u0430 \u043a\u043e\u0442\u043e\u0440\u043e\u0439 \u0441\u043b\u044b\u0448\u0438\u0442\u0441\u044f \u0430\u0434\u0441\u043a\u0438\u0439 \u0441\u043a\u0440\u0435\u0436\u0435\u0442 \u0438 [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":28056,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-37393","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.2.1 - aioseo.com -->\n\t<meta name=\"description\" content=\".\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<meta name=\"author\" content=\"Yuri Gagarin\"\/>\n\t<link rel=\"canonical\" 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