发表于2024-11-27
Alligators & Crocodiles pdf epub mobi txt 电子书 下载 2024
, I I I l, ~ I *~ I; , ~ R t) I (~ I) I I, I ~<br > CI~,()(]OIMLIAN,.; ~,,~. ,.~ .,.,.,.,d~.-v p.l.., :..]. n.p ~. ~l,,, I.,~e of tl,e<br > Of Giants and Dragons ..,~,,e e,,able croc.odilians u~ dose off the wi,~dpipe, a,,d<br > thus Io open Ihe month under waver when they seize their<br >TI. ~.roc~clilian~ mt memlwrs ~1 .u order ~d repHh s prey. They have a partition sep~ ali~ the chest from the<br >.,m~.hnu ,d I1. :tilit~au>rs. tl. ~lmria]. m~d the true erm o- rest of the body cavity, rather like the diaphragm of<br >di5.~. The :m I1 1;,~1 Mn-vi,,m sofl}le,ffyc:d ~reupof rulin~ mammals, This partition can be moved by means of a<br >~cplllcs . he alchosam s Amm1~ Owiv exiinc! relalives, lhe muscle, so thai crocodiliaes can breathe mere ef]]eiently<br >bp~bl, town are Ih( mi~hh dim~sams, All descended frmn thal~ ether reptiles.<br >cCmnnm~ ;~ neestm s IIw theeodonts, wl i ich tlomished durin~~ The crocodilian heart, too, is closer to that of a mammal<br >th~ e~u-I~ "lvia~si( period. 225 million years a~~o. The fossil than to those of oth er reptiles. ~iving them a more effieien!<br >[,.q/)rd ~11o ~ , I}IM ii}l)derll croeodi]iauts have ehan~ed very circulatory syslem. In most reptiles the heart has three<br >]lille sim ~ Iht!~ lirsl appeared, about 160 million years a~e. chambers. Oxygenated blood from the hmgs and oxygen-<br > III |lit nid~q el an mlcxplained increase in lhe mlmbers of exhausted blood fi om the muscles and internal organs<br >]mu~ n.plih s. Vl.,n that stlr~Ce died down about sixty-five arrives in separate auricles, but is then mixed in a common<br >millit.~ w.m-s a~.o. al the end of the Cretaceous period, and ventricle, The result is that some of the blood being pumped<br >II. rcsl ~t Ihe areho~ams disapl>eared - an equally unex- out into the ~eneral circulation is oxygen-deficient, not<br >pl,su,,,~ ,,v~m! - urns| ot ~l~(~ croeodilians survived. Tl)ey are having passed throqg], the lungs to l)e recharged. In the<br >t1., ]ur~,~st livimz reptiles m the world, fearsome and widely heart era croeodilian, the ventricle is divided into two parts<br >fi~ared by a partition, so that ~te-oxy~cenated blood goes only to the<br > COl.D-BLOODED IIORROR lungs and only fleshly oxygemtted blood passes into the<br > eireulation. ,<br >Th,.ve w sm.ethint" aboul the combination of great size and These t~atures make erocodilians especially interesting to<br >cold blood thai i.spires horror in humans, Elephants or biologists. As the only IMng relatives of the :treat dinosaurs,<br > ~zovillas ~t,* hu"e.ev Iml lhey are mammals like ourselves, they provide a clue to the adaptations which may have made<br > inte]ti~. n! with d ]5mi]~ liD. Even lions and tigers are less the dinosaurs so successful tbr such a long period in the<br > ;(~csoll~t- atlcl p~q stq ~lllOvl Ivy Kenerations of hunters, all anilnal history of the earth.<br > l)m the sick ,,~ devau~ ed sh er well clear of mankind. We DRAGONS FROM FAR AWAY<br > t,v~,dil whale, wilh tn ,*al intelliKenee, and there are many<br > ~1,,~ ~es ~d their ~clJ|]c belmvieur, l~,ut crocodilians have no When the first explorers returned fl om Egypt to Greece and<br > I,.a~ m,,I ,.~~.ep, it their parental be|mviour they are by no Rome, they brought back stories of these powerful pre-<br > m~ am, ~m~(le "l he~ are pvedators, of relatively limited daters, Although their reports were t~ctual, they mus~ have<br > mlclli~ n, , cmd when they see a meal, they take it, I)een hard to believe, anad legends inevitably grew up<br > wh~gh.-r it I,a~ Ibur h Ks m" two. The dread in which they are around them. It cammt have been long betbre these stories<br > h(,hl I)~ mr),,t oil].( hlllllall Yaet has hastened several Sl)ecies stirred recollections of ancient accounts of other great<br > ,cr,,,ard, px~mct,o,, Fern has mtlt ushed many a spear, and reptiles, sprung not from travellers tales but fi om the<br > dl]~,.~ m~mv ~ .a]hq ~t~ its mark, ilnaginalion t)J story-tellers, or even fl Olll sollle distant<br > ANGIENTOR MODERN? tblk-u|emory of days when erocodilians still tlourished in<br > F, urope and North America- and dragons were thus reborn.<br > Thr., .,.,, h.~ ;tm .q.v. but cr*}, odilians arc t]ol primitive in Long betbre the (h eeks and Romans, the Egyptians had<br > ,I,~ l, ~m I hci~ bre;tlhiu~g al)par:flt~s is ].ighly de- first-hand knowledge el crocodiles, fi em the cradle of their<br > . . i~(li/~d. The .,)strils m, phte, d al the very civilisation along the banks of the Nile. They regarded them<br > . th.d I1.. :twilnal can I;.t athc whcll Ihe i csl with awe, and soon inehtded a crocodile, Sebek, among<br > d,,m J,,~ ,I ,~ xil,d aid h) ~.;um).fl;,~,c when il is their go(Is. Its eml>odiment on ear/h was a series (1~ sacred<br >
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Alligators & Crocodiles pdf epub mobi txt 电子书 下载 2024