therefore，probably，itwasanestuarydeposit。
TheremainsatPuntaAltawereembeddedinstratifiedgravelandreddishmud，justsuchastheseamightnowwashuponashallowbank。Theywereassociatedwithtwenty-threespeciesofshells，ofwhichthirteenarerecentandfourothersverycloselyrelatedtorecentforms。[1]FromthebonesoftheScelidotherium，includingeventheknee-cap，beingintombedintheirproperrelativepositions，andfromtheosseousarmourofthegreatarmadillo-likeanimalbeingsowellpreserved，togetherwiththebonesofoneofitslegs，wemayfeelassuredthattheseremainswerefreshandunitedbytheirligaments，whendepositedinthegraveltogetherwiththeshells。[2]Hencewehavegoodevidencethattheaboveenumeratedgiganticquadrupeds，moredifferentfromthoseofthepresentdaythantheoldestofthetertiaryquadrupedsofEurope，livedwhilsttheseawaspeopledwithmostofitspresentinhabitants；andwehaveconfirmedthatremarkablelawsoofteninsistedonbyMr。Lyell，namely，thatthe“longevityofthespeciesinthemammaliaisuponthewholeinferiortothatofthetestacea。”[3]
ThegreatsizeofthebonesoftheMegatheroidanimals，includingtheMegatherium，Megalonyx，Scelidotherium，andMylodon，istrulywonderful。
Thehabitsoflifeoftheseanimalswereacompletepuzzletonaturalists，untilProfessorOwen[4]solvedtheproblemwithremarkableingenuity。Theteethindicate，bytheirsimplestructure，thattheseMegatheroidanimalslivedonvegetablefood，andprobablyontheleavesandsmalltwigsoftrees；theirponderousformsandgreatstrongcurvedclawsseemsolittleadaptedforlocomotion，thatsomeeminentnaturalistshaveactuallybelieved，that，likethesloths，towhichtheyareintimatelyrelated，theysubsistedbyclimbingbackdownwardsontrees，andfeedingontheleaves。Itwasabold，nottosaypreposterous，ideatoconceiveevenantediluviantrees，withbranchesstrongenoughtobearanimalsaslargeaselephants。ProfessorOwen，withfarmoreprobability，believesthat，insteadofclimbingonthetrees，theypulledthebranchesdowntothem，andtoreupthesmalleronesbytheroots，andsofedontheleaves。Thecolossalbreadthandweightoftheirhinderquarters，whichcanhardlybeimaginedwithouthavingbeenseen，becomeonthisview，ofobviousservice，insteadofbeinganincumbrance：
theirapparentclumsinessdisappears。Withtheirgreattailsandtheirhugeheelsfirmlyfixedlikeatripodontheground，theycouldfreelyexertthefullforceoftheirmostpowerfularmsandgreatclaws。Stronglyrooted，indeed，mustthattreehavebeen，whichcouldhaveresistedsuchforce！TheMylodon，moreover，wasfurnishedwithalongextensiletonguelikethatofthegiraffe，which，byoneofthosebeautifulprovisionsofnature，thusreacheswiththeaidofitslongneckitsleafyfood。Imayremark，thatinAbyssiniatheelephant，accordingtoBruce，whenitcannotreachwithitsproboscisthebranches，deeplyscoreswithitstusksthetrunkofthetree，upanddownandallround，tillitissufficientlyweakenedtobebrokendown。