reptiles endemic new_zealand resembling distinct lineage order derives language means peaks single species surviving member order flourished million years ago recent common ancestor extant group snakes reason great interest study evolution snakes reconstruction appearance habits earliest group includes include birds greenish brown gray measure head tail tip weigh crest especially pronounced males rows teeth upper jaw overlap row lower jaw unique living species unusual having pronounced eye eye thought involved setting seasonal cycles able hear external ear present number unique features skeleton apparently retained fish called living fossils recent work shown changed significantly era mapping researchers discovered species billion base pairs dna sequence protected law second species recognised use discontinued like new_zealand native animals threatened habitat loss introduced predators rat extinct mainland remaining populations confined offshore islands mainland release heavily monitored routine maintenance work late nest uncovered found following autumn thought case successfully breeding new_zealand mainland years outside captive facilities taxonomy evolution extinct members order belong surviving taxon caudal loss tail tip threatened transverse slits origin probably lies close split resemble similarity superficial family characteristics unique reptiles typical shape common early oldest known fossil resembles modern originally classified received skull genus remained noted features similar birds turtles proposed order meaning head fossil relatives related species subsequently added resulting taxon proposed include closest fossil relatives derived greek wedge tooth referred living fossils means retain basal characteristics time split taxonomic work shown group undergone variety changes march molecular study showed rate molecular evolution fastest animal examined occupied today held successful group aquatic known differed markedly living cold weather adaptations allow thrive islands new_zealand adaptations unique ancestors lived warmer climates species known saint fauna proper entirely clear assumed closely related species extant species northern confined specific latin spotted refers german born british named species known misleading species spots brother island olive brown skin yellowish patches colour species ranges olive green grey dark pink brick red white spots addition considerably smaller extinct species identified november sent incomplete sub fossil specimen local coal named new species divided subspecies unnamed subspecies lives islands near northern lives islands north paper examined genetic bases distinguish species concluded represent geographic variants species recognized description considered living brain mode resemble amphibians heart primitive lungs single chamber lack species sexually males larger males measure length females cites length males weigh females brother island slightly smaller weighing greenish brown colour matches environment change lifetime shed skin year adults times year juveniles sexes differ size crest triangular soft skin larger males display male abdomen narrower female skull course evolution skull modified original version evident fossil record original features preserved openings temporal skull complete arches addition upper jaw firmly attached skull makes rigid construction turtle lack temporal condition considered primitive evidence strongly indicates lost temporal holes having tip upper jaw like separated remainder jaw notch single row teeth lower jaw double row upper row fitting perfectly upper rows mouth closed specific tooth arrangement seen snakes double row teeth upper jaws arrangement function different jaws joined backwards forwards movements combined action force bite suitable bone fossils indicate jaw structure began developing million years ago teeth replaced separate structures like real teeth sharp projections jaw bone teeth wear older switch softer prey larvae eventually food smooth jaw bones brain fills half volume proportion actually trying estimate volume dinosaur brains based fossils proportion occupied brain good guide proportion modern birds surviving brains occupy greater relative volume sensory organs eyes focus independently specialized contains types visual cells day night vision reflects enhance vision dark eye membrane eye head called eye lens rod like structures degenerated nerve connection brain suggesting evolved real eye eye visible translucent patch centre skull months covered scales pigment purpose unknown useful absorbing rays produce determine light dark cycles help extant eye pronounced complex night shown use bodies perceive light determine position sun cloud cover aiding navigation turtles primitive hearing organs middle ear cavity filled loose tissue tissue comes contact hair cells nerve respond low frequencies hearing organs poorly developed primitive visible external ears frequency response peak sensitivity spine ribs spine shaped concave usual condition fish amphibians unique rib like bones called abdominal ribs presumed ancestral trait found attached spine ribs true ribs small projections small hooked bones called processes found rear rib feature present birds living developed processes early ribs processes bony elements bony plates skin collar bone formed sort body protecting belly helping hold inner organs details likely evolved structures involved ventured land involved breathing process early amphibians reptiles shoulder arranged differently case parts internal anatomy scales tail plates tail resemble shares ability break tail caught predator behaviour adult terrestrial nocturnal reptiles sun warm bodies hide logs stones likely adults thrive temperatures lower tolerated reptiles winter remain active temperatures low temperatures generally fatal optimal body temperature lowest body temperature lower reptiles ranging day reptiles body temperatures low body temperature results slower share island habitat birds nesting seasons use birds shelter available dig helps maintain populations predominantly prey including beetles spiders consist frogs bird eggs chicks eggs young available food provide beneficial sexes defend territories threaten eventually bite bite cause injury bite approached let easily reproduction reproduce slowly taking years reach sexual maturity mating occurs females mate lay eggs years courtship male makes skin darker raises female slowly walks circles female legs female submit allow male mount retreat males reproduce male lifting tail female placing vent sperm transferred female like mating process birds eggs soft like shell takes females years provide eggs yolk seven months form shell takes months hatching means reproduction occurs year intervals slowest wild known years age henry male new_zealand father possibly time january age sex depends temperature egg warmer eggs tending produce male cooler eggs producing females eggs equal chance male female likely males likely females females evidence indicates sex determination determined genetic environmental factors probably slowest growth rates continuing grow larger years lives average lifespan years live years old experts believe captive live long years conservation distribution threats widespread new_zealand main remains found sand dunes caves wiped main islands european settlement long confined offshore islands free mammals islands difficult animal species indicating animals absent islands caused disappear mainland rats recently established islands breeding islands additionally rat inhabited islands recent discovery mainland indicates attempts establish breeding population new_zealand mainland success total population estimated greater rats removed maintained captivity allow rats islands populations bred captivity successful rats individuals including new juveniles returned islands origin season found hold taken captivity females produced eggs resulting offspring subsequently held enclosure island released wild rats pacific rats following program juveniles seen islands contrast rats persist group juvenile seen holds considered possible rats swim islands hold rats prevent carried east prepare release juveniles raised present naturally small island population approximately juvenile adult moved establishment monitored years later half animals seen gained weight juveniles captive breeding wild caught adults similarly transferred publicly accessible location captive juveniles induced wild females late october collected eggs hatched released long_island outer sounds animals cared wellington zoo years kept secret specially built enclosure zoo display country population given housed display facility successful reproductive efforts reported northern naturally occurs islands population estimated individuals adult northern moved carrying capacity estimated individuals island allow public viewing wild northern introduced mercury group occasionally seen visitors island mainland release occurred heavily monitored second mainland release took place october transferred early recorded wild born offspring observed captive breeding successful breeding captivity believed achieved sir university offices residence street late 1880s new home early 1890s breeding programmes active new_zealand institution breeding programme breed breed release wild 1990s discovered temperature eggs determines sex animal maintains research programme captive breeding mount bruce wildlife centre keeps pair juvenile breeding enclosure notable captive breeding success story took place january eggs belonging year old henry year old hatched story especially remarkable henry required surgery remove order successfully breed january announced succeeded breeding captivity time outside homeland cultural significance feature number indigenous legends held god forms regarded god death disaster women forbidden eat indicate borders sacred restricted meaning consequences boundary crossed women tattoo images represent near today regarded special treasure featured new_zealand cent coin phased october subsequently published victoria institutions live
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