genus extinct lobe fish late period million years ago having features akin legged animals possibility representative evolutionary transition fish amphibians example lines ancient fish developing adaptations oxygen poor shallow water habitats time environmental conditions thought led evolution similar animals possibly common ancestors broad terrestrial fauna amphibians reptiles birds mammals preserved fossils found canada etymology word meaning freshwater fish related true genus received suggestion elders canada fossil discovered specific honours anonymous donor taking detailed look internal head skeleton october issue nature researchers gaining structures allow support solid ground breathe air key intermediate step transformation skull accompanied shift life land distant ancestors description provides insights features extinct closest relatives unlike previous transitional fossils fins basic wrist bones simple rays reminiscent fingers elements uncertain suggestions incompatible digital arch developmental model supposed structures reconstructed rays series directly compared fin clearly weight bearing attached massive shoulder expanded elements attached body armor large muscular ventral surface highly mobile joints bones large muscle suggesting fin muscular ability like wrist joint wrist like features helped anchor creature fast moving current notable head suggest creature primitive lungs gills attribute useful shallow water higher water temperature lower oxygen content development led evolution robust key evolutionary trait land living creatures robust helped support animal body time ventured outside fully aquatic habitat lacked characteristic fishes bony plates gill area restrict lateral head movement makes earliest known fish neck pectoral separate skull creature freedom hunting prey land compared family shares number characteristics diamond shaped scale patterns common class species scales overlapping teeth structured rows internal external nostrils tubular streamlined body absence anterior dorsal fin broad compressed skull paired frontal bones marginal mouth lung like organ generally characteristics lobe fish fins featuring arm like skeletal structures akin including shoulder elbow wrist fossil discovered include rear fins tail rows sharp teeth predator fish neck independently body common fish extant exceptions animal flat skull resembling eyes head suggesting spent lot time looking neck ribs similar ribs support body aid breathing lungs developed jaws suitable catching prey small gill called derived animals ear fossils found deposits stream systems near equator suggesting benthic animal lived shallow waters water short periods skeleton indicating support body force gravity shallow water land period time deciduous plants annually leaves water attracting small prey warm oxygen poor difficult larger fish swim said likelihood limbs primarily floor streams pulled shore brief periods discovery animal pelvic announced strongly built indicating animal moving shallow water leaders team searching fossils making hypothesis animal specialized living shallow stream systems habitats ponds maybe occasionally specialized fins moving overland particularly important animal developing features eventually allow animals exploit land classification evolution species classified genus lived approximately million years ago suggest representative transition non fish known fossils million years old early known fossils million years old mixture primitive fish derived characteristics led characterize transitional fossil birds ancestor living animal serve evidence different types exist mixture fish characteristics found include traits fish fish gills fish scales fish fins half fish half limb bones joints including functional wrist joint fish like fins instead toes half fish half ear region rib bones mobile neck separate pectoral lungs phylogenetic position phylogenetic analysis placed sister taxon directly preceded inserted transitional form true missing link order phylogenetic tree initially adopted experts notably questioned paper noted derived portion closer author study considered possibility fin having evolutionary return primitive form january group including published paper accompanied extensive material discussed nature documentary showed appeared long conclusions based numerous individual discovered quarry poland origin tracks established based distinct limb morphology reflecting diagonal walk body tail drag marks wide stride relation body length fish size unusually big wide indicating body lengths track bearing layers assigned lower middle based index fossil samples zone previous data obtained underlying strata subsequent studies confirming dating skeptical said trace evidence modify theory evolution argued produced similar later study expressed significantly modified opinion lacked walking fish insisted tracks possibly formed natural processes transitional species instead authors publication suggested based available morphology animals study indicated advanced terms reconstruction identical author article claimed polish discovery theory ancestors notion partially shared number new suggested possible origin phylogenetic position including phylogenetic position remains unchanged found attributed result long ghost separating species late surviving relics direct transitional forms evolutionary dead end result parallel evolution striking similarities found evolved twice noted considered responsible uniquely features found non fish period like finger like radial bones like spine regions estimates published discovery tracks suggested appeared early ago questioned attempts read absolute timing evolutionary events early evolution data available phylogenetic position remains uncertain discovery skeletons discovered rock formed late river sediments northern canada estimated ages reported ago ago ago time species existence continent modern eastern north_america greenland centered equator warm climate discovered found sticking cliff inspection fossil found excellent condition million year old specimen discovery university_of_chicago harvard_university professor published april issue nature quickly recognized transitional form cambridge_university expert evolution said things point told exist years digging far north hit pay dirt collection fish beautifully preserved skeletons intact team studied species saw excitement exactly missing intermediate looking found split difference right middle says
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