order greek eagle extinct order heavily armoured large sized late small heads erect limbs body covered plate like belong family distinct subdivisions currently recognized based primarily differences morphology bony groups genera described recently controversy description genera fossil remains known europe parts africa india armoured plates preserved abundant certain serve important late index fossils wide geographic ranges ranges relatively short presence particular accurately date site found remains found early 19th century remains described mistaken fish scales later recognized relatives early considering considered entirely terrestrial animals forms characteristics adaptations digging food evidence nests description head small relative large body distinctive shape flat blunt like snout pig teeth shaped small leaf like indicating probable diet like teeth snout considered possible adaptations species feeding colonial insects study shown similarities indicate close relationship pillar erect erect limb posture similar seen related group pillar erect limb posture vertically hip angled downward leg positioned beneath body acts pillar bearing weight limb posture similar feet resemble like retention primitive characteristics smaller hind limbs heavily armored certainly defense predators large bony plates protecting sides belly tail heavily pitted upper surfaces smooth centers bone called outer portions compact bone life plates probably covered horn dorsal found backs radial grooves dorsal found animal wide small boss called dorsal dorsal surface plate plates raised depressed anterior edges plates articulate ones anterior edge raised area called anterior bar depressed area called anterior lateral plates positioned plates dorsal enlarged prominent spike spike especially noticeable useful taxa species identified individual based ornamentation pattern primitive genera like widespread genus tended small metre length advanced forms larger metres length taxa possessing broad turtle like bodies like narrow bodied genus metres long equipped large spines shoulders added animal defensive armament history material described swiss named genus scotland considered fish considered strata age large scales thought arranged similar pattern thought supposed scales similar lobe fish large size english biologist fish scales described considered belong proposed went detail paper society quarterly journal time new material uncovered indicated fish known primarily preserved complete remains found lower germany 1870s complete articulated skeletons specimens found large sandstone near preserved area square metres size animals probably buried lake sediment soon died flow water bodies lake bed putting close proximity german assigned specimens newly erected genus named genus skull resemblance head eagle narrow skull pointed snout north_america described time american named new_mexico cope considered genera like aquatic common late new material found recent years american southwest longer considered valid cope later recognized remains type species actually belonged species reassigned north american genus called named marsh long time rivalry cope famous bone wars late 19th century tried compete field scientific literature unlike cope found eastern united_states connecticut marsh recognized initial description genus like cope tended consider belong time period named english naturalist zoologist considered order group group including post time cope considered belong order reptiles includes living thought tightly fitting thought fused ribs indicated transitional turtles placed single family considered similar living apart elongated compared fact marsh considered closely related similar material continued described early 20th century notable collecting specimens remains confused time usually considered members obsolete group consisting including similarities observed group initially referred 19th century skull features common parts skeleton particular similar distribution fossils found continents australia antarctica giving nearly worldwide distribution late remains found southwestern united_states fossils found arizona new_mexico texas remains found utah particularly national park known east_coast united_states states connecticut north_carolina genera known greenland found land known africa having found late formation morocco late morocco close proximity possible present africa fossils found algeria referred genus south american found argentina brazil chile argentina known common genera include brazil fossils found chilean represented genus found india south_america late early descriptions included material south central india inadequate assign specimens particular genus based descriptions indian closely resemble reports madagascar based probable belonging associated found brazil italy germany eastern united_states common southwestern united_states having found national park tracks narrow gauge meaning left right prints placed closely nearly functional analysis skeleton indicated range movement necessary produce tracks classification taxonomy belong clade includes living characterized distinctive structure ankle bones traditionally referred obsolete group called included primitive relatives lived rise later placed group called included later including originally considered members family early phylogenetic analyses split characterized projections called dorsal close distinguishing characteristics including grooves dorsal help lock lateral plates tight long spikes projecting lateral plates spikes especially prominent hand tend spikes smooth lack spikes altogether recent studies favored group like long spikes differs having sharply angled joints genus classified outside non making names longer synonymous genera phylogeny phylogeny investigated included phylogenetic analysis found form clade termed included living belong found group true clade consisting common ancestor descendants define identified shared characteristics concerned jaw tip wide form bone lower jaw broad reduced size simple conical shape teeth considered shared considered indication close phylogenetic relationship body covered dorsal ventral armor form complete wider long distinctive pitting final found structure limb bones limbs robust large muscle crest fourth ridge phylogenetic analysis found basal member clade earliest recent common ancestor smaller unknown clade diverged group clade containing included clade containing later study expanded number new included temporal holes opened skull lateral covering limbs found basal member phylogeny derived differed split different sister taxa respectively importantly new called included analysis found basal closely related appeared early fossil record previously basal members known later times occurring advanced examined previous phylogenetic studies criticized way certain characters produce concluded relationships previous studies true basal sister taxon closely related went correct trees previous analyses recently analysis resulted larger tree inclusion based tree parker defined parker gave revised phylogenetic definition mentioning previous definition lucas somewhat ambiguous defined stem based taxon claiming included closely related immediate sister group immediate sister group uncertain parker offered new definition non genera sister group according parker included taxa closely related parker conducted new phylogenetic analysis included newly described parker new genus named phylogenetic analysis study found grouping group share recent common ancestor ancestor non form clade parker analysis accepted definition lucas defined stem based taxon containing taxa closely related common ancestor study placed base clade traditional taxa placed derived positions analysis taxa actually closely related lucas definition restricted finding study lies outside phylogeny correct equivalent non following simplified analysis presented evolution known exclusively late currently accepted position phylogeny indicates originated basal early middle given highly specialized features seen group evolutionary origins poorly understood recent discovery complete specimens late indicate close ancestry phylogenetic analyses place sister taxon closest relative like rows cheek region skull fits groove bone phylogenetic analysis places middle sister taxon potentially making earliest known stem stem meaning lies branch includes stem described beds differs having long skull small fits large eye sharp curved teeth covering body like fits unnamed good fits ancestor double rows leaf shaped backs potentially evolved tightly fitting early interpretations american described aquatic animals order mentioning constitutes independent order probably freshwater short long forms analogous habits modern early remains found skeletons aquatic animals terrestrial animals led believe animals died environments large number skeletons animals normally inhabited swamps suggested animals trapped swamps died doubts later raised lifestyle teeth little indication weight armor suggests passive mode life regarded partly aquatic mid-20th century feeding likely feeding seed common shape snout suggests dug roots features adaptations digging including short radius relative seen digging large crest served attachment muscles large hind feet large claws likely digging origin manual muscles digging large process projects backward past elbow giving large area muscle studies suggested lifestyle characteristics animals adaptations digging likely able dig extent possibly food unable features limbs indicate probably dug food features skull teeth indicate kind food eating derived features seen indicate adapted different diet unlike sharp teeth simple conical teeth tips jaws probably supported teeth little wear suggesting consume stiff tough plant material likely consumed non vegetation soft leaves alternative theories proposed diet proposed based close proximity specimens large number skeletons likely study jaw south american genus suggested animal fed larvae insects hard lacks wear teeth jaw leverage designed strong forces crushing study recognized northern jaws supported strong likely better suited eating plant material nests built nests protected eggs discovered million year old bowl like nests arizona oldest nests found belonged nests appear similar nests modern day guard nests nests holes dug sand bank ancient river second possible nest site known northeastern italy nests preserved depressions rock circular shaped high ridges sides appear unusually complex nests created reptiles found nearby resembled present layer tracks found close nests likely built growth ages individual determined examining isolated claimed belong juvenile based size shape questioned example juvenile later identified small bodied juvenile relatively small body size maturity studies bone structure indicate new bone deposited edges plate course lifetime means lines arrested growth determine individual age comparing ages individual specimens total body lengths indicates increased length relatively constant rates increased body mass different rates depending wide bodies like narrow bodies like grown slowly modern analysis limb bones indicates grew quickly young slowly adults pattern growth seen species typically restricted fossil ranges abundant strata found useful common remains associated single identifiable accurately date layer found define land land time interval defined appearance occurrence index fossil commonly date late early terrestrial strata beginning stage starts beginning million years ago ends happens start genera developed dating strata southwestern united_states genera known occurring multiple short time spans recognized based presence number grew study lucas occurred included genera naming controversy new_mexico accused published articles dealing late genus erected replacement museum bulletin years earlier reassigned newly named genus unpublished thesis published considered described authors paper accused intellectual theft claimed knew parker eventually going species formally erect new genus according taylor authors rushed publish parker publish controversy occurred hunt lucas published paper mentioning left right came conclusion unpublished thesis taylor claimed form allegations brought attention response given regard found involved case try resolve issue entire controversy came known reference famous scandal 1970s received wide attention local newspapers science focus news article issue journal nature
Aetosaur