small fauna small fauna small fossils abbreviated fossils millimetres long nearly continuous record latest stages end early period diverse formal definition small fauna small fossils earlier rocks familiar fossils preserved covered quickly method preservation mainly limited late early periods animals actually arisen earlier persisted time span fossils represent entire skeletons small organisms including mysterious like bulk fossils fragments remains larger organisms including like like organisms close ancestors early explanations appearance evolution skeletons suggested sudden increase ocean concentration calcium constructed minerals appear time organisms started avoid predation likely represent early steps evolutionary arms race predators increasingly defended prey hand skeletons evolved simply stronger cheaper produce organic skeletons like insects true animals minerals easily accessible small size nature makes difficult identify classify provide important evidence main groups marine invertebrates evolved particularly pace pattern evolution explosion including earliest known representatives modern great advantage presenting nearly continuous record early organisms bodies include hard parts history discovery term small fossils coined says small commonly term equally apply pleistocene unable better term frustration parodies small silly fossils small term abbreviated small great majority morphological features later shelled organisms appear attempted formal definition small fauna small fossils similar phrases specimens rich collections fossils discovered drew conclusion early contained diverse range animals addition traditionally recognized etc late 1960s soviet discovered richer collections beds earlier containing unfortunately papers described discoveries russian paper brought attention non russian reading world vigorous debate early evolution animals argued process explosive early 1970s developed theory punctuated views evolution long intervals near punctuated short periods rapid change hand time argued animal kingdom long history hidden lack fossils occurrence rich collections found china australia antarctica moderately diverse ones india pakistan iran europe north_america different views time range russian discoveries late 1960s assigned age period time term small fauna applied age hand includes fossils like post fossils like found layers contain fossil mass extinction end period age thought wiped exception mode preservation small fossils typically preserved whilst originally cases represents replacement original usually extracted limestone placing limestone weak acid typically acid fossils remain rock dissolved away preservation common early result increased disturbance sea floors animals fossil forming mode small fossils preserved impossible extract rock animals produced fossils lived early apparent extinction end illusion decades thought armor plates common type perished end mass extinction armor plates reported mid rocks australia good million years recent minerals shells small fossils composed variety minerals important calcium calcium minerals organism influenced chemistry oceans organism evolved continue ocean chemistry changes example period age animals calcium form called hand animals appeared following age form recently discovered modern lives near deep sea illustrates influence earlier contemporary local chemical environments shell found earliest fossil armor plates sides foot iron previously found ingredients emitted large quantities methods constructing shells vary widely cases exact mechanisms known evolution skeletons production parts organisms explain evolution include adaptation changing chemistry oceans defense predators opportunity grow larger functions vary understood components armor skeletons skeleton fairly rigid structure animal joints skeletons definition skeletons provide wide range possible advantages including protection support attachment surface platform set muscles act traction moving surface food handling provision chambers storage essential substances suggested evolved response increase concentration calcium seas happened boundary main benefit store minerals disrupted organisms internal processes example suggested increase length food chains contributed animals higher food chain accumulate greater amounts waste products relative size way excess consumed prey skeleton fairly expensive way dispose safely excess minerals main construction cost organic matrix proteins minerals combined form composite materials idea response changes ocean chemistry undermined fact small fossils calcium appeared virtually simultaneously range environments organisms started avoid predation time suggested skeletons defense predators marking start evolutionary arms race cited example hardened defenses time fact earliest protective skeletons included collections objects example early worm built tube covered strategy required adaptations allowed organisms collect objects moderately sophisticated nervous systems behavior hand argued skeletons arose engineering reasons defenses defensive strategies available prey animals including mobility acute senses chemical defenses mineral organic stronger cheaper build organic skeletons advantages possible animals grow larger cases muscular animals certain size larger muscles greater leverage produce forces organic skeletons rigid withstand development modern includes progression organic mineral organic composite shells clue evolutionary development evolution rigid started arms race predators developed drills chemical weapons capable penetrating shells prey animals developed heavier tougher shells etc suggested explanation appearance start evolved flourished cold waters slowed left insufficient spare energy signs global warming start easier similar pattern visible living marine animals skeletons fragile polar waters tropics evolutionary significance locations fossils holes thought predators similar fossil found locations affected addition distribution suggests selection size largest holes appear largest shells evidence selective attacks predators suggests new species arisen response predation presented potential cause rapid animals early small provide relatively continuous record early provide useful insight explosion instances exceptional preservation difficult identify assigned positions modern taxa stem groups evolutionary cousins enable scientists assess pattern speed animal evolution strength small evidence assessment shows earliest small basal time goes placed stem group smaller clade words earliest small tentatively considered words main tissue layers later convincingly higher animals subsequently fossils placed stem group looks recent arguments stem group stronger assigned crown group modern gives impression animals late basal members later subsequently appearing rapid orderly fashion sudden reveals true pace explosion types small fossil forms collections period limited range forms fully partially tubes common form mixed collection structures compositions walls vary widely specimens classified members wide range including tube millimetres long consisted calcium left gaps built long thin tubes flexible probably ridges probably coral like organism built dwellings metre calcium spines star like combinations spines thought remains closely related built like dwellings millimetres long type shape known test test biology means roughly spherical shell forms finds early tubes abundant diverse new types appear attributed known groups like like organisms close ancestors multitude problematic tubular fossils characterize earliest small skeletal consists fragments external armor early animals scale worms fairly complete assembled sets rare called cases body shapes creators distribution bodies known coat mail generally animal died fragments dispersed elements usually relies fully articulated fossil found exceptionally preserved discoveries turn enable sense similar fragments labelled type called shell space originally filled organic tissue evidence growth clear evolved independently different groups animals inherited common ancestor produced spine shaped complete specimens animals shaped cap shaped shell plates ends addition produced star shaped composite known animals looked like described internally like closely related calcium calcium wide range shapes internal structures fact represent set words independently developed common ancestor hand closely related ancestors modern animals sight look like stand internal anatomy different small pieces debris regarded remains include tooth shaped hook shaped plate like objects unknown origin known including produced animals looked like worms legs thought close ancestors shells fairly common cap shaped shells thought covering creators known parts complex armor system like thought early somewhat like shells horizontal exhaust pipes concave edges shells debate pointed forwards backwards left small conical shells animals worm like shells found canada shells found parts joined include fossils found resemble close openings armor attributed small animals conical shells worm like small like shells found early beds china fossils represent spines snapped post forms start pick recognizable modern groups mid majority simply represent
Small shelly fauna