Note for BSC 373 with Professor Harris at UA-Lecture 11
Note for BSC 373 with Professor Harris at UA-Lecture 11
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This 16 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Alabama - Tuscaloosa taught by a professor in Fall. Since its upload, it has received 23 views.
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Date Created: 02/06/15
Sarcopterygii and the Invasion of Land 2 115 i CHOANATA 5 H a p GNATHOSTOMATA OSTEICHTHYES What are the Sarcopterygii Synapomorphies Fleshy lobe supports fin Single series of bones supports Chondnchthyes Actinoptarygii Lama chammnaa nol D menmdncMus n monoaXIal rm support 3mm Skull is never as Pumimmm kinetic as in ray Tm dnmmairium Macinle dud inocqu lung structure imusingiy Wm nned fishes Pulmonary vein Lung derived from out Monaxial fins Coracoid bar g d Compare this shark n dwarf with three supports M attached to the limb girdle film tribasic n to this lungfish n which 1 is attached to the pectoral Anoclelthrurn 5 77 7 girdle and supported 39 along its length by a single row of bones Actinistia Tetrapoda True limbs Flat head and body eye orbits on top loss of dorsal and anal fins Labyrinthodont teeth 39 Separate pulmonary circulation 39 Monobasic fins with flesh lobes Actinistia Coelacanths Thought extinct since Cretaceous ca 65 mya In 1938 a living coelacanth was caught off the east coast of S Africa Others found in Comoros Islands In 1997 a new species was discovered off Indonesian coast 190 lufm warm IIIM Actinistia Coelacanths Epichordal lobe on tail fin Monaxial fin supports 34quot gt1 913 A quot m 3 v t at v 47 39 2 a quot quoty un I c x Actinistia Dipnoi Tetrapoda True limbs Flat head and body eye orbits on top loss of dorsal and anal fins Labyrinthodont teeth Separate pulmonary circulation Monobasic fins with flesh lobes PJQ39WP REV 2 mar he n Vpsllul animus Senrume and arunmnrux uncuts Camid anmn mum at m m H lul pun 39 er un39umry more PO39J39JWUV G39H can Amyr gIa uav QuantumJ bowl 3 Dru a uh H5303 DlpnOl lungfish Very little change in over 400 my of evolution Their quotlungquot is a modified swim bladder absorbs oxygenllf39 quotv 7 and removes wastes Respiration using the lungs is critical for survival i 39 lungfish can drown if they can t breathe air quot African and 8 Am lungfish survive dry season by estivation burrow into the mud and seal themselves within a M I a mucouslined burrow Fossilized lungfish burrows found in Permian age rocks with the lungfish still inside older empty burrows are known from the Carboniferous and Devonian Six living species 1 Australia 1 S America 4 Africa Three genera Australia Neoceraz odus South America Lepidosiren Africa Protopz erus Though Neoceratodus today is found only in Australia fossils ofthat genus and the related Ceratodus have been found almost worldwide in Mesozoic strata indicating that this group once had a much wider distribution So which group is closer to tetrapods Lungfish are believed to be the closest living relatives of the tetrapods and share a number of important characteris ics with them Tooth enamel separation of pulmonary blood flow from body blood flow arrangement of the skull bones and the presence of four similarly sized limbs with the same position and structure as the four tetrapod legs But both groups are so specialized that neither taxon includes the direct ancestor of tetrapods j we v39 5 Actinistia Dipnoi Osteolepiformes Panderichthyidae Tetrapoda I I True limbs Flat head and body eye orbits on top loss of dorsal and anal fins Labyrinthodont teeth Separate pulmonary circulation Monobasic fins with flesh lobes Osteolepiformes Extinct group of lobe nned sh Labryinthodont teeth teeth in crosssection that show complex infoldings Osteolepiformes Comparison of n supports K 7 Lungfish Crossopterygian Neocerotodus Eusthenopteron Note both preaxial and Note loss of postaxials postaxial elements branching from the axis Panderichthyidae Extinct group of lobe nned sh most are known only from fossil fragments but there are a few complete specimens Have more tetrapodlike characters Flattened skull with snout Eyes on top of head No dorsal or anal fin Reduced tail fin 6 i p 399 Actinistia Dipnoi Osteolepiformes Panderichthyidae aging V Tetrapoda True limbs Flat head and body eye orbits on top loss of dorsal and anal fins Labyrinthodont teeth Separate pulmonary circulation Monobasic fins with flesh lobes Now what In late Devonian a lineage of lobe ns evolved characters that would prove useful in terrestrial environments Development of free digits Increased mobility of limb joints Pelvic girdle attaching to spinal column Pectoral girdle becoming free from its attachment to the skull Vertebrae develop stronger interlinkages Zygapophyses Characters of Tetrapoda fourfeet Tiktaalik roseae Nature April 2006 Symplesiomorphies w more primitive Sarcopterygians 39 Similar body scales fin rays lowerjaw and palate bones Autapormorphies 39 Shortened skull roof dorsally placed eyes a modified ear region a mobile neck imbricate ribs a pectoral girdle and forefin capable of complex movements and substrate support and a functional wrist joint xiv Tiktaalik roseae Transition to Land Advantages to invasion of land New food resources Avoidance of aquatic predators and competitors Oxygen abundant Disadvantages Obstacles Water becomes limiting factor in distribution desiccation respiration reproduction Gravity necessitates new morphological designs 0 Water provides buoyancy and allows for good support even though it is more difficult to move through than air Water has high heat capacity 0 Most aquatic animals especially marine species do not have problems with the drastic temperature changes that occur on land Transition to Land Locomotion Modi ed axial skeleton with zygapotheses Strengthened shoulder and pelvic girdles Loss ofskull bones eeing the shoulder 39om the skull allowing a exible neck shoulder girdle supported by serratus musculature Attachment of ilium to sacral rib Transition to Land Locomotion cont Evolution of paired limbs Proximal limb elements are homologous with bones of rhipidistian early sarcopterygian shes39 ns Fins are divided into axiali preaxial and postaxial elements To make a limb from a firi the axis Ofthe limb has to curve around need an elongate laterally directed humerus and femur Some preaxials were incorporated into tne arrn and Wrist or fused With other bones Some postaxials end up as digits Transition to Land Locomotion Evolution of paired limbs a mun v s newwinning niwm in we a Ur an in stemgm Wm In Win quota at new Kelbyw umuwnnlyi my ng a hmkm Transition to Land Respiration Airversus water Arr nas nrgner 02 content 20 Xmore per voiurhe raster drrrusron 500000 X Less energy ror vehtriatroh up to 25 or totai metabohsrhrorhsh 172r0rarr breathers Arrrs not hyperr or hypotohrc ho sait garn or i055 Arr does not remove as rnucn heat Arr causes prooternswrtn desiccation structures iocated deep wrtnrn body iohg passageways rnorstunze arr Transition to Land Respiration Airversus water Stmctural adaptations Absence or rnternat griis Reductron and i055 or opercuiurh Better deveioped iuhgsthah were present rn sarcopterygrans Three chambered heart With discrete systemic and puirhohary crrcutatron Three chambered heart With separation of biood in the vehthcie Loss or scaies to aHoW ror cutaneous resprratron Transition to Land Water Balance Excretion Urea rs the pnncrpar nrtrogen ous waster Lahmeha and the nvrng iuhghsh can syntnesrze urea rn therrhvers iuhghsh use urea retentron forwater conservatron durrng estrvatron Dehydration 8th a probierh rorrnost arnpnrbrans Sense Organs Middle ear Denved rrorn sprracie Hyorhahdrbuiar freed from raw support rnodrrred to columella stapesL rnrtrany the stapes rs iarge and heavy and when rt becarne soieiy thvoived rn aertai sound transrnrssron rs questroned Evorutron or otrc notcn 7 supports a tyrhpahurh Transition to Land Water Balance Sense Organs Middle ear Vision Change in shape of lens associated with different refractive indices of air and water Reproduction Usually external fertilization eggs laid in water spermatophore in salamanders Stegocephalians tetrapods and other digitbearing vertebrates 5 etc Tulevpeiun e Veniasiega e Meiaxygnalhus e Stegocephalians Synapomorphies Loss of several cranial bones ln panderichthyids the skull was rigidly linked to the shoulder girdle by several bones that disappeared early in the evolution of terrestrial vertebrates The loss of these bones also allowed the appearance of a mobile neck that allows the head to be moved relative to the trunk This decoupling allows the head to remain relatively stable while walking Loss of the opercular bones that cover the gill chamber in bony shes The operculum was no longer needed in early choanates because they had lost the internal gills oftheir early ancestors However the operculum may have disappeared before the internal gills Coates and Clack 1991 Stegocephalians Synapomomhles cont 7 A reduclinn nllhe nnlnchnrd and a d spine The vermde cemva u1us12u 2m1uvms ave mu and sunuund the nutuchuvd e mm mm mesem m au chumates andma nevsmsm man asme mtervenebva msks wnhum cunsmctmg n gvea v m Euucephahans he came ave mck andWEv cummm quotmucth Specwa anmmamw smaces Unzrmrhyses m m neuva avches m each umev vuwmiwom asIEoLEvaRM crmwuarzmu Stegocephalians Synapomomhles cont 7 Ashnner nnlnchnrd um dues nut and hrzincase Thenu uchuvdMu eu EWuvmsExtendedumume vmmlv mm pmmaN 7 Fnur musculzrlimhs with d39screle dlglls lingers and luvs O eu epnmmshad esw nswnhe emems humumguusmme humevus vamus mna ntevmemum mnavE Vemuvmmambma and bmave mm hummuw came mm hmb ebments s uncenam and nu mans WEYE mesem m the 10 Stegocephalians Synapomorphies cont A sacral rib connecting the axial skeleton the spine to the pelvic girdle the hip This allows the weight of the body of tetrapods to be transmitted to the hind limb There was no bony connection between the pelvic girdle of osteolepiforms and their axial skeleton The loss of dermal fin rays the modified scales that support the fins This simply represents the elimination of a structure that was no longer needed and may even have been harmful on land Stegocephalians These characters did not appear simultaneously and suddenly The oldest known Stegocephalians such as Ichthyostega and Acanthostega possess intermediate conditions for some of these characters and lack others For instance Ichthyostega retained a subopercular a bone that was part of the opercular complex that covered the gill chamber of osteolepiforms Acanthostega retained an anocleithrum which is one of the elements that linked the shoulder girdle to the skull in osteolepiforms The notochord of Ichthyostega and Acanthostega extended deeply into the braincase and most of its caudal vertebrae lacked zygapophyses The connection between the sacral rib and the pelvic girdle of Acanthostega was still poorly de ned Finally both Ichthyostega and Acanthostega retain lepidotrichia in the tail indicating that these taxa still had a caudal n Acanthostega New fossil evidence indicates that first tetrapods were more aquatic than once thought Acanthostega Upper Devonian First complete tetrapod with free digits eight quot on each hand 39 Based on recent reports the limbs and gross morphology of the basal form Acanthostega were unsuitable for overland travel Instead Acanthostega probably propelled itself along the bottom with its limbs or held itself motionless in wait for an ambush Retained some sh like characters 39 Internal gills tail n partial connection between skull and pectoral girdle labyrinthodont teeth lateral line ulna shorter than radius Acanthostega lchthyostega Stmttat to Acanthostega but Strunger hmbs radtus and utrta Elf eduat tengm Nu gtHstn adutt Reduced number Elf skutt bunes Reta tns skutt We Pandertchthytdae tatt m tabyrtnthodontteeth taterat 7 H e Ftrsttetrapod capabte ot ttte on tand tmportantcharacters Fecturat gtrdte nu tunger attached tct skuH Fetvtc gtrdte ts attached tn vertebrae Seven tues Dn htndhmb Reduced number Elf bunes tn SkuH Ichthyostega FISHUKE TERRESTRVN lNTERMFDlKTE arhculallnp expanded nbs mum Hot In cotltacl wtttt a venetuae 39ott Oldt dermal rays Inpatttte petwc girdle lateral prer amp sut tine upemular lettunud 1mm medtatt 1m nt tympamtm I 1 m icht 0519 a lateyDev 9 cos old states 12 Why move onto dry land Old theory sh were living in habitats that dried up survivors were the ones that crawled to new ponds 7 Natural selection for limbs 7 Buta problem with this scenario is thatthe Devonian is no longerviewed as having been seasonally dry 7 Pius early tetrapod limbs couldn39t supportthe anirnai on land New theory Acanthostega and other early tetrapods had fully formed limbs but never ten the water 7 Limos were useful quotartertne factquotf0rrnoving onto land but originally had a oirrerent runction Any Living Analogues Frog shes use their modi ed pectoral ns for support and to move themselves around on the bottom Frog sh can even gallop in short bursts Then what Early tetrapods diversi ed into an astounding variety of evolutionary lineages and species during the Mississippian and Pennsylvanian periods Interrelationships ofthese lineages are not well understood Most are extinct Fossil record i5 poor One lineage included the ancestors ofthe Lissarrphibia the living amphibians Another lineage the Anthracosaurs led to amniotes reptilesquot birds and mammals 13 Stegocephalians Animate reptiles mammals biids dinosaur etc Suleiiudunsamus Living Amphibians frug salamander and caecilians Lysmopma Microsami Neclridea Aislupuda Adelugyrimdae Wesllulmana A Luxummalidae Tlllerpelan Hyneypemm Melaxygnalhus e Additional Fossil Evidence Tulerpeton and Hynerpeton these two tetrapods were more adept on land than lchthyostega Had six toes Hynerpeton bassetti is the first Late Devonian tetrapod discovered in mainland North America It is also one of the earliest known tetrapods found anywhere in the world Additional Fossil Evidence Crassigyrunus Aquatic stemtetrapod notable for combining bizarre specializations such as tiny forelimbs with a number of primitive features such as the palatal construction 14 Stegocephalians Ammula reptiles mammals buds dlnusaurs etc Ammawsm I E Bladecwmww r Suleimdunsaums meg Amphibians frug salamander and caeclllans Lysumpma Mlclusaurla Necmdea r Alslupuda Adelugyrlmdae Wesllulmana Sewnuuuamamnu Embulumell r Gephymslegldae Whalcheerla Temliosgundyll r Culusleldae r Luxummalldee r Crasslgyrmus e Tlllerpelun Hynevpemm lchlhyoslsga e m l Venlaslegay Melaxygnalhus e Elgmerpelun Additional Fossil Evidence Seymouriamorpha A small but widespread group of early terrestrial choanates opening between the nasal cavity and nasopha rynx Originally believed to be closely related to amniotes or even to represent the most archaic amniotes But discovery of larval seymouriamorphs with external gills contradicts this hypothesis Have long been considered amphibians simply because they are not amniotes and all nonamniotic terrestrial vertebrates were considered amphibians before classifications were modified to include only monophyletic groups However seymouriamorphs are not closely related to lissamphibians and are not amphibians in the modern sense of this word external nans choana lrnaxma M pamhne g vomer 15 Hm
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