Maria Sanchez-Elias

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MariaSanchez-Elias

Assignment3

EvolutionaryBiology

29March 2017

CoverLetter

Iam delighted to submit a research study entitled “The FlappingFlayer that did not Stand the Test of Time: Understanding why theSingle Spar Wing of the Pterosaur did not Survive evolution.” Thecompleted draft addresses many factors related to pterosaurs and whatmight have led to their extinction. Although the draft paper providessome information about the factors associated with the demise of thepterosaurs, it has some weaknesses and strengths. The strengths ofthe draft included inclusion of information about factors that led tothe demise of pterosaurs. They included the morphology of thepterosaur’s wing and competition over resources with other animalsin the environment. The draft successfully described how themorphology of pterosaur’s wings influenced their ability to flylike other flight animals. On the other hand, the draft has someweaknesses including providing insufficient information aboutadaptation of pterosaurs. The information provided shows that onlycompetition and wing morphology impaired with the survival ofpterosaurs. However, I am confident it will meet the requiredstandard of a good term paper.

Thankyou in advance.

Yourssincerely

Outline

  1. INTRODUCTION: The Flapping Flayer That Did Not Stand The Test Of Time: Understanding Why The Single Spar Wing Of Pterosaurs Did Not Survive Evolution

  1. A brief explanation of the three groups of flying vertebrates

  2. Reasons pterosaurs did not adapt to the environment similar to birds and bats

  1. BODY

  1. Detailed explanation about the taxonomic, morphological, and physiological features of pterosaurs

  2. Detailed explanation on the similarities and differences between pterosaurs and other flying vertebrates.

  3. Detailed information on the morphology of pterosaurs’ wings and competition from birds led to the demise of pterosaurs

  1. CONCLUSION

  1. A brief summary about pterosaurs, their similarity with other vertebrates, and factors that led to the demise of the pterosaurs

  2. Discussion on what should be done to improve what is known about pterosaurs

  3. Discuss missing elements to research that would be essential for further studies on the flight and extinction of pterosaurs

Understandingwhy the Single Spar Wing of the Pterosaur did not Survive Evolution

Abstract

Pterosaursare flying vertebrates that existed many years ago. These vertebrateshad unique flight morphology that enabled them to fly just like batsand birds. Unlike bats and birds, pterosaurs became extinct withtime. Some of the reasons attributed to their extinction include themorphology of their wings, adaptability to the environment, andcompetition from bats and birds. The research paper expounds on thepterosaurs, explaining some of the taxonomic, morphology, andphysiological characteristics. The study employs diverse literaturematerials to expound on some of the similarities and differencesbetween these flying reptiles with birds. In addition, the studyprovides detailed information on the factors that influenced theirdemise from the world. The study concludes with the recommendationfor more studies on the factors that might have triggered theirextinction as well as detailed research on the morphology of thepterosaur’s wingtip.

Understandingwhy the Single Spar Wing of the Pterosaur did not Survive Evolution

Theworld of flying vertebrates breaks down into three groups bats,birds, and pterosaurs. However, most people know only two types offlying animals bats and birds. These groups have different modes offlying that determine their survival. The largest known flyinganimals in the world today are birds. Most birds are moderate in sizewhich is essential for their locomotion. Despite this, there are somelarge birds such as the ostrich that do not fly probably because oftheir weight (Hone and Buffetaut 2008). Bats are mammals that aresmaller in size than most birds, and they fly through their developedpowered flight. Pterosaurs are brought about by paleontologists whoargue that there existed flying reptiles many years ago (Prentice,Marcello, and Benton 2011). According to them, these giant flyinganimals were vertebrates with locomotors and physiological featuresrelated to those of birds. The majority of the flying animals thatare extinct today were incredibly huge (Middleton and English 2015).The wings of some of those biggest beasts exceeded the size of thebus. The advantages of the large wings included flying long distancesto collect food (Hone and Buffetaut 2008). These wings howeverrestricted the flying giants from accessing dense forests. In fact,biologists associate the extinction of the flying giants with thepoor accessibility of food. The research study aims at explaining whythe single spar wing of the pterosaur did not survive evolution. Inaddressing this, the paper will provide detailed information aboutpterosaur, the difference between pterosaur and birds and bats, andhow physiological features in addition to competition led to theirextinction.

Pterosaursare flying animals that existed in the Late Cretaceous period(Silverstone, Witton, Arbour, and Currie 2016). These vertebrates arerenowned for having very long wings. The wingspan of the largestpterosaurs such as Arambourgianiaphiladelphiaeand Hatzegopteryxthambemaexceeded ten meters. The smallest pterosaurs like Montanazhdarchominorand Eurazhdarcholangendorfensishad wingspans measuring between 2.5 and 3 meters (Silverstone,Witton, Arbour, and Currie 2016). The flapping flight of animalsfirst developed in pterosaurs. In addition to wingspans, pterosaurhad a ribcage characterized with a big ossified sternum in additionto unique vertebral and sterna ribs. They lacked intermediate ribswhich are common in basal lepidosaurs as well as extant crocodylians,regulating its thoracic movement over not only the archosaur, butalso the conditions referred to as basal amniotes. The sterna ribs ofpterosaur were irregular in shape and its posterior facets exhibitedlarge increase in length. Just like in birds, the pterosaur’ssternum slanted posteroventrally. As a result of these morphologicalcharacteristics, a greater displacement took place in the posteriorregion of its sternal (Claessens, Connor, and Unwin 2009). The sternaribs of pterosaurs had sternocostapophyses lengthened theintercostals muscles’ moment arm, increasing the sterna ribscapacity for adequate lung ventilation. The features of theseprojections correlate with that of uncinate in birds. However, theirmechanical advantage differed from that of uncinate processes inbirds. Unlike uncinate that are located on vertebral ribs,sternocostapophyses are attached on the sterna ribs. Moreover, thereare many sternocostapophyses projections in every sternal ribcompared to the singular uncinate process in birds (Claessens,Connor, and Unwin 2009). Just like uncinate in birds,sternocostapophyses projections lowered the breathing function of theintercostals musculature, allowing displacement of the sternal.Unlike in birds, the greatest importance of the projections occurredin the ventral region instead of the dorsal thoracic region.Pterosaurs had air sacs like birds. These air sacs played asignificant role in their movement since they reduced their density,boosting their ability to fly.

Pterosaursare the only vertebrates that exhibited pneumatization of what isreferred to as postcranial skeleton. This process is associated withthe opening and formation of excavations in the animal’s bonesthrough inversion of the respiratory epithelium in some parts of thepostcranial skeleton. According to Claessens, Connor, and Unwin(2009), the pneumacity of the animal’s vertebral column is commonin all types of pterosaurs but varies in different groups. A recentstudy on the largest pterosaurs, which include the Cretaceous taxasuch as Quetzalcoatlusnorthropi,shows that these animals were elongate with edentulous jaws. Theirnecks were not only long but also cylindrical (Naish and Witton2016). Naish and Witton also claim that the necks of the pterosaurswere made of nine vertebrae. However, there is also evidence for theexistence of pterosaurs with proportionally short necks. The extremeneck length of most animals is mostly associated with thedisproportionate increase in cervical vertebrae size. According toNaish and Witton, the neck bones of larger animals are elongated,influencing their neck length. However, the cervical vertebrae ofpterosaurs seemed not to change with the increase in neck length. Inaddition, large pterosaurs have long tails. The long tails and neckincreased their stability. These features are also claimed to havereduced their maneuverability in restricted areas (Hone and Buffetaut2008).

Justlike ducks, pterosaurs were filter feeders. The assertion isevidenced by their jaws and comb dentition (Zhou et al. 2017). Someof the pterosaurs such as Gnathosaurushad long rostrum with approximately 128 to 136 sharp teeth. Inaddition to this, Gnathosaurushada rostral tip that was shaped like a spoon with large projectingteeth (Zhou et al. 2017). The jaw structure as well as the morphologyof the teeth allowed Gnathosaurusto filter their foods including crustaceans together with other smallanimals from water. Similarly, Ctenochasmahad a long rostrum, covering about 64 percent of its skull, withabout 200 to 552 sharp teeth. Such teeth were efficient for filteringtiny animals from water. Pterodaustroalso known as ‘flamingo pterosaur’ had a very long skull. Itsrostrum covered approximately 85 percent of its skull and was curvedupwards. Pterodaustrohad more than 1000 teeth that were cluttered together. It had alsoflexible bristles at the lower jaws for sieving small organisms fromopen water (Zhou et al. 2017). A close look at the morphology ofpterosaurs’ teeth leads to the conclusion that the flying reptilesdepended on their long rostrum in addition to a curved rostral tip inaccessing food. The high number of teeth in their mouths enabled themto grip tight on the captured animals. Equally, the needle-like teethdefined their mode of feeding. With such teeth, pterosaurs couldcapture smallest organisms from water.

Oneoutstanding feature of the pterosaurs is the wing. The main wing ofthis vertebrate is claimed to have formed from a membrane that wasattached to a massive middle finger of its hand (Hone, Rooijen, andHabib 2015). However, the flight capability of these animals wasattributed to a part of the wing, wingtip. According to Hone,Rooijen, and Habib, the shape of the wing plays a critical role asmuch as the flight is concerned it affects how the wing functions.Apart from affecting stall thresholds and the efficiency of vortexshedding, the shape of the wing affects gust load alleviation inaddition to other factors (Hone, Rooijen, and Habib 2015). Pterosaurssuper-elongate finger is thought to be straight. Although one canargue that the wing metacarpal, as well as its phalanges is straight,the phalanx on which the wing is attached deviates from posteriorbend throughout its length. The fourth wing of the pterosaurs ischaracterized with a blunt surface with a sharp edge (Prentice,Marcello, and Benton 2011). Also, it has a posterior extension thatmatches with one of its phalanx (Hone, Rooijen, and Habib 2015). Aclose look at the pterodactyloid known as Anhanguerashowed that pterosaurs had phalanx that were triangular in shape atthe point of intersection and oval the entire length. The bone of thepterosaurs tapered at the initial point and remains constantthroughout its diameter. The posterior midline of pterosaur’s bonehad a groove that modified the shape of the wing into a C-shape. Thisgroove is claimed to occur specifically in areas associated withtensile strength just like the ventral grooves in bird’s rachis(Hone, Rooijen, and Habib 2015). The grooves help the bones of thepterosaurs resist bending and as a result bring about a spanwisetwist of the animalss wing as well as restrict bending. The spanlocated on the distal phalanx smaller pterosaurs and largerpterosaurs vary significantly. In smaller pterosaurs, the span may beextremely short. For instance, it measures about 17 mm in the adultbelonging to Jeholopterusand about 10 mm for a young Pterodactylusantiquus.Some, however, can be as long as 330mm like that in Coloborhynchuspiscator.

Thewings of pterosaurs are complex structures made up of many types oftissues organized in layers. Apart from two epidermis layers,pterosaurs have one or many stratums of stiffening actinofibrils, alayer of a blood vessel in addition to a muscle tissue fascia layer(Hone, Rooijen, and Habib 2015). Actinofibrils are more concentratedat wingtips, leading to the formation of densely packed fibers at thetips. The tip of pterosaur’s distal phalanx had a soft tissuestructure to prevent the collapse of wing as well as prevent thedistal end from dragging.

TheSimilarities and Variations between Flying Vertebrates

Asit was noted before, pterosaurs had different wings that enabled themto be differentiated from other types of Mesozoic archosaurs(Hazlehurst and Rayner 1992). Their membranous wing in addition toelongated forelimb mainly on the fourth finger distinguished themfrom other Mesozoic archosaurs (Palmer 2010). The wing variation ofpterosaurs, however, is not that much to differentiate them from thatof bats and birds. Considering this, it is apparent that there aresome similarities between pterosaurs’ wings and that of bats andbirds. The need to ensure the flight design best fits a specificanimal for its living style leads to convergence in the proportionsof wings for animals despite them coming from different phylogeneticbackgrounds (Hazlehurst and Rayner 1992). Although the underlyinganatomies of birds, bats and pterosaurs vary, they all operate in thesame environment, same mechanical, and produce mechanical forcethrough a similar aerodynamic mechanism (Hazlehurst and Rayner 1992).Some people argue that the morphological characteristics of bats’wings are related to those of pterosaurs’. However, many studies onpterosaurs compares these extinct flying reptiles with birds. Thecomparison of flight characteristics and ecological factors ofpterosaurs with birds are considered the best since birds are largerin size when compared with bats. A good number of authors have foundout that pterosaurs have a birdlike wing. For instance, thecomparison of hamphorhynchuswith gulls, frigate birds, and swallows showed the similarity of somewings. Similarly, the comparison of Pteranodonwith birds referred to as frigate birds showed the similarity of somewings. Many researchers have also associated pterosaurs with onlygliding. However, it was noted that they are also capable of soaring.The claim is backed by the gliding in addition to soaring ability ofPteranodon(Hazlehurstand Rayner 1992). Like the large birds today, gigantic pterosaursprobably soared through the energy generated from moving air ratherthan their flapping fight. This might have been influenced by themetabolic power requirements of animal’s flight. As a flying animalincreases in size, the metabolic power required for flight becomes asignificant part of that animal’s energy budget. Thus, huge animalsare likely not to fly because their flight muscles cannot generatethe required power (Hazlehurst and Rayner 1992). However, studieshave shown that the pectoral girdle of most pterosaurs wassufficiently strong to withstand the forces associated with flappingflight (Hazlehurst and Rayner 1992). Some studies have also reportedconvergence between pterosaur’s shoulder girdle with that of thebird, evidencing not only complex physiology but also an extremestructural modification of the flight surface as well as forelimb(Hazlehurst and Rayner 1992). The ability of the pterosaurs to fly islinked to the generation of a net thrust like birds and bats. Justlike bat and bird’s wing, pterosaur wing created “concertinawake” through reducing upstroke wingspan (Hazlehurst and Rayner1992).

Initially,it was noted that pterosaurs had air sac system. Just likepterosaurs, birds also have air sac system that lowers their densityto enable flight. Considering this, one can assume that the air-sacsystems of the two types of animals were similar. The pectoralmusculature of these animals is also believed to be similar. Largeportion of these animals’ muscles lay on their shoulders. In birdsas well as in pterosaurs, the pectoral musculature is approximated tobe about 15 to 20 percent of their total mass (Hazlehurst and Rayner1992). The long bones of many small-sized pterosaurs correlated withthose of birds. However, gigantic pterosaurs had large bones thatwere hollow to cut weight. Thus, lightening the skeleton of giganticpterosaurs was the solution to mass increase with the size issue.

Despitehaving some morphological similarities, pterosaurs evolved at adifferent time with bats and birds. These animals evolved theirflapping flight autonomously for the about 200 million years ago.Since ecology as well as wing morphology of pterosaurs, bats, andbirds overlap, some competitive exclusion might have influenced theirsurvival. Considering this, it is possible that some ecologicalcompetitors declined while others increased regarding taxonomicdiversity. Macgowan and Dyke refer to this type of modification‘double wedge’ (Macgowan and Dyke 2007). The current coexistenceof bats and birds may make one think that competition among flyinganimals, specifically vertebrates, never existed. However, thesuccessful coexistence of bats and birds is as a result ofsubdivision bats are active at night whereas birds are active duringthe day. With such kind of lifestyle, bats and birds do not competefor resources. While bats accessed their foods at night, pterosaurswere active during the day. Thus, their extinction might have beeninfluenced by the survival of birds. Birds and pterosaurs lived inthe same environment. Although studies show that the niche exploitedby pterosaurs has not been utilized by birds, the similarity in typesof foods consumed by these birds shows competition might haveinfluenced the extinction of pterosaurs. Macgowan and Dyke (2006)argue that the disappearance of pterosaurs did not open up new nichesfor the current flying animals. The claims show that the survival ofbirds might have been as a result of their ability to granivory. Theyalso relate the diversity of birds with the evolution of what isreferred to as secondary flightlessness. Thus, the inability ofpterosaurs to exploit granivory like birds as well as theirrestricted evolution contributed to their extinction.

Pterosaursalso had some physiological and morphological features that differedfrom those of birds. For instance, they were heavier than birdsbecause of the mass of bones and the size of their bodies. Apart frombody mass and huge size, the morphology of pterosaur’s wingdiffered significantly from that of bats and birds. Unlike bats andbirds, pterosaurs had a flexible as well as membranous wing which wassupported by a middle super-elongated finger. Pterosaur also had awingtip that played a critical role to its flight pattern. Itrelieved the pressure of any single spar wing structure (Hone et al.2015). The strength of pterosaurs wing, however, could have beenweaker that of bats and birds. The is backed by the assumption thatpressure on the outer part of pterosaurs wing could cause an overbending or micro fractures within the single bone that supports thewing, thus not lending itself to the longevity of the wing (Hone etal. 2015). An assumption that can be made about the pressure that canbe placed on the wing is that bone flexibility, as well as theirshape, influenced the success of flight (Hone et al. 2015). Theflight bone of pterosaurs is also cited to have had a groove. Thisfeature is evident in the flight bone of pterosaurs mainly. Also,studies show that pterosaurs had curved bones with grooves, allowinggreater tendency to twist with the load. This is because the curvemakes an effecicient moment arm therefore, rotating or turning underair pressure from the wing can lead to washout (Hone et al. 2015).Washout means there is a twisting of the wing that reduces drag atthe edge of the wing, preventing stalling. These effects areespecially important for animals that use flap as a means of flyingsince the movement of their distal wing bypasses that of the proximalwing at the time of takeoff as well as acceleration. Based on this,it is evident that pterosaurs benefitted from some wingtip curvaturesince it rounds out their wingtip while flying. Competition fromBirds and Bats and Updraft Limitation

Oneof the reasons attributed to the lack of morphology in pterosaurs aswell as bats is that their wings are attached to the lower limb(McGowan and Dyke 2007).Unlike pterosaurs and bats, the attachment ofa bird’s wing occurs at the upper limb, allowing greaterdiversification. The lower limb attachment of the wing in pterosaursresults in a more difficult variation in body size and shape, whichis contrary to the bird’s wing attachment. When looking at themorphology of bats, fossil records show that their bodies haveundergone slight changes. In fact, the oldest fossil of bats presentsbody types that correlate with that of bats today with insignificantchange (Simmons and Geisler 1998). Birds, on the other hand, have arange of size, shape in addition to other adaptations that haveevolved continually to this day. Based on this, it is apparent thatlack of morphology did not contribute to the extinction ofpterosaurs.

Withthe concept of aerodynamics, one could expect pterosaurs to survivetoday. The vertebrates had large wings that exceeded their body mass,allowing them low loading. With such wings, pterosaurs flew withoutusing a lot of energy. For instance, R.longicaudus,as well as R. intermedius and all Pterodactylus species, benefittedgreatly from their small size and large wings. The maneuverability ofthe majority of small sized pterosaurs was also excellent because itwas maximized by their small size in addition to low loading(Hazlehurst and Rayner 1992). The aerodynamic efficiency levels ofpterosaurs were also high when compared to that of birds and bats.This is in relation to the fact that they benefitted from lowtransportation cost brought about by low loading in addition to highaspect. As it was noted before, pterosaurs portrayed immense soaringperformance. Hazlehurst and Rayner argue that the outstanding souringperformance of pterosaurs was linked to the low loading. With thistype of loading, pterosaurs required weaker air movements to maintainhorizontal flight. Also, they assert that soaring becomesenergetically efficient for large species since they can soar forlong periods. Thus, small animals with light weights such as bats andbirds employ intermittent flight in addition to periods of glidingand flapping to move. Equally, small pterosaurs would requireintermittent flight soaring when air movements were not suitable.

Competitionfor resources might have contributed to the demise of pterosaurs.Since bats, birds, and pterosaurs occupied the same niche,competition would have influenced their survival. Studies byscientists, however, show that bats, pterosaurs, and birds existedtogether in the past. With this finding, one can conclude that batsposed no competitive threat to any of the two groups. In contrast,there is a high likelihood that birds and pterosaurs competed forfood, shelter, and nesting grounds. These factors greatly influencedthe survival of these animals.

Lowloading also has a disadvantage as much as flying is concerned. Lowloading means low glide speeds. Low glide speeds complicate soaringwaves due to the need to fly at high speed to overcome the thrust ofthe head winds (Hazlehurst and Rayner 1992). Pterosaurs were largewhen compared to bats and birds. Their large size in addition to ahuge body mass influenced their flights significantly. This is intandem with the fact that the metabolic power necessary for animal’sflight is affected by the size of the flying animal. The large sizeof pterosaurs was a significant part of their energy budget. Sincethey were huge, flying was not that easy like that of birds and bats.Based on this claim, it is apparent that flight speeds of pterosaurswere low to conform to their low loading. A blend of low loadingtogether with high aspect means the acquisition of reasonably longwings (Hazlehurst and Rayner 1992). Long wings make roosting inmuddled environment complex. Due to this, pterosaurs had lowmaneuverability than birds. According to Hazlehurst and Rayner,maneuverability is influenced by both wing shape and the body size ofan animal. In other words, larger animals require larger space toturn. Some pterosaurs had long as well as a stiff bone tail with asail that was vertical to deal with low maneuverability challenge(Hazlehurst and Rayner 1992). Due to their large size, pterosaursexperienced difficulties in collecting food. For instance, it wastough for pterosaurs to explore dense forests to access food. Birdsare renowned for their migratory habit in search of food andprotection from adverse conditions. Their small size favors theirsurvival in any niche. Pterosaurs, on the other hand, were extremelyhuge to practice the migratory habit of habits. Most niches could notaccommodate them because of their size. Also, pterosaurs had lowspeed when compared to birds and bats (Hazlehurst and Rayner 1992).They size and weight could not allow them to fly as fast as lightanimals (Hone and Buffetaut 2008). Considering this, it is evidentthat pterosaurs could not survive Darwin’s theory “struggle forthe fittest.” It is possible that light animals accessed food andother survival requirements faster than pterosaurs.

The wings of pterosaurs were also not appropriate for underwaterflights (Hazlehurst and Rayner 1992). The claim is in connection withthe size of the wings. With such wings, pterosaurs would have coveredvery large areas and as a result cause displacement of aquaticanimals. Equally, the wings would have generated large amounts ofdrag. The assertion is in relation to the fact that pterosaurs wouldhave been forced to displace a lot of water to navigate through thewater. Majority of the birds that fly in the water like ducks haswings that are shorter than those of pterosaurs, but with higherloadings. Equally, all the birds that fly underwater have moderatelystrong wing bones that are significantly different from those ofpterosaurs (Hazlehurst and Rayner 1992). Based on this argument, itis apparent that pterosaurs had specific sources of food. Since theycould not fly underwater, their foods were restricted on the surface.The competition for food on the surface as a result of many consumersmight have led to the reduction of food, leading to the death ofpterosaurs. In other words, the birds managed to survive because theyexplored different ecosystems.

Takeoff from the ground as well as water at high angles was not easyfor pterosaurs (Hazlehurst and Rayner 1992). Pterosaurs had highaspect wings. Wings of a low aspect according to Hazlehurst andRayner improve the rate of climbing from takeoff through developinghigh power at extremely low speed. Similarly, a low aspect wing isshort enough or small sized to be beaten through vast heights innearness to the surface. According to Hazlehurst and Rayner, anincrease in size of the wing reduces the change in the formation ofthe wing The large wings of pterosaurs were of great importance tothe birds. They provided large surface that was necessary for theirfloating in air. Based on this argument, it is arguable that mostpterosaurs relied on updrafts and breezes to fly. The power of flightfor the largest pterosaurs was not enough to enable them to fly likebirds and bats. Although large wings enhanced the takeoff performanceof pterosaurs, it also made their flight performance less efficient(Hazlehurst and Rayner 1992). The inability of pterosaurs to takeofflike birds and bats affected their accessibility of foods (Hone andBuffetaut 2008). Flying animals depend on their wings to move closerto food or to run after food. Since they were carnivores, pterosaursflew to water bodies to capture marine organisms including fish andcrustaceans for consumption (Zhou et al. 2017). The inability ofpterosaurs to catch with the increased competition made them toconsume dead animals on the surface. Consumption of moving animalssuch as fish and insects required the predator to be very fast. It isevident that preys escape when they see their predators. Pterosaursmust have experienced many challenges when accessing food. Theincreased time required by the animal to takeoff to capture a movingfood affected their access to food. Similarly, pterosaurs might havereduced in number and eventually became extinct because they tooklong to escape in case of danger. As it was noted before, the largewings of pterosaurs influenced their takeoff speed. The takeoffflight of pterosaurs was not comparable to that of birds. The wingsof pterosaurs were closer to the ground, limiting their flappingwhich is necessary for takeoff (Hazlehurst and Rayner 1992).

Equally,adaptation to the changing environmental conditions might have led tothe extinction of pterosaurs. Just like dinosaurs, the environmentalconditions might have changed greatly and affected the survival ofpterosaurs (Dyke, McGown, Nudds, and Smith 2008). For instance,pterosaurs might have found it hard to survive in extremetemperatures associated with evolution. Evolution of the earth mightalso have led to the extinction of pterosaur’s food. The assumptionthat pterosaurs consumed foods similar to those of birds might bewrong. Pterosaurs were larger in size when compared with birds,making their foods to slightly vary from that of birds.

Conclusion

Pterosaursare flying reptiles that existed many years ago. Their morphology andphysiological features somehow related to those of bats and birds.Pterosaurs were larger in size than bats and birds but managed tofly. The ability of these vertebrates to fly is attributed to themorphology of their wings. They had elongated wings that measuredbetween 2.5m and 3m. Pterosaurs ranged in size there weresmall-sized and gigantic pterosaurs. The small-sized pterosaursbenefitted significantly from low loading and high maneuverability.Large pterosaurs also benefitted from low loading. With large wings,pterosaurs covered long distances in their flights (Dyke, McGown,Nudds, and Smith 2008). The morphology of pterosaur’s wing includedelongated wingtip at its fourth finger (Prentice, Marcello, andBenton 2011). The wingtip influenced the ability of pterosaurs tofly. The wing of the pterosaurs was lighter than those of birds sincetheir bones were hollow. The extinction of pterosaurs is attributedto their morphology and competition from other two groups of flayinganimals. The elongated wings restricted the takeoff of pterosaurssince they were proximal to the ground (Hazlehurst and Rayner 1992).The weight of the pterosaurs also affected their ability to fly forlong because their wings had to generate a lot of power for them tofly. The large wings of pterosaurs impaired with their movement inclattered areas. Pterosaurs were unable to fly in water due to theexcessive drag that would have been created by their elongated wings.The morphology of pterosaurs wings made birds be at the advantagepoint since they both occupied the same niche. With light wings andsmall sized bodies, birds explored all areas included clusteredforests. The small-sized wings of the birds allowed them to takeofffrom the ground easily and faster than pterosaurs. Apart from theland surface, birds exploited water bodies in search of food. Themorphology of pterosaurs’ skulls shows pterosaurs were filterfeeders. The shape of their rostrum in addition to the increasednumber of teeth enabled them to capture marine organisms with muchease. With such advanced teeth morphology, pterosaurs would have beenat more advantage than many filter feeders (Zhou et al. 2017).

Althoughthere are many studies on pterosaurs, research needs to be done toascertain the main cause of their demise. The findings of many peoplecontradict as some claim that birds and pterosaurs rarely sharedtheir niche to be affected with competition whereas others citecompetition from birds as the cause for pterosaurs’ demise.According to some recent studies, birds have not occupied or takenadvantage of the niches that were left as a result of the extinctionof pterosaurs. Based on this claim, one can argue that fight overlimited resources was not the contributing factor for the demise ofpterosaurs. Equally, some findings show that these two groups ofanimals, birds and pterosaurs, consumed almost the same types offoods. They all ate fish, crustaceans, and insects (Zhou et al.2017).. With this claim, a person may also argue that competitioninfluenced the survival of both pterosaurs and birds (Dyke, McGown,Nudds, and Smith 2008). Similarly, some studies noted that themorphology of pterosaur’s wing contributed to their demise.According to the studies, the wings of the pterosaurs were very muchelongated. With such wings, pterosaurs flew faster than birds as wellas covered longer distances than birds (Hazlehurst and Rayner 1992).Contrary to this claim, studies also show that the elongated wingscontrolled the mobility of pterosaurs. Gigantic pterosaursexperienced difficulties in navigating corners as well as exploitingcluttered niches. Some studies also relate the morphology ofpterosaurs wings together with competition from birds with theirextinction. Based on these variations of information about theextinct of pterosaurs, it is recommendable for extensive research tobe carried on the biomechanics of the pterosaurs wings and wingtips.The information provided about the wingtips of pterosaurs isinadequate since few types of research have been carried onpterosaur’s wingtip. Since more fossils are located, and technologyhas improved, pointing out the features of pterosaur’s wing willassist in understanding the factors behind the extinction of theflying reptile. Equally, extensive research also needs to be carriedout to confirm whether birds and pterosaurs consumed similar foods aswell as occupied same niches.

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