plateosauria is a node-based taxon .

in galton 's and upchurch 's study also coloradisaurus , euskelosaurus , jingshanosaurus , massospondylus , mussaurus , sellosaurus , and yunnanosaurus proved to be plateosaurians .

however , recent cladistic analyses suggest that the prosauropoda as traditionally defined is paraphyletic to sauropods .

prosauropoda , as currently defined , is a synonym of plateosauridae as both contain the same taxa by definition .

the following cladogram simplified after an analysis presented by apaldetti and colleagues in 2011 .

the following cladogram simplified after an analysis presented by blair mcphee and colleagues in 2014 .

plateosauria

plateosauria is a clade of sauropodomorph dinosaurs which lived during the late triassic to the late cretaceous . the name plateosauria was first coined by gustav tornier in 1913 . the name afterwards fell out of use until the 1980s .
plateosauria is a suborder sauropodomorpha , lived during the late triassic to the late cretaceous period . plateosauria by gustav tornie proposed in 1913 . by the 1980s , plateosaurus rarely used this term , until a new generation of paleontologists began to re - use it . plateosauria contains plateosauridae and the famous plateosaurus , and belong to the prosauropoda . peter m . galton and paul upchurch also included coloradisaurus , euskelosaurus , lufengosaurus , jingshanosaurus , massospondylus , mussaurus , sellosaurus , and yunnanosaurus . some paleontologists believe massospondylus its relatives belonging to another independent family , massospondylidae .
plateosauria is a node - based taxon . in 1998 , paul sereno defined plateosauria as the last common ancestor of plateosaurus engelhardti and massospondylus carinatus , and its descendants . peter galton and paul upchurch in 2004 used a different definition : the last common ancestor of plateosaurus engelhardti and jingshanosaurus xinwaensis , and its descendants . in their cladistic analysis the plateosauria belonged to the prosauropoda , and included the plateosauridae subgroup . in galton ' s and upchurch ' s study also coloradisaurus , euskelosaurus , jingshanosaurus , massospondylus , mussaurus , sellosaurus , and yunnanosaurus proved to be plateosaurians .
we used different sources for phylogenetic definitions of taxa within dinosauria : sauropodomorpha [ 32 ] , anchisauria [ 2 ] , massospondylidae [ 33 ] , plateosauria [ 34 ] , eusauropoda and neosauropoda [ 35 ] .
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argentinean basal sauropodomorphs are known by several specimens from different basins ; ischigualasto , el tranquilo , and mogna . the argentinean record is diverse and includes some of the most primitive known sauropodomorphs such as panphagia and chromogisaurus , as well as more derived forms , including several massospondylids . until now , the massospondylidae were the group of basal sauropodomorphs most widely spread around pangea with a record in almost all continents , mostly from the southern hemisphere , including the only record from antarctica .
we describe here a new basal sauropodomorph , leyesaurus marayensis gen . et sp . nov . , from the quebrada del barro formation , an upper triassic - lower jurassic unit that crops out in northwestern argentina . the new taxon is represented by a partial articulated skeleton that includes the skull , vertebral column , scapular and pelvic girdles , and hindlimb . leyesaurus is diagnosed by a set of unique features , such as a sharply acute angle ( 50 degrees ) formed by the ascending process of the maxilla and the alveolar margin , a straight ascending process of the maxilla with a longitudinal ridge on its lateral surface , noticeably bulging labial side of the maxillary teeth , greatly elongated cervical vertebrae , and proximal articular surface of metatarsal iii that is shelf - like and medially deflected . phylogenetic analysis recovers leyesaurus as a basal sauropodomorph , sister taxon of adeopapposaurus within the massospondylidae . moreover , the results suggest that massospondylids achieved a higher diversity than previously thought .
our phylogenetic results differ with respect to previous analyses by rejecting the massospondylid affinities of some taxa from the northern hemisphere ( e . g . , seitaad , sarahsaurus ) . as a result , the new taxon leyesaurus , coupled with other recent discoveries , suggests that the diversity of massospondylids in the southern hemisphere was higher than in other regions of pangea . finally , the close affinities of leyesaurus with the lower jurassic massospondylus suggest a younger age for the quebrada del barro formation than previously postulated .
citation : apaldetti c , martinez rn , alcober oa , pol d ( 2011 ) a new basal sauropodomorph ( dinosauria : saurischia ) from quebrada del barro formation ( marayes - el carrizal basin ) , northwestern argentina . plos one 6 ( 11 ) : e26964 . urltoken
copyright : © 2011 apaldetti et al . this is an open - access article distributed under the terms of the creative commons attribution license , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are credited .
funding : this work was supported by instituto y museo de ciencias naturales of the universidad nacional de san juan ; consejo de investigaciones de ciencia tecnologãa y arte ( cicitca ) , and the jurassic foundation . the funders had no role in study design , data collection and analysis , decision to publish , or preparation of the manuscript .
basal sauropodomorphs are non - sauropod sauropodomorphs that diversified and spread to most continents from the late triassic through the early jurassic , and constitute the first global radiation of herbivorous dinosaurs [ 1 ] , [ 2 ] . in south america they are exclusively known from brazil and argentina . the brazilian record includes saturnalia tupiniquim [ 3 ] – [ 5 ] from the carnian santa maria formation ; and the possible basal sauropodomorph guaibasaurus candelariensis [ 6 ] – [ 8 ] and unaysaurus tolentinoi [ 9 ] from the carnian - norian caturrita formation . the record from argentina comprises eoraptor lunensis [ 10 ] , [ 11 ] , panphagia protos [ 12 ] , and chromogisaurus novasi [ 8 ] from the carnian - norian ischigualasto formation ; riojasaurus incertus [ 13 ] , [ 14 ] , coloradisaurus brevis [ 15 ] and lessemsaurus sauropoides [ 16 ] , [ 17 ] from the norian los colorados formation ; mussaurus patagonicus [ 18 ] , [ 19 ] from the norian laguna colorada formation ; adeopapposaurus mognai [ 20 ] , [ 21 ] from the lower jurassic cañón del colorado formation ; and riojasaurus sp . from the norian ? quebrada del barro formation [ 22 ] .
the assignation of the latter record— riojasaurus sp—is questioned in this paper ( see age of quebrada del barro formation ) , because the specimen is known only by a partial pes without any diagnostic features .
herein we report a partial skeleton of a new basal sauropodomorph from the upper levels of the quebrada del barro formation that has implications for our understanding on the diversity of massospondylid sauropodomorphs in south america and for the supposed age of this stratigraphic unit .
the quebrada del barro formation ( marayes - el carrizal basin ) crops out 140 km southeast of san juan city , northwestern argentina ( figure 1 ) . this formation is the uppermost unit of the marayes group [ 23 ] . the marayes group unconformably overlies lower paleozoic metamorphic rocks , and is covered by remnants of the upper cretaceous el gigante group [ 24 ] . the thickness of the marayes group is 2300 meters and it is composed of three units : the esquina colorada , el carrizal and quebrada del barro formations ( figure 1b ) .
. a : location and geologic map ; b : section of the marayes group at the type locality . the red circle indicates the site of the holotype of leyesaurus marayensis gen . et sp . nov . , near the top of the quebrada del barro formation . ( b : modified from bossi [ 23 ] ) .
the esquina colorada formation is composed of approximately 500 meters of conglomerates , sandstones , diamictites and ash layers [ 25 ] , [ 26 ] ( figure 1b ) . some fragments of vertebrate fossils were found in this unit , but these were not studied in detail [ 26 ] . the age of this unit was identified as to be middle triassic , correlated with chañares , ischichuca and los rastros formations from the neighboring ischigualasto - villa unión basin [ 27 ] .
the second unit is the el carrizal formation with 100–350 meters of sandstones , quartz conglomerates , siltstones and coal [ 26 ] ( figure 1b ) . this unit has provided flora and pollen that belong to the “ dicroidium flora” , suggesting a late triassic age by correlation with the ischigualasto formation from of the ischigualasto - villa unión basin [ 23 ] .
the quebrada del barro formation [ 26 ] tops the sequence with 900–1400 meters of reddish alluvial fan deposits that are mostly fine conglomerates and sandstones [ 23 ] ( figure 1b ) . the age of this unit was originally proposed as cretaceous [ 28 ] , [ 29 ] , and later as upper triassic [ 23 ] , [ 30 ] . in 1978 , bossi and bonaparte [ 22 ] assigned a norian age for quebrada del barro formation based in the discovery of some vertebrate remains questionably assigned to riojasaurus ( see below ) .
the instituto and museo de ciencias naturales has the appropriate permits needed to unearth the fossil materials that have been described in this paper ( pvl 706 ) .
the new specimen is a disarticulated incomplete skeleton . the proximity of all elements in an area of one half square meters , as well as the lack of duplicated elements and their relative size , suggest this association belongs to a single individual .
the specimen is well preserved and all the bones of the partial skeleton are three dimensional , complete , and most preserve fine anatomical details . the incompleteness of the skeleton is likely attributable to pre - burial processes .
the white bones of the holotype were embedded in a red fine - grained sandstone matrix with clay cement . the bones were prepared using a pneumatic air scribe pin vice , and water immersion .
we employ traditional anatomical and directional terms over veterinarian alternatives [ 31 ] . “anterior” and “posterior” , for example , are used as directional terms rather than the veterinarian alternatives “rostral” or “cranial” and “caudal” .
the comparisons with other sauropodomorphs and some theropods made in the description of the new specimen were based on the literature and on personal observation of specific taxa detailed in table 1 . except in those cases where the source is specified , all the other references are based on the literature listed in this table .
the electronic version of this document does not represent a published work according to the international code of zoological nomenclature ( iczn ) , and hence the nomenclatural acts contained in the electronic version are not available under that code from the electronic edition . therefore , a separate edition of this document was produced by a method that assures numerous identical and durable copies , and those copies were simultaneously obtainable ( from the publication date noted on the first page of this article ) for the purpose of providing a public and permanent scientific record , in accordance with article 8 . 1 of the code . the separate print - only edition is available on request from plos by sending a request to plos one , 1160 battery street , suite 100 , san francisco , ca 94111 , usa along with a check for $ 10 ( to cover printing and postage ) payable to “public library of science” .
in addition , this published work and the nomenclatural acts it contains have been registered in zoobank , the proposed online registration system for the iczn . the zoobank lsids ( life science identifiers ) can be resolved and the associated information viewed through any standard web browser by appending the lsid to the prefix “ urltoken ” . the lsid for this publication is : urn : lsid : zoobank . org : pub : 66a4c4d7 - e726 - 4c5b - 8a0f - 47fd9a109b01 .
bmnh : natural history museum , london , uk . bp : bernard price institute for palaeontological research , university of the witwatersrand , johannesburg ; brsmg : bristol city museum and art galleries , bristol . pvl : instituto miguel lillo , tucumán , argentina . pvsj : instituto y museo de ciencias naturales , universidad nacional de san juan , argentina . ypm : peabody museum of natural history , yale university , new haven .
urn : lsid : zoobank . org : act : 3772093a - e5cd - 48cf - 9163 - 54e55feda240
the generic name honors the leyes family , inhabitants of the small town balde de leyes , who made the discovery and notified the paleontologists of the san juan museum .
urn : lsid : zoobank . org : act : f7cd3d40 - c64c - 463e - a063 - 9e3fecf9c50d
marayensis refers to the marayes - el carrizal basin , where the specimen was found .
pvsj 706 , a partial skeleton including skull with articulated mandible , lacking both nasals , left prefrontal , middle section of the left maxilla , anterior half of the left lower jaw , supraoccipital , both exoccipitals , ophistotics , laterosphenoids and vomers ; atlas - axis articulated with anterior cervical vertebrae ( c3 - c7 ) ; an anterior and a middle caudal vertebra ; proximal region of the left scapula , coracoid and humerus ; partial blade of the right pubis lacking distal and proximal ends ; proximal region of both ischia ; partial left pes that includs distal tarsals iii and iv , metatarsal iii lacking its distal end , complete metatarsals iv and v , first phalanx of digit i , second phalanx of digit ii , and second phalanx of digit iv ( figure 2 ) .
) . reconstruction only shows preserved bones . modified from martinez [ 21 ] . scale bar equals 25 cm .
the type specimen was found near the locality balde de leyes , caucete department of san juan province , northwestern argentina ( figure 1a ) .
the type specimen was found in red silty mudstones with a low clay cementation in the uppermost level of the quebrada del barro formation [ 23 ] , [ 26 ] , 2 meters below the contact with the cretaceous unit , marayes - el carrizal basin .
the age of the quebrada del barro formation was regarded as norian by bossi and bonaparte [ 22 ] based on the presence of a single basal sauropodomorph specimen composed of an incomplete articulated right pes ( including astragalus , calcaneum , two distal tarsals , metatarsal ii , iii , iv and v , and eight phalanges ) , and four incomplete caudal vertebrae . based on the similarities between these materials and the basal sauropodomorph riojasaurus incertus from the norian los colorados formation in the neighboring ischigualasto - villa unión basin , bossi and bonaparte [ 22 ] identified the specimen as riojasaurus and proposed a norian age for this unit [ 22 ] . unfortunately , only the incomplete pes is housed at the instituto miguel lillo , tucumán , argentina ( pvl 4087 ) and the location of the caudal vertebrae mentioned by bossi and bonaparte [ 22 ] are currently unknown and precluding further analysis .
the lack of diagnostic characters in the pvl 4087 precludes its identification as riojasaurus incertus ( or any other basal sauropodomorph taxon ) . since pvl 4087 lacks diagnostic characters , we interpret the specimen as a non - sauropod sauropodomorpha incertae sedis . consequently , the rationale for the norian age of the quebrada del barro formation proposed by bossi and bonaparte [ 22 ] is pulled into question .
the close affinities of the new specimen reported here with the basal sauropodomorph adeopapposaurus [ 21 ] , as well as the close affinity of these two taxa with the early jurassic sauropodomorph massospondylus from south africa likely indicates a younger age for quebrada del barro formation . massospondylus is a typical vertebrate of the lower jurassic upper elliot and clarens formations in south africa and the forest sandstone group in zimbabwe [ 39 ] , [ 40 ] , but is absent from the late triassic lower elliot formation [ 41 ] , therefore we suggest that the quebrada del barro formation may be of lower jurassic age .
a basal sauropodomorph diagnosed by the following autapomorphies and combination of characters ( asterisks indicate autapomorphies ) : sharply acute angle ( 50° ) formed by the ascending process of the maxilla with the alveolar margin * ; straight ascending process of the maxilla with a longitudinal ridge on its lateral surface ; noticeably bulging labial side of the maxillary teeth ; greatly elongated cervical vertebra ( length / height ratio of sixth cervical centrum more than 5 * ) ; neural arches of the cervical vertebrae with sinuous dorsal margin of the neural spines and short epipophyses—extending two - third of the length of the postzygapophyses— ; and proximal articular surface of metatarsal iii shelf - like and medially deflected * .
the skull is relatively short and low ( figure 2 , 3 ) . including the mandible , its height represents approximately 40 % of the total length , although this may be an underestimate given the slight dorsoventral crushing of the specimen . its maximum dorsoventral depth is in the anterior region of the postorbital , and its greatest transverse width is at the level of the sutural contact between the frontals and parietals ( see table s1 for measurements ) . the shape and size of the external naris cannot be inferred due to the lack of the nasals and dorsal processes of the premaxilla ( figure 3 ) . the triangular antorbital fenestra is surrounded by a well - developed fossa along its anterior and ventral margins . the greatest anteroposterior length of the antorbital fenestra is approximately half the diameter of the orbit . the orbit extends over 30 % of the total skull length , although this could be accentuated by the dorsoventral deformation ( figure 3 ) . the infratemporal fenestra is hourglass - shaped in lateral view , with a dorsal end that is much narrower than the ventral end , which projects anteriorly below the orbit . the supratemporal fenestra has a subtriangular outline in dorsal view , and is slightly longer anteroposteriorly than it is transversely wide . this fenestra is also visible in lateral view , given that the posterior process of the postorbital lies below the dorsal rim of the orbit ( figure 3 ) . both external mandibular fenestrae are damaged and their margins have not been preserved .
photograph of the skull ( a ) and interpretative drawing ( b ) in lateral view . dark grey color represents matrix and light grey color represents foraminae . abbreviations : a , angular ; aof , antorbital fenestra ; aofo ; antorbital fossa ; apmx , ascending process of the maxilla ; d , dentary ; f , frontal ; itf , infratemporal fenestra ; j , jugal ; l , lacrimal ; laofo ; lacrimal antorbital fossa ; mf , mandibular fenestra ; mx , maxilla ; n , nasal ; o , orbit ; p , parietal ; pf , prefrontal ; pm , premaxilla ; po , postorbital ; rug , platform - like rugosities ; q , quadrate ; qj , quadratejugal ; rmx , ridge of the ascending process of the maxilla ; sa , surangular ; snf , subnarial foramen . scale bar equals 1cm .
both premaxillae are preserved , but are lacking their dorsal processes ( figure 3 , 4 ) . in lateral view , the main body of the premaxilla is subquadrangular , as in adeopapposaurus and massospondylus . its anterior margin is straight although its dorsal region is posterodorsally directed . both premaxillae lack the dorsal processes and only preserve their bases , which are transversely compressed and oval in cross - section ( figure 4 ) . the slender posterolateral process tapers backward and overlaps the dorsal edge of the anterior ramus of the maxilla . the posterolateral process and the posterior margin of the main body of the premaxilla form a right angle that produce an l - shaped suture between premaxilla and maxilla . an elliptical subnarial foramen is situated on the suture between the premaxilla and the maxilla . the anterolateral surface of the premaxilla has rugosities ( figure 3b ) that form a similar platform to that of adeopapposaurus and riojasaurus ( pvsj 849 ) . moreover , this region is pierced by several small foramina scattered over the surface , the largest of which is located at the base of the dorsal process . in medial view , the premaxilla has a wide sulcus for the reception of the anteromedial process of the maxilla . leyesaurus has a toothless gap between the first tooth and the symphysis . the gap or diastema has a length equals to the half of the anteroposterior length of the first dentary tooth .
photograph of the skull ( a ) and interpretative drawing ( b ) in dorsal view . dark grey color represents matrix and light grey color represents foramina . abbreviations : apmx , ascending process of the maxilla ; bo , basioccipital ; d , dentary ; f , frontal ; j , jugal ; l , lacrimal ; mx , maxilla ; n , nasal ; o , orbit ; p , parietal ; pf , prefrontal ; pm , premaxilla ; po , postorbital ; sa , surangular ; stf , supratemporal fenestra ; sq , squamosal . scale bar equals 1 cm .
the right maxilla is almost complete whereas the left element lacks its middle portion ( figure 3 , 4 ) . the maxilla has the typical triradiate morphology present in other sauropodomorphs . the anterior process of the maxilla contacts the premaxilla , the ascending process forms the anterior edge of the antorbital fenestra , and the posterior process extends along the ventral margin of the antorbital region ( figure 3 ) . the length of the anterior process of the maxilla is anteroposteriorly shorter than its dorsoventral height , with parallel dorsal and ventral margins , as in massospondylus and adeopapposaurus . the ascending process is straight and posterodorsally oriented . the ascending process of the maxilla of leyesaurus forms an angle of 50 degrees with the alveolar margin ( figure 3 ) . this angle is more acute than the rest of non - eusauropod sauropodomorphs , in which the ascending process diverges from the alveolar margin of the maxilla at an angle ranging between 60 and 90 degrees ( see discussion ) . as in the massospondylids adeopapposaurus and massospondylus ( sam pk k1314 ; a . yates , pers . com . ) , the ascending process of the maxilla is entirely straight , not posteriorly deflected at its dorsoventral end ( where the nasal overlaps the maxilla ) , and differs from that of other basal sauropodomorphs in which the ascending process is posteriorly deflected along this region ( see discussion ) . in addition , the ascending process of the maxilla of leyesaurus also differs from the rest of basal sauropodomorphs in that its lateral surface bears a rounded ridge that extends along its entire length ( see discussion ) . this ridge is broad at the base of ascending process and tapers dorsally ( figure 3 ) . the posterior edge of the ascending process is sharp and forms the entire anterior border of the antorbital fenestra , as in adeopapposaurus . the dorsal region of the ascending process is damaged and has not preserved its contact with the lacrimal . the posterior process of the maxilla forms the main body of this bone and tapers posteriorly . at least six neurovascular foramina are present on the lateral surface of the maxilla ; most of them are aligned parallel to the alveolar border and open ventrally ( figure 3 ) . the posterior end of the maxilla is crushed and is not possible to observe its contact with the jugal .
the ventral halves of the lacrimals are preserved ( figure 3 ) , but both dorsal ends are damaged and the lacrimal foramen and its sutural contacts with the prefrontal , nasal , and ascending process of the maxilla cannot be determined . as in most sauropodomorphs , the main shaft of the lacrimal is anterodorsally inclined in lateral view ( figure 3 ) . the lateral surface is straight , anteroposteriorly narrow , and its ventral portion is not as anteroposteriorly expanded as in plateosaurus , anchisaurus , massospondylus , mussaurus , unaysaurus , and adeopapposaurus . the antorbital fossa has a triangular shape and extends along the lower third of the total lacrimal height , as in other basal sauropodomorphs ( e . g . plateosaurus , massospondylus , lufengosaurus , adeopapposaurus ) .
only the right prefrontal has been partially preserved ( figure 3 – 4 ) . in dorsal view , the prefrontal is anteroposteriorly elongated and lateromedially narrow , as in other basal sauropodomorphs ( e . g . mussaurus , massospondylus , lufengosaurus , adeopapposaurus ) , but different from the transversely broader prefrontal of riojasaurus , coloradisaurus , plateosaurus , and melanorosaurus . the prefrontal contributes to the anterodorsal margin of the orbit ( figure 3b ) , as in most basal sauropodomorphs . posteriorly the prefrontal fits into a triangular slot on the anterolateral region of the frontal . the posterior end of the prefrontal extends less than one - third of the anteroposterior dorsal margin of the orbit .
the left frontal is complete and better preserved than the right element ( figure 4 ) . the frontal is longer than wide , transversely constricted at midsection , and reachs its maximum lateromedial width at its posterior end . the midline suture is straight at its anterior half , and interdigitated at its posterior half , similar to massospondylus , melanorosaurus , and adeopapposaurus . the anterior region has a shallow and triangular depression for the nasal and a subtriangular slot for the reception of the prefrontal at its anterolateral region ( figure 4 ) . the lateral margin of the frontal forms most of the dorsal rim of the orbit ( figure 3b , 4b ) , as in riojasaurus , massospondylus , pantydraco , mussaurus , yunnanosaurus , and adeopapposaurus , which differs from the small contribution to the orbital margin present in other taxa ( e . g . plateosaurus , coloradisaurus , melanorosaurus , lufengosaurus ) . posterolaterally , an elongated slot on the dorsal region of the frontal is overlapped by the anteromedial process of the postorbital ( figure 4b ) . posteromedially , the frontal contacts the parietal but the location of the fronto - parietal suture cannot be precisely determined . the posterior edge of the frontal reaches the anterodorsal margin of the supratemporal fossa as in most basal sauropodomorphs .
the parietals are not fully preserved but it is clear that they are not medially fused ( figure 4 ) . the anterolateral process of the parietal contacts the frontal and the postorbital and forms the medial half of the anterior wall of the antorbital fossa . the parietal - postorbital suture is located midway along the supratemporal fossa , as in massospondylus and adeopapposaurus . the posterolateral process tapers distally , and is lateroventrally overlapped by the medial process of the squamosal ( figure 4b ) . similar to the condition of most basal sauropodomorphs , the posterolateral process forms an angle of approximately 45 degrees with the longitudinal axis of the skull ( figure 4 ) . this process is ventrally deflected and forms the entire medial and posteromedial walls of the supratemporal fossa . dorsally , the posterolateral process has a sharp dorsal margin . in posterior view , this process is strap - like and directed posterolaterally with a shallow concave surface .
both postorbitals of leyesaurus are completely preserved ( figure 3 , 4 ) and these elements are proportionally wider and thicker than that in adeopapposaurus . the postorbital of leyesaurus has a long anteromedial and descending processes and a short posterior process . the main body of the postorbital is smooth and bears small foramina scattered on its lateral surface . the anteromedial process is the most robust of the three processes , with a tongue - shape widening distal end ( figure 4 ) . the ventral portion of the anteromedial process contacts medially with the parietal , and both form the anteroventral wall of the supratemporal fossa . the dorsal portion of the anteromedial process fits into a slot on the posterolateral region of the frontal , being excluded from the dorsal margin of the orbit . the anterior edge of the main body of the postorbital and of the descending process forms the entire posterior orbital rim ( figure 3 ) , as in riojasaurus , coloradisaurus , massospondylus , lufengosaurus and adeopapposaurus . the descending process of the postorbital is thin and tapers distally . the shaft of the descending process is wider transversely than anteroposteriorly at its midlength ( figure 4 ) . the latter condition is only shared with adeopapposaurus , ignavusaurus , anchisaurus , and neosauropoda . the posterior surface of the descending process has a deep groove that lodges the ascending process of the jugal . the posterior process of the postorbital is posteromedially directed , almost horizontal , and anteroposteriorly longer than deep ( figure 3 ) . this process forms the lateral margin of the supratemporal fenestra and the dorsal margin of the infratemporal fenestra , similar to other basal sauropodomorphs .
the left jugal is complete but somewhat damaged and displaced from its natural position , whereas the right element is only partially exposed ( figure 3 ) . the anterior suborbital process of the jugal is the most robust and forms the main body of the jugal . approximately two thirds of its dorsal edge forms the ventral margin of the orbit . this process articulates the maxilla anteriorly and the lacrimal anteromedially . the minimum dorsoventral depth of the suborbital region of the jugal is slightly more than 20 % of its anteroposterior length ( measured from the anterior tip of the jugal to the anteroventral corner of the infratemporal fenestra , figure 3 ) , similar to other basal sauropodomorphs ( e . g . coloradisaurus , massospondylus , lufengosaurus , adeopapposaurus ) . the anterior end of the jugal is pointed and reaches the posteroventral corner of the antorbital fossa . the posterior processes of the jugal are displaced from their original position and the angle between them cannot be calculated . the quadratojugal process is posteriorly directed , and extends approximately along two thirds of the ventral edge of the infratemporal fenestra , as in others basal sauropodomorphs ( e . g . riojasaurus , massospondylus , yunnanosaurus , and adeopapposaurus ) .
the quadratojugals are partially exposed on both sides of the skull . only the anterior process of the left element is preserved , whereas the right quadratojugal consists of an incomplete main body and anterior process ( figure 3 ) . the main body of the quadratojugal is at the posteroventral corner of the infratemporal fenestra . the jugal and squamosal processes of the quadratojugal almost form a perpendicular angle in lateral view ( figure 3 ) , as in the basal saurischian herrerasaurus and some basal sauropodomorphs ( e . g . , eoraptor , riojasaurus , melanorosaurus , unaysaurus , adeopapposaurus ) and subadult specimens of massospondylus and mussaurus . the anterior process is slender and tapers distally , and extends along most of the ventral margin of the infratemporal fenestra .
both quadrates are preserved but they are somewhat distorted and displaced from their natural position ( figure 3 ) . the quadrate shaft is sinuous in lateral and posterior views . the dorsal head of the quadrate is suboval and forms an elongated condyle that abuts to the ventral region of the squamosal , at the level of the dorsal margin of the infratemporal fenestra . the shaft of the quadrate of leyesaurus is dorsoventrally shorter and transversely narrower than in adeopapposaurus , but the quadrate head of leyesaurus is markedly reduced in size compared with adeopapposaurus . the ventral third of the quadrate shaft is stout and subtriangular in cross - section . its anterior surface is concave , whereas its posterior surface is convex and bears a dorsoventrally oriented ridge . the shaft expands ventrally to form the articular surface of the quadrate condyles . this articular area is subtriangular in ventral view and subdivided into a medial and a lateral condyle ( figure 3 ) . the medial condyle is anteroposteriorly longer and projects more ventrally than the lateral one , as in other basal sauropodomorphs ( e . g . pantydraco , lufengosaurus , massospondylus , adeopapposaurus ) . the quadrate foramen is a deep gap that opens on the anterior margin of the shaft , slightly posterior to the quadrate - quadratojugal suture . the two anterior processes of the quadrate are set at an angle of approximately 90 degrees to each other . the anteromedial process occupies more than 70 % of the total length of the quadrate shaft , similar to plateosaurus , lufengosaurus , jingshanosaurus , melanorosaurus , unaysaurus , and adeopapposaurus ; but differs from other sauropodomorphs in which this process does not exceed 70 % of the total quadrate height ( e . g . saturnalia , coloradisaurus , massospondylus , pantydraco , mussaurus ) .
the squamosal is a tetraradiate element that forms the posterolateral corner of the supratemporal fenestra and the posterodorsal corner of the infratemporal fenestra ( figure 4 ) . the complete right squamosal of leyesaurus is disarticulated from the skull , whereas the left element has preserved its descending and anteromedial processes in articulation with the quadrate and the parietal , respectively . the anterolateral process of the squamosal is short and broad , and v - shaped in lateral view . the descending process is the longest , anteroventrally directed , and ventrally tapered . laterally , the descending process diverges from the anterolateral process at an angle of approximately 45 degrees . the posteroventral process is short , laminar , and tapers distally . in lateral view , the posteroventral and the descending process of the squamosal form an angle of approximately 90 degrees . the anteromedial process is laminar ( figure 4a ) and has a medial sulcus along its contact with the parietal .
most of the palatal elements are damaged , incompletely preserved , and overlap each other , precluding the observation of anatomical details .
the ventral side of both ectopterygoids is exposed in ventral view , but both are displaced from their natural position . the main body of the ectopterygoid has a typical flat triangular shape with a slender and strongly recurved anterolateral process . its ventral surface is smooth and bears a shallow depression on its posteromedial area . the ectopterygoid of leyesaurus lacks the pneumatic fossa present in pantydraco .
both pterygoids are partially exposed in ventral view . the main body of the pterygoid is anteroposteriorly longer than transversely wide , with an irregular ventral surface . its posteromedial process is narrow and wraps around the basipterygoid process , as in other basal sauropodomorphs ( e . g . plateosaurus , adeopapposaurus ) , and differs from the broad curved process of riojasaurus and melanorosaurus . the transverse process is slender and extends laterally from the main body of the pterygoid . this process curves anterolaterally and contacts the medial side of the mandible . other details of the pterygoid cannot be observed .
the occipital region has been strongly eroded and is missing most of its elements . only the basioccipital and the posterior half of the basisphenoid - parasphenoid complex have been preserved .
the dorsal surface of the basioccipital is anteroposteriorly elongated ( figure 4b ) and forms most of the floor of the endocranial cavity . the anterior half of the dorsal surface is wider than the posterior one and has a longitudinal medial ridge . the anterior edge is transversely straight and contacts the posterior edge of the basisphenoid . the posterior dorsal half of the basioccipital has a longitudinal median sulcus flanked by two anteroposteriorly elongated lateral facets ( figure 4b ) where the exoccipitals articulate . in lateral view , the main body of the basioccipital is anteroventrally curved , with its anteroventral margin that extends well below the ventral margin of the occipital condyle . this low region is laterally expanded and forms the basioccipital component of the basal tubera . the basioccipital condyle has a suboval shape with a convex posterior and ventral surface . in posterior view , the basioccipital condyle of leyesaurus is transversely wider but dorsoventrally shorter than that in adeopapposaurus .
the dorsal surface of the basisphenoid forms the anterior region of the floor of the braincase . this surface is concave and strongly rugose , and contacts the anterior edge of the basioccipital posteriorly . the anterior half of the basisphenoid of leyesaurus is transversely narrower than the posterior half . the basipterygoid processes are laterally compressed and extend ventrolaterally as well as anteriorly . these processes are set at an approximately perpendicular angle . the basipterygoid processes of leyesaurus are anteroposteriorly and transversely thinner than those of adeopapposaurus , and lack the expanded distal end present in that taxon . moreover , in ventral view the basispterygoid processes of leyesaurus extend laterally to approximately the level of the basal tuberae , whereas in adeopapposaurus these processes extend laterally well beyond the level of the basal tuberae . the basisphenoid component of the basal tuberae is directed laterally and dorsally expanded . overall , the basioccipital and the basisphenoid component of the basal tuberae of leyesaurus are lateromedially wider than those in adeopapposaurus . the parasphenoid cannot be observed . the basal tuberae , the bases of the basipterygoid processes , and the parasphenoid rostrum are approximately aligned in lateral view , as in some basal sauropodomorphs ( e . g . efraasia , thecodontosaurus ( ypm 2192 ) , massospondylus , anchisaurus , adeopapposaurus ) .
most of the right mandibular ramus is preserved and exposed in lateral view , whereas only the posterior half of the left ramus has been preserved ( figure 2 – 4 ) . as preserved , the mandible is shorter than the skull length , although the angular , surangular , and articular are incomplete and severely distorted ( see table s1 for measurements ) .
the dentary is the largest bone of the lower jaw ( figure 3 ) . its anteroposterior length is five times its maximum depth and its dorsal and ventral borders are parallel to each other . in lateral view , the anterior end of the dentary has a rugose surface with several foramina scattered around the symphyseal region ( figure 3b ) , resembling the condition of adeopapposaurus . a row of foramina extends parallel to and just below the alveolar margin of the dentary ( figure 3b ) . these foramina open anterodorsally , with the exception of the posteriormost foramen that opens posteriorly . this foramen is larger , and spaced further from the others . the first dentary alveolus is inset a short distance from the symphysis ( less than the width of an alveolus ) as in panphagia , pantydraco , and anchisaurus . the dentigerous portion occupies almost the entire length of the preserved dorsal margin of the dentary .
the angular , surangular , and articular are incomplete , partially exposed , and severely distorted ( figure 3 ) , hence they do not offer many details for description . overall , the coronoid eminence of leyesaurus is strongly arched , and the convexity of the dorsal margin is more pronounced than that of adeopapposaurus . moreover , the coronoid eminence of leyesaurus tapers posteriorly to form the retroarticular process that exhibits an abrupt concave curvature in lateral view ( figure 3b ) , whereas in adeopapposaurus this curvature is much less pronounced . the splenial and intercoronoid cannot be identified because they are obscured by the matrix and other bones on both sides .
leyesaurus has a moderate degree of heterodonty ( figure 3 ) . all preserved crowns are leaf - shaped and longer apicobasally than they are wide mesiodistally . the teeth are constricted between the crown and the root and the maximum mesiodistal expansion of the crown is located on the proximal third . the upper tooth crowns have a markedly convex labial side ( figure 5a ) whereas dentary tooth crowns are compressed labiolingually with slightly convex labial sides .
a , photograph of the teeth of leyesaurus marayensis ( pvsj 706 ) , the circle shows fifth maxillary tooth in distal view ; b , cross - sections at mid - height of an anterior maxillary tooth of leyesaurus pvsj 706 ( a ) , adeopapposaurus pvsj 568 ( b ) , massospondylus sam - pk - k1314 ( c ) , and riojasaurus pvsj 849 ( d ) . red lines represent the maximum mesiodistal length and labiolingual width at mid - height of the tooth . abbreviations : r , ratio between mesiodistal length and labiolingual width . scale bar equals 2 mm .
leyesaurus has four premaxillary teeth , which are the longest elements of the dentition ( figure 3b ) . the mesial and distal margins of the premaxillary teeth are asymmetric and lack serrations . the apices of the premaxillary teeth are pointed and lingually inclined .
the maxillary teeth are shorter than those of the premaxilla ( figure 3 ) . maxillary and dentary crowns are almost symmetrical in labial view , and bear blunt denticles along the apical two - thirds of the mesial and distal margins . the denticles are oriented at approximately 45 degrees from the edge . unlike adeopapposaurus , all denticles of leyesaurus form an angle of 45 degrees with the basal - apical axis of each crown , whereas some maxillary teeth of adeopapposaurus have parallel serrations .
labial surfaces of the maxillary and dentary crowns of leyesaurus are smooth and lack the moderate enamel wrinkling ( figure 3 , 5a ) present in anchisaurus [ 42 ] , or the more developed wrinkling of sauropod taxa [ 35 ] . the labial surfaces of the anterior maxillary teeth are strongly convex , whereas the lingual surfaces are almost flat and d - shaped in cross - section ( figure 5 ) . this convex labial surface of the anterior maxillary teeth has the labial highest point mesially displaced , and gives an irregular d - shaped cross - section of the tooth ( figure 5b ) . the noticeably bulging labial side of the maxillary teeth of leyesaurus is more pronounced than that of other basal sauropodomorphs ( e . g . , massospondylus , mussaurus , anchisaurus , plateosaurus ) , and represents a distinctive feature of the upper teeth of leyesaurus ( figure 5 ) ( see discussion ) .
in many respects , the dentary teeth exhibit a similar morphology as the maxillary teeth , although the dentary teeth are more flattened labiolingually . moreover , the dentary teeth have their maximum mesiodistal width closer to the base than the maxillary teeth . the anterior dentary teeth are slightly longer than the posterior dentary teeth , similar to most basal sauropodomorphs . the labial surface of the crowns is slightly convex , while the lingual surface is slightly convex to flat . dentary teeth are slightly rotated giving an imbricated arrangement , similar to other basal sauropodomorphs such as massospondylus , yunnanosaurus , thecodontosaurus ( brsmg c4529 ) , lufengosaurus , adeopapposaurus , premaxillary teeth of mussaurus , as well as some teeth of plateosaurus and ignavusaurus .
a pair of ceratobranchials is joined to the palatal elements , and they extend anteroposteriorly . the ceratobranchials are thin , elongate and gently curved along their length . they are subcircular in cross section and are almost constant in diameter , with blunt anterior and posterior ends .
the right proatlas lacks its posterior end ( figure 6a ) and the left proatlas lacks its posterior half . in lateral view , the proatlas is subtriangular and transversely flattened ( see table s1 for measurements ) , unlike the subrhomboidal proatlas of adeopapposaurus . the anterior end has a rectangular surface that faces anterolaterally and articulates with the dorsolateral region of the foramen magnum . the anterodorsal border of the proatlas is rounded , anteroposteriorly directed , and contacts the other proatlas to form the roof of the neural canal ( figure 6a ) . the dorsal end of the proatlas bears a lateral bulbous projection . the medial surface is slightly concave whereas the lateral side has an undulated surface , and several foramina are present on both sides . the laminar posterior end , or postzygapophysis , presents a smooth medial surface for the articulation with the prezygapophysis of the atlantal neural arch ( figure 6a ) .
a , right proatlas in medial view ; b , odontoid in dorsal view ; c , intercentrum in dorsal view ; d , right atlantal neural arch in medial view ; e–f , axis in dorsal ( e ) and lateral ( f ) view . abbreviations : apax , articular projection with the axis ; apoc , articular projection with the occipital ; asan , articular surface with the atlantal neural arch ; asfm , articular surface with the lateral region of the foramen magnum ; asin , articular surface with the intercentrum ; asoc , articular surface with the occipital ; epi , epipophysis ; fr , foramen ; k , keel ; nc , neural canal ; ns , neural spine ; pap , parapophysis ; poz , postzygapophysis ; prz , prezygapophysis . scale bar equals 1 cm .
all elements of the atlas are disarticulated , and consist of the odontoid , intercentrum , and both incomplete neural arches ( figure 6b–d ; see table s1 for measurements ) . in dorsal view the odontoid is subcircular with a concave surface ( figure 6b ) . its anterior margin bears a pointed projection that fits on the occipital condyle . ventrally , the odontoid has a transversely directed deep groove covered by several foramina , which articulates with the posterodorsal margin of the atlantal intercentrum . the posterior surface bears a rounded projection on its dorsal third that fits on the anterior articular surface of the axial centrum ( figure 6b ) .
the intercentrum is subrectangular u - shaped in anterior and posterior views and subtriangular in lateral view . the dorsal surface of the intercentrum bears two transversely oriented concavities for the articulation of the occipital condyle ( anteriorly ) and the odontoid ( posteriorly ) ( figure 6c ) . the posterior surface of the intercentrum is convex with a concave dorsal margin and a straight ventral margin . the ventral surface is rugose and slightly concave . the circular articular surfaces for the atlantal ribs are located on the lateral side of the odontoid , and face dorsolaterally .
the right atlantal neural arch is almost complete whereas only the anterior half of the left neural arch has been preserved ( figure 6d ) . the atlantal neural arch is anteroposteriorly elongated , approximately three times longer than high ( measured from the anterior end of the pedicle to the posterior end of the postzygapophysis ) , as in adeopapposaurus ( see table s1 for measurements ) . the medial surface is smooth and anteroposteriorly concave . the anteroventral corner bears a subtriangular pedicle that articulates ventrally with the laterodorsal depression of the intercentrum and anteriorly with the occipital region . anterodorsally , the atlantal neural arch has an anteromedially directed bilobated lamina that forms the lateral wall of the neural canal ( figure 6d ) . the anterolateral surface of this lamina forms the prezygapophysis that articulates with the proatlas . the postzygapophysis is tongue - shaped with a pointed posterior end ( figure 6d ) . the epipophysis is medially curved , projects posteriorly , and overhangs the posterior end of the postzygapophysis ( figure 6d ) .
the length of the axial centrum is more than four times longer than high and anteroposteriorly shorter than any of the postaxial cervical ( figure 2 , 6e–f ; see table s1 for measurements ) . the shape of the axial centrum of leyesaurus differs from other basal sauropodomorphs where the length : height ratio approximately ranges between 2 and 3 . 5 ( yunannosaurus , 2 . 1 ; melanorosaurus , 2 . 5 ; unaysaurus , 2 . 0 ; riojasaurus , 3 . 3 ; and adeopapposaurus , 3 . 5 ) . the ventral surface of the axis bears a ventral keel that extends along the entire length of the centrum ( figure 6f ) , similar to unaysaurus and adeopapposaurus . other sauropodomorphs lack a ventral keel on the axis ( e . g . riojasaurus and thecodontosaurus ( bmnh p24 ) ) . the anterior articular surface is markedly rugose and bears a circular concavity at its dorsal third , which lodges the posterior projection of the atlantal odontoid . the lateral surface of the centrum is not fully preserved , so that the diapophyses cannot be identified , whereas the parapophyses are small and shallow depressions located on the anteroventral region of the centrum ( figure 6f ) . most of the neural arch of the axis is broken ( figure 6e–f ) . the prezygapophyses are small and smooth surfaces placed at anterior and of the neural arch . the postzygapophyses are medially connected by a thin lamina that forms the roof of the posterior exit of the neural canal . the articular surfaces of the postzygapophyses are elongated and face ventrolaterally . the posterior end of the centrum is poorly preserved and it is not possible to determine whether the postzygapophyses extend beyond the posterior margin of the centrum ( figure 6f ) . the neural spine only preserves its posterior half , which is low , laminar , and thickens at its posterior end . posteriorly , the neural spine is divided into two spinopostzygapophyseal laminae that project ventrolaterally and merge distally with the epipophyses . the epipophyses are robust , have a sharp dorsal margin , and extend along two - thirds of the total length of the dorsal surface of the postzygapophyses ( figure 6e–f ) .


blenniella leopardus is a species of combtooth blenny found in the eastern indian ocean .

it can reach a maximum length of 6 centimetres ( 2.4 in ) sl .

blenniella leopardus

citation : - blenniella leopardus . malaysia biodiversity information system ( mybis ) . urltoken downloaded on 10 july 2018 .
springer , v . g . and j . t . williams , 1994 . the indo - west pacific blenniid fish genus istiblennius reappraised : a revision of istiblennius , blenniella , and paralticus , new genus . smithson . contrib . zool . 565 : 1 - 193 . ( ref . 9962 )
female picture by springer , v . g . / williams , j . t .
marine ; demersal ; depth range 0 - 2 m ( ref . 90102 ) . tropical
maturity : l m ? , range 3 - ? cm max length : 6 . 0 cm sl male / unsexed ; ( ref . 9962 ) ; 5 . 0 cm sl ( female )
dorsal spines ( total ) : 12 - 14 ; dorsal soft rays ( total ) : 17 - 20 ; anal spines : 2 ; anal soft rays : 19 - 22 ; vertebrae : 37 - 38 . diagnosis : dorsal fin xii - xiv , 17 - 20 , notched between spinous and segmented - ray portions ; anal fin ii , 19 - 22 ; pectoral rays 13 - 15 ; pelvic fin i , 3 ; caudal fin , procurrent rays 10 - 14 , segmented rays 12 - 13 . vertebrae 11 - 12 + 26 - 27 . orbital cirrus simple filamentous ; nasal cirri short and palmate with 2 - 5 branches ; nape with cirri bilaterally . lateral line , continuous anterodorsally below dorsal spines from 7 - 8th to 10th , disconnected posteroventrally up to below dorsal spine 9th to 12 - 13th . mandibular pores 5 - 6 lips margin entire . occipital crest absent but males have low fleshy median predorsal ridge ( ref . 9962 ) . body depth at anal - fin origin 5 . 7 - 6 . 8 in sl . male back with dark brown saddles from dorsal base to middle of side , and midlaterally with a row of blue dashes . female with dark vertical dark h - shaped bars and many spots posteriorly ; dorsal and caudal fins spotted ( ref . 90102 ) .
specimens were collected from an inner portion of reef flat in small , irregular sand pool , between limestone outcrops with coral fragments , at 0 . 1 m ( ref . 9962 ) . adults are found in intertidal zone ( ref . 90102 ) . oviparous . eggs are demersal and adhesive ( ref . 205 ) , and are attached to the substrate via a filamentous , adhesive pad or pedestal ( ref . 94114 ) . larvae are planktonic , often found in shallow , coastal waters ( ref . 94114 ) .
) : 28 . 3 - 29 . 4 , mean 28 . 9 ( based on 216 cells ) .
phylogenetic diversity index ( ref . 82805 ) : pd 50 = 0 . 5020 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .
bayesian length - weight : a = 0 . 00741 ( 0 . 00330 - 0 . 01663 ) , b = 3 . 00 ( 2 . 80 - 3 . 20 ) , in cm total length , based on lwr estimates for this ( sub ) family - body shape ( ref . 93245 ) .
trophic level ( ref . 69278 ) : 2 . 9 ±0 . 3 se ; based on size and trophs of closest relatives
resilience ( ref . 69278 ) : high , minimum population doubling time less than 15 months ( preliminary k or fecundity . ) .
vulnerability ( ref . 59153 ) : low vulnerability ( 15 of 100 ) .
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kimura , s . , satapoomin , , u . & matsuura , k ( 2009 ) . fishes of andaman sea : west coast of southern thailand . national museum of nature and science , japan . pp . 346 .
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d xii - xiv , 17 - 20 ; a ii , 19 - 22 ; p 1 13 - 15 ; p 2 i , 3 ; v 11 - 12 + 26 - 27 = 37 - 35 . body elongate . single low occipital crest present in males more than 29 mm . single nape cirrus usually present . supraorbital region with single long cirrus . nasal with small and palmate cirri . gill opening continuous across ventral surface of head . soft rays of caudal fin branched . color : head pale brown with white spots and orange lines ; body reddish pale brown with brownish bands , 3 bands on middle of body with black and white spot ventrally ; spinous dorsal reddish basally and dusky distally , with several reddish spots ; soft dorsal reddish basally , with orange and reddish spots and oblique dark red lines ; anal fin dusky , yellowish distally ; caudal fin pale brown , with orangish posterior margin . distribution : ranging from the andaman sea to sumatra . ( hisashi imamura )
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to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .
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photo by springer , v . g . / williams , j . t .
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the effective management and conservation of biodiversity is predicated on clearly defined conservation targets . species number is frequently used as a metric for conservation prioritization and monitoring changes in ecosystem health . we conducted a series of synoptic surveys focusing on the fishes of the bootless bay region of papua new guinea to generate a checklist of fishes of the region . bootless bay lies directly south of port moresby , the capital of papua new guinea , and experiences the highest human population density of any marine area in the country . our checklist will set a baseline against which future environmental changes can be tracked .
we generated a checklist of 488 fish species in 72 families found in bootless bay during a two - week sampling effort . using incident - based methods of species estimation , we extrapolate there to be approximately 940 fish species in bootless bay , one of the lowest reported numbers in papua new guinea .
our data suggest that the bootless bay ecosystem of papua new guinea , while diverse in absolute terms , has lower fish biodiversity compared to other shallow marine areas within the country . these differences in faunal diversity are most likely a combination of unequal sampling effort as well as biophysical factors within bootless bay compounded by historical and / or contemporary anthropogenic disturbances .
understanding the magnitude and direction of ecosystem change requires careful documentation of thespecies present within that ecosystem . without quantitative data , large - scale changes in one generation can be overlooked , resulting in a gradual shift towards increasingly degraded natural states being accepted as the baseline for future comparisons [
] . the reefs of papua new guinea are some of the most diverse in the world and are part of a region dubbed the “coral triangle , ” an area bounded by the philippines , papua new guinea and indonesia . the coral triangle is the epicenter of marine biodiversity [
of reefs represent 6 % of the world’s reefs . over 50 % of papua new guinea’s reefs are currently threatened , a number that may rise to an estimated 78 % when models of increasing thermal stress are incorporated [
] ) do exist , there is a real potential for the faunal and structural composition of papua new guinea to be substantially altered in the timescale of a single human generation .
bootless bay is a semi - enclosed bay on the southwest coast of papua new guinea . the bay is approximately 9 . 5 km along its longest axis ( northwest - southeast ) and 2 km wide . the bay is shallow with a maximum depth of approximately 30 m . the main interface with the pacific ocean is on the southwest side . there are no major rivers emptying into the bay but several small creeks do provide a constant freshwater influx . the surrounding vegetation is largely savannah with a
] . there is also a small mangrove restoration project in the northeast portion of the bay .
) . population pressure is one of the major threats facing the reefs in papua new guinea . in part due to their proximity to the markets in port moresby [
] . before quantifying the degree of environmental change potentially caused by anthropogenic or other stressors , we need to establish a baseline of fish biodiversity to which future sampling can later be compared .
approximate sampling locations indicated by a star . actual latitude and longitude for sampling locations are given in table
in this paper we use a combination of empirical field sampling , literature review and collections - based research to compile a checklist of the fishes found in bootless bay . this paper , in conjunction with the collections in natural history museums , will serve as a baseline of fish diversity found in bootless bay in the early 21 st century .
sampling 33 stations over a two - week period yielded 384 fish species with a mean of 23 . 32 individuals representing 19 . 36 species collected per site ( table
) showed a continued increase in species per station indicating that additional sampling in the area is likely to provide new records . the confidence intervals for our species accumulation curve suggest a species richness between 340 and 399 species . the inclusion of other records from published literature and museum collections added another 101 species , bringing the total in this preliminary checklist to 485 species representing 72 families ( table
) . the ten most species - rich families accounted for 57 . 5 % of the total number of identified species ( figure
list of location , collecting methodology , habitat type and numbers of individuals and species recorded for all collecting stations .
were not observed during the january 2011 survey , but reported in the literature or in museum collections species were identified to the finest taxonomic resolution possible .
we used two different methods to generate species richness estimates , using a combined data set that includes both our field - based sampling records and reports from the literature . we first calculated allen’s [
] coral fish diversity index ( cfdi ) , which is the sum of species numbers in the acanthuridae , chaetodontidae , pomacanthidae , pomacentridae , labridae and scaridae families . the cdfi value for bootless bay is 158 , which when used to estimate total number of fish species in the region yields values between 515 and 558 .
] . the results from the incident - based estimators resolved consistently larger values , with the incident - based coverage estimator ( ice ) estimating 949 species and the chao 2 estimating 939 species ( 95 % confidence : 767–74 to 1187 species ) .
papua new guinea lies within the coral triangle , the global epicenter of marine biodiversity . while the mechanisms underlying the coral triangle epicenter of diversity phenomenon remain to be fully explored [
] . different analytical methods used to estimate species number in bootless bay have resulted in varying species estimates . our species cfdi estimates ( n = 515 - 558 ) are substantially lower than those estimated for other areas in png ( n > 800 , [
] . despite the large absolute number of species , the relative species composition of bootless bay , when compared to other sites in papua new guinea , is rather depauperate . allen et al… [
] reported species numbers of 1313 reef fish for milne bay and 850 for madang , while munday et al… list 881 for kimbe bay , png , using the more conservative cfdi methodology ( pers . com with phil munday , james cook university for reference our bootless bay value using the same methodology estimated 515–558 species ) . other species lists for sites in papua province in the republic of indonesia include 1511 species for the bird’s head peninsula as a whole [
] . we urge caution in making direct comparisons among these regions , as sampling effort is unequal , disproportionately influencing low diversity areas such as bootless bay . as additional surveys are carried out within bootless bay we anticipate an increase in the diversity of species recorded .
bootless bay differs in habitat complexity from other regions of papua new guinea , which could contribute to the differences seen in species numbers . while milne bay and kimbe bay contain a wide diversity of habitats [
] , bootless bay has relatively low complexity with fewer habitat types ( allen pers . com . ) , suggesting that habitat availability could be a contributing factor to differences in species diversity .
bootless bay’s reefs lie less than 10 km from port moresby , a city with an urban population of over 300 , 000 , the largest in melanesia . a large portion of this population comes from internal migration from rural areas into port moresby . because of this influx , the marine resources of bootless bay are increasingly used to provide protein for this rapidly growing urban population [
] . port moresby has been the country’s major population center since colonial times , and the impacts of its population on local reefs , while certainly larger than historical levels , are by no means new occurrences .
along with primary resource use , the reefs of bootless bay are also influenced by siltation from freshwater sources . the quality of these inflows has been severely impacted due to upstream conversion of primary and secondary forests into agricultural land coupled with the unplanned urban growth around squatter villages [
] . it is likely that the proximity of these reefs to the country’s population center , and the resource exploitation and habitat degradation that proximity entails , also contribute to the low species diversity in bootless bay .
] examining the percentage of living coral cover at four stations located on fringing and patch reefs reported a steady decline in coral cover that correlated with distance from the bootless bay coastline . although a correlation between percentage coral cover and sediment levels was not significant due to the small sample size , a detailed study is required to better understand the impact of siltation on living coral decline in the bay and how this can contribute to habitat loss and a reduction in fish diversity . furthermore , this will allow for appropriate management decisions to be made regarding construction projects and land use practices in nearby areas .
] . despite these threats , the reefs still house a high diversity of fishes and are a critical national resource for hundreds of thousands of people . proper management of these reefs depends on first identifying the state of the reefs and then taking actions to mitigate threats to them .
the results presented here regarding fish biodiversity represent an important step in identifying the state of the reefs of bootless bay . while we acknowledge that our species list is incomplete , listing the species living here in 2011 establishes a baseline of fish diversity that is necessary for future conservation action . tracking species’ presence and absence is an important way to monitor ecosystems , and future surveys that fail to detect species present in our list will suggest a further degradation of these reefs . additional studies that record species abundances as well as species richness would complement our study and enrich the conservation utility of ichthyologic surveys . recording abundance of several key fisheries species which are indicative of healthy reefs , including large groupers (
] . additionally , by placing emphasis on large , easily identified species , one is able to leverage citizen scientists to help monitor changes in reef quality . such recreational diver surveys have been helpful in tracing large scale biodiversity patterns in the caribbean [
] highlighted the role that bioinformatic resources can play in conserving biodiversity . a major point was the ability of on - line resources to facilitate research countries that are rich in biodiversity but poor in conservation resources . in this spirit we have chosen to publish our work here , in an open - access journal , so that the people who are most in need of these data are not limited in their access to them . we have also published the species list in dryad , an international , freely accessible , data depository site (
) to facilitate the wide distribution of our data . it may be accessed with the
we also envision this checklist serving as a living document that has an updated list augmented annually as new species are described or identified or as existing taxonomies are modified . in addition , we will work with other researchers in the region to maintain a comprehensive record of species as they are observed . this checklist is an excellent avenue to engage citizen scientists in monitoring . by encouraging submission from recreational divers , snorkels and anglers we are able to incorporate a more thorough temporal and spatial sampling regime that complements existing synoptic surveys . similar programs have been instrumental in recording shifts in species abundance brought about by climate change [
] . this type of dynamic publishing would not have been possible as little as five years ago , and we encourage other researchers to follow this model and make their data as broadly accessible as possible .
sp . ) that was isolated by at least 2 m of sand . the depth of each station varied between 3–32 m , all within safe scuba depth . approximately 1 kg of rotenone mixed with 1 l of saltwater and a small portion of dish soap to act as an emulsifier was combined and distributed
over the surface of the tabular coral by one diver . two to four additional individuals positioned themselves 1–2 m above the initial rotenone ‘cloud’ to capture larger fishes escaping . after an initial period of ~ 10 min all divers descended to the bottom and searched in expanding circles for fish that had succumbed to the effects of rotenone . collections typically took 2 person / h .
for spear fishing stations we targeted fishes along isolated patch reefs or a section of barrier reef . sampling individual fishes in this way maximizes diversity and minimizes the ecological impact of collecting . because larger predatory fishes were extremely rare ( e . g . , only two individual sharks were spotted despite 120 hours of diving ) , we chose to record but not collect large members of serranidae ( e . g . ,
) . collecting effort as measured by raw number of individuals decreased as spear sampling effort increased simply because we collected common species early . however , the number of new species collected continued to increase even up until the final spear fishing station ( 2 new species collected at station 33 - table
we also collected specimens from one of four large fish markets in port moresby . the market was stocked by ~ 40 individual retailers , and from interviewing them we found that most fishing was done with hand lines or nets on small boats driven by < 60 hp engines . because this was an active market all species were , by definition , commercially exploited . we saw several species for sale at the market that were not found during our collections ( e . g .
suggests that the fishers were expanding their effort to offshore , non - reef areas , although the power of the boats’ engines and lack of refrigeration onboard probably precludes the fishers from traveling too great a distance from the region . port moresby lies on a shallow continental margin , but because the shelf break occurs relatively close ( figure
individual fish were photographed and identified to species level within two hours of collecting . most individuals had small pieces of muscle or gill tissue subsampled and preserved in 95 % etoh for future dna analysis . all specimens were then fixed in formalin or skeletonized and ultimately deposited in the collections of the field museum of natural history . field identifications were later validated or revised in the laboratory using keys and the field museum’s reference collections . current taxonomic rank assignment , valid names and species distributions were evaluated using fishbase [
] ) for our field based sampling . we first randomized our sampling sites with 50 randomizations and then generated the mau tau richness function and the associated 95 % confidence intervals [
] coral fish diversity index ( cfdi ) . this index is the sum of species numbers in acanthuridae , chaetodontidae , pomacanthidae , pomacentridae , labridae and scaridae . the cdfi can then be used to generate an estimate of total species number for the larger region ( > 50 , 00 km
finally , we calculated two estimates of species richness using the software estimates 8 . 2 [
] . because we tried to minimize the ecological impacts of our collecting , in general we did not collect more than a few individuals of any individual species , thus metrics that require abundance information to estimate species richness would be skewed by our collecting methodology .
we would like to thank j . m . henss and c . p . west for their helpful thoughts and comments . field collections were assisted by t . daure , r . gabiobu , m . maniwavie , b . petsul , e . tovue , b . sabub , r . totome and n . vincent . two anonymous reviewers and s . blanchet greatly improved the quality of an earlier version of this manuscript .
funding was provided by a national science foundation ( nsf ) postdoctoral fellowship to j . a . d . ( dbi - 0805458 ) and an nsf grant to m . westneat ( deb - 0844745 ) with additional support from the marshall field fund of the field museum of natural history and the john d . and catherine t . macarthur foundation support of the encyclopedia of life . the funders had no role in study design , input into analyses presented , drafting or editing .
sampling strategy and trip logistics were designed by jd mw and am . samples were collected by jd mw jm and cb , with permitting help from am . species were identified by mw jd jm cb ar and dh , with species richness estimates performed by jd ar and dh . the manuscript was written by jd jm mw and am . all authors read and approved the final manuscript .
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