sign in sign up
<<
Home , Antorbital fenestra, Chindesaurus, Guaibasaurus, Herrerasauridae, Herrerasaurus, Lagerpeton

This article was downloaded by:[University of ] [University of Chicago] On: 23 April 2007 Access Details: [subscription number 769429254] Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Historical Biology An International Journal of Paleobiology Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t713717695 The phylogenetic relationships of early : a comparative report

To cite this Article: , 'The phylogenetic relationships of early dinosaurs: a comparative report', Historical Biology, 19:1, 145 - 155 To link to this article: DOI: 10.1080/08912960601167435 URL: http://dx.doi.org/10.1080/08912960601167435

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf

This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

© Taylor and Francis 2007 Downloaded By: [University of Chicago] At: 00:23 23 April 2007 utemr,nal 0preto hrce tt crsvr o dnia,o oprbe nru aa eovn these Resolving taxa. phylogenesis. ingroup comparable, early data, or understanding of in identical, portion made shared for be that vary will of In progress half scores analysis. future only opposing state results; where the differing character clearly into behind is of factor incorporated interpretations percent major is conflictive a 40 interpretation is each nearly choice for character furthermore, that critical first, data show, character to the here taken is approach comparative vrtels w eae.Pirt h icvr of discovery the to Prior decades. two analysis and last and Dinosauria commentary the of much over radiation to subject early been the have of studies for h nobtlfsa nta ldsi nepeainplaced interpretation cladistic Initial fossa. antorbital the O:10.1080/08912960601167435 DOI: online 1029-2381 USA. print/ISSN 60637, 0891-2963 IL ISSN Chicago, Street, 57th East 1027 Chicago, of University Sereno, C. P. Correspondence: 1993). Novas 1993; Novas and Sereno diminutive the bodied including work, lunensis this of course light the to came in dinosaurs first the of 2004), skeletons 228 al. et complete (ca. Gradstein 1993; al. earliest et Rogers the Ma; Now to early 1982). precisely of more (Bonaparte view dated life complete vertebrate most which Triassic the Late , Ischigualasto yielded Province, had the Juan earlier the San of in in outcrops Formation work fossiliferous field richly re-opened expeditions American the at patterns complete Dinosauria. phylogenetic of of outline skeletons base handful help yielded a to Only have enough 1999). locales Rogers 1997, Sereno -rich 1988; 1993; (Benton among al. transitions et faunas great the long vertebrate of has one terrestrial dinosaurs as of interest radiation of been early and origin The Introduction Keywords: dinosaurs early the for light to come has information ischigualastensis anatomical new Surprising Abstract USA 60637, IL Chicago, Street, 57th East 1027 Chicago, of University SERENO C. PAUL report comparative a dinosaurs: early of relationships phylogenetic The Biology Historical Eoraptor Argentine- of pair a 1980s, late the in Initiated errsuu ischigualastensis Herrerasaurus and Dinosauria aebe lcda h aeo arshao ihnTeooai w ag-cl uniaieaaye.A analyses. quantitative large-scale two in within or of base the at placed been have . Eoraptor Herrerasaurus 07 91:145–155 19(1): 2007; , Srn ta.19)adlarger- and 1993) al. et (Sereno a i adblrjwjit and joint, jaw mandibular mid a has oatr Herrerasaurus, Eoraptor, , eantepvtltaxa pivotal the remain q 07Tyo Francis & Taylor 2007 Srn 1993; (Sereno hlgntctaxonomy phylogenetic Herrerasaurus Herrerasaurus n agr(04 n agradBno (2006) Benton and both Langer positioning and favored of (2004) view Langer al. phylogenetic and et initial Fraser theropods the and Herrerasaurus (1999) to (2003) al. returned as et Rauhut (2002) Langer and position 3B); (1999) (Figure their Sereno taxa: maintained these of al. et Sereno 3A; 1993; 1993). (Figure Novas Sereno 1993; 1992; theropods Novas basal and Sereno as reinterpreted were sampling, character from exten- more sive material and expeditions discovered Argentine-American newly the basal plus With 1987; of 1992). Sues analyses and Novas (Saurischia Brinkman cladistic 1986; first (Gauthier dinosaurs proper the in ) Dinosauria outside material, complete more n etn20)aecmae nmr detail. more in compared are Langer 2006) Benton 1999; and (Sereno results contrasting and datasets available with three analyses comprehensive most the two Rather, evaluated, the and of is hypotheses. each above presented of viewpoints these favour phylogenetic in of presented evidence all the covering analysis 3C). (Figure saurischians basal as Dinosauria inside nlssi h atdcd aeofrdtreviews three offered have decade last the in Analyses h rsn ae snta xasiecomparative exhaustive an not is paper present The a rmxlayfnsr tteatro n of end anterior the at fenestra promaxillary a has usd ioara ic then, Since Dinosauria. outside , saptnildnsuinoutgroup; dinosaurian potential a as oatrlunensis Eoraptor Herrerasaurus Herrerasaurus Eoraptor and and a positioned was Herrerasaurus and Herrerasaurus Eoraptor Eoraptor and Downloaded By: [University of Chicago] At: 00:23 23 April 2007 h aeo ioaract raelne nayseilwyt the to way special any in linked are or of cite at position Dinosauria definitions the of of base None the definitions). of phylogenetic definitions for position phylogenetic I the Table (arrow) showing (see stem-based Dinosauria and basal of (dot) node-based 1. Figure are taxa these for definitions Dinosauria. phylogenetic all of and previous definitions base these of the development historical at The working framework taxonomists heuristic solution. a for taxonomic provide may “established” they an Nonetheless, as intended not function are to they 2004), PhyloCode Queiroz the de by and taken (Cantino view the to Contrary dations. Ornithischia subordinate Saurischia. and its taxa. and anchors by stem-based configuration Dinosauria this linked subordinate triplet, node-stem of is a pair Called node-based dichotomy a a a to definition by the at maintained taxa Finally, best three complexity. between intro- relationship interpretational inevitably (apo- they duce form-qualified as maintain definitions, avoided phylogenetic that morphy-based) have alternative I and under arrangements. known content are well of that taxonomic chosen stability nested, were and deeply specifiers simplicity content, For taxonomic 2005). 1999, 1998, Fundacio PVL, abbreviations Institutional 146 rtrauo hc hlgntctxnm is phylogenetic which measured— 1992; the paper upon maximize Gauthier to and this aim criteria definitions a Queiroz These in de so 2005). I; Sereno adopted and Table 1, varied, is (Figure has taxonomy taxa phylogenetic dinosaurian and basal Dinosauria of other (content) meaning taxonomic The taxonomy Phylogenetic San Juan. de San Nacional Juan, Universidad Naturales, Ciencias de Tucuma de h entospeetdhr r recommen- are here presented definitions The .C Sereno C. P. Eoraptor ´ ,SnMge eTucuma de Miguel San n, stability ´ iulLlo nvria Nacional Universidad Lillo, Miguel n rHerrerasauridae. or , simplicity and , ro use prior ´ ;PS,Museo PVSJ, n; (Sereno esr htdpnso o h hrce sdefined. is character the how relative on a depends that is measure ‘Elongate’ centrum. the (Ischi- beyond anteriorly related formation projecting prezygapophyses elongate closely same has that a the gualasto) in from preserved is (unnamed) however, tail, distal herrerasaurids in a unknown Eoraptor in remain neotheropods, and and reported 1993) rib (Novas previously fused vertebrae, broad blade. a iliac the with with articulation primordial distal each the substantial are pair, vertebrae distal process. two sacral preacetabular a posterior the with next of The base rib) the fused to sacral a attachment (and/or slender without process first relatively a or has transverse The which dorsosacral, (with a articular rib). is girdle an associated has pelvic which the distinguishable vertebra with a as contact here defined is neotheropods. and herrerasaurids thought to previously restricted and be was to character (Sereno This herrerasaurids convex) 1993). in Novas transversely present process condition opposed (splenial dinosaurs reversed as the neotheropod concave), to transversely in concavoconvex process occurs a (splenial has elements as joint usual articulation The the angular). an between (splenial, has hand, joint other the intramandibular on jaw, lower recorded The Dinosauria. feature in primitive here time. definitively remarkably that the a on at teeth palatal exposed pterygoid, rudimentary of fully rows and two not are 1), There Figure were 1993; details to al. several prior et figured (Sereno preparation originally final was referred unpublished The several individuals. and skeleton holotypic lunensis Eoraptor lunensis Eoraptor both few for a Herrerasaurus import clarifying phylogenetic at of directed features literature. are below the comments entered The has been misinformation have 1993). casts available, al. or material et fossil original (Sereno the Although description preliminary 1993; a Sereno from Sereno 1993; Novas 1987; 2000). 1993; Galton Sues 1992, and Novas Brinkman and 1970; (Colbert relative close eal h kl n kltnof skeleton unequal and very skull in The known In detail. are follow. they that literature, current arguments the phylogenetic the to central lunensis Eoraptor evidence anatomical New www.taxon- 2005; al. et (Sereno search.org). online available lnaepeyaohssi h itlcaudal distal the in prezygapophyses Elongate sacral A vertebrae. three of composed is The eas h itlti sntpeevd The preserved. not is tail distal the because , . Eoraptor and sbsdo h erycomplete nearly the on based is Eoraptor errsuu ischigualastensis Herrerasaurus ncnrs,i nw only known is contrast, in , o h rttm within time first the for Herrerasaurus r eldescribed well are Eoraptor n its and and are Downloaded By: [University of Chicago] At: 00:23 23 April 2007

Table I. Phylogenetic definitions for key taxa used in this paper (for background information, see Sereno in press or www.taxonsearch.org).

Taxon Phylogenetic definition Definitional

Dinosauriformes Novas 1992 The least inclusive containing Passer domesticus (Linnaeus 1758) and lilloensis (Romer 1972) Node Dinosauria Owen 1842 The least inclusive clade containing horridus Marsh 1889 and Passer domesticus (Linnaeus 1758) Node Ornithischia Seeley 1888 The most inclusive clade containing Triceratops horridus Marsh 1889 but not Passer domesticus (Linnaeus 1758) or Stem loricatus Bonaparte and Powell 1980 Saurischia Seeley 1888 The most inclusive clade containing Passer domesticus (Linnaeus 1758) but not Triceratops horridus Marsh 1889 and Stem including Saltasaurus loricatus Bonaparte and Powell 1980 Huene 1932 The most inclusive clade containing Saltasaurus loricatus Bonaparte and Powell 1980 but not Passer domesticus (Linnaeus Stem 1758), Triceratops horridus Marsh 1889 Theropoda Marsh 1891 The most inclusive clade containing Passer domesticus (Linnaeus 1758) but not Saltasaurus loricatus Bonaparte and Powell Stem 1980 Bakker 1986 The least inclusive clade containing bauri (Cope 1889) and Passer domesticus (Linnaeus 1758) Node h nobtlfsaof fossa antorbital The ischigualastensis Herrerasaurus centrum of percent in than elongate 15 considerably more are themselves (about centra the the because low length) length, centrum is the to beyond percentage relative prezygapophyses measured the is of centrum projection the If al iegso dinosaurs. several of in pterygoid, lineages independently the lost early on presumably teeth was palatal theropods. which of with rows ectop- rudimentary associated the a long of is Eoraptor this feature aspect pocket, ventral derived ectopterygoid the the Termed on terygoid. fossa of skull modest in this in preserved exposed well is fossa the opening. skull. of the of area Eoraptor sides same be both on slit- cannot The present the is preservation; opens It of opening Here space. artifact shaped it 2). an matrix-filled as fenestra, (Figure away a explained fossa promaxillary into the the one anteriorly of as only end in identified anterior opening preserved the slit-shaped narrow at well a shows is which specimen, region neother- among This only known opods. and promaxillary are the fenestrae, fossa, pneumatic the maxillary of anterior wall Two the in 1993). openings openings Novas or invaginations and of (Sereno devoid band narrow a as eerdseie,cletdb yta n18 and 1988 Fundacio in team my the by collected of specimen, referred a collections 1963) Tucuma the in (Reig by Lillo 1961 Miguel in collected in mounted Bonaparte and , F. and J. dorsal the and last Herrera pair: V. the sacral of primordial relationship the the articulation of preservation of vertebra, state specimen. dorsosacral given and opinion, disarticulation a my in the determined of be cannot absence however, or that presence stated and have (2000) saurus authors Galton previous 2000). the several (Galton sacrals, but as pair modified vertebrae, clearly primordial are sacral the (1970) vertebrae three two Colbert to only described . attachment originally the had of weak process comparatively preacetabular a dorsosacral a that be with anticipate would present, would if sacral, one additional the speci- because needed, well-preserved are question, characterizes mens that as answer To vertebrae, pair? three least Eoraptor at have they and teeth. palatal any have h hlgntcrltosiso al dinosaurs early of relationships phylogenetic The te eal fteplt aebe recently been have palate the of details Other In in vertebrae sacral of number The Staurikosaurus Herrerasaurus a nyteetosca etba.The vertebrae. sacral two these only has hc osntehbtaydpeso or depression any exhibit not does which , n te ioar,o nyteprimordial the only or dinosaurs, other and steol ioarkont maintain to known dinosaur only the is w ata kltn rsrein preserve skeletons partial two , a eandcnrvril Do controversial. remained has ´ Herrerasaurus Herrerasaurus ,Agnia(V 56,and 2566), (PVL Argentina n, Herrerasaurus Herrerasaurus . a enshown been had n nld a include and Herrerasaurus osnot does Stauriko- 147 ´ n Downloaded By: [University of Chicago] At: 00:23 23 April 2007 ruc 94,ceryol aetosca vertebrae, sacral two have as only clearly 1994), such Dinosaur- Arcucci rib. outgroups, or process not transverse ian does distal It free its rib. a by shortened have ilium a the and/or with process a transverse distally is view modification articulates this that evolutionary in sacral vertebra the A character. is this with girdle associated pelvic for speci- attachments the bony with to disarticulated convenient vertebrae of in number be the mens, vertebrae may sacral ilium”. definition identifying the to this attachment for Although transverse modified the not of is dorsal form a process “the as because identified anyway, be it vertebra Galton that suggested information, 411) new dorsal (2000: this in Given posterior dinosaurs. as of other in base process the preacetabular that contacts the process than transverse Its larger transverse vertebrae. a no with dorsosacral a process is The question relation. in this clarifies vertebra girdle, pelvic articulated an of uncertain. process remain preacetabular ilium the the to many its and attachment mounted vertebra this potential of and condition original prepared the have ago, was not specimen location. could this its given it As rib dorsal specimen, separate a holotypic with the articulated the the of contact in base to ilium fails the it was Although toward process. which its preacetabular projects preserved, vertebra, As process ilia. dorsal the transverse of in blades last the comment between not the shown did vertebrae on and sacral ilium particular account, the two with detailed only contact ver- of more with presence a sacral the in incorporated” described (1993), “fully Novas two tebrae. Ciencias as series of de sacral the composed Museo described 1139) Sereno (1992: the 461). Novas (PVSJ and of Argentina Juan, San collections in Naturales the in lacrimal now l, jugal; j, fossa; antorbital antfo, fenestra; antorbital bar antfe, Scale Abbreviations: 407). fenestra. PVSJ promaxillary of pmfe, (cast maxilla; the of fossa antorbital the of of Skull 2. Figure 148 h eerdseie PS 6) hc includes which 461), (PVSJ specimen referred The .C Sereno C. P. errsuu ischigualastensis Herrerasaurus Marasuchus Eoraptor ¼ ,B otrltrlve ftesi-hpdpoailr eetalctdo h neirwall anterior the on located fenestra promaxillary slit-shaped the of view Posterolateral B, A, . cm. 5 Srn and (Sereno n many and 19)adFae ta.(02.Techaracter The (2002). al. et Fraser and Novas (1990), (1992) Benton by followed were and unite dinosaurs to synapomorphies herrerasaurids. o xml,teeaen yaoopisgvnfor given synapomorphies (Saurischia no was are dinosaurs there analysis, evidence example, saurischian for (1986) character Gauthier’s In supporting presented. no 1993), May and although Padian and 1989; (Gauthier Gauthier Several 1985; lead Padian above). this followed defined an authors (as cladogram—as subsequent Dinosauria a to on context phylogenetic Herrerasaur- place in to idae first was 1986) (1984, Gauthier outgroup dinosaurian a as considered taxa ingroup and II). the (Table characters in range quantitative of wide Benton Seven a number with (2002). (1989), published al. been have al. dinosaur (1985), et analyses Fraser et early Padian and Gauthier cover (1990) and (1986), that Gauthier on Gauthier matrix. sort include based character-taxon this phylogeny not a of are of Analyses but analysis characters parsimony on list based hypotheses analyses Qualitative hypotheses. into quantitative versus divided cladistic qualitative be 1970), regarding can Colbert commentary commentary 1963; (Reig pre-cladistic herrerasaurids aside Setting interpretations phylogenetic Previous modification. further a is vertebra attachment dorsosacral iliac the the of of Enlargement evidence, vertebrae. sacral and definition this Herrerasaurus By pair. primordial the rnmnadSe 18)wr rtt propose to first were (1987) Sues and Brinkman per ohv he,rte hntwo, than rather three, have to appears þ rihsha excluding Ornithischia) Herrerasaurus n other and ;m, Downloaded By: [University of Chicago] At: 00:23 23 April 2007

Table II. Profile of phylogenetic analyses that consider relationships at the base of Dinosauria.

Authors Matrix Character Documentation

Character Character figured No Analysis Printed e-Archived No. Ingroups No. Characters Character listed states listed Original author cited Character description (%)

1 Novas 1992 þ – 5 17 – þ ––24 2 Novas 1993 þ –6 51 þþ þ –0 3 Sereno et al. 1993 – – 12 132 – þ ––0 4 Sereno 1999 – þ 13 146 þþ ––0 5 Rauhut 2003 þ – 58 224 þþ ––0 6 Langer 2004 – þ 9 107 þþ ––80 7 Langer and Benton 2006 þ –1098– þþ þ ,10 oiu ouin agre l 19)cm the came (1999) al. et showing Langer closest, solution. either monious positions that Herrerasaurus ever has published hypothesis been quantitative rec- No Theropoda.” not Saurischia They or Dinosauria, should diagnosing for basis 1995). a characteristics as used be “its Padian further, and ommended, (Holtz of position abstract “the that claimed Herrerasaurus (2002:91) al. et Fraser 1995). Murry and herrerasaurid probable the in and in present herrerasaurid, process. is another however, fossa, postacetabular brevis better-developed swollen A autapomorphic preacetabular brevis an in a expressed the of weakly presence is to the fossa, feature, attaches second dorso- The one that process. and vertebra sacrals primordial sacral two of characterizes composed above argued or I both three vertebrae, first, sacral The more problematic. potentially unite are of which these exclusion the of The to two Dinosauria 2002:95). to al. cladogram, legend figure a et in a given was (Fraser these of six appendix for placement an were Seventeen in Dinosauria” listed of Dinosauria. characters diagnostic and “principal association, of elements isolated uncertain few a on their based taxon or named on newly matrix shown to limited ingroups are character-state cladogram The a and analysis. list lacked quantitative character but short a cladogram supporting presented paper hypothesis, recent a most this the (2002), to al. et Fraser reduced shelf trochanteric 1992). Femoral (Novas prominent (7) shelf Brevis 1990). (Benton expanded (6) transversely Distal (5) (Benton prominent trochanter 1990). (Benton anterior vertebrae Femoral 1987). sacral more Sues (4) and or (Brinkman Three developed small V (3) well digit Pedal less (2) wall, acetabular size Medial the (1) relative of ill-defined many on because based differences: part are in characters not convincing, has publication) of been order in below (listed evidence aa arsha.Si ob ae n4 characters, 40 on based be to positioned Said (1999) saurischian. basal al. et Langer Eoraptor was however, analysis, published. this not for matrix The polytomy. h hlgntcrltosiso al dinosaurs early of relationships phylogenetic The ept iie hrce nlssadn matrix, no and analysis character limited Despite rmnne(oa 1992). (Novas prominence 1990). 1987). Sues and (Brinkman Eoraptor n errsuia sbslSaurischia basal as Herrerasauridae and and sa eteuvcl”ctn published a citing equivocal,” best at is usd ioaraa h otparsi- most the as Dinosauria outside Herrerasaurus Herrerasaurus Staurikosaurus Herrerasaurus Herrerasaurus na neovdbasal unresolved an in Herrerasaurus h ar fwihare which of sacra the , Herrerasaurus Agnostiphys Clet1970), (Colbert , Agnostiphys Eoraptor hc has which , ohof Both . (Long sa as 149 and —a or Downloaded By: [University of Chicago] At: 00:23 23 April 2007 orykontx htaepriual ntbe ahdlnsidct oso eouinwt nraei relnt ftosesabove steps the two masks generate of taxa length these tree collapse in additional increase the with because resolution calculation, decay). identify this Benton of by Asterisks to and loss measured interpretations. Langer prior indicate support conflicting removed (C) of lines to were (1999), level central Dashed asterisks general Sereno are unstable. with (B) that (taxa particularly (1993), taxa length Sereno are those minimum (A) only that retaining dinosaurs. taxa cladogram basal known unresolved of poorly reduced, interrelationships a the (D) showing and (2006), 3. Figure al. either et Sereno positioning of that result (1993), phylogenetic confirmed subsequent general (2004) a most Langer In the al. characters, surprising. 107 et not of Sereno is analysis 1992; result this Novas theropod 1993), and taxon the provided to (Sereno new hand central hypothesis synapomorphies and the the skull of the in many that preserved Given 1999:515). not were ( hand” and they skull the as of features “excluded analysis the 150 aae f9 hrces(iue3) rwn the drawing 3C), (Figure characters conclusions—that 98 same of dataset a or scores, taxa? ingroup excluded character-state new data, (1999; alternative character are new data, Sereno result to new character due of this it for Was matrix reasons clear. the not and so and list 3B), Figure character made the were comparisons to global them no placing characters, several discussed than (2004) Langer steps) Although Theropoda. within (two parsimonious more steps. 14 positioning that by and argued length then tree (2004) increased Langer so Doing option. saurus ahrta aa hrpd.Temjrt fte98 16 (2004); the Langer of by previously majority used The were theropods. characters basal saurischians than basal rather as tenuously, albeit positioned, best Saturnalia oercnl,Lne n etn(06 analyzed (2006) Benton and Langer recently, More Herrerasaurus .C Sereno C. P. usd ioarai o parsimonious a not is Dinosauria outside hywr eciig(agre al. et (Langer describing were they ) sbslsuicin a slightly was saurischians basal as Eoraptor and Eoraptor Herrerasaurus or Herrera- Eoraptor are fteoiia 0 hrceswr mte,seven omitted, were characters and new, 107 are characters original the of eaiet h rxmled tt novsteshape the involves 2 blade state pubic end; the proximal of the end to distal relative the of and width 0 the States involve 30). 1 2006: Benton and the (Langer of (2)” than or deep broader part not (0) and proximal compressed as lateromedially (1) blade broad than as narrower nearly significantly by states “Distal character a listing themselves: of Langer, perils provides (M. the of 2 78 example and good Character 1 states communication). than rather personal 1 and 0 states ro ncaatr7,i diin ftepublished the of scoring addition, apparent in an 78, matrix; to character due in is 3C). no error resolution (Figure of with loss trees taxa 15). The length ‘eusaurischian’ minimum 2006:Figure among six resolution as Benton are there tree and Rather most-parsimonious (Langer a resolved yield reported not fully did ordered) single, characters multistate seven press). in Sereno 1997; of al. character et delineation exclusive (Hawkins mutually states clear of mandates composed the Morpho- characters data misinterpretation. infer character risks to logic that states, of needed proposition character given the tabulation a I from comparative 17–25) III), were (numbers (Table character a states data make character character To II). Only (Table taxa. ingroup eaayigti ulse aae wt i of six (with dataset published this Re-analyzing a crda oyopi with polymorphic as scored was iearsopolensis saddto added is Downloaded By: [University of Chicago] At: 00:23 23 April 2007 1L8 ii,mda onro itled hp:90 length shape: humeral end, of distal 80% of than corner (1), medial less Tibia, or vertebrae naris (0), dorsal external more anterior the length: (1), (1) to Radius, present than (1), (0); shorter ventral absent or or vertebra(e): (0), (0), Sacrocaudal longer posterior end) length: location: distal centra, ramus, blade-shaped cervical posteroventral broad Posterior of of tip (loss Premaxilla, III (1). metacarpal present of (0); diameter absent 50% foot: than Pubic less vestigial, (0); short diameter: shorter V, form: and I-III) LB87 IV (digits Metacarpals ungual and length LB51 blade III) of II, width (digits proximal phalanx (1), LB42 penultimate than I-III, (1) less digits elongate or Manual (0); 65% LB35 short or prezygapophyses: (0), caudal to Distal subequal (1) 21 LB5 width: present distal (0); blade, absent Pubic depressions: 20 S101 extensor asymmetrical I-III, (1) Metacarpals present 19 (0); approximately (1) Character absent (0), present joint: (0); 20–30% Intramandibular absent longest): 18 S100 fossa: is Ectopterygoid whichever III, width or 17 distal II times digit 3 along (1) than (measured present (1), 16 length (0); more centrum Manus absent or axial depression: (0), of attachment less width S99 anterior width: maximum end, distal than distal versus (1), Femoral length more 15 S97 blade, or Scapular (0), less width: (1) S95 intercentrum present Axial (0); (1) absent present process: (0); (1) S92 absent obturator extreme Ischial facets: (0); articular moderate intermetacarpal : 14 S88 I-III, long (1) Metacarpals and process S87 centra prong-shaped of (0); 13 cavitation rugosity Internal or crest shape: 12 , Cervical S69 11 S102 10 S98 9 S96 S94 8 S91 7 S90 6 S89 5 4 No 3 Character 2 1 No etn(06 1 etoe hs v n two two final and the cite five not exhibit did these but and 22) not 20, Langer mentioned (numbers do others 41) 23–25). which (2006: 18, Benton of 17, (numbers five homoplasy and 17–25), herrerasaurids numbers exclu- the of to sion sauropodomorphs and be theropods to unite appear thus less this ‘Eusaurischia’ illusory. naming for taxon need inclusive the and and saurischians other herrerasaurids of basal The characters. position unordered or seven additional ordered two with or steps the one with collapses Ordering resolution Saurischia all within effect; collapse. little has also one-step characters multistate this alter in one 78 genera shaft character known the with for to relative score resolution (1), collapses expanded either Guaibasaurus dorsoventrally 3 All or metacarpal with (0), than clades equal (1), step minor. width: longer I-ungual additional transverse or digit end, subequal than saurischian is distal or (1), , (0), shorter shorter however, or among length: subequal (1), 2, or than tree, Metacarpal mutually (0), broader longer or length: (0), be independent published 1, to Metacarpal subequal to width: to anteroposterior end, appear distal belong of not margin medial therefore 1 Tibia, do characters. and and 0 thus, States exclusive 2, blade. the state of and portion LB80 proximal the LB61 of LB57 25 LB89 24 23 22 of exclusion the to saurischians linking synapomorphies “eusaurischian” S as (2006) Benton and Herrerasaurus Langer by of used interpretation were the linking for states) nodes synapomorphies key as at (1999) synapomorphies Sereno as listed by Characters III. Table ¼ ieuabgossnpmrhe,nonetheless, synapomorphies, unambiguous Nine resolved fully single the with difference The eeo(99;LB (1999); Sereno hdn niae h rsneo 2caatr nbt nlss(e al Vfrcaatrsaecmaio) Abbreviations: comparison). state character for IV Table (see analyses both in characters 12 of presence the indicates Shading . Fgr C.Rmvlo h poorly the of Removal 3C). (Figure ¼ agradBno (2006). Benton and Langer and Guaibasaurus Eoraptor o eaaplI)(1) II) metacarpal (or preceding than longer (1) (0); unguals unguals recurved recurved strongly moderately long short phalanx, phalanx, preceding to subequal or of length (2) 50–70% or (1), 40% h aea margin lateral the Eoraptor Eoraptor TbeIII, (Table eaieto relative and/or osnot does Herrerasaurus diinlsesaerqie eoeterbasal III). Table (with their collapses before saurus Theropoda required within Eight are position (Neotheropoda). steps theropods additional other of position outside sup- the analysis each port in dozen not a synapomorphies did than been unambiguous that More arrangements. papers has alternative short which discuss in 1999 presented and for 1993 were the matrix analyses Both 3B). and (Figure online list available (CI characters character 146 the a of by obtained analysis was result subsequent same The 12 published. not characters, was CI (132 taxa, transformation terminal listed were delayed All nodes 3A). under internal (Figure critical 1993) at al. synapomorphies et of analysis (Sereno an characters on 132 based originally was hypothesis This Eoraptor characters conflictive of present. be number must node equivalent the a of nearly (‘Eusaurischia’), instability support synapomorphies the these Given that 87). 42, (numbers h hlgntcrltosiso al dinosaurs early of relationships phylogenetic The ihohrteoos hrces1–5(nerdfo character from (inferred 17–25 characters theropods; other with and 8 Eoraptor n errsuia sbslTheropoda basal as Herrerasauridae and rmr 0;ls hn90 than less (0); more or þ ais sae1- (state radius. Chindesaurus and ¼ Herrerasaurus .5,atog h arxitself matrix the although 0.85), Eoraptor . 2) eoe;Fgr 3B, Figure removed; 8 hrces11 eelisted were 1–16 Characters . n Herrerasauridae and Eoraptor ¼ Pisano- 0.81), and 151 Downloaded By: [University of Chicago] At: 00:23 23 April 2007 osntcag iiu relnt,atrthe alter length, tree minimum of example, change for relationships (2006), not Benton and does Langer of analysis of Removal ornithischian fragmentary the of handful including a forms, of absence or presence influenced the by significantly not are solutions different The species fragmentary of role The different in resolve analyses ways. these six that the and taxa) outgroup shows terminal (an 1D problem Figure phylogenetic compared. common and are Langer and (2006) (1999) Benton Sereno solutions, arrive different analyses at comparable how understand better To problem the Isolating state results. character those behind or lie phylogenetic characters that that the scores compared than rather principally because results or unclear, analyses (2004) remain (2006) these Langer Benton (2003), and Langer Rauhut by obtained (1999), results overlapping Sereno reasons or The varying the 2003:162). behind (Rauhut extra respectively eight and steps, five required 2006) Benton and Langer aa hrpdrltosis eoiinn either Repositioning relationships. Eoraptor theropod basal Herrerasaurus 152 crea rtclnds(al I) ntecs fSereno that of case the In synapomorphies III). (Table nodes critical at unambiguous accrue the and compiling analysis each running by ascertained quickly be can (1999) evidence character Sereno Key (2006). in Benton and areas Langer and two those of assessment a quick a be is follows What choice. to state character and character appear to due not likely most are does results differing the factor, sampling significant taxon that Given evidence character Key differing the of in role interpretations significant a play to appear not does forms, like fragmentary of one Sampling links Theropoda. to that both alternative or an and differential saurischians length basal are to branch One greatest that hypothesis topology. the the between on is effect steps little three has the also of these unordered leaving six dataset; the ordered in characters (2006) multistate seven Benton 3C). and Langer (Figure effect. Saurischia of absence or within presence the Likewise, position basal collapse to their needed step additional single the increase or “Eusaurischia,” outside groups successive as sauridae) saurid saurischian ible aht(03 lopositioned also (2003) Rauhut iaoars Guaibasaurus Pisanosaurus, .C Sereno C. P. Chindesaurus or Herrerasaurus Pisanosaurus sbslteoosi i uvyof survey his in theropods basal as Eoraptor Guaibasaurus Eoraptor Fgr ;tx ihasterisks). with taxa 3; (Figure and or sabslsuicin( saurischian basal a as and Eoraptor Herrerasaurus Guaibasaurus rpsil herrera- possible or , Herrerasaurus and , Pisanosaurus Silesaurus and Silesaurus Eoraptor Herrerasaurus (Herrera- . rmthe from a little has poss- , thus, , and fide TbeI) itels hnhl fti aito is variation this These hypotheses of species. by half represented the taxa than terminal between less for scored little shared A IV). are (Table that critical from nodes characters 12 the for scores state character ques- important has resolve. are the (or to tions included These of not coming omitted/rejected)? is results most been that differing evidence Is character How the from analysis? for partition? character each signal unshared of for phylogenetic alone the partition run about phylogenetic shared if yield What the data evidence shared III). does character is (Table the structure characters) is analyses of (25 It between nodes half choice. critical only state supporting that character and remarkable choice character review). in facilitate (Sereno to resolution turn, and in consensus needed, future is and visualization III Tables Such in IV. visualized differences scores the state highlight character to and lists data efficiently character to opposing tools respective sort analytic lack is we their issues paramount, character clearly these Benton within resolving and Although hidden Langer matrices. and lie the (1999) between (2006) above Sereno outlined of differences analyses the of Most conclusions and Discussion the generating in role major state results. phylogenetic a character in differences play observed Thus, well 39%). may 72; choice (28 analyses of the out between differ mismatches states character the of 40% Nearly disparity. state character a or opposing mark, score question positive character a than state or rather character mismatch, scores, state this mismatched of comprises Most variation between IV). shared (Table are analyses that characters the 12 the of one every same in the role results. major answer phylogenetic a different play to obtaining must data choice Character into character question. tapping are different analyses The very finding. This significant III). (Table a analyses is both in present are 48%) 25; of position the on the effect Eoraptor between major a characters have that critical analyses 25 two sum, in are, There choice state character and Character of composed clade excludes a that 89), 87, Theropoda Eoraptor 80, and 61, Sauropodomorpha 57, 51, 42, 35, (LB5, Benton “Eusaurischia” and unite characters Langer nine of that (2006), case within the node In for a 96–102). (S69, at responsible clade Herrerasauridae and are 95) 94, characters 92, such of maintaining 16 (1999), ti lormral o uhvraineit in exists variation much how remarkable also is It concern study this in highlighted areas two The in manifest also is scores state character in Variation n Herrerasauridae. and and Eoraptor Herrerasaurus ttebs fTeooa(S87– Theropoda of base the at afo hs 1 u of out (12 these of Half . Downloaded By: [University of Chicago] At: 00:23 23 April 2007 ubrCaatrdsrpinONSAU ORN description Character number Character Staurikosaurus; 6 au egh(esrdaogdgtI rIII, or II digit along (measured length Manus S69 1 20) ORN (2006); 9 ui ld,dsa it:sbqa o() r65% or (0), to subequal width: distal blade, Pubic S95 depressions: extensor asymmetrical I-III, Metacarpals 5 S92 4 8 nrmniua on:asn 0;peet()11 1 0 (1) present (0); absent joint: Intramandibular (1) present (0); absent S88 fossa: Ectopterygoid 3 S87 2 eaue n qiaett Teooa nLne n etn(06.Abeitos S Abbreviations: (2006). Benton and Langer ( in NEO “Theropoda” ; to and equivalent Prosauropoda and Tetanure) for (1999) Sereno from score 9 itlcua rzgppye:sot() lnae()001 0 0 III) II, (digits phalanx penultimate I-III, digits Manual (1) elongate (0); short S99 prezygapophyses: caudal Distal 7 S97 6 10MtcrasI n ,daee:sot(0); short diameter: V, and IV Metacarpals S100 8 nlss hrcessaesoe r hw o i aapeeti ohaaye Fgr D.SU( SAU 3D). (Figure analyses are both that in characters present 12 taxa for six (2006) of for Benton position shown and phylogenetic are Langer the scores and to state (1999) Characters key Sereno analysis. and between analyses disparity) both (mismatch, variation in state present Character IV. Table 11Pbcfo:asn 0;peet() ls fbroad of (loss (1). present (0); absent foot: Pubic S101 9 0S3 eaaplIlnt:lne 0,o hre (1), shorter or (0), longer length: I Metacarpal S133 10 2S3 sha itled neootro ieso:ls (0), less dimension: anteroposterior end, distal Ischial S134 III, digit longest: metacarpals, and digits Manual 12 S131 11 LB55 B2010000 0 0 0 0,1 LB20 LB16 LB52 B71010 1 1,0 LB47 B820002 0 0 0 2 LB63 LB78 LB64 B61000 0 0 1 LB76 LB57 LB61 LB80 ¼ NEO rihsha SAU Ornithischia; ¼ 0 1,o 07%()lnt fhumerus of length (2) 50-70% or (1), approximately 40% (0), 20-30% longest): is whichever rls hn() rxmlwdho blade. of width proximal (1), than less or (1) present (0); absent rcdn hln,ln togyrcre nul (1) unguals recurved strongly long phalanx, than preceding longer (0); unguals recurved moderately short phalanx, or preceding shorter to form: subequal I-III) (digits ungual and length fmtcra I o eaaplI)(1) II) metacarpal (or III metacarpal of diameter 50% than less vestigial, ld-hpddsa end) distal blade-shaped hnpaax1o nulo ii I digit of ungual or 1 phalanx than rmr 1,ta raetwdho ihrischial present) either “foot” of (i.e., width peduncle greatest than (1), more or (1) II metacarpal II, digit (0); III metacarpal Neotheropoda. ¼ Sauropodomorpha; Eor Eoraptor ¼ þ oatrlunensis Eoraptor radius ¼ eteooa sacmoiei eeo(1999:Ceraosauria Sereno in composite a is Neotheropoda) h hlgntcrltosiso al dinosaurs early of relationships phylogenetic The and Herrerasaurus ; Her , 2 2 1 1,0 0 01111 01?1 ¼ h rfi ncaatrnmesietf the identify numbers character on prefix The . ¼ errsuu ischigualastensis Herrerasaurus eeo(99;LB (1999); Sereno 0,1 1 0 1 0? 0 10 01 ? aa(hrce tt scores) state (character Taxa ¼ arpdmrh)lssacomposite a lists Sauropodomorpha) o e Sta Her Eor 0? 1 0 ¼ agradBenton and Langer ; Sta 1 1 ? ? ¼ þ NEO 153 Downloaded By: [University of Chicago] At: 00:23 23 April 2007 rnmnD,Se -.18.Asarksui ioarfo the from dinosaur staurikosaurid A South 1987. H-D. of Sues DB, Triassic Brinkman the in replacement Faunal 1982. JF. Bonaparte Geol In: dinosaurs. Modern of interrelationships dinosaurs. and of Origin 1990. origins MJ. Benton The 1988. MJ. Benton and Simpson of W. material the Masek, final of preparation R. the Eoraptor detailed for figures, for Abraczinskas Vodden all R C. of thank to drafts like would I Acknowledgements -based future. of rigorous practice a has the if path, must in we this Indeed, differences character follow 2004). the (Jenner the scores decrease state in and character all accuracy employ we and will evidence overlap outgroups the suprageneric increase seems light, basal within specimens, the this of condition in on consideration steps, and descriptions, observations two character or Further one differ as questionable. that little lengths as tree by of significance taxa. the comparable or Pondering in same the variation for startling scores state exhibits character sidelined or either rejected) is data or of (omitted partition relevant very a that exemplars. as consulted are taxa suprageneric which as within well of as relationships taxa statement basal explicit more assumed Future a the state. include to that character ought of assumption studies choice unstated, influences is often directly taxa and terminal important, suprageneric basal the an about these ideas of within Different issue. 2001), structure at is Prendini taxon terminal 1995; (Yeates or condition, basal groundplan the estimating cases, these In poda. Neothero- or suprageneric Sauropodomorpha involves as such hand, taxa, other terminal the on scores, state observational outstanding these issues. resolving be to nevertheless, ought because study, future not part for imperative in is An available. manuscript, that of morphology present outset, detailed original the the the to of at recourse goal the by mentioned resolvable As is materials. conflict this most Presumably, of some- specimen. single which a to materials, limited is times of observation direct involve 154 References and participate manuscript, to invitation symposium. the the this for in Pol on D. and Langer comments M. helpful for nec ftetoaaye oprdw aeseen have we compared analyses two the of each In character in variation the of half than more little A pe rascIciulsoFraino retn n the and Argentina of Formation Ischigualasto Triassic Upper 2:362–371. Paleontol Vertebr J America. 11–30. Califor- p of Press. University nia Berkeley: dinosaurs. of Osmo interrelationships P, Dodson DB, Weishampel 13:41–56. .C Sereno C. P. and Herrerasaurus .Lne n .Wilson J. and Langer M. , oatrlunensis Eoraptor ´ saH dtr.Oii and Origin editors. H, lska sntyet not is ahtOM 03 h nerltosisadeouino basal of and interrelationships in The 2003. terminals OWM. Rauhut as taxa supraspecific or Species 2001. L. Prendini SG, Lucas In: dinosaurs. earliest The 1993. CL. May and K, Padian the on information New 1993. FE. Novas dinosaurs, basal the of relationships Phylogenetic 1992. FE. Novas ) and (Carnian Triassic Late 1995. PA. phylogenetic Murry A RA, dinosaurs: Long Early 2006. MJ. A Benton 1999. MC, Langer MJ. Benton M, Richter F, Abdala MC, Langer P, Dodson DB, Weishampel In: Saurischia. Basal 2004. MC. Why Langer cladistics: metazoan of status scientific Thero- The of 2004. diagnosis RA. Jenner and Definition 1995. K. Vertebr Padian J Jr, Theropoda. TR the Holtz of phylogeny new A 1995. Jr. TR Holtz homology Primary 1997. PW. Scotland CE, Hughes time JA, geologic Hawkins A 2004. editors. AG, Smith JG, Ogg FM, Gradstein aeyS,Da P 96 rmfodt fan: to frond From 1996. KP. Dial SM, Gatesy Are 2000. PM. Galton dinosauriform Basal 2002. V. Stewart GM, Walkden NC, Fraser Rev Annu of taxonomy. Phylogenetic Triassic 1992. J. the Gauthier K, from Queiroz de dinosaur saurischian A 1970. EH. Colbert code phylogenetic A PhyloCode: 2004. K. Queiroz de PD, Cantino atirJ ainK 95 hlgntc ucinland functional Phylogenetic, 1985. K. Padian J, Gauthier 1989. T. Rowe AG, Kluge K, Quieroz de D, Cannatella J, Gauthier systematic In: higher . of origin the the and of Saurischian 1986. analysis J. Gauthier cladistic A 1984. J. Gauthier hrpd.Se a aaotl69:1–213. Palaeontol Pap Spec theropods. Syst 50:290–300. revisited. Biol exemplars versus Groundplans Albuquerque. analysis? cladistic Science. and Mexico History New 379–381. Triassic. Natural p Nonmarine of The Museum editors. M, Morales Formation 13:400–423. Ischigualasto Paleontol Vertebr J the Argentina. of Triassic) from (Upper Herrerasauridae) poda: of skeleton postcranial 35:51–62. Palaeontol Herrerasauridae. the 4:1–254. Science and the History of Natural Bulletin of Museum States. Mexico United New southwestern the from 4:1–50. Palaeontol Syst of terre Journal study. la de Sciences Paris, de 329:511–517. Sci planetes Acad des R et (Carnian) C Triassic . Upper southern of the from dinosaur sauropodomorph 25–46. p Press. California Osmo 33:293–310. Scr Zool change. must practice current Suppl.):35A. 15(3, Paleontol Vertebr J taxa. related and poda Supplement):35A. Cladistics 15(3, Paleontol states. character and 13:275–283. characters assessment, 589. p Press. University Cambridge Cambridge: scale. ean rmBianadtedansso h Dinosauria. the of diagnosis the and 45:79–95. Palaeontol Britain from remains 23:449–480. Syst Ecol 2405:1–39. Novitates Mus Amer Brazil. http://www.ohio.edu/phylocode/. nomenclature, biological of 30: Palaeontology Staurikosauridae. the 493–503. of relationships eh K srmJ,VolG elhfrP editors. P, Wellnhofer Eichsta flight. Eichsta their G, and origin birds the Viohl of of analyses JH, In: aerodynamic and flight. functional their Ostrom Phylogenetic, and birds MK, of origin Hecht the of Science analyses aerodynamic Elsevier York: H, New 337–353. Jornvall p phylogeny. K, Publishers. Bremer B, editors. Fernholm In: of phylogeny. 1–55. origin Tetrapod p Berkeley the 8, Number and Sci, monophyly Acad Calif Saurischian Mem birds., editor. K, Padian 564. p Berkeley, Calif, Univ thesis, PhD Diapsida. of categories 50. Evol birds. short-tailed of evolution the ai omto,Mdl-pe rasc rzl h oldest the Brazil) Pala Triassic, dinosaurs? saurischian Middle-Upper Formation, Maria ´ saH dtr.BslSuici.Bree:Uiest of University Berkeley: Saurischia. Basal editors. H, lska t.p185–197. p ¨tt. errsuu ischigualastensis Herrerasaurus otlZi 74:393–423. Zeit ¨ontol t:FenedsJura-Museums des Freunde ¨tt: and Staurikosaurus (Thero- (Santa and Downloaded By: [University of Chicago] At: 00:23 23 April 2007 eeoP.Lgclbssfrmrhlgclcaatr in characters morphological for basis Logical PC. 284: Sereno Syst Science taxonomy. phylogenetic of dinosaurs. basis logical of The 2005. PC. evolution Sereno The 1999. PC. with Sereno definitions, phylogenetic for rationale A 1998. Rev PC. Ann Sereno dinosaurs. of evolution and origin The 1997. PC. Sereno oesR,CSII eeoP,MntaA,Mrie N 1993. RN. Martinez AM, Monetta PC, Sereno III, CCS RR, Rogers eeoP.19.Tepcoa ideadfrlm ftebasal the of and girdle pectoral The 1993. PC. Sereno egO 93 apeecad ioaro arsuo nlos en saurisquios dinosaurios de presencia La 1963. O. Reig hlgntc.Caitc.i press. in Cladistics. phylogenetics. 54:595–619. Biol 2137–2147. Jahr N Dinosauria. of Pala taxonomy Geol higher-level the to application 25:435–489. Sci Planet Earth 425–450. h shgaat erpdasmlg Lt rasc Argen- Triassic, and (Late assemblage tina) tetrapod Ischigualasto The 3:3–20. Ameghiniana theropod 260:794–797. rvnisd a unyL ij (Repu Rioja las La de y Juan superior) San (Mesotriasico de Ischigualasto” provencias de “Estratos otlAh210:41–83. Abh ¨ontol errsuu ischigualastensis Herrerasaurus 40 Ar/ 39 rdtn fdnsu rgn.Science origins. dinosaur of dating Ar etb aeno 13: Paleontol Vertebr J . ´ lc Argentina). blica etsD.19.Gonpasadeepas ah otete of tree the to Paths exemplars: and Groundplans 1995. DK. Yeates eeoP,NvsF.19.Tesuladnc ftebasal the of neck and skull The 1993. FE. Novas PC, Sereno an of skeleton and skull complete The 1992. FE. Novas A PC, Sereno TaxonSearch: 2005. SL. Brusatte S, McAllister PC, Sereno Primitive 1993. AM. Monetta RR, Rogers CA, Forster PC, Sereno eeoP,AcciA.19.Dnsuinpeusr rmthe from precursors Dinosaurian 1994. AB. Arcucci PC, Sereno the from precursors Dinosaurian 1993. AB. Arcucci review. PC, in Biol. Sereno Syst cladistics. Comparative PC. Sereno h hlgntcrltosiso al dinosaurs early of relationships phylogenetic The ie ldsis11:343–357. Cladistics life. 451–476. theropod 258. Science dinosaur. phylogenetic early and taxa suprageneric 8:1–20. PhyloInformatics for definitions. database relational of evolution early the and 361:64–66. Nature Argentina Dinosauria. from skeleton dinosaur 14:53–73. Paleontol Vertebr J ideTisi fArgentina: of Triassic Middle 13:385–399. Paleontol Argentina: of Triassic Middle errsuu ischigualastensis Herrerasaurus aeptnchanarensis aauhslilloensis, Marasuchus etb aeno 13: Paleontol Vertebr J . Vertebr J . e.nov. gen. 155