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A new Late Devonian bothriolepid (Placodermi, Antiarcha) from Victoria, with descriptions of other species from the state

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A new Late Devonian bothriolepid (Placodermi, Antiarcha) from Victoria, with descriptions of other species from the state
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   PLEASE SCROLL DOWN FOR ARTICLE This article was downloaded by: [Museum of Victoria]  On: 22 April 2009  Access details: Access Details: [subscription number 905085277]  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 Alcheringa: An Australasian Journal of Palaeontology Publication details, including instructions for authors and subscription information:http://www.informaworld.com/smpp/title~content=t770322720 A new late Devonian bothriolepid (placodermi, antiarcha) from Victoria, withdescriptions of other species from the state J. A. Long a ; L. Werdelin ba Department of Geology, University of Western Australia, Nedlands, Australia b Department ofPalaeozoology, Swedish Museum of Natural History, Stockholm, SwedenOnline Publication Date: 01 January 1986 To cite this Article Long, J. A. and Werdelin, L.(1986)'A new late Devonian bothriolepid (placodermi, antiarcha) from Victoria, withdescriptions of other species from the state',Alcheringa: An Australasian Journal of Palaeontology,10:4,355 — 399 To link to this Article: DOI: 10.1080/03115518608619146 URL: http://dx.doi.org/10.1080/03115518608619146 Full terms and conditions of use:http://www.informaworld.com/terms-and-conditions-of-access.pdfThis article may be used for research, teaching and private study purposes. Any substantial orsystematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply ordistribution in any form to anyone is expressly forbidden.The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae and drug dosesshould 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 directlyor indirectly in connection with or arising out of the use of this material.  A new Late Devonian bothriolepid (Placodermi,Antiarcha) from Victoria, with descriptions ofother species from the state J. A. LONG AND L. WERDELIN LONG, J. A., & WERDELIN, L., 1986:08:25. A new Late Devonian bothriolepid (Placodermi,Antiarcha) from Victoria, with descriptions of other species from the state. Alcheringa10, 355-399. ISSN 0311-5518.A new species of bothriolepid antiarch, Bothriolepis tatongensis sp. nov., from the Late Devonian basal conglomerate of the Hollands Creek Rhyodacite, near Tatong, northernVictoria, is described. B. tatongensis sp. nov. can be distinguished from all other speciespossessing a trifid preorbital recess by the short postpineal plate with paired pits openinganteriorly into the orbital fenestra, and by coarsely reticulate dermal ornament. B. gippslandiensis Hills, B. cullodenensis Long, B. fergusoni Long, B. bindareei Long and B. warreni Long are described and illustrated. Metric analysis of headshield and premedianplate measurements of B. gippslandiensis, B. cullodenensis and B. fergusoni are comparedwith ontogenetic variation in B. canadensis Whiteaves. The phylogenetic position of B. fergusoni and B. tatongensis sp. nov. is discussed and the significance of the preorbital recessin bothriolepid evolution re-evaluated. A trifid preorbital recess is suggested to be apomorphicwithin the Bothriolepidoidei by comparison with the homologous structures in other antiarchs.The composition of the Tatong fauna indicates a late Givetian-early Frasnian age for thebase of the Hollands Creek Rhyodacite, and the onset of post-Tabberabberan sedimentationin the southern end of the Lachlan Fold Belt. J. A. Long, Department of Geology, University of Western Australia, Nedlands, W.A. 6009,Australia; L. Werdelin, Department of Palaeozoology, Swedish Museum of Natural History,Box 50007, 104 05 Stockholm, Sweden; received 13 February 1985. THE ANTIARCH Bothriolepis is perhaps thebest known of all placoderm fishes, with oversixty species described from worldwideoccurrences in both terrestrial and marinedeposits of Middle and Late Devonian age(Stensi6, 1948; Miles, 1968; Denison, 1978;Long, 1983). In Australia bothriolepids havebeen recorded from several localities insoutheastern Australia (Hills, 1929, 1931,1932, 1936; Ritchie, 1969; Campbell & Bell,1977; Fergusson et al., 1979; Young & Gorter,1981; Long, 1982a, 1983), central Australia(Gilbert-Tomlinson, 1968; Hills, 1958) andWestern Australia (Gardiner & Miles, 1975).Despite this documentation until recently onlytwo species have been formally described, B. gippslandiensis (Hills, 1929, 1931) and B. verrucosa (Young & Gorter, 1981). In aprevious paper one of us (JAL) diagnosedfour new species, B. cullodenensis, B.fergusoni, B. bindareei and B. warreni (Long,1983) and gave a brief account of new 0311/5518/86/020355-45 $3.00 © AAP morphological features, antiarchan phylogenyand classification, and a biostratigraphiccorrelation of Victorian Late Devoniancontinental successions. In this paper the newspecies are described fully, together with B. tatongensis sp. nov., another new formdiscovered in early 1983 as part of a new faunafrom Tatong, Victoria. Although fish remainshave long been known from Tatong (Brown,1961) the site has only recently been excavatedto produce well preserved material.Preliminary study of the Tatong fishesindicates a fauna containing bothriolepids, aphlyctaenioid and other euarthrodires, aphyllolepid, and crossopterygians.Fossil localities mentioned in this work areshown in Long (1983, fig. 1). Recent workson the radiometric dating of Middle and LateDevonian igneous rocks in Victoria (Richards& Singleton, 1981; Williams et al., 1982)together with discussion of taphonomicprocesses of Late Devonian fish sites (Long,1982b) has enabled confident use ofbothriolepid faunas in biostratigraphic  D o w nl o ad ed  B y : [ M u s e u m  of  Vi c t o ri a]  A t : 04 :38 22  A p ril 2009  356 J.A. LONG AND L. WERDELIN ALCHERINGA correlation. In this paper the Tatong faunahas been added to the existing scheme (Long,1982b), but there is still much undescribedmaterial of Devonian fishes from Victoriawhich will lead to further refinement. Thebiostratigraphic use of placoderm fishes forDevonian correlations is well established in thenorthern hemisphere (Westoll, 1951, 1979;Jarvik, 1961; Lyarskaya, 1978; P'an Kiang,1981).Bothriolepid placoderms are also of interestto problems of palaeozoogeography. As agroup they were widely dispersed in LateDevonian continental successions. Young(1981) proposed a possible srcin in the EastGondwana or South China province, andYoung (1984b) has further discussed problemsof antiarchan phylogeny and zoogeography.The oldest bothriolepids are from the Eifelianof Australia and China, and one of thesespecies, B. verrucosa from Australia, may beone of the most primitive members of thegroup (Long, 1983; Young, 1984b). It isinteresting that in Victoria most of thebothriolepids are also primitive bycomparison with contemporaneous faunas,except for B. tatongensis sp. nov. whichbelongs to a specialized subgroup ofbothriolepids.The well preserved bothriolepids from theMt Howitt site are of particular importancein showing the structure of the tail, otherwiseseen only on B. canadensis (Stensi6, 1948).The Mt Howitt bothriolepids are mostlycomplete individuals in all stages of growth,enabling even the juveniles of some species tobe diagnosed. New material of B. gippslandiensis from both Mt Howitt andTaggerty has enabled a redescription of thiscontroversial species (Stensi6, 1969; Young &Gorter, 1981; Long, 1983).Terminology used herein follows Miles(1968, p. 17) and adopts homologies proposedby Young (1984a) for bothriolepid cheek andmouth plates. Measurements were taken withvernier calipers on srcinal specimens, notcasts, from the designated points of Stensi6(1948, p. 11-16). Some proportions will beexpressed as indices, after the work of Stensi6(1948). To standardize measurements withoutreference to restored angles, the flatmeasurement (maximum dimension from ashield, plate or lamina) is expressed as anindex alongside the true or restored index. Allindices preceeded by 'external' refer to thedimensions of that plate externally visible inthe articulated armour, excluding all overlapareas. The breadth/length angle of the lateralplate is defined as the angular measurementbetween the lines of length and breadth asdesignated by Stensi6 (1948, p. 11-16). Allplate names will be abbreviated forconvenience (e.g. AMD instead of anteriormedian dorsal plate), and the words 'breadth,length and height' are abbreviated as B, L andH respectively (see list of abbreviations at theend of the paper). In all text figures the barscale equals one centimetre.Standard statistical methods are used in thesection concerned with metric analysis (Miller& Kahn, 1962; Sokal & Rohlf, 1981).Regression axes are reduced major axesthroughout. Tests for significant differencesin slope and location of regression axes followMiller & Kahn (1962). Systematic palaeontology Repositories. AM -- Australian Museum,Sydney; CPC -- Bureau of MineralResources, Canberra; MUGD -- MelbourneUniversity Geology Department, Melbourne;NMV -- Museum of Victoria, Melbourne.Subclass PLACODERMIOrder ANTIARCHASuborder BOTHRIOLEPIDOIDEI Diagnosis. As in Long (1983, p. 318).Family BOTHRIOLEPIDIDAE Diagnosis. As in Long (1983, p. 318).BOTHRIOLEPIS Eichwald 1840, designated byWoodward, 1891. Type species. Bothriolepis ornata Eichwald Diagnosis. As in Young & Gorter (1981, p.93).BOTHRIOLEPIS TATONGENSIS sp. nov. (Figs 1,2, 3).1983 'bothriolepidoid pectoral appendagebone' Long, p. 299.  D o w nl o ad ed  B y : [ M u s e u m  of  Vi c t o ri a]  A t : 04 :38 22  A p ril 2009  ALCHERINGA VICTORIAN BOTHRIOLEPIS 357 Etymology. After the town of Tatong, southof Benalla, Victoria, near where the fossilswere collected. Diagnosis. A moderately large Bothriolepis having a headshield length of at least 75 mm,and a B/L index of 120 042 flat). Orbitalfenestra large, with posterior margin situatedbehind the level of the posterolateral cornersof the headshield. PP plate short, with pairedpits open to the orbital fenestra, B/L indexof 180. Preorbital recess trifid. PrM plateslightly flared with a B/L index of 95.Trunkshield low, bearing a well developed E Fig. 1. Bothriolepis tatongensis sp. nov. A, B, holotype headshield, NMVPI59868, in dorsal (A) and ventral (B)views, × I. C, D, imperfect AMD plate, NMVP159869, in ventral (C) and dorsal (D) views, x 1. E, detail of dermalornament from the ventral lamina of imperfect AVL plate, unnumbered specimen from Melbourne University GeologyDept. (M. Brown specimens), x 10. All latex casts whitened with ammonium chloride.  D o w nl o ad ed  B y : [ M u s e u m  of  Vi c t o ri a]  A t : 04 :38 22  A p ril 2009  358 J.A. LONG AND L. WERDELIN ALCHERINGA median dorsal ridge enclosing a median dorsalangle of 140 ° Ornamentation coarselyreticulate with low tubercular swellings atanastomoses, developing a radial lineardisposition close to plate margins. Holotype. NMVP159868, an almost completeheadshield (Figs 1A, B; 2). Material studied. All from Tatong:NMVP159869-P159873. Occurrence. From the basal conglomerates ofthe Hollands Creek Rhyodacite, about 5 kmsouth-west of Tatong, Victoria (Marsden,1976, p. 105). Remarks. The similar dermal ornament showsthe material is conspecific. Bothriolepistatongensis sp. nov., is distinguished from allother species possessing a trifid preorbitalrecess, by the peculiar PP plate, and frommany species by the shape of the PrM plate,large orbital fenestra and coarsely reticulateornament. Description. The headshield size indicates amid-dorsal armour length of at least 210 mmfor B. tatongensis, comparable to the largestknown Victorian species, B. cullodenensis and B. fergusoni. The headshield (Figs 1-3) is weakly vaulted,the occipital region enclosing a median angleof 114 °. The preorbital division, which formshalf the headshield length, is gently inclinedwith an almost straight rostral margin (rm) asrestored from the imperfect holotype. Thereare well defined anterolateral corners (alc) butindistinct lateral processes. The prelateralnotch is poorly defined. As the obstanticmargin (om) is relatively long theposterolateral corners of the headshield (plc) are anterior to the PP plate. The posteriormargin of the headshield is slightly convexwith well marked postobstantic corners (ptoc) and a median posterior process developed (ppr). The obtected nuchal area (nm) is short,comprising 22°7o of the paramedian nuchallength. The orbital fenestra (oJ) is large, witha B/L index of about 180.The ventral surface of the headshield showsthe normal bothriolepid features (Stensi6,1948, fig. 11). The broad otico-occipitaldepression (ood) is well defined by theparamarginal cristae (cr.pm). An unusualprocess is developed on the lateral corner ofthe posterior crista (cr2) of the right transverselateral groove (tlg). The transverse lateralgroove narrows strongly towards thepreorbital recess (prh) which is distinctly trifidwith extended lateral horns and a pointedmedian division. A shallow, broad depressionmesial to the transverse lateral groove couldbe the lateral pit (?p), although this featureis not as clearly defined as the large, deeplyembayed lateral pits of B. gippslandiensis, B.cullodenensis or B. fergusoni. The supraoticthickening (sot) on the Nu plate contains abroad depression with supraotic pits (sop) situated posterolaterally, close to theprominent transverse nuchal crista (cr. tv). A median occipital crista was clearly visible onthe holotype when collected in the field. Theparanuchal trochlea (pnt) is stronglypronounced. The suborbital fenestra (soj') issmaller than the orbital fenestra. The pairedpits of the PP plate open anteriorly into theorbital fenestra. The anterior margin of thePP plate is well preserved so this is not anartefact of preservation.Although none of the trunkshield plates iscomplete, relative proportions of the restoredarmour can be gauged from the preservedangles and complete laminae of separatedplates. The trunkshield was low and relativelybroad, with a dorsal median angle of 140 o anda dorsolateral angle of c. 100 °.The AMD (Fig. 1C, D) is known from oneincomplete posterior half of a plate. Thebroad posterior margin has a well producedposterior process. The median dorsal ridge isthickened at the base and has a sharp dorsaledge. Normal overlap areas are present on thedorsal surface for the MxL and PMD plates.The ventral surface shows a well definedmedian ventral ridge which divides near theposterior end of the plate to form a broadmedian ventral groove.The remaining fragmentary trunkshield andpectoral appendage plates are too poorlypreserved to be of systematic value. However,it may be noted that the AVL plate has aprominent crista transversalis interna anterior, and bears a brachial process of the standardbothriolepid morphology and proportions.The ADL plate shows a strong infra-articularcrista present.  D o w nl o ad ed  B y : [ M u s e u m  of  Vi c t o ri a]  A t : 04 :38 22  A p ril 2009
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