Precis of Palaeozoic Palaeontology in the Southern Tablelands Region of New South Wales Ian G. Percival and Yong Yi Zhen Geological Survey of New South Wales, WB Clarke Geoscience Centre, 947-953 Londonderry Rd, Londonderry NSW 2753 ([email protected]) Published on 9 June 2017 at http://escholarship.library.usyd.edu.au/joumals/index.php/LIN Percival, I.G. and Zhen, Y.Y. (2017). Precis of Palaeozoic palaeontology in the Southern Tablelands region of New South Wales. Proceedings of the Linnean Society of New South Wales 139, 9-56. This compilation of all known palaeontological data from Lower Ordovician to Upper Devonian rocks exposed in the Boorowa-Crookwell-Taralga-Yass-Goulbum-Braidwood region of southeastern New South Wales, draws on a voluminous scientific literature of more than 270 papers and reports. Within this region are some of the most famous and intensively studied fossiliferous localities in the state, particularly in the Yass-Taemas area. Revised faunal lists provide the basis for new or refined age determinations, resulting in improved biostratigraphic correlation amongst the 64 formations and their members that yield fossils in the region. Early Silurian (early Wenlock) conodonts found in allochthonous limestones of the Hawkins Volcanics, the lowermost unit of the Yass Basin succession, are documented, as are representative conodonts from allochthonous limestone of late Silurian (Ludlow) age previously erroneously assigned to the early Silurian (late Llandovery) Jerrawa Formation. A new species of the coniform conodont Panderodus is described under open nomenclature. It is recommended that the name Hanaminno Limestone be suppressed. Manuscript received 19 October 2016, accepted for publication 8 May 2017. KEYWORDS: Biostratigraphy, Conodonts, Devonian, Graptolites, Ordovician, Palaeontology, Silurian. Introduction age constraints. However, unpublished works, such as student theses, are largely excluded to avoid the Palaeozoic strata exposed in the Boorowa- possibility of introducing nomina nuda or clouding Crookwell-Taralga-Yass-Goulburn-Braidwood the record with identifications that have not been peer- region of southeastern New South Wales (Fig. 1) reviewed. Although some parts of the present paper range in age from Early Ordovician to Late Devonian were incorporated into the Palaeontological Appendix (Fig. 2) and include, in the Yass-Taemas area, some of (published on DVD) for the Goulburn Geological the most famous fossiliferous localities in New South Sheet Explanatory Notes (Percival 2012b, in Thomas Wales. This compilation of all known palaeontological and Pogson 2012), several identifications and some information from these rocks draws on a voluminous correlations proposed therein have been revised scientific literature including more than 270 papers for this expanded review, which also incorporates and reports (approximately 15% of which have been previously unpublished data and fossil determinations published in the Proceedings of the Linnean Society of from the Braidwood region (Fitzherbert in press). New South Wales) in which Palaeozoic fossils from the Previous palaeontological studies in the Southern region have been documented. The region falls largely Tablelands region have been concentrated in two within the confines of the Goulburn 1:250,000 and highly fossiliferous areas: (1) the Silurian to earliest Braidwood 1:100,000 mapsheets that have recently Devonian succession of the Yass Basin, and (2) the been investigated and remapped by the Geological carbonate-dominated Murrumbidgee Group (of Early Survey of NSW (GSNSW), but palaeontological data Devonian age) surrounding Burrinjuck Reservoir. from adjacent mapsheets is also utilised to provide Additional research has focussed on faunas of the PALAEOZOIC PALAEONTOLOGY OF SOUTHERN TABLELANDS NSW 148'30'E 1 1 Lambie Group 1 1 Mount Fairy Group • Locality N -- (cid:9632) Mulwaree Group (cid:9632) Bungonia Group Highway (cid:9632) Munrumbidgee Group (cid:9633) Douro Group — Major road, sealed ( BE3 Black Range Group (cid:9632) Eurrmbla Formation --- Major road, unsealed n Bmd'ook Group (cid:9632) Jerrara Formation (cid:9632) Hattons Corner Group (cid:9632) Bendoc Group 0 20 40 km (cid:9632) Campbells Group (cid:9633) Adaminaby Group i_i_i Figure 1. Map of the Southern Tablelands region of southeastern New South Wales, showing the main localities mentioned in the text. Simplified geology, including sedimentary groups referred to in the text, is adapted from the Goulburn 1:250,000 Geological Sheet, Second Edition (Thomas et al. 2013) and the preliminary Second Edition of the Braidwood 1:100,000 Geological Sheet (Fitzherbert et al. 2011). Un¬ coloured areas are unfossiliferous rocks, predominantly granites. 10 Proc. Linn. Soc. N.S.W., 139, 2017 I.G. PERCIVAL AND Y.Y. ZHEN Early Devonian Windellama Limestone Member (top Cal). Co-occurrence of Oepikodus evae and of the Tangerang Formation, on Late Ordovician Paracordylodus gracilis restricts the possible age graptolites in the Bendoc Group, and conodont range of some chert horizons to the late Bendigonian biostratigraphy of cherts in the Early to Middle (Be3-4). An unusual assemblage identified in one Ordovician Adaminaby Group. chert sample comprised Cooperignathus cf. C. aranda, Prioniodus sp., and Periodon flabellum, together with various coniform elements including ORDOVICIAN STRATIGRAPHY AND Drepanodus. Murray and Stewart (2001) incorrectly BIOSTRATIGRAPHY attributed a Darriwilian-Gisbomian age to this horizon (their locality R16472) on the basis of a mis- Adaminaby Group identified Pygodus. Abercrombie Formation (0aa on Fig. 2) Remains of sponges preserved in siliceous The Abercrombie Formation ranges in age from siltstones grading to spiculites within the Mummel the Early Ordovician (?late Tremadocian to Floian, Chert Member are mostly in the form of disaggregated equivalent to Bendigonian) to the earliest Late spicules. However, in one sample from the Braidwood Ordovician (Sandbian, or early Gisbomian) (Fig. mapsheet, two different whole sponges are present. 2). This latter age is relatively well-constrained, the One of these, visible in transverse section across the maximum age less so, with almost all biostratigraphic cylindrical sponge body, shows remarkably well- data being derived from conodonts and other preserved nail-head spicules characteristic of lithistid microfauna preserved in cherts (Percival 2012a). demosponges (Percival 2012a:fig. 3L). Recent mapping of the Abercrombie Formation on the Goulburn 1:250,000 mapsheet has resulted in Unnamed cherts in middle Abercrombie Formation recognition of several new chert-dominated members (Oaac on Fig. 2) (Thomas and Pogson 2012). A summary of the Most occurrences of the distinctive conodont litho stratigraphy of this formation and its constituents Spinodus spinatus are in cherts from within the is given in Percival et al. (2011). undifferentiated middle part of the Abercrombie Formation (Thomas and Pogson 2012). Typical Unnamed cherts in lowermost Abercrombie coniform elements co-occurring in these cherts Formation include Paroistodus venustus, Protopanderodus A few very thin and discontinuous chert beds sp., Drepanoistodus sp. and “Drepanodus” sp. interbedded in a shale-dominated section beneath Rarer associates include Periodon macrodentatal, the Mummel Chert Member are characterised by the Baltoniodus sp., Protoprioniodus simplicissimus, presence of Paracordylodus gracilis and the absence and Amelia? sp. Cherts containing this assemblage of Oepikodus evae. This suggests an age range for the are most likely of early Darriwilian (Dal?-2) age, lowermost Abercrombie Formation of late Tremadoc although Spinodus spinatus has a longer range, to early Floian (early Bendigonian). extending into the Late Ordovician. For example, in one sample (interpreted to be of Da3 age) from the Mummel Chert Member (Oaam on Fig. 2) Goulburn 1:250,000 mapsheet, S. spinatus occurs Conodonts commonly observed in thick sections with fragmentary Histiodella together with a probable of cherts from the Mummel Chert Member include Paroistodus horridus element. Oepikodus evae (often abundant), Paracordylodus Jenkins (1982b) documented a diverse gracilis, Periodon flabellum, Acodus sp., Drepanodus graptolite fauna from black mudstone interbedded arcuatus, and other coniform elements probably with turbiditic sandstone near the crossing of the assignable to Drepanoistodus. Bergstroemognathus Kings Highway over the Mongarlowe River, 15 extensus is a rare but distinctive associate, km east of Braidwood. Species recognised include Microzarkodina (species indeterminate) is equally Didymograptus cognatus, Tetragraptus sp .,Isograptus uncommon, and one element possibly referrable to sp., Glossograptus acanthus, Glossograptus sp., Fahraeusodus marathonensis was observed. Where Paraglossograptus cf. tentaculatus, Apiograptusl O. evae is present (e.g. Percival et al. 2003:fig. 1.19, crudus, Cryptograptus inutilis, Glyptograptus 21-22; Percival et al. 2011:photograph 1; Percival intersitus, Pseudoclimacograptus differtus and 2012a:fig. 3F), the age of this assemblage could Diplograptusl decoratus, together with a Ungulate potentially span the range of the eponymous zone, brachiopod. Jenkins deduced an age close to the i.e. late Bendigonian (Be3-4) to early Castlemainian boundary of the Da2 and Da3 zones for this fauna. Proc. Linn. Soc. N.S.W., 139, 2017 11 PALAEOZOIC PALAEONTOLOGY OF SOUTHERN TABLELANDS NSW HATTONS CORNER CROUP INSET Carboniferous HERVEY GROUP z >(cid:9632) Lochkovian HATTOGNRSO CUOPR NESRh el Koorawatha Formation - -Dhk 9>in "She =- 4= O Elmsicte Formation Bumberry Formation -j-Dhb Pndoli ShcShra^- —Cawndg* Slltetane Frasnian FBoremndaitciCoknp m rradigb ee= puODJyVeU ’i- -DDhhem CI1Cj Late Ludlow SshhS(rb5h ) s R o' nseWbank'SS Shhtsbael'er- ' g~h r~ri U—-M mM36 l Formation GO — Yanewe Formation HATCHERY CREEK "" Ladrtw VoicanlesV- —Sdl WFeoer Jmaastpioenr _^y w GROUP UnJ Wenlock Sdw DOURO<{ 12G >) RRBOlaaiUcnkbP oB wo gH iSllh Maleem ber <3> Yarwood Siftstone Member Dmln - - Cnnoidai Limestone Member ({54)) SHiulvmeerd Laliem Fatosrtmonaeti oMfle mber MURRJMBGIDROGUEEP JWTJaVnwA LAimDAemg.VltownV e MWemVbWer, -Patmore Limestone Member m(6) BBoamwsapnrdienlgla L Simhaelset oMnee mber Taemas Dmt Limestone Dmtk Dmtr - Cockatoo Point Limestone Member MULWAREE GROUP Dmlb Dmtc Bongalaby Formation Dmts T- SpiriferYassensis Limestone Member Dmj- Majurgorrg Formation Dwb Dmf Dmc Cavan Bluff Limestone DwbO Dmf = nAn/t|AAAAAAAAA Sugarloaf Creek nh. BLACK RANGE Formation GROUP Tarago -v _,J Dbkc Dbk . Kira win Conglomerate Formation Mountain Creek Volcanics Sharpeningstone Conglomerate Glen Bower Hawkins Sdhs Sdhl Sdhs ~_~ Llandovery MundoonenF ormation Volcanics FoYrmaastsi on FEorumriamtibolna Sjx e ' | Sandstone CABONNE_ | MARGULES GROUP rG'°RrO"U'rP‘ 1 ©mm;!] <L—’ ' Bmmf ' ' Jj BEN DOC GROUP Eastonian ©c0uCei U S© cul 0bws 0mmsB aas ©bw Warbisco Shale ; (cid:9632) ©cub 4ar Damwilian Kenyu ©aans <•_ eLaa < eaac v Yapeenian Formation Castlemainian Bendigonian Abercrombie Formation A0AMINA8Y GROUP Figure 2 (above and right). Correlation chart for Ordovician, Silurian and Devonian fossiliferous strata (discussed in the text) in the Southern Tablelands region of southeastern New South Wales, mainly adapted from the Time-Space Plot in the Explanatory Notes for the Goulburn 1:250,000 Geological Sheet (Thomas and Pogson 2012), except for Mulwaree Group (modified from Fitzherbert et al. 2011). Units depicted on left side of figure are generally distributed in the western part of the region; those on the facing page are represented in the eastern part of the region. Stratigraphic groups are outlined in solid coloured lines (same colour as their names, in capital letters). Space constraints require many units at formation and member levels to be designated by three- and four-letter codes; for full description of these units refer to Thomas and Pogson (2012). 12 Proc. Linn. Soc. N.S.W., 139, 2017 I.G. PERCIVAL AND Y.Y. ZHEN Carboniferous Joaramin Ignimbnte Murruin Formation fcS— Dkms Dkmc ^Idrumrnie/''1-- - - - Sfdt^1 WONT F«K¥WOUF 5frfr5fdF ' Severing "Cbnglomerafe Formation n ^ Sxji ' CV1J JFeorrrmaraati on MARGULES GROUP AOAMINABY GROUP Peach Tree Chert Member (0aap on Fig. 2) Creek (approximately 20 km NW of Taralga), and Murray and Stewart (2001) first identified recognisedPeriodon aculeatus in a separate chert band conodonts including Cordylodus (now Paroistodus) nearby (sample R16476). Resampling of the latter horridus and Histiodella sp. from what is now locality (GR 747433 6217083) during the GSNSW called the Peach Tree Chert Member (their sample Goulbum mapping project yielded Paroistodus R16475) near the junction of Silent Creek and Oaky horridus, Periodon macrodentata and Histiodella Proc. Linn. Soc. N.S.W., 139, 2017 13 PALAEOZOIC PALAEONTOLOGY OF SOUTHERN TABLELANDS NSW sp. (Percival and Sherwin 2005). Those species were for the Nattery Chert Member of late Darriwilian (late depicted by Percival and Zhen (2007:pl. 1, figs 5-9, Da3) to early Gisbomian (Gil). 16) together with the less common Baltoniodus cf. Other microfauna observed in thick sections parvidentatus and Nordioral sp. Other conodonts of cherts from the Nattery Chert Member include recognised in the Peach Tree Chert Member include radiolaria (generally poorly preserved as silica blebs, Erraticodon sp., Multioistodus sp., Drepanoistodusl though occasionally with relic skeletal structure and sp., “Oistodus” tablepointensis,Pseudobelodinal sp., spines), sponge spicules, and fragmentary acrotretide Protopanderodus sp. and Spinodus spinatus. brachiopods (Percival 2012a). Paroistodus horridus locally ranges through most of Darriwilian 3 (although occurrences reported Uppermost Abercrombie Formation (above Natterv outside Australia rarely extend beyond the upper Chert Member) part of Da2). At least four species of Histiodella are Graptolites are relatively common in two horizons known worldwide, and provide the basis for fine- within the uppermost Abercrombie Formation. scale subdivision of the Darriwilian from Dal to Siliceous black siltstones interbedded with, and the middle of Da3, but these species are extremely immediately overlying, the uppermost Nattery Chert difficult to differentiate in chert sections. Baltoniodus Member contain pyritised graptolites, identified cf. parvidentatus resembles a species typical of the by L. Sherwin as Dicellograptus geniculatus and early Darriwilian Kundian stage in Baltoscandia. Pseudoclimacograptus cf. riddellensis. These Pygodus anitae (associated with Paroistodus indicate an age range of latest Darriwilian (Da4) to horridus and Histiodella sp. in a chert from the Silent early Gisbomian (Gil), consistent with the age of Creek fire trail on the Taralga 1:100,000 mapsheet) the chert. Also present in these siltstones is a trace is of middle Darriwilian age (Da3, pre Pygodus fossil preserved in epirelief with three straight arms serra Zone). Overall the age of the Peach Tree Chert diverging at 120° from a central point (Percival and Member is interpreted as middle Darriwilian (early- Sherwin 2004). This trace fossil could not be identified middle Da3). from the literature, and its significance is unknown. Elsewhere in shales in the upper Abercrombie Natterv Chert Member (Oaan on Fig. 2) Formation, Nemagraptus gracilis has been identified Characteristic conodonts found in the Nattery (Percival and Sherwin 2003). This graptolite is the Chert Member are Periodon aculeatus and Pygodus zonal indicator for the early Gisbomian (Gil) zone serra (Percival and Zhen 2007 :pl. 1, figs 1-3, 10, 12), but also ranges through the entire Gisbomian stage. Ansella sp., Baltoniodus sp., together with a variety Constraints from fossils in underlying and overlying of generally indeterminate coniform elements. stratigraphic units imply that the most likely age Microzarkodina sp. is rarely encountered. Where P. for the top of the Abercrombie Formation is early aculeatus and P. serra co-occur, the potential age Gisbomian. of the sample corresponds to the range of P. serra, i.e. very late Da3 to the top of Da4. The presence of Bendoc Group P aculeatus alone may indicate a late Da3 age, as Bumballa Formation (0bb on Fig. 2) it slightly precedes the first occurrence of P. serra. Most fossils obtained from the Bumballa However, the latter is relatively uncommon, and Formation are graptolites, but at many localities hence a sample containing just P aculeatus may also these are poorly preserved, so identifications and be more broadly constrained to the entire range of age connotations are not necessarily precise. Typical that species, i.e. late Da3 to early Gisbomian (Gil) species present include Climacograptus bicornis, - although this younger limit is somewhat imprecise. C. cf. cruciformis, Dicranograptus nicholsoni, D. Stewart and Fergusson (1995) illustrated a specimen sp. and Orthograptus calcaratus subsp. The most of Pygodus serra from the Sunlight Creek Formation diverse fauna occurs at GR 765682 6165816 and (now regarded as Nattery Chert Member) in a includes Dicellograptus sextans, D. cf. divaricatus, cutting on the Bungonia-Goulbum road, where it is D. cf. intortus, Nemagraptus gracilis, Reteograptusl associated with Periodon aculeatus. Two occurrences geinitzianus, Pseudoclimacograptus cf. scharenbergi of Pygodus anserinus were noted in the Nattery Chert and Glyptograptusl sp. (identifications by L. Sherwin). Member on the Boorowa 1:100,000 mapsheet; this This assemblage, located approximately 320 m above youngest species of Pygodus overlaps with the range a chert containing Darriwilian conodonts, clearly of P. serra in latest Da4 time and extends into the indicates a Gisbomian age, probably Gil (Percival early Gisbomian (Gil). Thus all palaeontological and Sherwin 2004). A graptolite fauna from GR evidence consistently points to a maximum age range 764830 6216182 on the Taralga 1:100,000 mapsheet 14 Proc. Linn. Soc. N.S.W., 139, 2017 I.G. PERCIVAL AND Y.Y. ZHEN includes several other species whose ranges overlap are of Eastonian age. Similar fauna was collected in the late Gisbomian (Gi2), including Glossograptus from the Braidwood 1:100,000 mapsheet in the ciliatus, Pseudoclimacograptus sp., dicranograptid vicinity of Sally Trigonometric Station, about 7.5 fragments and Corynoidesl sp., associated with km WSW of Tarago (Strusz and Nicoll 1973). Ungulate brachiopods and indeterminate caryocaridid The preservation of some specimens does not arthropods (Percival and Sherwin 2005; Sherwin et permit confident recognition of species necessary al. 2006). for precise age determinations, so the following Conodonts found in cherts assigned to the faunal lists only include material that is distinctive Bumballa Formation at GR 747703 6216870 on or well preserved. The oldest species identified is the Taralga 1:100,000 mapsheet (Percival and Climacograptus tridentatus, indicative of a late Sherwin 2005) include a pygodiform element of Gisbomian (Gi2) age, from GR 767540 6181065. No Pygodus anserinus (with four clearly-defined rows species restricted to the earliest Eastonian (Eal) zone of nodes), which dates this sample to the anserinus were recognized. One assemblage from GR 765010 Zone (ranging from topmost Da4 to basal Gil, i.e. 6169658 comprises long-ranging species that overlap straddling the Middle to Late Ordovician boundary). in Ea2, such as Dicranograptus nicholsoni, D. hians, The haddingiform element of Pygodus is also present, Dicellograptus sp., Cryptograptus cf. insectiformis, as well as numerous elements of Periodon aculeatus. Diplacanthograptus spiniferus, Orthograptus Fergusson and Fanning (2002) illustrated trace cf. amplexicaulis, and O. ex gr. pageanus. Other fossils interpreted as unidentified animal tracks (i.e. graptolites of middle to late Eastonian (Ea2-4) age are grazing trails) on bedding planes at the base of turbidite widespread, including Dicellograptus species with the beds in the Bumballa Formation from the Shoalhaven rhabdosome formed into a distinctive figure-8 shape Gorge, and Jones et al. (1993) reported Nereites trace (D. cf. caduceus), D. flexuosus, D. elegans, D. n. sp. fossils from this area in rocks now attributed to the cf. D. minor, D. gravis, Orthograptus ruedemannil, Bumballa Formation. Both occurrences imply that Dicranograptus kirki, Pseudoclimacograptus? sp., the ocean floor at the time of deposition of these Leptograptus eastonensis, Ensigraptus caudatus and turbidites was at least partially oxygenated, rather Normalograptus tubuliferus. Williamson and Rickards than being anoxic. (2006) described a similar fauna from weathered black shales now included in the Warbisco Formation at Ryrie Warbisco Shale (0bw on Fig. 2) Hill, 8 km SSE of Michelago (south of Canberra), to Graptolites of Late Ordovician age were first which they assigned an Eastonian 2-3 age, based on documented from the Goulbum-Marulan-Bungonia the presence of Leptograptus flaccidus cf. macer, L. region by Naylor (1936), who provided brief Iflaccidus spinifer, Dicellograptus morrisi, D. cf. descriptions and line drawings of Orthograptus caduceus, Climacograptus [=Ensigraptus\ caudatus, quadrimucronatus and O. calcaratus tenuicornis. C. [=Normalograptus\ tubuliferus, C. mohawkensis, Although not specifically referring to Naylor’s paper, Orthograptus quadrimucronatus, O. calcaratus VandenBerg and Cooper (1992) examined other calcaratus, O. c. Ipriscus, O. c. cf. vulgatus, O. c. specimens attributed to O. calcaratus tenuicornis aff. tenuicornis, O. amplexicaulis pauperatus, O. a. and concluded that its presence in Australasia was intermedins and Glyptograptus daviesi. Graptolites doubtful. Sherrard (1943) listed a large number of found in the Warbisco Shale that are typical of (though graptolite species (none of which were described notnecessarilyrestrictedto)theearlyBolindianinclude or figured) from localities in the Jerrawa district, Appendispinograptus longispinus, Dicellograptus east of Yass. She distinguished two horizons, one ornatus, D. cf. morrisi, Euclimacograptus probably in the latter part of the Gisbornian (from hastatus, Leptograptus sp. or Pleurograptus sp., three localities), and the other level (recognised at Orthograptus cf. thorsteinssoni or O. fastigatus, O. 30 localities) of definite Eastonian aspect. From the quadrimucronatus and O. cf. amplexicaulis. The Goulbum-Marulan-Bungonia area, Sherwin (1972) early Bolindian age of this association is confirmed briefly noted the occurrence of conodonts preserved by co-occurrence, e.g. at GR 765732 6151522 and on bedding planes in siliceous shales (now assigned GR 756841 6109803, of Styracograptus uncinatus, to the Warbisco Shale) with graptolite faunas of the zonal indicator species for Bol (although this is Gisbomian and Eastonian ages. quite rare). This species was also noted at Ryrie Hill The majority of graptolites identified from by Williamson and Rickards (2006), possibly from a the Warbisco Shale on the Goulbum 1:100,000 different level to that yielding the middle Eastonian mapsheet (Percival and Sherwin 2004) and Taralga fauna. Very occasionally, e.g. at GR 758848 6128704, 1:100,000 mapsheet (Percival and Sherwin 2005) cherty silicified siltstone is present in the Warbisco Proc. Linn. Soc. N.S.W., 139, 2017 15 PALAEOZOIC PALAEONTOLOGY OF SOUTHERN TABLELANDS NSW Shale. Thin sections prepared of this lithology reveal Jerrara Series near Bungonia, and subsequently proximal fragments of graptolites, identified (by (Naylor 1939) provided expanded faunal lists from L. Sherwin) as Diplacanthograptus spiniferus of this area. One locality on the Bungonia Road was Eastonian 2-4 age. Conodonts are very rare, generally resampled by Sherwin (1968) who reappraised only represented by simple coniforms, including a the fauna, identifying Streptograptus exiguus and possible eobelodiniform element of Belodina sp. Monograptus cf. M. nudus, and assigning a late Flandoverian (turriculatus Zone) age. Cabonne Group Kenvu Formation (0cu on Fig. 2) Percival et al. (2008) documented the conodonts EARFY SIFURIAN TO EARFY DEVONIAN Belodina compressa, Scabbardella cf. S. altipes, Drepanoistodus suberectus, Panderodus gracilis, History of study of Yass Basin fossils Periodon aculeatus, Phragmodus undatus, The Silurian to earliest Devonian rock succession Protopanderodus liripipus, Yaoxianognathus wrighti, in the Yass Basin contains arguably the best known and Yaoxianognathus sp. from an allochthonous and most intensively studied shallow water shelly limestone lens (Ocul) towards the top of the Kenyu faunas of this age in Eastern Australia. Fossil groups Formation. This fauna indicates a Fate Ordovician that are particularly well represented in the Yass Basin (late Gisbornian to earliest Eastonian) age for the succession include trilobites, brachiopods, corals, limestone. Also present in the insoluble residue were conodonts and graptolites; other less conspicuous the acrotretide brachiopod Scaphelasmal sp., the groups include stromatoporoids, molluscs (bivalves, discinide brachiopod Orbiculoidea sp., indeterminate gastropods, nautiloids), bryozoa, and algae. Relatively large thick-shelled lingulide brachiopods, flat-spired precise age constraints (particularly in the upper part gastropods and hyolithids. of the succession) are provided by conodonts obtained from limestones that are interbedded with siltstones bearing abundant well-preserved graptolitic faunas. EARFY SIFURIAN STRATIGRAPHY AND The first documentation of fossils from the “Yass BIOSTRATIGRAPHY Plains” resulted from their discovery by the explorer Paul de Strzelecki, whose record of his journey in Eurimbla Formation (Sxe on Fig. 2) southeastern Australia included a description of a Two samples attributed to this formation (defined tabulate coral questionably referred to Favosites by Thomas and Pogson 2012) give conflicting ages gothlandicus by Fonsdale (1845). Shortly thereafter, (Percival 2001). Thin sections of dark grey-black W.B. Clarke described the first trilobites from this area siltstone, from a small road quarry at GR 662240 (Clarke 1848). Unfortunately, Fonsdale’s specimens 6202708 on the Boorowa 1:100,000 mapsheet, (though still extant in the Sedgwick Museum at contain fragments of graptolites that resemble hair¬ Cambridge University, UK) bear only very generalised like species of Monograptus s.l. comparable with locality details, and Clarke’s collection - the fossils mid-late Flandoverian forms (F. Sherwin, pers. from which had been described by de Koninck (1876- comm.), together with very well-preserved spinose 77, transl. 1898) - was destroyed in the Garden Palace radiolaria, and a partially disaggregated sponge. fire in Sydney on September 22, 1882. This presumably represents the depositional age of An important series of palaeontological the Eurimbla Formation. Another site nearby on the investigations in the Yass Basin, particularly Gunnary Road yields clasts of translucent pale brown- concerning trilobites and brachiopods, was yellow chert in which conodonts (predominantly undertaken between the 1870s and the early 1920s by Paracordylodus gracilis, with a few associated Charles Jenkins, A. J. Shearsby, John Mitchell, Robert Oepikodus evae) are abundant and well-preserved. Etheridge Jr and Felix Ratte. The first three mentioned These chert clasts therefore have an age equivalent were self-taught amateur scientists; Robert Etheridge to the lower part of the evae Conodont Zone (Early Jr was palaeontologist in the Geological Survey of Ordovician, late Bendigonian to early Chewtonian), NSW and subsequently Director of the Australian and are interpreted as having been reworked into the Museum. W.S. Dun, Etheridge’s assistant curator lower Silurian Eurimbla Formation. at the Geological Survey (and later palaeontologist there), also participated in several papers. Jenkins Jerrara Formation (Sxj on Fig. 2) (1879) illustrated (without description) several Naylor (1936) described several species of trilobites. Ratte (1887a, 1887b) contributed two monograptids from what was then known as the papers describing several species. Etheridge and 16 Proc. Linn. Soc. N.S.W., 139, 2017 I.G. PERCIVAL AND Y.Y. ZHEN Mitchell (a local schoolteacher who later was head Following the initial documentation of the diverse of Newcastle Technical College) had a productive Silurian coral faunas by Lonsdale (1845) and de collaboration describing the trilobite faunas of the Koninck (1876), A.F. Foerste (1888) described a few Yass region, in a series of six major papers from 1892 rugosans (and trilobites) sent to his laboratory in the to 1917 published in the Proceedings of the Linnean USA. Other early contributions on the rugosan faunas Society of New South Wales. Significant later trilobite byR. Etheridge Jr (1881-1894, 1904c, 1913) and A. J. studies revising and expanding these earlier works are Shearsby (1905, 1906), and subsequently O.A. Jones those of Chatterton (1971), Chatterton and Campbell (1932, 1936), were revised and expanded by Dorothy (1980), and Strusz (1980). Hill (1940). Jones (1937) described favositid tabulates Pioneering work on the graptolites of the and collaborated with Hill to document the heliolitids Yass Basin was carried out by T.S. Hall in 1903, (Jones and Hill 1940). Pickett and Jell (1974) and but a detailed study of the faunas throughout the McLean (1974, 1976) have systematically revised succession was not published for another 34 years. some of the earlier identifications. Other generic Kathleen Sherrard, initially with assistance from R.A. reassignments have been made by Strusz and Munson Keble, described a considerable number of Silurian (1997) for the rugosans, and Munson et al. (2000) for graptolites, forming the basis for her subsequent the tabulate corals and chaetetid sponges. recognition of several biostratigraphically significant assemblages (Sherrard and Keble 1937, Brown and Reinterpretation of the age of the Yass Basin Sherrard 1952). Many of the earlier identifications sequence based on conodonts of Sherrard and co-workers have been systematically Link and Druce (1972) recognised four conodont revised, initially by Jaeger (1967) and subsequently assemblages in rocks of the Yass Basin, the oldest by Rickards and Wright (1999), establishing ties to Neoprioniodus excavatus fauna succeeded by the the global standard graptolite zonation. Spathognathodus sp cf. ranuliformis, Ancoradella Study of the conodont faunas of the Yass Basin ploeckensis-Kockelella variabilis, and Belodella was part of a detailed Ph.D mapping project by A.G. triangularis-Polygnathoides siluricus faunas. They Link in the late 1960s and early 1970s. Link (1971) suggested correlations with the conodont zonation reported initial results, followed by publication of the Camic Alps (Austria) established by Walliser of the systematic descriptions of the faunas (Link (1964). Thus the two older Yass Basin faunas were and Druce 1972). Although based on the form- inferred by Link and Druce (1972) to correlate with species concept prevalent at the time (prior to the the Zone of Ozarkodina crassa, of early Ludlovian establishment of multi-element taxonomy), this work age, although this zonal indicator species was not was of great significance in establishing a rigorous recognised at Yass. The two younger assemblages biostratigraphic framework especially in the upper part contained the zonal indicator conodont species A. of the succession. Subsequent analysis of the faunas ploeckensis and P. siluricus, respectively, providing (Simpson 1995) has revised the maximum age of the precise correlation with international biostratigraphic lower formations from Ludlovian to Wenlockian (see zonations. Graptolite faunas were consistent with a discussion later in this paper). late Ludlovian to latest Pridolian age for the upper part The history of research into Silurian brachiopods of the succession, overlying the limestone containing of the Yass Basin was recently reviewed by Strusz siluricus Zone conodonts. (2010b). The initial phase of systematic descriptions, At the time of publication of Link and Druce’s commencing with Etheridge (1892b), Dun (1907), research, conodont taxonomy was just commencing Mitchell and Dun (1920), Mitchell (1921, 1923) a fundamental revolution which would see the and Booker (1926), was followed in the 1940s by elimination of single-element species nomenclature the studies of Johnston (1941), St Joseph (1942) in favour of a multielement apparatus-based species and Brown (1949) who revised and synonymised concept. Link and Druce (1972) was also a pioneering several of Mitchell’s (1923) species. Commencing work, in that there was no previous local Silurian in the 1980s, D.L. Strusz published descriptions of biostratigraphic zonation using conodonts to correlate the Silurian brachiopods of the Canberra district, with. Link’s mapping and stratigraphy was (with some also recording identical species from the Yass Basin minor revisions in nomenclature) sufficiently rigorous (Strusz 1984, 1985a). In a series of papers between to be widely accepted to the present day. Not until 2002 and 2010, Strusz completed description and the revision by Simpson (1995) of Australian Silurian revision of all brachiopods represented in the Yass biostratigraphy was a reassessment of the Link and Basin. Druce conodont faunas undertaken (Table 1). Proc. Linn. Soc. N.S.W., 139, 2017 17 PALAEOZOIC PALAEONTOLOGY OF SOUTHERN TABLELANDS NSW Yass Basin conodont identifications Revised and multielement identifications Table 1 Revised iden¬ of Link and Druce (1972) (based on Simpson and Talent 1995) tifications of those conodonts originally Acodus curvatus Walliserodus curvatus described from the Yass Ancoradella ploeckensis Ancoradella ploeckensis Basin using form-species Belodella devonica Belodella silurica nomenclature by Link Cordylodusl dubius Coryssognathus dubius [Sc element] and Druce (1972). Coryssognathus dentatus Coryssognathus dubius [Pa element] Distomodus curvatus Coryssognathus dubius [Pb, Pc] [Note: species not Hindeodella equidentata Wurmiella excavata italicised in first column Icriodus woschmidti possibly I. woschmidti hesperius have no revised equiva¬ Kockelella variabilis variabilis & K. variabilis Kockelella variabilis lent in second column] ichnusae S and C 1998 S and C 1998 = Serpagli Ligonodina elegans Oulodus elegans and Corradini 1998 Ligonodina salopia Kockelella variabilis [Sc element] S and C 1999 = Serpagli Ligonodina silurica Kockelella variabilis and Corradini 1999 Lonchodina detorta Lonchodina greilingi Kockelella variabilis [Sb element] Lonchodina walliseri Pseudolonchodina fluegelil or Oulodus elegans Neoprioniodus bicurvatoides Neoprioniodus bicurvatus Ozarkodina confluens Neoprioniodus excavatus Wurmiella excavata Neoprioniodus latidentatus Neoprioniodus multiformis Ancoradella ploeckensis [M element]? or Kockelella variabilis [M element] Oneotodusl beckmanni Pseudooneotodus beckmanni Ozarkodina crassa Ozarkodina denckmanni Ozarkodina gaertneri Ancoradella ploeckensis [Pb element]? Ozarkodina media Wurmiella excavata Ozarkodina ortus Ozarkodina typica Ozarkodina confluens Ozarkodina ziegleri aequalis Ozarkodina cf. 0. ziegleri tenuiramea Ozarkodina cf. O. ziegleri ziegleri Kockelella variabilis [Pb element] Ozarkodina sp. Panderodus gracilis Panderodus unicostatus Panderodus panderi Panderodus recurvatus Panderodus simplex Panderodus unicostatus Panderodus unicostatus serratus Panderodus serratus Panderodus unicostatus unicostatus Panderodus unicostatus Plectospathodus extensus s.l. Wurmiella excavata Plectospathodus extensus lacertosus Plectospathodus flexuosus Ozarkodina confluens Polygnathoides emarginatus Polygnathoides siluricus Polygnathoides siluricus Scolopodus diplicatus Spathognathodus fundamentals Kockelella absidata sardoa S and C 1999 Spathognathodus inclinatus inclinatus Wurmiella excavata Spathognathodus primus Ozarkodina confluens Spathognathodus cf. S. ranuliformis Kockelella ranuliformis Spathognathodus remscheidensis Zieglerodina remscheidensis S. cf. S. steinhornensis eosteinhornensis Oz. remscheidensis eosteinhornensis Synprioniodina silurica Ancoradella ploeckensis [M element]? Trichonodella excavata Wurmiella excavata Trichonodella inconstans Kockelella variabilis [Sa element] Trichonodella symmetrica Ozarkodina confluens Trichonodella trichonodelloides Aspelundial fluegeli 18 Proc. Linn. Soc. N.S.W., 139, 2017