Memoirs of the Museum of Victoria 52(1): 1-135(1991) ISSN 0814-1827 https://doi.org/10.24199/j.mmv.1991.52.01 31 March 1991 BENDIGONIAN GRAPTOLITES (HEMICHORDATA) OF VICTORIA BY BARRIE RlCKARDS 1 AND AMANDA CHAPMAN 2 Sedgwick Museum, Department of Earth Sciences, Cambridge, CB2 3EQ, United Kingdom 2 30 Stanley Ave., Birkdale, Southport, Lancashire, United Kingdom Abstract Rickards, B. and Chapman, A., 1991. Bendigonian Graptolites(Hemichordata) of Victoria. Memoirs of the Museum of Victoria 52(1): 1-135. Sixty graptolite species and subspecies are described mostly from the Bendigonian, but including a few involved in a proposed reclassification of the family Dichograptidae. Emphasis in choice of described species is placed upon those more or less endemic to Vic- torian sequences. Two new multiramous dichograptid genera are described: Kellamograptus and Praegoniograptus. The following new species are described: Clonograptus erdtmanni, Orthodichograptus wilkinsoni, Tridensigraptus zhaoi and Zygograptus steward. The genus Clonograptus is informally divided into two groups with differing thecal type; and the sub- family Dichograptinae is redefined and subdivided into the following sections: Anomalo- grapti (nov.); Dichograpti (Group A, emend. Group B, nov.); Temnograpti (emend.): Schizograpti (Group A, emend.; Group B, nov.); Pendeograpti (nov.); Tetragrapti (emend.); Mimograpti (nov.); Didymograpti (emend.). The scheme depends on the recognition of a proximal end template based upon the following modes, coupled with an appraisal of the branching type: clonograptid mode; dichograptid mode; tetragraptid mode; didymograptid mode. The subfamily Sigmagraptinae is redefined to include Praegoniograptus and to exclude Laxograptus. The following genera are redefined: Clonograptus, Tetragraptus (Pendeograptus), Sigmagraptus, Goniograplus and Trichograptus. Reconstructions are attempted for the first time of several of the giant dichograptids. The general evolutionary framework of Bendigonian graptolite faunas is briefly described and several possible lineages are outlined, notably the Goniograplus macerXo Didymograp- tus gracilis plexus; the Clonograptus to Tetragraptus chapmani line; and the possible Adelo- graptus to Didymograptus adamantinuslperditus line. A study of the Pendeograpti results in Pendeograptus pendens and P. fruticosus being redescribed in terms of their detailed proximal development. The stratigraphic occurrences of these two are revised in such a fashion that the recognition of the Bendigonian Bel-Be4 subdivisions is enhanced. The foregoing has resulted in necessary clarification of rhabdosomal terminology, and in a discussion of dichograptid branching patterns in multiramous genera and species. Contents Introduction 1 Bendigonian stratigraphy 4 International correlations of the Bendigonian 5 Rhabdosome terminology 10 Dichograptid branching patterns 11 Preservation and reconstructions of the giant clonograptids and dichograptids 13 Evolutionary notes 21 Systematics 28 28 Family Anisograptidae • Clonograptus 28 Family Dichograptidae 34 Subfamily Dichograptinae 34 Section Dichograpti 37 Loganograptus 37 Dichograptus • • 39 1 B. RICKARDS AND A. CHAPMAN Orthodichograptus 42 Kellamograptus gen. nov 45 Section Temnograpti 46 Zygograptus 46 Section Schizograpti 54 Trochograptus 54 Tridensigraptus 57 Triaenograptus 58 Section Pendeograpti 61 Pendeograptus 6 Pseudobtyograptus 65 Section Tetragapti 67 Tetragraptus {Tetragraptus) 67 Section Mimograpti 68 Mimograptus 68 Section Didymograpti 70 Didymograptus 70 Subfamily Sigmagraptinae 82 Sigmagraptus 82 Goniograptus 87 Praegoniograptus gen. nov 91 Etagraptus 92 Trichograptus 93 Acknowledgements 94 References 94 Plates 97 Introduction do although of course the Bendigonian is already more subdivided than is the Arenig in many The Bengidonian (early Arenig)graptolite fau- parts of the world. But the potential for further nas represented a critical stage in the evolution fine subdivisions will increase as geologists con- of graptolites being the first very rich graptolite tinue to log temporary sections and to recollect (Fig. assemblage 31) derived from an oceanic others. In the palaeontological sphere it is pos- plankton. The Victorian localities, particularly sible that with a revision of several Scandinav- around Bendigo, are probably the richest in the ian and North American faunas long overdue world for graptolites of this age and the preser- some of the apparently endemic Victorian forms vation is in our view rather better than is con- might prove to be junior synonyms but we have veyed in previous literature, although specimens been unable to confirm this. We have, in fact, have not so far been chemically isolated from the concerned ourselves largely with full and proper rock matrix. It is our long term intention to descriptions of the Bendigonian graptolites and examine further the hydrodynamics of particu- a small number of species from other horizons larly the giant dichograptids but the present pur- which tie in with them in some evolutionary or pose is to document the diversity of Bendigon- classificatory manner. These latter are listed in ian graptolite faunas, concentrating on endemic Table 1 along with Bendigonian species. forms, and to place them in an international set- Most of the material described is housed in the ting. The research has posed a whole series of collections of the Museum of Victoria in Mel- questions related to classification of the aniso- bourne. Specimen numbers are prefixed by graptids and dichograptids. We have felt it in- P; where appropriate, numbers in brackets cumbent on us to comment in preliminary following the P numbers are the old numbers of fashion upon the Bendigonian stratigraphy, the the Geological Survey of Victoria (often these evolution of some graptolites, and the mode of latter are the only numbers previously pub- life and preservation of others. In the sphere of lished). Specimens from other museum deposi- stratigraphy there is surely much more work to tories are mentioned by institution as appro- BENDIGONIAN GRAPTOLITES WERONA TROUGH BULLA SYNCLINE Figure 1. Locality map showing Bendigo and Central Victorian Goldfield region and general distribution of Bendigonian strata with position of some of the main localities mentioned in the text. With permission of the Department of Minerals and Energy. 4 B. RICKARDS AND A. CHAPMAN priate. Always a scale bar of 1 mm or 5 cm is marised by several modern workers (e.g. Dewev given with text-figures an et al., and appropriate scale 1970; Cooper, 1979; Webby et al., 1 98 T; bar with the plates. Cas and VandenBerg, 1 988). Beavis ( 1 976) pub- The selection of type species for existing gen- lished a range chart of the species most crucial to era follows Bulman (1970). international correlation, then the most up to date opinion since Bendigonian stratigraphy Thomas (1960a); and also a family distribution diagram based upon the data It has long been recognised that the Bendigon- in Thomas (1960a). In his chart (Beavis, 1976: ian can readily be divided into four successive Table 3.1) there is little distinction between Bel subdivisons based upon faunal changes, Bel- and Be2, except that the upper part of Be2 lacks Be4, the last being the latest. Largely this has T. approximatus. His ranges agree with those of been result a of research over many years by T.S. Thomas who recorded T. approximatusTrom the Hall and by W.J. Harris and D.E. Thomas, and lower part ofBe2. However, in our examination supplemented more recently by collections of the collections (Table 2). the records, and the by officers made of the Mines Department (Geo- literature we can find no evidence that this spe- logical Survey of Victoria). Most of the material cies occurs higher than Be 1 . This is confirmed by collected by Hall, Harris and Thomas is now O.P. Singleton (pers. comm.) from his own held by the Museum of Victoria, officers and of researches and by Webby et al. (1981) and by both departments have been responsible for Cas and VandenBerg ( 1 988). Even Beavis (1976: much accurate curating of the collections. 26) stated when writing of the occurrence of T, Although our own stratigraphic notes lean heav- ". fruticosus and T. approximatus . but in Be2 ily on the earlier results of Harris and Thomas the latter is absent". On the evidence we agree (e.g. 1938b) and, indeed, to a considerable with this statement but not the range chart. extent confirm them, we have incorporated in Beavis also stated (1976: 26) that "the aniso- Table 1 not only our own findings but those of graptids are restricted to the lowest zones of the several modern workers who have given us Ordovician sequence - the Lancefieldian" yet access to unpublished stratigraphic or locality his chart (fig. 3 1 , second page) shows them rang- information, most notably O.P. Singleton, F. ing into Bel. and ourown research (Table l)has VandenBerg and I. Stewart. We have also re- them ranging into Be2. Thomas (1960a) had examined the Harris and Thomas faunal lists for Clonograptus sp. ranging as high as the a large number of localities in the Bendigo Darriwilian although he regarded that group as region. They had over 2 600 Ordovician grapto- belonging to the Dichograptidae not the Aniso- lite localities in the vicinity of Bendigo alone. Of graptidae. Beavis (1976) distinguished Be2 from this number more than 500 are referable to the Be3 in that T. frulicosus (3 branched) appears Bendigonian. Not all the faunas have been fully half way up the latter division (again