IBIS 135: 8-18 A new cockatoo (Psittaciformes: Cacatuidae) from the Tertiary of Riversleigh, northwestern Queensland, and an evaluation of rostral characters in the systematics of parrots W AL TER E. BOLES Division of Vertebrate Zoology (Birds), Australian Museum. 6-8 College Street. Sydney, N.S. W. 2000, Australia : The first Tertiary cockatoo or any psittaciform from Australia is recorded from an incom- plete rostrum from the Riversleigh deposits of northwestern Queensland.Australia. It is placed in the extant genus Cacatuabut cannot be diagnosed at the specific level. This cockatoo was probably similar in size to the modern C. roseicapilla.with a short. unspe- cialized crest and probably white plumage. The rostrum is useful in studies of the system- atics of parrots. Rostral characters support sometraditional subdivisionsof the order. while suggestingthat others warrant re-examination. Parrots comprise one of the most distinctive orders of birds. Milne- Edwards (1867 -1871 ) described Psittacus verrauxi from The approximately 340 living speciesof Psittaciformeshave the Early Miocene of France. for which Lambrecht (1933) a pan-tropical and southern distribution. Of these birds, the later proposed the new generic name Archaeopsittacus. Wet- cockatoos (Cacatuidae),with 18-21 speciesin five genera, more (1926) named Conuropsisfratercula. the only pre-Pleis- centred on the Australo-Papuan region, form one of the tocene record of this order from the New World. No bills or most characteristic groups. With five generaand 10-12 spe- skulls of these Tertiary forms have thus been reported. and cies, Australia is' the centre of cockatoo diversity, although it is not possible to determine at what stage these early speciesextend as far as the Philippines in the north, Sulawesi parrots were in the evolution of the distinctive cranial mor- and the Sunda Islands in the west and the Solomon Islands phology that characterizes parrots. in the east (Forshaw 1981). Thesebirds form one of the most All previous Australian records of the Psittaciformes are distinctive elementsof the Australian avifauna. Despite this of Quaternary age and are indistinguishable at specific It:vel wide distribution, there is only a very limited fossil history from Recent taxa (Baird 1991). Smaller, non-cacatuine forms of parrots (Olson 1985). At present the known record con- have been reported from several sites (e.g. Hope et al. 1977 , tains only a handful of Tertiary taxa, none of which is a Rich et al. 1983. Baird 1985; summarized in Baird 1991); cockatoo. Fro!D Australia, with 55 extant species,no pre- other psittacine material has not yet been evaluated. Cock- Pleistocenematerial has been reported (Vickers-Rich 1991). atoos have only recently been reported from the fossil rec- The only cockatoos are of Pleistoceneage and can be as- ord-none was listed by Brodkorb (1971)-and these have signed to extant species(Baird 1985, 1991). been only from southeastern Australian sites. The identified Describedhere is a fossil cockatoofrom the Early to Middle species are all referable to living taxa: Red-tailed Cockatoo Miocene of northwestern Queensland,constituting the old- Calyptorhynchus magnificus, Glossy Cockatoo C. lathami, Black est fossil record of the order for Australia and of the Caca- Cockatoo C. funereus. Gang-gang Callocephalon fimbriatum. tuidae for the world. Long-billed Corella Cacatua tenuirostris and Galah C. rosei- capilla. Other cockatoo material. as yet unpublished. has been recovered from a number of other Pleistocene sites (R.F. Baird. pers. comm.). FOSSIL HISTORY The fossil record of the Psittaciformes has been summarized by Olson (1985). The earliest report is Palaeopsittacusgeorgei GEOGRAPHIC AND GEOLOGIC SETTING Harrison (1982) from the Lower Eocene of England. al- though there have been doubts expressed about the iden- The Riversleigh depositsare located on Riversleigh Station, tification (Olson 1985). Mourer-Chauvire (1982) noted re- approximately 200 kID north of Mount Isa, northwestern mains from the Upper Eocene of France. which she assigned Queensland.More than 100 sites and local faunas are now to the Psittacidae without elaboration. known from this area but few of these have been described Only two Miocene records have so far been published. in the literature. Preliminary stratigraphic relationshipshave although P. Ballman (pers. comm. to Olson 1985) has drawn been determined by Archer et al. (1989), but these, as well attention to the recovery of some as yet undescribed parrot as the interpreted ages,must be regarded as tentative. remains from the Middle Miocene of Germany and France. The fossil subject of this paper came from the RSOLocal 1993 A NEW COCKATOO FROM QUEENSLAND 9 Fauna from RSO Site. This site is at the lower end (180 m some characters. Some taxa do not fit comfortably into the a.s.I.) of the Godthelp Hill Sequence. which forms part of categoriesadopted, but some limitation has been made on System B of Archer et al. (1989). System B. a collection of the number of categoriesused to accommodateunique ex- regionally clustered sites differing in age but not significantly amples. The rhamphotheca often bears little resemblanceto in position and/or spatially isolated but approximately con- the underlying bone and, together with the cere, prevents temporaneous. is considered to be ?Early to Middle Miocene. any external assessmentof the rostral characters. The taxa It appears to represent fossil assemblages accumulated in examined are listed in Appendix II. Rostral characters for pools or shallow lakes (Archer et al. 1989). many Australo-Papuan and selected extralimital psittaci- Based primarily on information derived from the rich and form genera are given in Appendix III. These should be diverse mammal remains, Archer et al. (1989) have inter- useful in the identification of unknown rostra. preted the vegetation of Riversleigh at this time to have been "dense. species-rich gallery rainforests probably similar to those that persist today in mid-montane New Guinea.'. SYSTEMA TIC P ALAEONTOLOGY The Riversleigh rostrum clearly belongs to the Cacatuidae. A suite of character statesserves to identify any member of MA TERIALS AND METHODS this family. Most of the character states are found in other Measurementswere made with vernier calipers accurate to taxa; however. the shape of the naso-frontal hinge and the 0.05 mrn and rounded to the nearest 0.1 mm. specializedconfiguration of the cere region are diagnostic. Names of psittaciform taxa follow Forshaw (1981) except Five genera of cockatoos are currently recognized: Pro- for changesbased on more recent studies. For convenience bosciger(palm Cockatoo. 1 species).Calyptorhynchus (black of reference. three families of Psittaciformesare recognized cockatoos. 3-5 species). Callocephalon(Gang-gang. 1 spe- in the discussionof this fossil (after Forshaw 1981): Loriidae cies). Cacatua(white cockatoos. 12-13 species)and Nym- {lorikeetsand lories). Cacatuidae(cockatoos) and Psittacidae phicus (Cockatiel. 1 species).The character states, particu- (all other parrots). larly of the nostrils, and the shape and size of the rostrum, The fossil material referred to herein is currently held in indicate that the fossil parrot from Riversleighis most similar the collections of the Vertebrate PalaeontologyLaboratory . to. and indeed inseparable from. Cacatua. University of New South Wales but will be transferred to The other cacatuine genera can be distinguished from the Queensland Museum at the completion of this study; Cacatuaby the following rostral characters: prefixesto registration numbers for theseinstitutions are AR Callocephalon. Cere region saddle-shapedwith thin centre; and QM. respectively. nostrils oriented to the side (300from midline of culmen); length: width ratio smaller than in all cacatuid speciesex- cept for some individuals of C. sulphurea. ANAL YSIS OF CHARACTERS Calyptorhynchus. Cere region saddle-shapedwith thin cen- The decurved upper mandible of parrots is distinctive. con- tre; internarial septum wider; nares small. directed to side; size large (compared with small Cacatuaspecies). stituting one of the major external charactersby which these birds are recognized. A few other orders of raptorial birds Probosciger. lnternarial septum wider; nares small. direct- have superficially similar hooked bills, but each group can ed to side; size very large; shape diagnostic. be easily distinguished from parrots by a combination of Nymphicus. Cereregion spade-shaped(Fig. 18); internarial characters, not all applicable to each group, e.g. presence and shape of the naso-frontal hinge, shape of the nostrils, septum narrow; size small. presenceof a nasal tubercule, absenceof a bifurcated groove on the culmen and degreeof lateral compressionof the ros- trum. Order PSITTACIFORMES Wagler. 1830 The most easily recognized feature of parrot bills is the Family CACA TUIDAE groove on the upper surface that runs from the cere region down the internarial septum and then bifurcates. continuing (Rostrum) Naso-frontal outline with centre raised and along each side of the culmen towards the tip. The presence rounded. extending above point of attachment with skull; of this groove is diagnostic for the Psittaciformes. cere region smoothed and raised as saddle-shapedplatform There are about 340 speciesof living or recently extinct (shapedifferent in one species);corners of naso-frontal hinge speciesof parrot placed in 81 genera (Forshaw 1981). In entended into acutely angled horns (approximately 90" in order