Scott A. Hocknull

New Mid-Cretaceous (Latest Albian) Dinosaurs from Winton, Queensland, Australia

Background Australias dinosaurian fossil record is exceptionally poor compared to that of other similar-sized continents. Most taxa are known from fragmentary isolated remains with uncertain taxonomic and phylogenetic placement. A better understanding of the Australian dinosaurian record is crucial to understanding the global palaeobiogeography of dinosaurian groups, including groups previously considered to have had Gondwanan origins, such as the titanosaurs and carcharodontosaurids. Methodology/Principal Findings We describe three new dinosaurs from the late Early Cretaceous (latest Albian) Winton Formation of eastern Australia, including; Wintonotitan wattsi gen. et sp. nov., a basal titanosauriform; Diamantinasaurus matildae gen. et sp. nov., a derived lithostrotian titanosaur; and Australovenator wintonensis gen. et sp. nov., an allosauroid. We compare an isolated astragalus from the Early Cretaceous of southern Australia; formerly identified as Allosaurus sp., and conclude that it most-likely represents Australovenator sp. Conclusion/Significance The occurrence of Australovenator from the Aptian to latest Albian confirms the presence in Australia of allosauroids basal to the Carcharodontosauridae. These new taxa, along with the fragmentary remains of other taxa, indicate a diverse Early Cretaceous sauropod and theropod fauna in Australia, including plesiomorphic forms (e.g. Wintonotitan and Australovenator) and more derived forms (e.g. Diamantinasaurus).

Dragon's Paradise Lost: Palaeobiogeography, Evolution and Extinction of the Largest-Ever Terrestrial Lizards (Varanidae)

Background The largest living lizard species, Varanus komodoensis Ouwens 1912, is vulnerable to extinction, being restricted to a few isolated islands in eastern Indonesia, between Java and Australia, where it is the dominant terrestrial carnivore. Understanding how large-bodied varanids responded to past environmental change underpins long-term management of V. komodoensis populations. Methodology/Principal Findings We reconstruct the palaeobiogeography of Neogene giant varanids and identify a new (unnamed) species from the island of Timor. Our data reject the long-held perception that V. komodoensis became a giant because of insular evolution or as a specialist hunter of pygmy Stegodon. Phyletic giantism, coupled with a westward dispersal from mainland Australia, provides the most parsimonious explanation for the palaeodistribution of V. komodoensis and the newly identified species of giant varanid from Timor. Pliocene giant varanid fossils from Australia are morphologically referable to V. komodoensis suggesting an ultimate origin for V. komodoensis on mainland Australia (>3.8 million years ago). Varanus komodoensis body size has remained stable over the last 900,000 years (ka) on Flores, a time marked by major faunal turnovers, extinction of the islands megafauna, the arrival of early hominids by 880 ka, co-existence with Homo floresiensis, and the arrival of modern humans by 10 ka. Within the last 2000 years their populations have contracted severely. Conclusions/Significance Giant varanids were once a ubiquitous part of Subcontinental Eurasian and Australasian faunas during the Neogene. Extinction played a pivotal role in the reduction of their ranges and diversity throughout the late Quaternary, leaving only V. komodoensis as an isolated long-term survivor. The events over the last two millennia now threaten its future survival.

New Australian sauropods shed light on Cretaceous dinosaur palaeobiogeography

Australian dinosaurs have played a rare but controversial role in the debate surrounding the effect of Gondwanan break-up on Cretaceous dinosaur distribution. Major spatiotemporal gaps in the Gondwanan Cretaceous fossil record, coupled with taxon incompleteness, have hindered research on this effect, especially in Australia. Here we report on two new sauropod specimens from the early Late Cretaceous of Queensland, Australia, that have important implications for Cretaceous dinosaur palaeobiogeography. Savannasaurus elliottorum gen. et sp. nov. comprises one of the most complete Cretaceous sauropod skeletons ever found in Australia, whereas a new specimen of Diamantinasaurus matildae includes the first ever cranial remains of an Australian sauropod. The results of a new phylogenetic analysis, in which both Savannasaurus and Diamantinasaurus are recovered within Titanosauria, were used as the basis for a quantitative palaeobiogeographical analysis of macronarian sauropods. Titanosaurs achieved a worldwide distribution by at least 125 million years ago, suggesting that mid-Cretaceous Australian sauropods represent remnants of clades which were widespread during the Early Cretaceous. These lineages would have entered Australasia via dispersal from South America, presumably across Antarctica. High latitude sauropod dispersal might have been facilitated by Albian–Turonian warming that lifted a palaeoclimatic dispersal barrier between Antarctica and South America.

New Australovenator Hind Limb Elements Pertaining to the Holotype Reveal the Most Complete Neovenatorid Leg

We report new skeletal elements pertaining to the same individual which represents the holotype of Australovenator wintonensis, from the ‘Matilda Site’ in the Winton Formation (Upper Cretaceous) of western Queensland. The discovery of these new elements means that the hind limb of Australovenator is now the most completely understood hind limb among Neovenatoridae. The new hind limb elements include: the left fibula; left metatarsal IV; left pedal phalanges I-2, II-1, III-4, IV-2, IV-3; and right pedal phalanges, II-2 and III-1. The detailed descriptions are supported with three dimensional figures. These coupled with the completeness of the hind limb will increase the utility of Australovenator in comparisons with less complete neovenatorid genera. These specimens and the previously described hind limb elements of Australovenator are compared with other theropods classified as neovenatorids (including Neovenator, Chilantaisaurus, Fukuiraptor, Orkoraptor and Megaraptor). Hind limb length proportion comparisons indicate that the smaller neovenatorids Australovenator and Fukuiraptor possess more elongate and gracile hind limb elements than the larger Neovenator and Chilantaisaurus. Greater stride lengths to body size exist in both Fukuiraptor and Australovenator with the femur discovered to be proportionally shorter the rest of the hind limb length. Additionally Australovenator is identified as possessing the most elongate metatarsus. The metatarsus morphology varies with body size. The larger neoventorids possess a metatarsus with greater width but shorter length compared to smaller forms.

Morphological comparisons of metacarpal I for Australovenator wintonensis and Rapator ornitholestoides: implications for their taxonomic relationships

WHITE, M.A., FALKINGHAM, P.L., COOK, A.G., HOCKNULL, S.A. & ELLIOTT, D.A., 2013. Morphological comparisons of metacarpal I for Australovenator wintonensis and Rapator ornitholestoides: implications for their taxonomic relationships. Alcheringa 37, 1 - 7. ISSN 0311-5518. Various comparisons of left metacarpal I of the Australovenator wintonensis holotype have been made with Rapator ornitholestoides. These specimens were identified as being morphologically more similar than either was to that of the neovenatorid Megaraptor namunhuaiquii. Owing to the poor preservation of A. wintonensis and R. ornitholestoides, distinct morphological separation between the two appeared minimal. The recent discovery of a near perfectly preserved right metacarpal I of A. wintonensis enables a direct and accurate comparison with R. ornitholestoides. Distinct morphological differences exist between the metacarpals of the two species. A re-evaluation of the age of the A. wintonensis holotype site (AODL 85 ‘Matilda Site’) with zircon dating reveals a maximum age of 95 Ma, 10 Ma younger than the Griman Creek Formation at Lightning Ridge, from which R. ornitholestoides was recovered. This age difference detracts from the probability that the specimens belong to the same genus. Matt A. White∗ [fossilised@hotmail.com], School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia; Peter L. Falkingham† [pfalkingham@rvc.ac.uk], Department of Comparative Biomedical Sciences, Structure and Motion Laboratory, Royal Veterinary College, London, UK; Alex G. Cook [alex.cook@y7mail.com] and Scott A. Hocknull [scott.hocknull@qm.qld.gov.au], Ancient environments, Queensland Museum, Hendra, Queensland, 4011, Australia; David A. Elliott [david.elliott@aaod.com.au], Australian Age of Dinosaurs Museum of Natural History, The Jump Up, Winton, Queensland, 4735, Australia. ∗Also affiliated with Australian Age of Dinosaurs Museum of Natural History, The Jump Up, Winton, Queensland 4735, Australia. †Also affiliated with Department of Ecology and Evolutionary Biology, Division of Biology and Medicine, Brown University, USA. Received 22.9.2012; revised 13.1.2013; accepted 17.1.2013.

Tigershark Rockshelter (Baidamau Mudh) : Seascape and Settlement Reconfigurations on the Sacred Islet of Pulu, Western Zenadh Kes (Torres Strait)

Abstract Tigershark Rockshelter, a small midden site on the sacred islet of Pulu in central western Zenadh Kes (Torres Strait), was visited intermittently by small groups of marine specialists between 500 and 1300 years ago. The diverse faunal assemblage demonstrates procurement of turtle, dugong, shellfish, fish, shark and ray from mangrove, reef and open water environments. Apart from a characteristic flaked quartz technology, the site contains shell body adornments. Establishment of Tigershark Rockshelter reveals increasing preference for shoreline settlements possibly for enhanced intervisibility, intimacy and liminality between newlyconceptualised territorial land- and seascapes. Intensified occupation 500–700 years ago matches concomitant demographic expansions across the region. As local settlement patterns focused on large open village sites 500 years ago, Tigershark Rockshelter became obsolete and was abandoned. These settlement reconfigurations were part of broader social transformations that eventually saw the status of Pulu change from a residential to a ceremonial and sacred place.

Hammer-toothed ‘marsupial skinks' from the Australian Cenozoic

Extinct species of Malleodectes gen. nov. from Middle to Late Miocene deposits of the Riversleigh World Heritage Area, northwestern Queensland, Australia are enigmatic, highly specialized, probably snail-eating marsupials. Dentally, they closely resemble a bizarre group of living heterodont, wet forest scincid lizards from Australia (Cyclodomorphus) that may well have outcompeted them as snail-eaters when the closed forests of central Australia began to decline. Although there are scincids known from the same Miocene deposits at Riversleigh, these are relatively plesiomorphic, generalized feeders. This appears to be the most striking example known of dental convergence and possible competition between a mammal and a lizard, which in the long run worked out better for the lizards.

Invictokoala monticola gen. et sp. nov. (Phascolarctidae, Marsupialia), a Pleistocene plesiomorphic koala holdover from Oligocene ancestors

Koalas (Phascolarctidae) are uncommon elements within the Australian fossil record. The earliest representatives are recorded from late Oligocene rainforest assemblages of central Australia. In contrast, the extant Koala Phascolarctos cinereus Blainville, 1816 (the only surviving member of a once diverse family) is found only in eastern Australian open woodlands. Extinction of koalas from rainforests was previously thought to have occurred after the middle Miocene. Recent systematic cave excavations at Mt. Etna, central eastern Queensland, Australia, have revealed several remarkable new middle Pleistocene vertebrate assemblages that are dominated by rainforest-adapted taxa. Within one of the deposits, we have identified a new, but archaic, genus and species of koala. Invictokoala monticola gen. et sp. nov. shares affinities with the most plesiomorphic member of the family, Madakoala Woodburne et al., 1987 (late Oligocene), but is distinguished by possessing higher-crowned upper molars, with a tricsupate (rather than linear) paraconule on M2 (autapomorphic condition within koalas), closely positioned stylar cusps, and better-developed posterior cingulae. Thus, not only does I. monticola represent a ‘holdover’ from an Oligocene ancestor, but the Madakoala–Invictokoala stem represents a ‘ghost’ lineage within the Phascolarctidae, with no representatives known between the late Oligocene and middle Pleistocene. Previously, it was thought that the post-middle Miocene loss of koalas from rainforests may have been a result of a co-evolved dependence of koalas to open eucalypt woodlands, and/or competitive exclusion with koala-like rainforest-adapted ringtail possums. However, the inferred diet of middle Pleistocene I. monticola (i.e. non-Eucalyptus) and coeval occurrence with numerous rainforest-adapted ringtail possums does not support that hypothesis. It appears more likely that koalas had always been closely associated with rainforests, at least until the late Quaternary extinction of I. monticola. Generally, the paucity of rainforest faunal assemblages, and specifically, records of fossil koalas through the late Cenozoic drastically limits our understanding of their evolution.

Two new species of Antechinus Macleay (Dasyuridae : Marsupialia) from mid-Pleistocene cave deposits in eastern central Queensland

The dasyurid genus Antechinus occurs in numerous Cainozoic fossil sites but until now only one extinct species has been described, Antechinus puteus Van Dyck. Antechinus yammal sp. nov. and A. yuna sp. nov. are described here on the basis of dental remains recovered from middle Pleistocene (between >500 and 205–170 thousand years ago) cave deposits at Mount Etna, eastern central Queensland. Most of these sites are interpreted as closed rainforest palaeoenvironments, and this is the likely habitat of both species. Both taxa are morphologically variable. A. yammal is characterised by complete anterior cingula and well developed posterior cingula on the upper molars; a relatively unreduced, robust P3; and small entoconids. A. yuna is a relatively large species, typified by poorly developed or absent posterior cingula on M1–3, lack of a metacone on M4, and large entoconids on M1–3. Dental morphology suggests that A. yuna was a near relative of the extant A. leo. The dentition of A. yammal shows some similarities to that of A. flavipes, but its exact phylogenetic position is unclear. A. yammal became extinct coincident with the loss of its rainforest habitat some time between 280 and 205–170 thousand years ago. A. yuna survived somewhat longer, but by the late Pleistocene had been replaced by A. flavipes.

Traditional and computed tomographic (CT) techniques link modern and Cenozoic fruits of Pleiogynium (Anacardiaceae) from Australia

Computed tomography (CT) and traditional techniques were used to study the internal morphology of modern fruits of Pleiogynium timoriense (DC.) Leenh., and phosphatized and silicified fruits that were considered to belong to the genus. The results demonstrate that phosphatized fruits from the Oligocene–Miocene Dunsinane site at Riversleigh and silicified fruits from the Oligocene Glencoe Site, which are both in Queensland, are referable to Pleiogynium. The Riversleigh material (Pleiogynium wannanii Rozefelds, Dettmann & Clifford sp. nov.) is very similar to extant P. timoriense (DC.) Leenh. Both possess locules that, in the vertical axial plane, are asymmetrically reniform and enclosed by a two-layered endocarp, the inner layer woody and resistant to decay, the outer of fibres and parenchyma, surrounded by a mesocarp of fibres and sclereids and a parenchymatous exocarp. The outer mesocarp is sculpted by meridionally arranged, elongate depressions (germination apertures) situated at the dorsal surface of each locule; erosion of the mesocarp and outer endocarp provides passage for emergence of the embryo’s radicle on germination. The silicified material from Glencoe (P. parvum Rozefelds, Dettmann & Clifford sp. nov.) is smaller in all its parts and has locules that are ovate in the vertical axial plane. Discrete, cap-like, opercula are not evident in the fruit wall of the fossil and extant fruits studied. The presence of Pleiogynium, and associated taxa, indicates the existence of rainforest communities at Glencoe, and mixed open forest/rainforest at Riversleigh during Oligocene–Miocene times. The multilocular, fossil fruit described as Pleiogynium mitchellii Collinson, Manchester and Wilde from the Eocene deposits at Messel Quarry, Germany, is not considered to belong in the genus, as evidence of elongate depressions on the dorsal surface of the fruit stones has not been demonstrated conclusively, and its internal morphology/anatomy differs significantly from that of Pleiogynium.