Henk Godthelp

Fossil Mammals of Riversleigh, Northwestern Queensland: Preliminary Overview of Biostratigraphy, Correlation and Environmental Change

Aspects of the results of studies of the fossil-rich Cainozoic deposits of Riversleigh, northwestern Queensland, are reviewed. A summary of five selected Riversleigh faunas representing the primary periods of the regions Cainozoic history is provided. Faunal and environmental changes over the last 25 000 000 years in the Riversleigh region are identified and changes in Australias rain forest mammal communities over the same period are discussed. Evidence for the origin of Australias modern mammal groups from ancestors now known to have lived in the Tertiary rainforests of northern Australia is reviewed. The geological record for Riversleighs more than 100 local faunas is considered. At least three primary intervals of Oligo-Miocene deposition, one of Pliocene and many of Pleistocene and Holocene deposition are identified. An appendix is provided in which the principal faunal assemblages from Riversleigh are allocated to these depositional intervals. The evidence for correlating Riversleigh local fauna...

Australia's oldest marsupial fossils and their biogeographical implications.

Background We describe new cranial and post-cranial marsupial fossils from the early Eocene Tingamarra Local Fauna in Australia and refer them to Djarthia murgonensis, which was previously known only from fragmentary dental remains. Methodology/Principal Findings The new material indicates that Djarthia is a member of Australidelphia, a pan-Gondwanan clade comprising all extant Australian marsupials together with the South American microbiotheres. Djarthia is therefore the oldest known crown-group marsupial anywhere in the world that is represented by dental, cranial and post-cranial remains, and the oldest known Australian marsupial by 30 million years. It is also the most plesiomorphic known australidelphian, and phylogenetic analyses place it outside all other Australian marsupials. Conclusions/Significance As the most plesiomorphic and oldest unequivocal australidelphian, Djarthia may approximate the ancestral morphotype of the Australian marsupial radiation and suggests that the South American microbiotheres may be the result of back-dispersal from eastern Gondwana, which is the reverse of prevailing hypotheses.

Current status of species-level representation in faunas from selected fossil localities in the Riversleigh World Heritage Area, northwestern Queensland

Current lists of species-level representation in faunas from 80 Cenozoic fossil localities at the Riversleigh World Heritage Area have been compiled by review of recorded occurrences of taxa obtained from both published and unpublished sources. More than 290 species-level taxa are represented, comprising mammals, amphibians, reptiles, birds, fishes, molluscs and crustaceans. The data are presented for the purpose of ongoing palaeoecological and biochronological studies.

First Eocene bat from Australia

ABSTRACT Remains of a bat, Australonycteris clarkae, gen. et sp. nov., are reported from freshwater clays radiometrically dated at 54.6 million years old in southeastern Queensland, Australia. It is the oldest bat yet recorded for the Southern Hemisphere and one of the worlds oldest. Previously, the earliest records for bats came from the Northern Hemisphere and were of Sparnacian age in Europe, Wasatchian in North America, and late early Eocene in North Africa. The North American Wyonycteris chalix, originally described as a latest Paleocene bat and as such the worlds oldest, is re-examined. Its lack of key bat synapomorphies and overall morphology do not support the claim that it is a bat. Early bats probably entered Australia via Asia rather than South America, although their appearance in Australia predates the final breakup of Gondwana. The Australian fossils described here (a lower molar, upper premolar, edentulous dentary fragment, and part of a periotic) may corroborate the hypothesis that moder...

A New Marsupial from the Early Eocene Tingamarra Local Fauna of Murgon, Southeastern Queensland: A Prototypical Australian Marsupial?

Djarthia murgonensis, a new genus and species of marsupial from the early Eocene Tingamarra Local Fauna of Murgon in southeastern Queensland, is described on the basis of dental material. The combination of marsupial synapomorphies and symplesiomorphies present in D. murgonensis suggests phylogenetic placement within either Didelphidae or Australidelphia. Tarsal morphology, fundamental to the concepts of Ameridelphia and Australidelphia respectively, is not yet known for this taxon. Consequently, it cannot be assigned to either clade with confidence. If this taxon is australidelphian, it constitutes support for the hypothesis that the common ancestor of the Australian marsupial radiation was didelphoid-like in dental features. Some previous authors have contended that marsupial faunas of South America and Australia are manifestly distinct, excepting for the australidelphian affinity of South American microbiotheres. However, because tarsal anatomy is unknown in some generalized Australian fossil taxa, including D. murgonensis, and character analysis reveals that no synapomorphies of the dentition unequivocally define either Ameridelphia or Australidelphia to the exclusion of the other, we consider this interpretation to be premature. In short, available evidence neither supports nor refutes the argument of distinct South American and Australasian marsupial faunas. A further ramification is the need to reconsider the phylogenetic position of Ankotarinja tirarensis and Keeuna woodburnei. These central Australian fossil taxa might be referred to either Australidelphia or Ameridelphia, and it is recommended that both be treated as Marsupialia incertae sedis until further material comes to light.

The Rise of Australian Marsupials: A Synopsis of Biostratigraphic, Phylogenetic, Palaeoecologic and Palaeobiogeographic Understanding

The origins, evolution and palaeodiversity of Australia’s unique marsupial fauna are reviewed. Australia’s marsupial fauna is both taxonomically and ecologically diverse comprising four extant orders (Dasyuromorphia, Peramelemorphia, Notoryctemorphia and Diprotodontia) and one extinct order (Yalkaparidontia). Molecular divergence dates estimate a Palaeocene origin for the Australian marsupial orders yet ordinal differentiation is obscured by significant gaps in the fossil record with a single terrestrial mammal-bearing deposit known between the late Cretaceous and the late Oligocene. This deposit, the 55 million-year-old early Eocene Tingamarra Local Fauna of southeastern Queensland, contains Australia’s oldest marsupial (Superorder Australidelphia) as well as taxa tentatively interpreted to represent South American groups (Order Polydolopimorphia). Palaeobiogeographic hypotheses regarding the distribution and interordinal relationships of Australian and South American marsupials are discussed. Dasyuromorphia and Peramelemorphia were possibly also present in the early Eocene, Diprotodontia in at least the late Oligocene and Notoryctemorphia and Yalkaparidontia in the early Miocene. Palaeobiodiversity was highest during the early to middle Miocene as evidenced by a spectacular array of marsupial groups in the rainforest assemblages of the Riversleigh World Heritage Area. The onset of icehouse conditions during the middle Miocene saw significant faunal turnover with loss of many archaic groups and the emergence of a range of modern lineages. Few deposits of late Miocene age are known. Development of Australia’s first grasslands and arid habitats occurred in the Pliocene, accompanied by an explosive radiation of grazing kangaroos. The Pleistocene was characterised by severe and unpredictable climatic conditions and the extinction of the Australian megafauna. Lowered sea levels allowed faunal interchange between mainland Australia and neighbouring New Guinea as well as the arrival of the first humans. Resolution of the role of humans and/or climate change in megafaunal extinction requires more precise dating of late Pleistocene deposits. We reflect on the predictive power of the fossil record to enhance understanding of the effects of climate change and humans on the future of the Australian marsupial fauna.

Mystacinid bats (Microchiroptera) from the Australian Tertiary

A new genus and three new species of the microchiropteran family Mystacinidae are described from Miocene freshwater limestones in northern Australia. The type species, Icarops breviceps new genus and species, is from the middle Miocene Bullock Creek deposit, Northern Territory; I. aenae new species and I. paradox new species are from the slightly older (early Miocene) Wayne9s Wok and Neville9s Garden Sites at Riversleigh, northwestern Queensland. Fossil mystacinids are rare in each deposit and represented so far only by lower teeth and dentary fragments. They are characterized by a suite of apomorphies shared only with Quaternary mystacinids endemic to New Zealand. The family Mystacinidae has no pre-Pleistocene record and its relationships to other groups of bats remain unclear. Possible sister-groups include South American noctilionoids and the cosmopolitan molossoids and/or vespertilionoids. The presence of plesiomorphic mystacinids in the Australian Tertiary suggests an Australian origin for the family.

Integrating ecology and economics: Illustrating the need to resolve the conflicts of space and time

Abstract Although derived from a common linguistic root, ecology and economics are widely varying and often conflicting disciplines, each with temporal and spatial frameworks that seem to preclude the concerns of the other. This conflict becomes an important consideration in environmental management for which economic and political time frames and spatial boundaries are usually too short and too small to accommodate the dimensions of entire ecosystems and evolutionary time. Past attempts to reserve land for nature conservation have often been ad hoc and have resulted in an ineffective system of protected areas concentrated on the least economically valuable land. Moreover, the current reserve system increases the long-term costs of establishing a truly representative system because it is relatively inefficient at sampling the range of natural variation. From the palaeontological evidence it has been estimated that at least 20% of the area of the continent needs to be preserved for the sake of intergenerational equity, that is, to allow the long-term persistence of present natural variation for future generations to enjoy. This paper offers insights into an ecological view of time and space, which, it is argued, are essential if decisions aimed at conserving biodiversity are to be effective.

Reconsideration of Monotreme Relationships Based on the Skull and Dentition of the Miocene Obdurodon dicksoni

In this chapter, we (1) describe and illustrate the anatomy of a complete skull, posterior half of a dentary, and cheektooth dentition of a Miocene ornithorhynchid, Obdurodon dicksoni from Riversleigh, Queensland, Australia; (2) use this new information to reevaluate understanding of the anatomy of the living Ornithorhynchus anatinus; (3) revise previous understanding about the monotreme dentition; and (4) reconsider monotreme relationships.

A New Order of Tertiary Zalambdodont Marsupials

Yalkaparidon coheni and Yalkaparidon jonesi are described here as the first-known members of the marsupial family Yalkaparidontidae and order Yalkaparidontia. Before discovery of these zalambdodont marsupials in unnamed Tertiary sediments from northwestern Queensland, only five orders of australidelphian marsupials were known. Dental and basicranial morphology suggest that notoryctids and yalkaparidontids, which both have highly specialized zalambdodont molars, are dentally convergent. Yalkaparidontids lived in lowland rainforests of northern Australia and appear to have vanished, with the rainforests, sometime in the middle to late Tertiary. Discovery of yalkaparidontids demonstrates a significantly greater breadth of diversity for Australian marsupials.