Peter A. Jell

Australian cretaceous terrestrial faunas and floras: biostratigraphic and biogeographic implications

Abstract Nonmarine Cretaceous sediments representing fluvial/lacustrine deposits occur in 22 of Australias 23 Mesozoic depositional basins. They are associated with open to marginal marine sediments whose enclosed planktic faunas and floras provide tie points to the Tethyan and European stages. Integration of marine and nonmarine sequences has been effected through spore-pollen biostratigraphies which in turn are linked to macroplant zones, vertebrate ranges and radiometric dates. This evidence is reviewed and it is concluded that the C. hughesii-P. pannosus spore-pollen Zones define Aptian to Albian ages and that their zonal boundaries are isochronous across Australia; the P. mawsonii-F. longus spore-pollen Zones in south-eastern Australia are datable as Turonian-Maastrichtian. However, evidence for a Cenomanian age for the intervening A. distocarinatus Zone is not indubitable. Also, the position of the Jurassic-Cretaceous boundary and the temporal significance of several index taxa of the ?latest Jurassic-Barremian C. australiensis-F. wonthaggiensis Zones in eastern Australia and the B. eneabbaensis-lower B. limbatus Zones in Western Australia is not certain. Isochronous incomings of individual spore-pollen taxa on a regional scale relate to the mode of dispersal of the source plant, and to the distribution of environments suitable for dispersal. For the Aptian-Albian, when Australia was inundated by shallow seas and lake/river systems that fed into them, several index taxa sourced from aquatic and strandline plants appear to have temporal significance. By contrast, anemophilous pollen are stratigraphically useful and temporally significant in the Turonian-Maastrichtian of south-eastern Australia. Throughout the Cretaceous, Australia supported a succession of coniferous forests. Early Cretaceous podocarp/araucarian/ Ginkgo canopy associations were modified in the Late Cretaceous by the loss of Ginkgo and the introduction of rainforest Proteaceae and Nothofagus . Regional variations in the vegetation reflect topographic, edaphic and climatic variations between the disparate sedimentary basins. Floral migration within Australia and between associated land masses occurred in a step-wise fashion, and was mostly west to east. Two dinosaur faunas are recognized: one, in the Aptian-early Albian of Victoria, consists of small ornithopods and theropods; and the other, in the middle Albian-Cenomanian of Queensland, comprises ankylosaurs, sauropods and theropods. The Victorian herbivorous dinosaurs were low feeders and probably shared a single mode of feeding, whereas those from Queensland may have had several feeding modes and fed up to 6 m from the ground. The small ornithopods, mostly from Victoria, were hypsilophodontians with grinding dentitions; their food source may have been lycopods or diaspores of podocarps and Ginkgo . Ankylosaurs seem to have preferred soft vegetation, some possibly aquatic. The Queensland sauropods may have fed on living and dead vegetation, perhaps including fleshy seeds of podocarps/taxads and gleicheniaceous ferns that apparently proliferated in the region. The lungfish had grinding toothplates and were probably omnivorous like extant Neoceratodus forsteri . Victorian faunas contain several relicts including the youngest known temnospondyl, the theropod Allosaurus , the lungfish Ceratodus avus , and the freshwater mussel Mesohydridella ipsviciensis . Australian earliest Cretaceous climates were temperate with cool temperatures (0–12°C) and high precipitation levels (750–1150 mm/year) in southern regions where winter freezing may have occurred during the Aptian. A warming trend during the Albian is indicated by land vegetation and verified by isotope palaeotemperatures (12–16°C) from the marine realm. Cool to warm temperate climates prevailed in the south-east during Turonian-Maastrichtian times; sea water temperatures were 16–28°C, and the vegetation is indicative of high humidities.

Australian Middle Cambrian molluscs and their bearing on early molluscan evolution

Twenty-eight species of fifteen genera of Middle Cambrian molluscs are described from tiny phosphatic moulds or silica replicas of the shells. The molluscs were etched from limestones at two sites: one in the earliest Middle Cambrian Coonigan Formation of the Mootwingee area, 130 km northeast of Broken Hill, New South Wales; and another in the middle Middle Cambrian Currant Bush Limestone of the Thorntonia area, 150 km northwest of Mt Isa, Queensland. These unusually diverse collections show that many different kinds of molluscs lived in the tropical Australian seas of the Middle Cambrian and provide new information on the way the molluscan classes Cephalopoda, Gastropoda, Rostro- conchia, and Pelecypoda evolved. In other sections, we discuss the problems of classifying and naming Cambrian molluscs; define a number of terms that can be used to describe shell form (including a new adjective, gyrogastric); reclassify the Class Monoplacophora after incorporating the helcionellacean and bellerophontacean “gas...

Early Middle Cambrian (Ordian) brachiopods of the Coonigan Formation, western New South Wales

A rich assemblage of early Middle Cambrian brachiopods from the ‘first discovery limestone’ of the Coonigan Formation, western N.S.W. contains 20 taxa (eight Articulata, 11 Inarticulata and one which cannot be assigned with certainty to either class). New articulate species are Nisusia grandis grandis, N. grandis glabra, Wimanella tricavata, Arctohedra alata, Acareorthis jelli, Cymbricia spinicostata, Austrohedra mimica and Glaphyrorthis fastigata, with the last four mentioned new genera. Inarticulate taxa include species of Trematosia and ?Kutorgina, Hadrotreta primaeva (Walcott), Micromitra nerranubawu Kruse and new species of Kleithriatreta lamellosa, Eothele granulata, Dictyonina australis, Palaeoschmidites horizontalis, Lingulella bynguanoensis, Westonia cymbricensis, and an indeterminate lingulacean; Kleithriatreta is a new genus. The enigmatic new genus and species Bynguanoia perplexa cannot be placed within either the Articulata or Inarticulata. Seven taxa are endemic, six are comparable with taxa...

Earliest known pelecypod on Earth — a new Early Cambrian genus from South Australia

A new genus and species of fordilloid pelecypod, Pojetaia runnegari gen. et sp. nov., is described from the lower part of the Parara Limestone, Yorke Peninsula, South Australia. Establishing the age of the sample on an international scale is difficult, as with almost all Early Cambrian formations, but evidence tends to suggest that this is the oldest pelecypod so far recorded. Clearly defined hinge teeth and sockets on both valves and on internal moulds help to confirm the pelecypod placement of fordilloids.

Trilobite respiration and genal caeca

Four different types of structures on fossil arthropods are shown to have been grouped under the term ‘genal caeca’. These are distinguished and the most conspicuous (i.e. the fine radiating cephalic ridges of trilobites that anastomose repeatedly before joining a major ridge in the border) are interpreted as the external representation of auxiliary respiratory systems at least in some Cambrian genera. A number of possible functions are considered for these ridges and none but respiration is found to be feasible. Supportive evidence for the hypothesis outlined is drawn from consideration of the paradigm for a dorsal respiratory system and from a comparison with living crustacea.

Plumulites and the machaeridian problem

Plumulites richorum sp. nov. is represented by two complete sclerite assemblages from Early Devonian strata of the Humevale Formation in a small quarry northeast of Kinglake West, Victoria. The completeness of these sclerite assemblages necessitates a revision of terminology applied to machaeridians. Moreover, the sclerite assemblages make it necessary to erect a new Family Plumulitidae and allow several deductions about the animal itself, namely: 1, there was a discrete head possibly with soft anterior projections; 2, there was considerable modification of sclerites and their arrangement near the head, indicating possible sexual dimorphism; 3, sclerites were almost certainly not rigidly attached to the soft parts of the animal. The material shows that Plumulites was neither an arthropod nor an echinoderm, but rather a vagile benthic animal probably belonging to the Annelida.

Early Middle Cambrian corals from western New South Wales

Three forms, Cothonion sympomatum gen. et sp. nov. with a bi-radially septate operculum, and the new species lissa and daseia of the genus Lipopora gen. nov., are described from the early Middle Cambrian Coonigan Formation in the Mootwingee district of western New South Wales, Australia. They may be representatives of hitherto unknown groups of organisms, but they are tentatively interpreted as coelenterates that reached a level of development comparable with the Anthozoa. Cothonion is placed in the new family Cothoniidae and questionably referred to the Rugosa. Lipopora is considered to be similar to Coelenteratella Korde; both are grouped in die new family Lipoporidae and tentatively referred to the Tabulata.

Thambetolepis delicata gen. et sp. nov., an enigmatic fossil from the Early Cambrian of South Australia

The acid insoluble sclerites of Thambetolepis delicata gen. et sp. nov. of late Tommotian or immediately post-Tommotian age from near Ardrossan, South Australia, are described. These sclerites, as well as those of Sachites Meshkova 1969 and Halkieria Poulsen 1967, are from multi-sclerite animals similar to Wiwaxia Walcott 1911 together with which they constitute the new class Thambetolepidea. Biological affinities of these fossils are discussed in the light of the complex internal structure of the sclerites. Possible assignments to the opisthobranch gastropods, the polyplacophorans, or the annelids are discussed but the taxonomic position of Thambetolepis and the Thambetolepidea is unresolved.

An early Late Cambrian trilobite faunule from Kashmir

An early Late Cambrian trilobite faunule of fewer than 20 specimens and including Monkaspis sp. cf. M. serrata Mong, ? Blackwelderia sp. and Cyclolorenzella sp. is recorded from the Trahagam Formation near the village of Trahagam in Hundwara Tehsil, Kashmir, India. The faunule occurs in green shales and provides the first unequivocal Late Cambrian date for sediments in Kashmir; Kashmiri fossil faunas previously ascribed Late Cambrian ages by Reed are now considered Middle Cambrian.

Australian Middle Cambrian molluscs: corrections and additions

The Cambrian Monoplacophora Anabarella, Mellopegma and Stenotheca were incorrectly referred to the Family Procarinariidae Wenz 1938 by Runnegar & Jell (1976) because Horný (1964a) has shown that Procarinaria is a bivalve. A new family, Stenothecidae, is therefore proposed. Also, two genera of Cambrian pelagiellids described by Horný (1964b) were omitted from a discussion of the family in Runnegar & Jell (1976). Information which has been obtained since 1976 shows that the snorkel of Yochelcionella cyrano was much longer than previously thought, that Yochelcionella occurs in Pennsylvania as well as Australia, that the Ordovician and Silurian microfossils Janospira and Jinoncella may be related to Yochelcionella, and that Runnegar & Jell were probably correct in referring all bellerophont univalves to the Monoplacophora, rather than to the Gastropoda where they have been traditionally placed.