Faunal Zones Research Articles

Phylogenetic evidence of historic mitochondrial introgression and cryptic diversity in the genus Pseudemoia (Squamata: Scincidae)

The Australian scincid genus Pseudemoia comprises six morphologically similar species restricted to temperate south-eastern Australia. Due to the high degree of morphological conservatism, phylogenetic relationships and taxonomic status within the Pseudemoia entrecasteauxii complex (comprising the nominal species P. entrecasteauxii, P. cryodroma, and P. pagenstecheri) remains unresolved. To further investigate the phylogenetic relationships and taxonomic status of Pseudemoia spp., and to test the hypothesis that P. cryodroma evolved from hybridization between P. entrecasteauxii and P. pagenstecheri, we sequenced one mitochondrial locus (ND4) and five nuclear loci (β-globin, LGMN, PRLR, Rhodopsin, RPS8). While we find strong support for the monophyly of the P. entrecasteauxii complex, there exists marked incongruence between the mitochondrial and nuclear markers, particularly in regards to the high altitude specialist, P. cryodroma. The most parsimonious explanation of this discordance is historic mitochondrial introgression, although a hybrid origin for P. cryodroma cannot be completely rejected. Within P. pagenstecheri sensu lato, we identified a strongly supported, highly divergent yet morphologically cryptic lineage restricted to northern New South Wales. Although more weakly supported by the nuDNA, we also identified a second geographically distinct lineage of P. pagenstecheri s.l., which may warrant separate conservation management. Our study reveals a more complex evolutionary history of the genus Pseudemoia than previously appreciated and contributes to our understanding of the biogeography and evolution of Australian mesic zone fauna.

New material referable to Wakaleo (Marsupialia: Thylacoleonidae) from the Riversleigh World Heritage Area, northwestern Queensland: revising species boundaries and distributions in Oligo/Miocene marsupial lions

Gillespie, A.K., Archer, M., Hand, S.J. & Black, K.H., 2014. New material referable to Wakaleo (Marsupialia: Thylacoleonidae) from the Riversleigh World Heritage Area, northwestern Queensland: revising species boundaries and distributions in Oligo/Miocene marsupial lions. Alcheringa 38, 513–527. ISSN 0311–5518.New material of Wakaleo oldfieldi and W. vanderleueri from the Miocene freshwater limestones of the Riversleigh World Heritage Area, northwestern Queensland, is described. This material includes the first known upper dentition of W. oldfieldi and dentaries of both species bearing the previously undescribed and morphologically distinct M3. Previously, the two species were distinguished only by size differences in P3 and the size of P3 relative to M1. Wakaleo oldfieldi exhibits a more plesiomorphic M3 that retains a well-developed talonid basin in contrast to W. vanderleueri, which has lost this structure. The phyletic succession and geological occurrences of Wakaleo species make this genus an important taxon in biochronological analyses of Australian Cenozoic assemblages. At Riversleigh, W. oldfieldi is found in deposits allocated to Faunal Zone B and Faunal Zone C, which are regarded as early and middle Miocene in age, respectively. The presence of this species in the Kutjamarpu Local Fauna of central Australia suggests that fauna may be of a similar age. Broader faunal correlations have suggested Faunal Zone C correlates with the middle Miocene Bullock Creek Local Fauna, which contains the more derived W. vanderleueri. Based on stage-of-evolution arguments, W. oldfieldi should occur in older deposits than those yielding W. vanderleueri. The presence of both species of Wakaleo in Faunal Zone C assemblages at Riversleigh suggests that current presumptions about the contemporaneity of the many Faunal Zone C Sites should be examined more rigorously.Anna K. Gillespie [a.gillespie@unsw.edu.au], Michael Archer [m.archer@unsw.edu.au], Suzanne J. Hand [s.hand@unsw.edu.au] and Karen H. Black [k.black@unsw.edu.au] School of Biological Earth and Environmental Science, UNSW 2052, Sydney, Australia. Received 3.1.2014, revised 21.2.2014, accepted 21.3.2014.

A probable shark dorsal fin spine fragment from the Early Triassic of the Arrow Rocks sequence, Whangaroa, northern New Zealand

The ornament on a small external cast in pink chert shows considerable similarity with that of various Middle Palaeozoic and Triassic fish genera. It comes from the Permian–Triassic Oruatemanu Formation of Arrow Rocks, Whangaroa area, eastern Northland. Conodont faunas from a few metres above and below the sample allow correlation with the Neospathodus pakistanensis zone of the Early Triassic, which is assigned to the late Dienerian (late Induan), with adjacent conodont zone faunas in their correct stratigraphic association. The cast is assumed to be that of a small fragment of fin spine, most likely from the junction area of the crown and root on the right-hand side of a dorsal fin spine, possibly anterior, of a marine ctenacanthoid shark, a basal shark order not previously recorded from New Zealand.

Three new Miocene species of musky rat-kangaroos (Hypsiprymnodontidae, Macropodoidea): description, phylogenetics and paleoecology

ABSTRACT Three new species of the macropodoid genus Hypsiprymnodon are described from early to middle Miocene fossil deposits in the Riversleigh World Heritage Area, northwestern Queensland. A phylogenetic analysis of macropodoid relationships that includes these new taxa is presented. Monophyly of Macropodinae + Sthenurinae is recovered, as is a clade comprising macropodines, sthenurines, bulungamyines, and potoroids to the exclusion of hypsiprymnodontids and balbarids. Monophyly of Balbaridae is also supported, but hypsiprymnodontids are unresolved at the base of Macropodoidea, rather than forming a clade; this is probably because the new Hypsiprymnodon species described here are currently known from relatively incomplete material (isolated maxillae and dentaries). On the assumption that these extinct forms were ecologically similar to the living species H. moschatus (as suggested by close similarities in dental morphology), their presence in Riversleigh Faunal Zones B and C corroborates previous interpretations of a wet rainforest environment in northwestern Queensland during the early to middle Miocene of Australia. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

A spatial analysis of larval fish assemblages in the Celtic Sea off Great Britain (47° to 51°N): implications of bathymetry and ocean warming

Fish larvae from the Celtic Sea were analysed to identify their distribution patterns, diversity and assemblage structure with regard to bathymetry and ocean warming. Samples were collected in April 2007 comprising larval stages of 60 fish species (3834 individuals) from 106 stations. Stations were divided into three major faunal zones, i.e. neritic, transition and oceanic. This zonation was confirmed by canonical discriminant analysis and cluster analysis. While all zones were dominated by Atlantic mackerel (Scomber scombrus), horse mackerel (Trachurus trachurus) and dragonets (Callionymus spp.), the oceanic zone was additionally characterized by typical mid-water taxa such as Myctophidae, Stomiidae and Bathylagidae. The neritic zone was characterized by Gadidae, Soleidae and Argentinidae. The transition zone showed the highest diversity with typical species from both the neritic and oceanic zone. It also exhibited the highest abundances of fish larvae. Bathymetry explains most (75%) of the three faunal assignments. S. scombrus and T. trachurus spawned earlier and shifted further north for spawning compared to recent years. It is inferred that the relatively high sea-surface temperatures in April 2007 and the overall warming in the Celtic Sea triggered the northward shift of spawning grounds and the earlier spawning of these species compared to previous years.

Comparative study on the fauna composition of intertidal invertebrates between natural and artificial substrata in the northeastern coast of Jeju Island

This study was carried out to learn about differences in the sessile macrobenthic fauna communities between the artificial and natural habitats. There were some differences in terms of species composition and dominant species and community structure between two habitat types. The dominant species include Pollicipes mitella and Granuilittorina exigua in natural rocky intertidal zones; Monodonta labio confusa, Ligia exotica, Tetraclita japonica in the artificial rocky intertidal zones. Among all the species, L. exotica and T. japonica occurred only in the artificial rocky intertidal zone. The results of cluster analysis and nMDS analysis showed a distinct difference in community structure between artificial and natural rocky intertidal zones. The fauna in the natural rocky intertidal zones were similar to each other and the fauna in the artificial rocky intertidal zones were divided depending on the slope of the substratum. In the case of a sloping tetrapod, M. labio confusa and P. mitella were dominant, but at the vertical artificial seawall, Cellana nigrolineata, L. exotica T. japonica were dominant. The analysis of the species presented in natural and artificial rocky intertidal areas showed the exclusive presence of 10 species on natural rocks and 12 species on artificial rocks. The species in the natural rocky intertidal area included mobile gastropods and cnidarians (i.e. rock anemones), and the species in the artificial rocky intertidal area mostly included non-mobile attached animals. The artificial novel structure seems to contribute to increasing the heterogeneity of habitats for marine invertebrate species and an increase the species diversity in rocky coastal areas.

The Distribution of Vertically Migrating Fishes Across the Central Equatorial Pacific

AbstractMidwater trawl samples of vertically migrating fishes indicated four latitudinal faunal zones in the central equatorial Pacific between Hawaii and Tahiti. Boundaries of the northernmost and southernmost zones coincided with the boundaries between the equatorial and central water masses. The equatorial water mass was divided into two zones with distinctly different faunas. Of the 112 species considered, 20 occurred in all zones, and most of the remainder fell into one of six groups based upon pattern of occurrence or absence in each of the faunal zones. Correlation of faunal boundaries with oceanographic features in the study area and consideration of distributional data on the species in other areas indicate that differences in thermal structure, and consequent differences in productivity, between the major water masses could account for some barriers to distribution, but that differences in the intensity and vertical extent of the oxygen minimum layer constitute barriers both within and between w...

Spotted stream frog diversification at the Australasian faunal zone interface, mainland versus island comparisons, and a test of the Philippine ‘dual‐umbilicus’ hypothesis

AbstractAimTo utilize comprehensive geographical sampling and a new, multilocus dataset to re‐examine the biogeography of spotted stream frogs (Hylarana signata complex) throughout Southeast Asia. To compare patterns of diversification among stream frog populations on land‐bridge islands and oceanic islands and to re‐evaluate a previous ‘dual‐invasion’ hypothesis for the origins of endemic Philippine taxa.LocationSoutheast Asia, Sundaland, and the Philippines.MethodsWe sequenced two mitochondrial and two nuclear gene regions for members of the Hylarana signata complex. We used summary statistics and phylogenetic networks to characterize genetic variation; phylogenetic relationships and ancestral ranges were estimated using Bayesian and likelihood methods. We used the preferred topology and Bayesian methods to evaluate a previous biogeographical ‘dual‐invasion’ hypothesis.ResultsIn contrast to expectations, we found highly divergent, demographically stable and geographically regionalized lineages on the mainland and on land‐bridge islands, but minimally divergent, widespread and clinally distributed populations, with evidence of recent demographic expansion, in adjacent oceanic island populations. Novel phylogenetic relationships depart from previous studies and our data strongly reject the previously published ‘dual‐invasion’ hypothesis.Main conclusionsOur results join new literature demonstrating that species on mainland and continental shelf islands may harbour high levels of unrecognized diversity, whereas adjacent oceanic island archipelagos can and do support naturally occurring widespread species. Although our data indicate that the individual identities of species previously hypothesized to be involved in the ‘dual‐invasion’ scenario may have been incorrect, this mechanism for faunal exchange between the archipelago and adjacent mainland undoubtedly has contributed substantially to the accumulation of endemic vertebrate diversity in the Philippines.

Uncovering cryptic evolutionary diversity in extant and extinct populations of the southern Australian arid zone Western and Thick-billed Grasswrens (Passeriformes: Maluridae: Amytornis)

The Western and Thick-billed Grasswrens (Aves: Passeriformes: Maluridae: Amytornis textilis and Amytornis modestus, respectively) exemplify issues surrounding the evolution, biogeography and conservation of Australia’s arid and semi-arid zone fauna. The two species together have historically occurred across much of southern Australia. They showed high intraspecific taxonomic diversity and short range endemism but suffered high rates of recent anthropogenic extinction. Of 11 named and 1 un-named subspecies, 5 are extinct and 3 are vulnerable or critically endangered. To clarify taxonomic issues, and to understand their pre-extinction phylogeography and identify extant populations and taxa of conservation value, we sequenced ~1,000 bp of the mtDNA ND2 gene from all extant populations and all but one extinct population. We confirmed reciprocal monophyly of A. modestus and A. textilis and identified strong phylogeographic structure associated with morphological divergence within each species. Populations of A. t. myall at the western edge of their range in South Australia may preserve “ghost” lineages of extinct subspecies from Western Australia as a result of ancient gene flow. Our results support recent taxonomic revisions, and highlight the critical importance of including samples of extirpated populations and extinct species to fully understand and interpret extant diversity. Conservation and management plans should recognise and seek to preserve the unique evolutionary diversity present in surviving populations.

Biogeographical implications of a new mouse-sized fossil bandicoot (Marsupialia: Peramelemorphia) occupying a dasyurid-like ecological niche across Australia

We describe Bulungu palara gen. et sp. nov., a new fossil peramelemorphian (bandicoot), based on a single well-preserved skull and additional dental specimens from Late Oligocene to Middle Miocene (Faunal Zones A–C) limestone deposits at the Riversleigh World Heritage Property, Queensland, and two dental specimens from the Early–Middle Miocene Kutjamarpu Local Fauna, South Australia. This is the first fossil peramelemorphian species to be reported from more than a single fossil fauna, with its inferred distribution extending from north-western Queensland (modern latitude ∼19°S) to north-eastern South Australia (modern latitude ∼28°S). The presence of Bulungu palara in Riversleigh Faunal Zones A, B and C and in the Kutjamarpu Local Fauna supports the current interpretation that these faunas span similar ages, namely Late Oligocene–Middle Miocene. Phylogenetic analyses of an expanded 74 morphological character dataset using maximum parsimony and Bayesian approaches, both with and without a molecular scaffold, consistently place Bulungu and the Oligo-Miocene forms Galadi and Yarala outside crown-group Peramelemorphia. These analyses also fail to support a close relationship between the Pliocene Ischnodon australis (previously considered the oldest known representative of the extant peramelemorphian family Thylacomyidae) and the modern thylacomyid genus Macrotis. With an estimated body mass of ∼130 g, Bulungu palara is smaller than any known Recent bandicoot from Australia, although some modern New Guinean species are similar in size. The small size and craniodental morphology of B. palara suggest that it was predominantly or exclusively insectivorous, perhaps ecologically similar to small New Guinean dasyurids such as Murexechinus melanurus. Together with the small-bodied (< 100 g), insectivorous Yarala burchfieldi and large-bodied (∼900 g), faunivorous Galadi speciosus, Bulungu palara demonstrates that Oligo-Miocene Australian peramelemorphians filled ecological niches that today are mostly occupied by dasyurids, and that a major faunal turnover event occurred at some point after the Middle Miocene.http://zoobank.org/urn:lsid:zoobank.org:pub:18955DCC-DB8C-4216-AF38-921E1E5C1F79

Spatial structure on ocean-exposed sandy beaches: faunal zonation metrics and their variability

Spatial ecological structure is expected to be amplified at interface regions, such as sandy beaches, which form the globe's largest ecotone between the oceans and the land. Yet, the dynamic and unstable nature of sandy shore habitats, coupled with the great mobility and behav- ioural plasticity of beach species, theoretically counteract the development and maintenance of stable spatial structure, such as faunal zonation across the intertidal. We examined spatial struc- ture across the non-vegetated beach-face, using a large data set (3120 replicate samples distrib- uted across 260 cross-shore transects) of intertidal macrobenthos distribution from eastern Aus- tralia. Most (94%) distribution data of the benthic assemblage contained distinct spatial structure, evident as faunal zonation across the shore from the swash to the dunes. A general model recog- nised a tripartite biological division of the shore, but variability in the number of zones was pro- nounced. This variability implies that designs employing low temporal replication may fail to accurately describe the spatial structure on many ocean-exposed sandy beaches. Overall, our data support the prediction of distinct spatial structure based on the prominent interface traits of beach systems as well as the prediction of heterogeneity in spatial structure based on the mobility of beach species and instability of their habitat.

Getting the bigger picture: Using precision Remotely Operated Vehicle (ROV) videography to acquire high-definition mosaic images of newly discovered hydrothermal vents in the Southern Ocean

Direct visual observations from submersible vehicles at hydrothermal vents typically only reveal a fraction of the vent environment at any one time. We describe the use of precision Remotely Operated Vehicle (ROV) videography to produce extensive mosaic images of hydrothermal vent chimneys and surrounding seafloor areas (c. 250m2), with sufficient resolution to determine distributions of macro- and megafauna. Doppler velocity log navigation (DVLNAV) was used to follow overlapping vertical survey lines in a fixed plane facing a vent chimney, while acquiring high-definition video imagery using a forward-looking camera. The DVLNAV also enabled the vehicle to follow overlapping horizontal survey lines while acquiring seafloor imagery from a downward-looking video camera and mapping variations in seawater temperature. Digital stills images extracted from video were used to compile high-resolution composite views of the surveyed areas. Applying these image acquisition techniques at vent fields on the East Scotia Ridge, Southern Ocean, revealed consistent patterns of faunal zonation around vent sources, variations in proportions of faunal assemblage types on different faces of a vent chimney, and differences in proportions of faunal assemblages between two different vent fields. The technique can therefore be used to determine the composition and spatial distribution of fauna across complex areas of topography, such as vent fields, where mosaic images of vertical structures cannot currently be acquired using other platforms such as autonomous underwater vehicles (AUVs). These image acquisition techniques, demonstrated here in the first ROV dives at newly discovered vent fields, may offer an appropriate technology for rapid baseline studies required by the potential mining of seafloor massive sulfides (SMS).

The genus Galadi: three new bandicoots (Marsupialia, Peramelemorphia) from Riversleigh’s Miocene deposits, northwestern Queensland, Australia

ABSTRACT We describe three new bandicoot species of the genus Galadi from the Miocene of Riversleigh World Heritage Area in northern Australia. The first species, which is represented by a complete dentary and several isolated upper molars, is restricted to Riversleigh's Faunal Zone B. It is the largest bandicoot as yet known from Riversleigh. The second species is represented by 19 specimens, including a partial skull and several maxillae and dentaries, from Riversleigh's Faunal Zone C. Several features distinguishing this species from the similarly sized type species G. speciosus are of interest, notably the presence of larger maxillopalatine fenestrae and additional maxillary fenestrae, incomplete centrocrista on all upper molars, a more complete posterior cingulum on upper molars, and higher degree of dental wear, which together suggest a more omnivorous diet. The third species is represented by a single maxillary, which exhibits a quite different combination of dental features compared with other Galadi species. All Galadi species appear to be restricted to Riversleigh's Faunal Zones B and C, which are interpreted to be early and middle Miocene in age, respectively, with rainforest habitats persisting throughout. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP

High potential subsidy of dry-season aquatic fauna to consumers in riparian zones of wet–dry tropical rivers

Aquatic fauna provide an important subsidy to terrestrial consumers. In the wet–dry tropics, important subsidies from rivers to riparian-zone consumers are expected in the dry season but may vary depending on riparian zone condition. We investigated the potential subsidy of aquatic fauna to consumers in riparian zones in 2 highly seasonal rivers in Australia’s wet–dry tropics. Stable carbon and nitrogen isotopes of invertebrate predators in riparian zones were closely aligned with aquatic invertebrates and emergent adult insects. Further, a considerable proportion (40–50%) of the observed vertebrate fauna in riparian zones were consumers of aquatic fauna, which included fish, crustaceans, inverte-brates, and flying adult insects with aquatic larval stages. For hydrologically disconnected waterbodies, estimates of potential insect emergence and the proportion of vertebrate species (in riparian zones) that consume these insects both increased as indicators of riparian plant regeneration and condition improved. Our findings suggest that aquatic fauna provide important subsidies to terrestrial-zone consumers (both invertebrates and vertebrates) during the dry season, and that these transfers can be moderated by riparian zone condition. The wide home and foraging ranges of some consumers also suggest that the importance of these subsidies may extend far beyond the waterbody of origin. Human activities and climate-driven alteration of flow regimes and riparian zones that reduce the availability of dry-season waterbodies or degrade their riparian zones are likely to have negative impacts on aquatic–terrestrial linkages in these systems.

On the estimated age of recent fauna in different latitudinal zones (by the example of brachiopods)

Maximum period of existence of endemic genera in the temperately warm-water (subtropical) and temperately cold-water (low boreal and subantarctic) faunal belts is revealed on the base of latest data on the composition of brachiopod fauna of recent seas and oceans and most full data on the paleontological finds of recent brachiopod genera. Most of the subtropical endemics inhabit southern hemisphere; one of them is Bouchardia, which is known beginning with the Late Cretaceous (Maastrichtian), that brings together southern subtropical faunal belt with the tropical zone and suggests that subtropical waters could serve as a refuge for representatives of ancient warm-water faunas during large geological and hydrological reconstructions at the Mesozoic-Cenozoic boundary. Most of the younger endemics of low boreal and subantarctic faunal belts appeared at the Paleogene-Neogene boundary, during the period of formation of modern contrast climate on the Earth that was caused by the formation of Antarctic Circumpolar Current. The appearance of recent species and genera in the Holocene was influenced by last considerable postglacial reconstruction of climate.

Microdistribution of Faunal Assemblages at Deep-Sea Hydrothermal Vents in the Southern Ocean

Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal vents, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered vent fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of vent biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal activity in a vent field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal activity, and a mosaic image of >250 m2 of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from vent sources and peak temperatures. Assemblages closest to vent sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m−2), followed by a peltospiroid gastropod (>1,500 individuals m−2), eolepadid barnacle (>1,500 individuals m−2), and carnivorous actinostolid anemone (>30 individuals m−2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of activity suggests a possible successional sequence for vent fauna in this new biogeographic province. An increase in δ34S values of primary consumers with distance from vent sources, and variation in their δ13C values also indicate possible zonation of nutritional modes of the vent fauna. By using ROV videography to obtain a high-resolution representation of a vent environment over a greater extent than previous studies, these results provide a baseline for determining temporal change and investigations of processes structuring faunal assemblages at Southern Ocean vents.

Locomotory activity and feeding strategy of the hadal munnopsid isopod Rectisura cf. herculea (Crustacea: Asellota) in the Japan Trench

Benthic fauna in the hadal zone (6500-11,000 m) rely on maintaining sufficient locomotory activity to exploit a low, patchy and uniquely distributed food supply while exposed to high pressure, low temperatures and responding to predator-prey interactions. Very little is currently known about the locomotory capabilities of hadal fauna. In situ video footage of the isopod Rectisura cf. herculea (Birstein 1957) (Asellota, Munnopsidae) was obtained from 6945 and 7703 m deep in the Japan Trench (NW Pacific Ocean). Measurements of locomotion revealed routine walking speeds of 0.19 ± 0.04 BL s(-1) (mean ± s.d.), increasing to 0.33 ± 0.04 BL s(-1) if naturally perturbed by larger organisms. When immediately threatened by the presence of predators (decapod crustaceans), the isopods are capable of eliciting backward escape jumps and burst swimming escape responses of 2.6 ± 1.5 BL s(-1) and 4.63 ± 0.9 BL s(-1), respectively. These data suggest no significant reduction in locomotory capability despite the extreme depths in which they inhabit. These observations also revealed the isopod to be a bait-attending and aggregative species and suggest that it may not be obligatorily selecting infaunal food sources as previously thought.

Taxonomic Revision of Therocephalians (Therapsida: Theriodontia) from the Lower Triassic of Antarctica

We reevaluate the taxonomic status of therocephalian fossils recovered from the lower Fremouw Formation (Lower Triassic) of the central Transantarctic Mountains, Antarctica. The material, which includes mostly fragmentary juvenile specimens, is reidentified using an apomorphy-based approach. We recognize the presence of three higher-level taxa: Eutherocephalia, Akidnognathidae, and Baurioidea. The only genus-level identification is for a partial lower jaw and pterygoid tentatively attributed to the baurioid, Ericiolacerta parva. An indeterminate theriodont partial skull is reassigned to the therocephalian family Akidnognathidae. The holotypes of Pedaeosaurus parvus and Rhigosaurus glacialis are represented by indeterminate juvenile baurioids and, in the absence of clear autapomorphies, are considered nomina dubia. The results of the taxonomic revision indicate that the therocephalian fauna of Antarctica lacks endemic genera and thus corresponds to that of the Triassic Lystrosaurus Assemblage Zone fauna of South Africa's Karoo Basin. More generally, we consider the southern Gondwanan basins of South Africa and Antarctica to sample a broadly distributed Lower Triassic tetrapod fauna, although the latter basin documents the first occurrence of several taxa (e.g., Kombuisia, Palacrodon). More precise (i.e., species-level) identifications are needed to better constrain the biogeographic signal for therocephalians, but the presence of juveniles strongly suggests that this group of therapsids, like dicynodonts, were year-round high-latitude inhabitants during Early Triassic times.

Spatial-typological organization of animal assemblages (results and conclusions)

The results of studies in factor zoogeography performed by the Laboratory of Zoological Monitoring (Institute of Systematics and Ecology of Animals SB RAS) over 50 years are briefly reported. The review deals with the distribution and abundance of terrestrial animals, changes in the shape of their assemblages in the West Siberian Plain, Altai, and adjacent areas, and faunal zonation of Northern Eurasia.

Revision in the marsupial diprotodontid genus Neohelos: systematics and biostratigraphy

Neohelos is a geographically and temporally widespread genus of Cenozoic diprotodontid marsupials commonly used to biocorrelate otherwise undated Australian fossil deposits. Here, we revise the genus and describe two new species from the Riversleigh World Heritage Area of northwestern Queensland. Neohelos solus sp. nov. is a small, relatively abundant, plesiomorphic form, while the rarer, larger Neohelos davidridei sp. nov. is the most derived species of the genus with an upper premolar morphology that is structurally antecedant to members of the Late Miocene genus Kolopsis. Additional material of Neohelos tirarensis and Neohelos stirtoni is described. A chronological morphocline is evidenced by a gradual change in morphology accompanied by an increase in size from Ne. tirarensis through Ne. stirtoni to Ne. davidridei, and is generally consistent with the biostratigraphic distribution of Neohelos species throughout Riversleigh's faunal zones A to D. Stage of evolution biocorrelation of Neohelos species co...