Opportunistic exploitation of dinosaur dung: fossil snails in coprolites from the Upper Cretaceous Two Medicine Formation of Montana

Multiple associations of fossil snails with dinosaur coprolites demonstrate that snails and dinosaurs not only shared ancient habitats but were trophically linked via dinosaur dung. Over 130 fossil snails representing at least seven different taxa have been found on or within herbivorous dinosaur coprolites from the Upper Cretaceous Two Medicine Formation of Montana. The terrestrial snail Megomphix is the most common taxon, but three other terrestrial taxa (Prograngerella, Hendersonia and Polygyrella) and three aquatic snails (Lioplacodes, ?Viviparus and a physid) also occur in coprolites. At least 46% of the shells in the faeces are whole or nearly so, indicating that most (if not all) of the snails were not ingested by dinosaurs, but were post‐depositional visitors to the dung pats. The sizeable, moist and microbially enriched dinosaur faeces would have provided both food and roosting sites for the ancient snails, and the large number of snail–coprolite associations reflect recurring, opportunistic exploitation of dung. The terrestrial taxa in the coprolites suggest that this Late Cretaceous locality included sufficiently moist detrital or vegetative cover for snails when dinosaur dung was not present. The aquatic snails probably entered the faeces during flood events. Dinosaur dung would have provided an abundant but patchy influx of resources that was probably seasonally available in the ancient environment.     

NEW AUSTRALIAN OLIGOCENE TO MIOCENE RINGTAIL POSSUMS (PSEUDOCHEIRIDAE) AND REVISION OF THE GENUS MARLU

Abstract:  Four genera of extinct ringtail possums have been reported from Australian Oligocene to Miocene sediments since 1987. The genus Marlu was described from two species, M. kutjamarpensis and M. praecursor (Woodburne, Tedford and Archer), from the Miocene Kutjamarpu Local Fauna (Leaf Locality) and late Oligocene Wadikali Local Fauna respectively, of northern South Australia. New fossil material referable to this genus has been collected from the Leaf Locality and the Oligocene to Miocene Riversleigh World Heritage Area in northwest Queensland. Three new species, Marlu karya sp. nov. from middle Miocene Riversleigh local faunas and Marlu syke sp. nov. and Marlu ampelos sp. nov. from the Leaf Locality as well as early to middle Miocene Riversleigh local faunas are described. A revision and rediagnosis of the genus and published species are made following the re-examination of referred material in conjunction with the new material. Marlu is characterized by simple dentition and synapomorphies with extant pseudocheirids such as a conjoined postmetacristid and preentocristid on m1 and the loss of the entostylid ridge. New material from middle Miocene Riversleigh deposits has been referred to M. kutjamarpensis , extending the known distribution and age of that species. Re-examination of M. praecursor has revealed the presence of a small m1 entostylid ridge, contributing further to differences between M. praecursor and all other Marlu species and raising the possibility that Marlu is paraphyletic. The new material does not contradict a sister group relationship between ' Marlu ' (excluding M. praecursor ) and the Pliocene–Pleistocene genus Pseudokoala. Homology of the pseudocheirid m1 protostylid identified in species of Paljara , Pildra and Marlu with that observed in extant species is reconsidered. The 'protostylid' of the extinct genera is herein described as the buccal stylid.     

Phenological shifts of three interacting zooplankton groups in relation to climate change

Over the past several decades, global warming has been linked to shifts in the distributions and abundances of species. In the southern North Sea, temperatures have increased in the last three decades and this will likely have consequences on the seasonality of marine organisms living in the area. Ctenophores such as Beroe gracilis and Pleurobrachia pileus could be particularly affected by changes in their own phenology and that of their prey, thus causing shifts in ecosystem function. Despite their global relevance and their potentially deleterious effect on the fishing industry, only a few long‐term records of ctenophore abundance exist, and most of these records are semiquantitative in nature. Therefore, our knowledge of the influence of environmental factors on their population development is presently very limited. In this study, the long‐term abundance dynamics of B. gracilis, P. pileus and their food calanoid copepods were analysed for a highly temporally resolved time series in the German Bight at Helgoland Roads. Special attention was focused on the response of these organisms to climate warming. Bayesian statistics showed that the phenology of the two ctenophores shifted in a step‐like mode in the year 1987/1988 to permanent earlier appearances. The seasonal change in the population blooms of P. pileus and B. gracilis correlated remarkably well with a step‐like increase in winter and spring sea surface temperatures of the southern North Sea. Possible explanations for the changes observed in these organisms include higher reproductive rates, increased winter survival rates or both. Interannual variations in ctenophore abundances correlated best with the interannual changes in spring temperatures, although the impact of temperature on B. gracilis appeared less pronounced. The changes in copepods abundance were not consistent with changes in P. pileus and B. gracilis. P. pileus showed longer periods of high abundance after the permanent seasonal advancement. These longer periods were correlated with a decline in the average autumn abundance of copepods. Changes in the phenology of these organisms raise the concerns on the declining state of fish stocks, which could potentially be exacerbated by gelatinous zooplankton outbreaks. These conditions may ultimately lead to trophic dead ends by channelling the flow of energy away from higher trophic levels.     

Isolation and characterization of polymorphic microsatellite loci from Wilsonia backhousei (Convolvulaceae)

Wilsonia backhousei is a clonal saltmarsh plant restricted to the southern latitudes of Australasia and threatened in New South Wales. We have identified eight informative microsatellite loci in the species from (AG)_n‐ and (AC)_n‐enriched libraries. In 48 samples from two populations we detected an average of five alleles per locus (range 2–8, average H_E = 0.45), of which 72% were unique to one population or the other. Six of the eight loci were also amplifiable in Wilsonia rotundifolia under the same reaction conditions. The markers will be excellent tools for use in the management and conservation of both species.     

Cost of shield defence for tortoise beetles (Coleoptera: Chrysomelidae)

Abstract.

• 1 Tortoise beetle larvae possess a shield composed of exuviae and faeces which functions as an effective defence against some invertebrate predators.
• 2 In the laboratory, Charidotella bicolor, Deloyala guttata and Chelymorpha cassidea larvae with their shields experimentally removed did not exhibit enhanced performance (i.e. decreased development time, increased body mass, or higher survival) compared to control larvae with shields intact.
• 3 Disturbance caused during shield removal did not adversely affect larvae because performance did not differ among controls (undisturbed larvae with intact shields), disturbance controls (shield removal simulated, but shield left in place), and larvae with shields removed.
• 4 Larvae without shields did not exhibit compensatory feeding to reconstruct the shield following its removal.
• 5 In a field experiment in which predators were excluded, larvae with shields removed did not develop faster than controls; in fact, survival was slightly reduced (10%) for larvae without shields and may have resulted from desiccation.
• 6 For slow-moving tortoise beetle larvae, the cost of bearing the shield is minimal. Thus, larval shields, composed of recycled waste products, provide an inexpensive mode of protection from some natural enemies.

     

Non-propagative translocation of velvet tobacco mottle virus in the mirid, Cyrtopeltis nicotianae

Nymphs of the mirid, Cyrtopeltis nicotianae became infective when injected with velvet tobacco mottle virus (VTMoV). Injections of amounts between 1 and 154 ng into the haemocoele induced 2/60 to infect test plants and these two nymphs contained 50 and 63 ng of virus respectively. Injection of amounts between 15 and 2400 ng rendered 11/47 nymphs infective. This observation is characteristic of a circulative association. However, there is no evidence that the salivary glands are involved in transmission and the virus is therefore defined as translocating, rather than circulating, in the mirid vector. Mirids which acquired infectivity by feeding lost it between 5 and 9 days after completion of acquisition, and the most rapid loss of infectivity occurred within 2 days. Nine days after acquisition none contained antigen detectable by ELISA, but detectable antigen decreased less rapidly than infectivity, and at all times more mirids contained antigen than were able to transmit. Mirids containing antigen carried between 150 and 3340 ng each. Thus, although VTMoV can be transmitted by its mirid vector following introduction of virus into the body cavity by injection, VTMoV is not propagative. Nor does the presence of virus within the mirid guarantee an ability to transmit.     

APPLICATION OF A DOUBLE TUBE SYSTEM FOR ENUMERATION OF CLOSTRIDIUM TYROBUTYRICUM

Clostridium tyrobutyricum, a spore-forming, gram-positive, anaerobic bacterium, is considered to be the main organisms responsible for the late spoilage of cheese by gas formation. Most methods for detecting C. tyrobutyricum are based on spore germination and vegetative growth and take 4–7 days plus an identification step for confirmation. The purpose of this study was to develop a faster detection method using a Double Tube System. Because no selective medium is available for detection of C. tyrobutyricum, three media (Reinforced Clostridial, AC, and Tomato Juice) were compared using two strains of C. tyrobutyricum and one strain of C. sporogenes. Each 4 day-old test strain was inoculated on duplicated plates of each agar that were then placed in anaerobic jars or in the double-tube systems for 2–4 days at 30 or 37C. All three agars consistently supported growth of the test strains. Counts did not differ with incubation at 30 or 37C and were comparable using the conventional anaerobic jar or a Double Tube System. However, in the Double Tube System, colonies could be counted accurately at least 6 h earlier than on the plates in anaerobic jars.     

Species of street tree is important for southern hemisphere bird trophic guilds

Abstract Urban environments are highly modified with unique assemblages of bird species. Much of the research on urban bird assemblages comes from the northern hemisphere. Southern hemisphere bird assemblages differ from northern hemisphere assemblages in that they contain a large proportion of nectarivores. In this study we focus on bird use of street trees in Australia. We investigate the relative influence of tree species (plane tree, Platanus x acerifolia; red gums, Eucalyptus camaldulensis; jacaranda, Jacaranda mimosifolia; bottlebrush, Callistemon citrinus), season and the environment surrounding street trees, on the abundance and species richness of birds in Adelaide, South Australia. Our study considers birds in terms of granivore, nectarivore and insectivore trophic guilds. Nectarivores accounted for the greatest proportion of observations, in terms of abundance, in each of the tree species investigated. Species of street tree was a significant influence on bird use of the trees for all birds and each dietary guild. Red gums were used more than the other tree species by nectarivores, while plane trees were used more than the other trees by insectivores. Use of the tree species by granivores varied with the season. The measures of the environment surrounding street trees were largely unimportant with the exception of traffic for nectarivores in some cases. Urban avifauna use street trees and the species of tree will strongly influence its use by birds. However, the pattern of use of street tree species varied at different times of year and differed between different trophic guilds of birds. The dominance of nectarivores in the southern avifauna will likely produce different patterns of urban environment use to northern hemisphere avifaunas.