The potential of bird remains for environmental reconstruction

Until relatively recently, studies of bird remains have been regarded as peripheral to mainstream research on early archaeological and palaeontological sites, rather than a potentially crucial factor in the reconstruction of the past environments in which hominids and other larger mammals were present This paper sets out to define the range of ecological information for a site which can be gained through study of the bird bones, using as an example the bones recovered in the excavations at Gorham's Cave, Gibraltar. © 1997 John Wiley & Sons, Ltd.     

Trace fossils on penguin bones from the Miocene of Chubut,southern Argentina

Several traces of biological interaction were found on penguin bones from the basal levels (Aquitanian) of the Miocene Gaiman Formation in the lower Chubut valley of the Provincia del Chubut, Argentina. The fossil-bearing beds were deposited in littoral to sublittoral environments within sediments of mostly pyroclastic origin. We interpret many traces to have been produced by predators and/or scavengers while the penguins were still in a breeding area. Many bones show cracking marks due to aerial exposure. The material is disarticulated as is usual in recent breeding areas. Potential predators were coeval terrestrial mammals, most probably marsupial carnivores. After a marine transgression, these bones were buried or exposed on the sea bottom where they could be colonized by algae, sponges, cnidarians, and other benthic organisms. We identified sponge borings in several bones. Other traces are interpreted to have been produced by echinoderms feeding on sponges or algae. No evidence of other invertebrate predators such as muricid or naticid gastropods, or decapods was found. Finally, other traces appear to have been generated by shark and possibly teleostean vertebrates feeding on epibionts. One coracoid is interpreted to have been marked by a shark that is common in the Gaiman Formation, the carcharhiniform Galeocerdo aduncus. From an ethological (Seilacherian) classification, traces on bones from the Gaiman Formation include Domichnia (sponge perforations), Praedichnia (terrestrial marsupials, sharks, teleosteans) and Pasichnia (echinoderms). Remarkably, remains of marine organisms with skeletons made of calcium carbonate are very poorly preserved in the Gaiman Formation. Only large oysters, sparse shell fragments, skeletal moulds, and bioturbation is evident. The fossil assemblage is mainly composed of phosphatic (e.g. teeth, bones, crustacean parts) and siliceous (sponge spicules, diatoms) remains.     

Ecydsial efficiency and evolutionary efficacy among marine arthropods: implications for trilobite survivorship

A comparison of ecdysial patterns between trilobites and other macrobenthic marine arthropods (crabs, shrimp, lobsters, horseshoe crabs) reveals differences that may have evolutionary consequences. Limulus and many malacostracans apparently have a signature ecdysial style; conversely, a range of moult configurations characterized trilobite ecdysis, and this variation is evident even within individual species. A canalised ecdysial habit may be safer or metabolically more efficient and therefore, summed over the history of the class, evolutionarily advantageous. Some trilobite clades show evolutionary trends toward morphologies that would have facilitated ecdysis (e.g. reduction in the number of thoracic segments, reduction in the number and prominence of spines), but co-adaptation or multiple-use effects complicate the evolutionary signal of ecdysial selection. Survivorship analysis supports a possible link between ecdysial habit and evolutionary success: genera with fewer thoracic segments (= easier ecydsis) are longer-lived. The increased predation pressure on trilobites through the Palaeozoic would have amplified the evolutionary impact of an inefficient moult habit. The cumulative effects of a less-than-optimal ecdysial habit, and a physiology that apparently required reconstituting a calcitic exoskeleton de novo with each moult, are compelling biotic factors to consider in examining functional interpretations, life histories, evolutionary trends, and ultimate disposition of the Trilobita.     

Neotaphonomic measures of carnivore serial predation at Ngamo Pan as an analog for interpreting open-air faunal assemblages

Here I present a neotaphonomic account of natural bone accumulations that have resulted from carnivore serial predation at Ngamo Pan, a vast complex of seasonal water holes located in Hwange National Park, Zimbabwe. Reconstructing the taphonomic histories of faunal assemblages from open-air archaeological sites is burdened with a host of interpretive complications, and this study is offered as a referential means for evaluating instances where stone tools and bone accumulations are associated in apparent archaeological contexts. While the presence of stone tools implies some involvement on the part of humans, open-air sites near water would also have served as prime locations for serial predation by large carnivores to ambush prey—a situation that, over time, can mimic archaeological bone accumulations. The taphonomic and zooarchaeological signatures of carnivore serial predation at Ngamo Pan show marked similarities with the open-air faunal accumulation from Kalkbank, a late Pleistocene site in Limpopo Province, South Africa, located along the margins of a relict pan. Many potential archaeological sites within the interior of southern Africa dating to the Middle Stone Age are known from open-air settings near permanent or ephemeral bodies of water, and the ability to decipher between hominin and non-hominin carnivore involvement with bone accumulations is paramount in determining the hunting and scavenging behaviors of our early ancestors. As much of our understanding of hominin subsistence during the Middle Stone Age is drawn from coastal cave locations, this study is intended to encourage a broadening of our perspective on the taphonomic histories of faunal accumulations dating to the Middle Stone Age by incorporating supplementary evidence provided by these open-air sites.     

Fossils,Hunters, and Controversies: Exploring Primate Evolution

The study of primate evolution opens a fascinating window onto the varied adaptations, behaviors, and origins of our closest relatives and therefore ourselves. Four books reviewed give different perspectives on the primate fossil record and cover diverse time periods, from the Eocene to the Pleistocene. Four major themes are explored in this article: defining “primatehood” and classifying primates, comparative approaches, reconstructing behavior and ecology, and the importance of non-fossil data. Together, the books show that the study of ancient and modern primates is rooted firmly in anthropology, sharing with other sub-disciplines fundamental aims like classification and relying on a comparative approach.     

Megafaunal extinction in the late Quaternary and the global overkill hypothesis

The global blitzkrieg hypothesis explains differential rates of megafaunal extinction between the world's landmasses in the late Quaternary based on a proposed leap in predation efficiency enjoyed by colonising societies. It is characterised by appealing simplicity. Selective over hunting, facilitated by naiveté to human predation, produced rapid mass extinctions of large animals wherever subsistence societies colonised new landmasses. Taken at face value the circumstantial case for blitzkrieg is compelling and despite a paucity of direct evidence it has gained considerable support. Our review of the model suggests that it overlooks much contradictory data and rests on simplistic interpretations of complex biogeographicat and anthropological phenomena. These interpretations and assumptions do not account for major differences between the biotas, ecologies and human cultures of the landmasses involved. The assertion that responses of remote island species to human predation provide realistic models for those of continental taxa is poorly founded, exaggerating the likely predation efficiency of humans colonising continents. An absence of terrestrial predators over evolutionarily significant periods, together with restricted ranges and small populations, renders island faunas uniquely vulnerable to invaders. The argument, that climate cannot explain these phenomena because previous Glacial Maxima did not cause comparable extinctions, presupposes that their local effects were at least as severe as those of the Last Glacial Maximum. This has yet to be demonstrated and at most it would indirectly support a role for anthropogenic influence, not overkill per se. Overlooked or underplayed are the influences of translocated and other invading species. Similarly, differences in the origins, technologies and traditions of colonising human societies are rarely considered. These factors strongly impact on the predation efficiency, density and range of human populations, critically affecting the outcomes of predator-prey modeling. When a fuller constellation of influences and constraints is considered it is reasonable to posit that rapid mass extinction through selective human predation may largely describe megafaunal extinctions on remote islands, but the argument is not convincing for continents. This is especially so regarding Australia. Because even the largest Australian species were prey to endemic carnivores, their responses to human predation would not have been comparable to those of oceanic island species. No kill-sites or specialized big-game hunting/butchering tools are known and, on the basis of ethnographic and archaeological data, it is probable that predation efficiency, population density and range of the first Australians were insufficient to effect rapid mass extinction. Chronologies of human arrival and the disappearance of megafauna remain poor, but the most recent estimates for human-megafaunal coexistence in Australia range from 10,000 to 43,000 years. Although human predation may have been a contributing factor in megafaunal extinctions, rapid overkill is unlikely to describe the actual mechanism in most instances. The role of human predation and its significance relative to competing factors, human and otherwise, varied considerably between landmasses, as did the speeds with which extinctions occurred. Blitzkrieg and other mono-factorial models are heuristically valuable devices, but a growing body of evidence suggests that extinction can rarely, if ever, be attributed to a single cause.     

Focused,intense and long-term: evidence for granular ark (Anadara granosa) exploitation from late Holocene shell mounds of Blue Mud Bay,northern Australia

Explanatory frameworks relating to the appearance of shell mounds and the exploitation of molluscs (particularly the sand/mudflat bivalve Anadara granosa) during the late Holocene have tended to emphasise stasis and continuity. Very few analyses have adequately investigated the intensity of human predation during the mound period and the potential effects on the particular prey species. To this end, the biological and ecological characteristics of A. granosa, the dominant molluscan species for much of the known period of occupation in the region, are considered in detail, in combination with assessing the potential for human impact through predation via the measurement of 9106 A. granosa valves from three shell mounds. In explaining long-term economic change in this region of northern Australia, the focus has been placed on the analysis of relative changes and trends through time in prehistoric resource exploitation.     

Taphonomic Analysis of Micromammal Remains from Striped Owl (Pseudoscops clamator) Pellets in Northeastern Buenos Aires Province,Argentina: Implications for Archaeological Sites Formation

The main objective of this study was to determine the taxonomic and taphonomic characteristics of the micromammal remains recovered from pellets of Pseudoscops clamator (striped owl), collected at three localities in northeastern Buenos Aires Province, Argentina (Punta Lara Natural Reserve, 34°49'02,6''S, 58°03'03,9''W; Costanera Sur Ecological Reserve, 34°36'6,44" S, 58°21'33,22" W; Los Robles Park, 34°40'22,03''S, 58°52'18,88''W). The main taphonomic variables (e.g. evidence of digestive action, breakage patterns and relative abundance of skeletal elements) suggest that this owl mainly produces intermediate to moderate modification. On the other hand, P. clamator preyed mainly upon large‐sized (>150 g) micromammals (e.g. Lutreolina crassicaudata, Cavia aperea, Holochilus brasiliensis and Rattus sp.), and to a lesser degree on medium‐ (50–150 g) and small‐sized species (<50 g) (e.g. Scapteromys aquaticus, Calomys sp., Oligoryzomys flavescens, Akodon azarae and Mus musculus). Fossil assemblages with a dominance of large‐sized micromammals are commonly associated with humans as agents of accumulation. However, this study demonstrates that this owl produces assemblages with abundant large‐sized micromammals, which introduces an equifinality problem. In that sense, digestive corrosion marks, breakage patterns and the relative abundance of skeletal remains are the main attributes to differentiate P. clamator from humans, as agents of accumulation. Finally, our results might serve as an analytical model for the taphonomic interpretation of the fossil record of micromammals from paleontological and archaeological sites, which fall within the distributional range and habitat of P. clamator. Copyright © 2013 John Wiley & Sons, Ltd.     

Muricid boreholes in Pleistocene acorn barnacles from the Beagle Channel: trophic interactions during the Last Interglacial in southern South America

Gordillo, S., 2013. Muricid boreholes in Pleistocene acorn barnacles from the Beagle Channel: trophic interactions during the Last Interglacial in southern South America. Alcheringa 37, 1–8. ISSN 0311-5518.

Acorn barnacles with boreholes were recovered from a Pleistocene marine deposit on Navarino Island, on the southern coast of the Beagle Channel. Balanomorph shells were identified as Balanus laevis (Bruguière, 1789 Bruguière, J.G., 1789. Encyclopédie méthodique. Histoire naturelle des vers 1, 158–173, pis. Paris, 164–166. [Google Scholar]), and a few bear small round holes located generally on the middle or apical part of the parietal plates, thus suggesting that they represent the work of small muricid predators. If so, this study is the first record of drilling predation on fossil barnacles reported in southern South America.

[Sandra Gordillo [sgordillo@cicterra-conicet.gov.ar], Centro de Investigaciones en Ciencias de la Tierra, Consejo Nacional de Investigaciones Científicas y Técnicas (CICTERRA, CONICET-UNC); Centro de Investigaciones Paleobiológicas (CIPAL), Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba. Av. Vélez Sársfield 1611 X5016GCA Córdoba, Argentina. Received 8.1.2013; revised 26.3.2013; accepted 2.4.2013