WM Keck Science Faculty Papers

A Geographic Information Systems Approach to the 19th Century Excavation of Brixham Cavern, Devon, England

Donald A. McFarlane et al. — Fri, 17 May 2013 11:23:08 PDT

The oldest known spatially-explicit archaeological excavation, conducted in Brixham cave, Devon, in 1858, is reconstructed using geographic information systems technology. Two dimensional plots of individual fossil taxa and flint artefacts demonstrate the utility of the technique for elucidating taphonomy and palaeobiology. The cave served as a den for hibernating brown bears, as a den for hyena and cave lion, and as a reliquary for their prey.

An Abbreviated Catalogue of the Australian Bats in the Collections of the Natural History Museum of Los Angeles County, California, USA.

Donald A. McFarlane et al. — Fri, 17 May 2013 11:23:04 PDT

The Natural History Museum of Los Angeles County (LACM) is the repository for some 90,000 mammal specimens of world-wide provenance, and is particularly strong in its collections of Chiroptera. As the result of numerous collecting expeditions undertaken by one of us (KES) since 1954, a substantial representation of Australian bats has been assembled. It is our intent in this paper to bring these collections to the attention of our Australian colleagues, so that this biogeographic and systematic resource might be more widely used.

Bones of Puffinus Lherminieri Lesson (Aves: Procellaridae) and Two Other Vertebrates from Cueva del Agua, Mona Isalnd, Puerto Rico (West Indies)

Angel M. Nieves-Rivera et al. — Fri, 17 May 2013 11:23:02 PDT

From a dive in Cueva del Agua, Mona Island, Puerto Rico, twelve un-mineralized bones of Puffinus Lherminieri Lesson, one of Cyclura stejnegeri Stejneger, and one of Moormops blainvilii Leach were collected. The subfossil evidence confirms that P. Lherminieri was a common species on Mona Island. Cyclura stejnegeri and M. blainvilii probably became trapped and died in the pool chamber.

Pengelly's Legacy Reconsidered: A GIS Approach to Spatial Analysis of Palaeontological and Archaeological Collections from Kents Cavern, England

Sorin Mihai et al. — Tue, 09 Apr 2013 13:26:27 PDT

Tens of thousands of palaeontological and archaeological remains were collected by William Pengelly during 19th century excavations of Kents Cavern, but are now widely dispersed between museums. This has previously precluded spatial analysis. We have now assembled available museum records into a single database, and, using our previously-reconstructed Pengelly excavation map as a base, we have been able to exploit the unique Pengelly location code to set up a GIS mapping system. This allows, for the first time, the analysis of spatial patterns. In addition, the GIS serves to highlight potential problems of recording or curation in the original data. Here we report on the construction of the GIS system and its first use in the analysis of spatial distribution of bear remains. The maps demonstrate that Ursus deningeri entered the cave through a now-sealed High Level Chamber entrance at the back of the cave in the middle Pleistocene, whereas Ursus arctos accessed the cave in the late Pleistocene through the now-sealed Northeast Gallery entrance. The denning areas are reconstructed as Labyrinth/Bear's Den for U. deningeri and Vestibule/Great Chamber for U. arctos. Considerable post-mortem re-distribution of the remains of both species is indicated.

A New Method of Calculating the Wing Area of Bats

B.R. Blood et al. — Tue, 09 Apr 2013 13:26:26 PDT

Wing area is a parameter important to any study of chiropteran flight behaviour (Struthsaker 1961 ; Findley et al. 1972 ; Lawlor 1973), because it is a necessary component for the calculation of aspect ratio and wing loading. Bats possessing high aspect ratio wings usually display swift and steady flight, often at high altitudes. Bats that possess low aspect ratio wings usually display slower, more manouverable flight and often fly at lower altitudes (Findley 1972 ; Findley et al. 1972 ; Mortensen 1977 ; Vaughan 1970). However, despite the importance of wing area, no-one has published a simple, yet accurate, method which can be used to calculate it.

Thrice Bitten: Late Quaternary Mammal Extinctions in the Continental and Insular New World

Clare Flemming et al. — Tue, 09 Apr 2013 13:26:25 PDT

West Indian Monkeys: New Fossils and Interpretations

Ross D. E. MacPhee et al. — Tue, 09 Apr 2013 13:26:23 PDT

The first new fossils of Xenothrix mcgregori discovered in 70 years--a femur and a humerus--were found by an AMNH expedition in caves at Jackson's Bay on the south coast of Jamaica in August, 1993. These finds closely resemble specimens from Long Mile Cave previously allocated to Xenothrix by MacPhee and Fieagle (Bull. Amer. Mus. Mar. Hisr. 206: 287-321 [1991]), and help to support the argument that this primate was a slow quadruped. The new material comes from the driest part of the island, which currently supports xerophytic bush rather than humid forest. Since there is evidence that this region was wetter in the past (?middle Holocene), human arrival may not have been the only stress factor pushing Jamaican mammals to extinction.

Cave Bats in Jamaica

Donald A. McFarlane — Tue, 09 Apr 2013 13:26:22 PDT

Jamaica has 22 native mammal species. One of these is an endangered rodent, the Jamaican hutia Geocapromys browni; the rest are all bats. Fifteen of these bats depend entirely or significantly on caves as roost sites, including two endemic species and seven endemic subspecies. These cave-dwelling bats often form large colonies whose guano deposits are of significant economic value as fertilizer, but which are vulnerable to disturbance and roost destruction. The author, who has visited and worked in many of Jamaica's bat caves over the past eight years, is currently researching the evolution and development of the Antillean bat faunas.

The Late Pleistocene Hutias (Geocapromys Brownii) of Red Hills Fissure, Jamaica

Donald A. McFarlane et al. — Tue, 09 Apr 2013 13:26:20 PDT

Red Hills Fissure (RHF) is an in-filled, karstic solutional feature exposed by a roadcut in southern Jamaica. The site was discovered in 1988 and immediately recognized as an unusually rich source of late Quaternary gastropods and vertebrate bone dating from the late Pleistocene. Recent work on RHF has focused on the abundant remains of the endemic, mid-sized rodent Geocapromys brownii. Morphological data on a collection of hemi-mandibles has facilitated the construction of a life table for the species in the late Pleistocene: the first for any West Indian Pleistocene vertebrate. Studies of fluorine uptake in the fossil bone have also defined the time-span of the RHF deposit, approximately 25–40 kyr BP.

A Unique Population of Cave Bears (Carnivora: Ursidae) from the Middle Pleistocene of Kents Cavern, England, Based on Dental Morphometrics

Donald A. McFarlane et al. — Tue, 09 Apr 2013 13:26:19 PDT

The ‘breccia’ stratum from Kents (we follow local tradition in using the form ‘Kents’, without an apostrophe) Cavern, England, has been well known for its rich yield of cave-bear material since excavations began in the mid-19th century. Recent work has established that the bears are of latest MIS 12 or earliest MIS 11 age. A life table based on a collection of 67 molariform teeth is consistent with the use of the cave as a hibernaculum. Univariate and morphological assessment of the teeth shows an unusual range of primitive and more derived characters. Multivariate morphometric analysis of cave-bear teeth from the site demonstrates that these animals, while currently assignable to Ursus deningeri sensu lato, are nevertheless morphologically distinct and not simply late deningeri on a hypothetical chronospecific continuum.

Post-speleogenetic Biogenic Modification of Gomantong Caves, Sabah, Borneo

Joyce Lundberg et al. — Tue, 09 Apr 2013 13:16:39 PDT

The Gomantong cave system of eastern Sabah, Malaysia, is well-known as an important site for harvesting edible bird-nests and, more recently, as a tourist attraction. Although the biology of the Gomantong system has been repeatedly studied, very little attention has been given to the geomorphology. Here, we report on the impact of geobiological modification in the development of the modern aspect of the cave, an important but little recognized feature of tropical caves. Basic modeling of the metabolic outputs from bats and birds (CO₂, H₂O, heat) reveals that post-speleogenetic biogenic corrosion can erode bedrock by between ~ 3.0 mm/ka (1 m/~300 ka) and ~ 4.6 mm/ka (1 m/~200 ka). Modeling at high densities of bats yields rates of corrosion of ~ 34 mm/ka (or 1 m/~30 ka). Sub-aerial corrosion creates a previously undescribed speleological feature, the apse-flute, which is semicircular in cross-section and ~ 80 cm wide. It is vertical regardless of rock properties, developing in parallel but apparently completely independently, and often unbroken from roof to floor. They end at a blind hemi-spherical top with no extraneous water source. Half-dome ceiling conch pockets are remnants of previous apse-fluting. Sub-cutaneous corrosion creates the floor-level guano notch formed by organic acid dissolution of bedrock in contact with guano. Speleogenetic assessment suggests that as much as 70–95% of the total volume of the modern cave may have been opened by direct subaerial biogenic dissolution and biogenically-induced collapse, and by sub-cutaneous removal of limestone, over a timescale of 1–2 Ma.

Reciprocal Altruism Between Male Vampire Bats, Desmodus Rotundus

Lisa K. Denault et al. — Tue, 09 Apr 2013 13:16:36 PDT

Reciprocal altruism is an example of social behaviour that has generated much interest among evolutionary theorists, but relatively few well-documented case studies. Among mammals, reciprocal altruism has been reported for the dwarf mongoose, Helogale parvula (Rood 1983), naked mole rats, Heterocephalus glaber (Jarvis 1978), impala, Aepyceros melampus (Hart & Hart 1992) and a few other species, but the best known and most intensively studied example is the regurgitation of blood-meals by successfully foraging adult vampire bats to unsuccessful individuals. This behaviour has apparently evolved in response to the finely balanced energy budget of vampires, which can result in starvation following as little as 48-72 h of food deprivation (McNab 1973). A foraging situation that results in an average of ~8% of adults failing to feed successfully on any given night (Wilkinson 1984), combined with the low fecundity of vampire bats, makes food sharing an essential element of survival.

The Late Pleistoscene Hutias (Geocapromys Brownii) of Red Hills Fissure, Jamaica

Donald A. McFarlane et al. — Tue, 09 Apr 2013 13:16:32 PDT

A Note on the Thermal Ecology and Foraging Behaviour of the Egyptian Fruit Bat, Rousettus Aegyptiacus, at Mt. Elgon, Kenya

Donald A. McFarlane et al. — Tue, 09 Apr 2013 13:16:31 PDT

The Egyptian fruit bat, Rousettus aegyptiacus, is an abundant and widely distributed African pteropid (Nowak, 1999). The species is unusual amongst pteropids in being an obligate cave-dweller (Kwiecinski & Griffiths, 1999), sometimes reaching colony sizes in the thousands (Kingdon, 1974). In the caves of Mt. Elgon National Park, western Kenya (1° 08′N, 34° 39′E), precision temperature loggers placed in major Rousettus roosts and intervening passages have allowed us to precisely monitor bat emergence and return times.

The major caves of Mt. Elgon National Park consist of geophagically modified tunnels and collapse chambers cut into Miocene-aged pyroclastic strata (Lundberg & McFarlane, 2006). These caves can be as much as 200-m deep (e.g. Kitum Cave) and can have volumes exceeding 4 × 10⁴ m³ (e.g. Makingeny Cave). The caves support at least 11 species of bats (Bauer, Weis-Spitzenberger & Weis, 1981). The caves are of interest in the present context because, being located at relatively high altitudes (∼2500 m), the ambient rock temperatures are low and the large biomass of bats produces significant temporal fluctuations that more than doubles roost temperature.

Ammonia Volatilization in a Mexican Bat Cave Ecosystem

Donald A. McFarlane et al. — Tue, 09 Apr 2013 13:16:27 PDT

Direct measurements of gaseous ammonia in the atmosphere of a dry bat cave containing several million insectivorous bats revealed a peak concentration of 1779 ppm (0.96 mg/dm³). Observations indicate that the origin of the gaseous ammonia is rapid microbial decomposition of bat urea, not chitinous guano. Modelling of ammonia distribution and diffusion indicates that ammonia production at the Cueva del Tigre is ∼257 g NH₃/day, equivalent to the decomposition of ∼454 g urea/day. Ammonia production is also characterized by significant isotopic fractionation favoring isotopically light (δ¹⁵N depleted) ammonia.

Pre-Wisconsinan Mammals From Jamaica and Models of Late Quaternary Extinction in the Greater Antilles

Ross D. E. MacPhee et al. — Tue, 09 Apr 2013 13:16:23 PDT

The vertebrate fauna recovered from indurated conglomerates at Wallingford Roadside Cave (central Jamaica) is shown to be in excess of 100,000 yr old according to uranium series and electron spin resonance dating. The Wallingford local fauna is therefore pre-Wisconsinan in age, and Roadside Cave is now the oldest radiometrically dated locality in the West Indies containing identifiable species of land mammals. In the absence of a good radiometric record for Quaternary paleontological sites in the Caribbean, there is no satisfactory basis for determining whether most extinct Antillean mammals died out in a “blitzkrieg”-like event immediately following initial human colonization in the mid-Holocene. Fossils of Clidomys (Heptaxodontidae, Caviomorpha), the giant Wallingford rodent, have never been found in situ in sediments of demonstrably Holocene age, and its extinction may antedate the middle Holocene. This is also a possibility for the primate Xenothrix mcgregori, although its remains have been found in loose cave earth. A major, climate-driven bout of terrestrial vertebrate extinction at about 14,000–12,000 yr B.P. has been hypothesized for the West Indies by G. Pregill and S. L. Olson (Annual Review of Ecology and Systematics 12, 75–98, 1981), but at present there is nothing to connect the disappearance of Clidomys with this event either. Quaternary extinctions in the Caribbean may prove to be of critical significance for evaluating the reality of New World blitzkrieg, but not until an effort is mounted to constrain them rigorously using modern radiometric approaches.

Early Holocene Vegetation Record from the Salton Basin, California

Roberta B. Rinehart et al. — Tue, 09 Apr 2013 13:16:21 PDT

Plant and vertebrate macrofossils in an early Holocene fossil packrat (Neotoma sp.) midden with a radiocarbon age of 8640 ± 100 ¹⁴ C yr B.P. are reported from the Chocolate Mountains, near the Salton Sea, Riverside County, California. An inventory of the midden has permitted a comparison of the modern flora and fauna of the site with that extant during the early Holocene. Whereas the biota had assumed most aspects of its modern Sonoran desert aspect by this date, statistically significant evidence of differences is attributed to an increased flow of surface water in Salt Creek, a high-standing, low-salinity Lake LeConte, and the late arrival of some characteristic Sonoran desert plants. These observations are consistent with models of significant fall-winter precipitation in the Sonoran Desert, although we cannot exclude alternative explanations.

Subaerial Freshwater Stromatolites in Deer Cave, Sarawak – A Unique Geobiological Cave Formation

Joyce Lundberg et al. — Tue, 09 Apr 2013 09:11:23 PDT

A suite of distinctive freshwater subaerial phosphatic stromatolites is developed close to the northeastern entrance of Deer Cave, Gunung Mulu National Park, Sarawak, Borneo, in conditions of very low light but ample supply of nutrients from guano. These stromatolites are not particulate; they are composed of alternating layers of more porous and more dense amorphous hydroxylapatite. This biomineralization occurs as moulds of coccoid (the majority) and filamentous (less abundant) cyanobacteria. Mineralization occurs at a pH of ~ 7.0 in the extracellular sheaths and in micro-domains of varying carbonate content in the surrounding mucus of the biofilm. The most recent surfaces that are not yet strongly mineralized show still-living filamentous, coccoid and rod-shaped forms. Trace element composition shows enrichment in metal ions, especially Mn and Zn. The stromatolites are present as horizontal shelves arranged in series on a steep rock face that is vertically under a guano-laden shelf. The rock face undergoes active dissolution from acidic guano drainage water (e.g., pH of 2.43) and from aggressive rainwater from an overhead discharge. However, the rock surface under the stromatolite is protected while the rest of the cliff face is backcut, creating a hoodoo-like effect. The stromatolites are ~ 15–20 cm deep, ~ 4–7 cm thick, and of variable width, generally ~ 50 cm. Eventually, guano and biological detritus in the descending water film lodge in the lee of the stromatolite lip, causing local acidification and erosion of stromatolite and rock on the underside of the ledge. A dynamic equilibrium is established between upward accretion of the fresh surface and destruction at the base such that the base of the stromatolite does not reflect the date of its inception and the stromatolite climbs up the wall.

Body Size Variability and a Sangamonian Extinction Model for Amblyrhiza, a West Indian Megafaunal Rodent

Donald A. McFarlane et al. — Tue, 09 Apr 2013 09:11:21 PDT

The megafaunal rodent Amblyrhiza inundata from Anguilla and St. Martin is often cited in lists of late Quaternary human-induced extinctions, but its date of disappearance has never been established. Here, we present a suite of uranium-series disequilibrium dates from three independent Amblyrhiza sites in Anguilla, all of which cluster in marine isotope Stage 5. Thus, there is no indication that Amblyrhiza survived into the late Holocene, when islands of the northern Lesser Antilles were first invaded by humans. We argue that the most probable cause of the extinction of Amblyrhiza was a failure of island populations to adjust to catastrophic reductions in available range which accompanied last interglacial sea-level maxima. We support this argument with quantitative extinction probability estimates drawn from persistence time models. Amblyrhiza exhibits body-size hypervariability, a common but underemphasized feature of island megafaunal species. We argue that hypervariability is a record of morphological response to oscillating natural selection, which in turn is driven by asymmetries in the relationship of population size, body mass, and persistence time. The fate of Amblyrhiza stands in marked contrast to that of most other West Indian land mammals, whose losses increasingly appear to have been anthropogenically mediated.

Bats and Bell Holes: The Microclimatic Impact of Bat Roosting, Using a Case Study from Runaway Bay Caves, Jamaica

Joyce Lundberg et al. — Tue, 09 Apr 2013 09:11:19 PDT

The microclimatic effect of bats roosting in bell holes (blind vertical cylindrical cavities in cave roofs) in Runaway Bay Caves, Jamaica, was measured and the potential impact of their metabolism on dissolution modelled. Rock temperature measurements showed that bell holes with bats get significantly hotter than those without bats during bat roosting periods (by an average of 1.1 °C). The relationship is clearest for bell holes with more than about 300 g aggregate bat body mass and for bell holes that are moderately wide and deep, of W:D ratio between 0.8 and 1.6. Measurement of temperature decay after abandonment showed that rock temperature returns to normal each day during bat foraging periods. Metabolic activity from a typical population of 400 g bat (10 individuals) yields 41 g of CO₂, 417.6 kJ of heat, and 35.6 g of H₂O in each 18 hour roost period, and could produce a water film of ~ 0.44 mm, that is saturated with CO₂ at ~ 5%. The resultant rock dissolution is estimated at ~ 0.005 cm³ CaCO₃ per day. The metabolic heat ensures that the focus of dissolution remains vertical regardless of geological controls. A typical bell hole 1 m deep may be formed in some 50,000 years by this mechanism alone. Addition of other erosional mechanisms, such as direct bacterial bio-erosion, or the formation of exfoliative organo-rock complexes, would accelerate the rate of formation. The hypothesis is developed that bell holes are initiated and formed by bat-mediated condensation corrosion and are governed by geographic distribution of clustering bats and their roosting behaviour.