Transcript Slide 1

Bones of Ol Pejeta: Neotaphonomic and Ecological Survey (BONES)
1
Kris Kovarovic & Briana Pobiner
1Department
2
Smithsonian
of Anthropology, University College London, United Kingdom, 2Human Origins Program, National Museum of Natural History, Smithsonian Institution, USA
This long-term project will address two major issues in human evolution in concert: 1) reconstruction of the environmental context of hominin evolution in Africa through the study of faunal remains and 2) the potential niche of hominins
within the carnivoran paleoguild through documentation of carnivore habitat preferences and predator-prey relationships. Both research questions – the habitats and mammal communities in and with which hominins were living, and
how hominins were interacting with carnivores to acquire prey resources - require approaches that are based on comparative analyses of living mammal communities. We will investigate both past and present ecologies in a long-term
study of the bones of modern mammals that accumulate on the ground in a mosaic of different habitat types in Ol Pejeta Conservancy (OPC) in the Laikipia District of Kenya. These “bone communities” will be used to:
1. generate models for reconstructing ecological conditions in the past, with a focus on predator-prey dynamics and mammalian habitat preferences and affiliations
2. pinpoint areas of difference between the bone communities we find on the ground in the modern landscape and the living mammal community that we observe today, and generate and test hypotheses to explain these differences
Ol Pejeta Conservancy: A Unique Opportunity
.
• 1989: Sweetwaters Game Reserve (SGR) opened as a
sanctuary for the endangered black rhino, ca. 97 km2
• 1999: Earthwatch project (Kenya’s Black Rhinos)
initiated to study the behavior, ecology, demographics of
mammals and vegetation associations
• 2004: SGR purchased by Fauna & Flora International
• 2007: removal of a fence that previously enclosed SGR
within the larger Ol Pejeta Ranch created Ol Pejeta
Conservancy, or OPC (>360 km2). See Fig. 2.
This recent fence removal has stimulated shifts in
mammalian behavior and habitat affiliations,
creating a unique opportunity for us to study the
taphonomy of ecological processes as they occur
and stabilize over time in a natural landscape.
Figure 1. Map of
Kenya, showing the approximate location of OPC.
BONES: The Longitudinal Study
BONES: A Study of Mammalian Communities
Over several years we will record information collected on all visible
mammalian skeletal remains encountered on pre-determined 1 km
transects in all of the OPC habitat types. Data collected will include:
We hypothesize that a long-term survey of bone communities at OPC will
track changes in the living mammal communities including:
• species-specific data (mammal taxa present, predator identity for kills)
Predator identity will be based on previously established taphonomic data
collection (Pobiner 2005), including prey size- and skeletal part-specific
bone damage and destruction profiles, tooth mark size and distribution.
• taphonomic data (skeletal elements present, weathering stage, indices of
carnivore damage such as long bone epiphysis : shaft ratio and relationship
to bone density)
• ecomorphological data (measurements of adaptive
morphologies that relate to the exploitation of particular habitats).
skeletal
Previously developed ecomorphological models, which predict the habitat
affiliation of mammals on the basis of adaptive skeletal morphologies that
are known to relate to habitat exploitation, will be applied to all encountered
ungulate remains (Kovarovic and Andrews 2007). We will analyze the
ungulate bones encountered on the transects in this way in order to
determine if the bones of these “ecomorphs” are accumulating in their
preferred habitats and if carnivores continue to sample preferred species
from these habitats, even after changes in the mammalian community occur
due to the removal of the fence.
• Changes in ungulate habitat preferences, using correlation and
multivariate analyses between abundances of bony remains of ungulate
species or “ecomorphs” and habitat variables (Andrews et al. 1979;
Kovarovic and Andrews 2007; Miller and Behrensmeyer 2005)
• Changes in relative predation level on specific ungulates, using
frequency data of predator-specific kill remains of different prey ages and
sexes (Pobiner 2005; Pobiner and Blumenschine 2002); and in specific
habitats, using frequency data of predator-specific kills of remains in each
habitat
• Changes in species composition of animals preyed on by different
predators indicating changes in prey preferences, also using frequency
data of predator-specific kills
• Changes in overall carnivore competition and predation pressure,
using differential bone survival and limb skeletal element and portion
relative abundance data (Blumenschine 1989; Faith and Behrensmeyer
2006)
• Changes in predation pressure in particular habitats based on
ecomorphological characteristics of prey species remains (Kovarovic and
Andrews 2007)
• Changes in overall prey biomass and prey species abundances,
using bone and species frequency encounter data
From these data we can create models for interpreting fossil mammal
ecologies. These data will be compared across the habitat types in
OPC and, eventually, over a period of several years.
An accurate assessment of hominin palaeoenvironments based
on analyses of fossil fauna requires an awareness of modern
mammal behaviour - including their relationships to one another
and to their habitats.
Figure 2. Vegetation map of Ol Pejeta Conservancy, also showing the delineation of the
former Sweetwaters Reserve and the adjacent Ol Pejeta Ranch, now comprising OPC.
Figure 3. SGR mammal census
data from 1996–2003.
Census data over the next few
years, collected in different
areas of the conservancy by
Earthwatch, will indicate which
species are migrating into new
habitats after the fence removal.
BONES will allow us to investigate how landscape-scale
taphonomy and carnivore predation affect ecomorphology-based
reconstructions of past environments. In particular we will be
determine if there are biases in the representation of certain
habitat types or in habitats dominated by particular predator or
ungulate prey species.
Acknowledgements
We thank the Kenyan government and OPC management for permission to conduct
research at the conservancy. We are also grateful for the involvement of our collaborators:
Dr. Geoffrey Wahungu (Wildlife Management, Moi University, Kenya), Nathan Gichohi
(OPC), Professor Peter Andrews (Natural History Museum, UK), Dr. Rhonda Quinn (Earth
and Planetary Sciences, Rutgers University, NJ) and Dr. Nick Walton (Legendware, UK).
Figure 4. The ecological relationships of carnivores
and ungulates can be understood through the
analysis of the visible bone communities (see above)
References
Andrews, P., Lord, J.M., Nesbit Evans, E.M., 1979. Patterns of ecological diversity in fossil and modern mammalian
faunas. Biological Journal of the Linnaean Society 11, 177-205.
Blumenschine, R.J., 1989. A landscape taphonomic model of the scale of prehistoric scavenging opportunities. Journal
of Human Evolution 18, 345-371.
Faith, J.T., Behrensmeyer, A.K., 2006. Changing patterns of carnivore modification in a landscape bone assemblage,
Amboseli Park, Kenya. Journal of Archaeological Science 33, 1718-1733.
Kovarovic, K., Andrews, P., 2007. Bovid postcranial ecomorphological survey of the Laetoli paleoenvironment. Journal of
Human Evolution 52, 663-680.
Miller, J.H., Behrensmeyer, A.K., 2005. Skeletal distributions across time: A multivariate approach to the changing
taphonomy of Amboseli Park, Kenya. Journal of Vertebrate Paleontology 25, 92A.
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Pobiner, B.L., 2005. African carnivoran taxon-specific bone modification patterns: experimental evidence. Journal of
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