1. Differing impact of carnivores on bone assemblages in two East African Ecosystems Anna K. Behrensmeyer Department of Paleobiology, Smithsonian Institution Briana L. Pobiner Department of Anthropology, Rutgers University

2. Goals: Test the effects of different dominant carnivores on recent bone assemblages Impact on models of carcass and prey availability for early hominins Flesh slicerBone crusher

3. Amboseli Laikipia

4. 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 wildebeeste Burchell's zebra Grant's gazelle Thomson's gazelle impala buffalo elephant giraffe hartebeest beisa oryx black rhino eland Frequency Laikipia Amboseli 1970's Laikipia and Amboseli: Live Census Data

5. LaikipiaAmboseli 1975 2002 X XX Different Ecosystems Different Times What is the taphonomic impact of different top predators? 11 transects12 transects

6. Variables to Compare: Average number of bones per individual Skeletal part survival Completeness of femora and humeri Damage to femora and humeri Juveniles vs. adults

7. Burchell’s zebra only

8. Laikipia Ecosystem

9. Laikipia Lions on Zebra Prey

10. Amboseli Ecosystem

11. Predators of Amboseli Park 1975 - 2003

12. Amboseli: Change in Patterns of Destruction Same transects, 1975 and 2002 Bones / Individual Increased Body Size HR, RO GAZ, IM WB, CW BF HP, RH EL ZB GF 1975 2002

13. Diverse predators Lions dominant Few hyenas Lions absent Hyenas increasing Many hyenas Few lions 1975 1990 2002- 2003 Abundant carcasses Low damage levels Abundant carcasses Few zebra deaths Fresh carcasses rare 71% decrease in bones High damage levels EcosystemTaphosystem Amboseli

14. Hyena dominance and intraspecific competition is driving the change in carcass and bone survival.

15. Working hypothesis: If the top predator controls the destruction patterns of prey skeletons, then Laikipia 2002 should be more similar to Amboseli 1975 than Amboseli 2002-03. LaikipiaAmboseli 1975 2002 Lion Hyena Different Ecosystems Different Times

16. 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 Ambo 1975Ambo 02-03Laikipia 02 Bones / MNI Average Bones per MNI

17. Zebra Skeletal Part Survival Amboseli 1975 and 2002-3 vs. Laikipia 2002 Observed / Expected Skull Jaw (hemi) Vertebrae Ribs Scapula Humerus Radius/ulna Metacarpal Innominate Femur Tibia Metatarsal Patella Podials Phalanges 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 Laikipia 02 MNI = 27 Ambo 1975 MNI = 45 Ambo 2002-3 MNI = 36 ForelimbHindlimb

18. 0.00 0.10 0.20 0.30 0.40 0.50 0.60 WholeProx.– Distal Pair Shaft only Prox. only Prox. + Shaft Distal + Shaft Distal only Frequency Completeness of Humerus and Femur Laikipia 02 (N = 9) Ambo 75 (N = 48) Ambo 02-03 (N = 17)

19. D: Fragments only B: Moderate: marginal gnawing; one end absent A: Minimal: tooth marks, scoring C: Heavy: both ends gnawed or absent Damage Categories

20. Damage to Humerus and Femur 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 No Damage A Minimal Frequency Increasing damage Ambo 75 (N = 48) Ambo 02 03 (N = 17) Laikipia 02 (N = 9) B Moderate C Heavy D Fragments

21. Adults vs. Juveniles 0 5 10 15 20 25 30 35 Ambo 1975Ambo 02 - 03Laikipia 02 MNI Adult Juvenile

22. LaikipiaAmboseli 1975 2002-03 Lion Hyena Dominant Predator

23. Conclusions Laikipia 2002 bone assemblage more similar to Amboseli 2002-03 than to Amboseli 1975. Our prediction is not supported. Lion vs. hyena dominance does not leave a clear taphonomic signal in the bone assemblage based on the variables we used. New Hypothesis: Damage levels may be better indicators of overall predator pressure on the prey populations than the signature of the dominant predator(s).

24. Skeletal part survival affected by: bone-processing capabilities of predators …but also probably by: intraspecific competition for prey predator social structure predator diversity Carcass availability and damage patterns can change over decades.

25. Carcasses (and prey) available to early hominins would have varied greatly in time and space because of variablity in predator consumption of carcasses. Recognition of this variability could have been an important adaptive strategy for meat-seeking hominin individuals and groups.

26. With Thanks to: The National Museums of Kenya The Kenya Wildlife Service The National Geographic Society David Western, Dorothy Dechant, Richard Leakey, and all the individuals who have helped with Amboseli bone research Fulbright-Hays Fellowship to B. Pobiner Sweetwaters Game Reserve, Laikipia, Kenya