Differing impact of carnivores
Download
1 / 26

Differing impact of carnivores on bone assemblages in two East African Ecosystems - PowerPoint PPT Presentation


  • 311 Views
  • Uploaded on
  • Presentation posted in: Pets / Animals

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. Flesh slicer. Bone crusher. Goals:

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

Differing impact of carnivores on bone assemblages in two East African Ecosystems

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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


Flesh slicer

Bone crusher

Goals:

Test the effects of different dominant carnivores on

recent bone assemblages

Impact on models of carcass and prey availability for

early hominins


Laikipia

Amboseli


Laikipia and Amboseli: Live Census Data

0.45

Laikipia

0.40

Amboseli 1970's

0.35

0.30

Frequency

0.25

0.20

0.15

0.10

0.05

0.00

eland

giraffe

buffalo

impala

elephant

hartebeest

beisa oryx

black rhino

wildebeeste

Grant's gazelle

Burchell's zebra

Thomson's gazelle


What is the taphonomic impact of different top predators?

Different Ecosystems

Laikipia

Amboseli

2002

X

X

Different Times

1975

X

12 transects

11 transects


  • 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


Burchell’s zebra only


Laikipia Ecosystem


Laikipia Lions

on Zebra Prey


Amboseli Ecosystem


Predators of Amboseli Park

1975 - 2003


Amboseli: Change in Patterns of Destruction

Same transects, 1975 and 2002

1975

Bones / Individual

2002

HR, RO GAZ, IM WB, CW BF HP, RH EL

ZB GF

Increased Body Size


Amboseli

Ecosystem

Taphosystem

  • Diverse predators

  • Lions dominant

  • Few hyenas

  • Abundant carcasses

  • Low damage levels

1975

1990

2002-

2003

  • Lions absent

  • Hyenas increasing

  • Abundant carcasses

  • Few zebra deaths

  • Fresh carcasses rare

  • 71% decrease in bones

  • High damage levels

  • Many hyenas

  • Few lions


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


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.

Different Ecosystems

Laikipia

Amboseli

2002

Lion

Hyena

Different Times

1975

Lion


Average Bones per MNI

16.00

14.00

12.00

10.00

Bones / MNI

8.00

6.00

4.00

2.00

0.00

Ambo 1975

Ambo 02-03

Laikipia 02


Laikipia 02 MNI = 27

Ribs

Skull

Tibia

Femur

Patella

Podials

Scapula

Humerus

Vertebrae

Metatarsal

Phalanges

Jaw (hemi)

Metacarpal

Innominate

Radius/ulna

Zebra Skeletal Part Survival

Amboseli 1975 and 2002-3 vs. Laikipia 2002

0.45

0.40

Ambo 1975 MNI = 45

Ambo 2002-3 MNI = 36

0.35

0.30

0.25

Observed / Expected

0.20

0.15

0.10

0.05

0.00

Forelimb

Hindlimb


Laikipia 02 (N = 9)

Completeness of Humerus and Femur

0.60

Ambo 75 (N = 48)

Ambo 02-03 (N = 17)

0.50

0.40

Frequency

0.30

0.20

0.10

0.00

Whole

Prox.–

Distal

Pair

Shaft

only

Prox.

only

Prox.

+

Shaft

Distal

+

Shaft

Distal

only


Damage Categories

A: Minimal: tooth marks,

scoring

B: Moderate: marginal

gnawing; one end absent

C: Heavy: both ends gnawed or absent

D: Fragments only


0.70

Laikipia 02 (N = 9)

0.60

0.50

0.40

0.30

0.20

0.10

0.00

Increasing damage

Damage to Humerus and Femur

Ambo 75 (N = 48)

Ambo 02 03 (N = 17)

Frequency

A

Minimal

B

Moderate

C

Heavy

D

Fragments

No

Damage


Adult

Juvenile

Adults vs. Juveniles

35

30

25

20

MNI

15

10

5

0

Ambo 1975

Ambo 02 - 03

Laikipia 02


Laikipia

Amboseli

Dominant Predator

Lion

2002-03

Hyena

1975

Lion


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).


  • 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.


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.


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


ad
  • Login