LONG BONES OSTEOHISTOLOGY OF GIRAFFIDS FROM LANGEBAANWEG (PLIOCENE), WESTERN CAPE, SOUTH AFRICA.

J. MARCOS JANNELLO; ANUSUYA CHINSAMY

Pune

Simposio; 6th International Symposium on Palaeohistology; 2022

Dept of AIHC and Archaeology, Deccan College PGRI Pune

The reconstruction of life history traits, such as growth rate, age at maturity and age at death can be estimated from the histology of bones of vertebrates. Here, we studied twenty long bones of juveniles and adults of Giraffe cf. Giraffa jumae and Sivatherium hendeyi that were recovered from the Miocene-Pliocene locality, Langebaanweg on the West Coast of South Africa. The sample comprised nine long bones of Giraffe cf. G. jumae comprising two Juvenile femora, seven bones from adult individuals (tibia, metacarpals, metatarsal and metapodials) and eleven long bones of S. hendeyi comprising two Juvenile metatarsals and nine adult limb bones (femur, tibia, metacarpal, metatarsal and metapodial. Our results show that, the fossil giraffids had similar bone wall thickness to the modern giraffes G. camelopardalis, and similarly showed a clear distinction between the thick cortical wall and the open medullary cavity. We also found that bone tissue types and vascular canal orientation varies during ontogeny, as well as between bones, and across single cross-sections of bones. Majority of our specimens appear to be still growing, young individuals with fast rates of growth, while more mature individuals appeared to have slower growth rates and extensive secondary reconstruction in the cortex. Only one metacarpal of S. hendeyi showed the presence of an Outer Circumferential Layer which indicated that it was skeletally mature. Since, the growth marks in the bones appeared to be unrelated to an annual/seasonal periodicity, we propose that they are likely related to periodic catastrophic events, such as droughts.