via KAPI proceedings, 30 December 2023: A recent study focuses on the bone compactness of Pleistocene proboscidean fossil fragments from Cabarruyan Island, Pangasinan, revealing crucial insights into the endemic dwarf elephant Palaeoloxodon beyeri. Utilizing cross-sectional geometry analysis on curated fossil fragments from the National Museum of Natural History and National Museum of Anthropology, the research compares bone areas to infer species characteristics. This micro-anatomical approach sheds light on the evolutionary adaptations of proboscideans in the Philippine Pleistocene, contributing to the broader understanding of Philippine biostratigraphy and the complexities of island dwarfism in large mammals. Paper by Basilia and Louys.
Cabarruyan Island, Pangasinan is the type locality of the endemic dwarfed elephant Palaeoloxodon beyeri, taxonomically updated from Elephas beyeri in this article, in the Philippine Pleistocene. However, proboscidean fossils from this site collected from local people and from geological surveys, and from systematic excavations are often co-mingled and highly fragmented. This paper attempts to provide new data from fossil fragments identified as possibly proboscidean from collections curated by the Geology and Paleontology Division at the National Museum of Natural History (NMNH) and the Archaeology Division at the National Museum of Anthropology (NMA) through bone compactness descriptions. Fossil fragments retaining complete cross-sections were analyzed using cross–sectional geometry (CSG). We compared two proboscidean fossil fragments (femur and rib) from the NMA recovered from a controlled excavation in 2000 to three fossils (one femur and two ribs) from the NMNH collected from surveys in 1957. Total bone area (TA), medullary cavity area (MA), and cortical bone area (CA) were calculated through image analysis. Our results show that the majority of the NMNH fragments had CA/TA percentage consistent with the NMA fragments, which followed previous descriptions of bone compactness for Stegodon and Elephas. One NMNH fragment exhibited a larger MA that may be indicative of a different mammal group that exhibits a larger medullary area and thinner cortical bone. Cross-sectional geometry through macro-photographs is an effective and affordable method to describe the microanatomy of fossil fragments.
Source: Proceedings Vol12_Basilia and Louys.pdf – Google Drive
