First osteohistological and histotaphonomic approach of Equus occidentalis Leidy, 1865 (Mammalia, Equidae) from the late Pleistocene of Rancho La Brea (California, USA).
Authors: Tomassini Rodrigo Leandro, Pesquero María Dolores, Garrone Mariana Carolina, Marin-Monfort María Dolores, Cerda Ignacio Alejandro, Prado José Luis, Montalvo Claudia Inés, Fernández-Jalvo Yolanda, Alberdi María Teresa
Journal: PloS one
Summary
# Editorial Summary Rancho La Brea's exceptional fossil assemblages have long provided insights into Pleistocene megafauna, yet detailed microstructural analysis of its abundant taxa remains scarce. Tomassini and colleagues conducted the first osteohistological examination of *Equus occidentalis* limb bones from the site, analysing thin sections under microscopy to characterise bone tissue distribution, growth patterns, and post-depositional alteration. Their findings revealed bone microstructure consistent with modern and other extinct equids, with cyclical growth marks enabling preliminary age estimations; critically, the excellent preservation of bone organisation across specimens indicated varying taphonomic histories between different pits at the locality, suggesting distinct depositional and diagenetic pathways. For equine professionals, this foundational work demonstrates how microstructural analysis can reveal not only species-level biological information (including growth rates and skeletal maturity indicators applicable to understanding modern equine development) but also the burial and preservation conditions affecting fossil assemblages—knowledge relevant to farriers and veterinarians managing age-related skeletal changes and to anyone interpreting equine biomechanical evolution. The methodology established here provides a template for future palaeontological investigations into equid material from complex fossil sites, potentially unlocking further understanding of how environmental and ecological factors shaped extinct horse populations.
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Practical Takeaways
- •This is foundational paleontological work with limited direct clinical application for modern equine practitioners
- •Understanding historical equine bone structure and growth patterns contributes to broader knowledge of equine evolution and skeletal development
- •The study demonstrates value of microstructural analysis for determining age and preservation quality in fossil equids, potentially applicable to archaeological contexts
Key Findings
- •Bone tissue distribution in E. occidentalis is similar to extant and other extinct equids
- •Cyclical growth marks in limb bones enabled preliminary age estimation through skeletochronology
- •Bone microstructure preservation at Rancho La Brea shows excellent quality with minimal pre- and post-burial alteration
- •Taphonomic variations among different pits indicate different preservation conditions and burial histories