New techniques for old bones: Morphometric and diffeomorphometric analysis of the bony labyrinth of the Reilingen and Ehringsdorf Neandertals

Alessandro Urciuoli ^1,2,3,4, Julia Diez-Valero ⁴, Ignacio Martínez ⁴

⁰Department of Paleontology, University of Zurich, Zurich, Switzerland.

Anatomical Record (Hoboken, N.J. : 2007) +

|

November 5, 2025

View abstract on PubMed

Summary

Early Neandertal inner ear fossils from Reilingen and Ehringsdorf show advanced morphology, challenging simple evolutionary models. This suggests a complex, mosaic evolution of Neandertals, with key traits appearing early in a variable population.

Area Of Science

Paleoanthropology
Human Evolution
Paleontology

Background

Neandertals exhibit unique bony labyrinth morphology, often used for fossil identification.
The evolutionary path to classic Neandertal inner ear traits remains debated.
Early Middle Pleistocene specimens are crucial for understanding Neandertal origins.

Purpose Of The Study

To analyze the bony labyrinth morphology of early Neandertal specimens (Reilingen and Ehringsdorf).
To provide new insights into the evolutionary processes of the Neandertal clade.
To refine the understanding of Neandertal inner ear evolution.

Main Methods

Diffeomorphic deformation analysis of semicircular canal and vestibule shape.
Morphometric analysis of cochlear shape.
Comparative analysis with fossil hominin samples (Sima de los Huesos, Krapina, late Neandertals).

Main Results

Reilingen and Ehringsdorf specimens display nearly fully derived, late Neandertal-like inner ear morphology.
This finding contradicts a simple anagenetic model of trait accumulation.
Early specimens exhibit advanced morphology, suggesting early emergence of Neandertal traits.

Conclusions

Neandertal inner ear evolution followed a mosaic pattern, not a simple linear progression.
A highly variable Middle Pleistocene metapopulation likely existed.
Classic Neandertal inner ear morphology emerged early but was fixed later, possibly post-Krapina, after a bottleneck.

Keywords:

cochlea diffeomorphism human evolution inner ear semicircular canals