Bert Hugo, Costeur Loic, Lazarev Sergei, Schulz Georg, Vasilyan Davit, Maridet Olivier
CNRS UMR 5125 "Paléoenvironnements & Paléobiosphère" Université Claude Bernard Lyon 1, Rue Raphaël Dubois 2, 69622 Villeurbanne, France.
Ecole Normale Supérieure de Lyon, Parvis René Descartes 15, 69342 Lyon Cedex 07, France.
Swiss J Palaeontol. 2025;144(1):19. doi: 10.1186/s13358-025-00357-6. Epub 2025 Apr 14.
We describe an almost complete fossil cranium of a shrew, identified as (Petényi, 1864) from the early Pliocene of Jradzor site, Armenia. The sedimentary unit, which yielded the specimen, is an 11-m-thick package composed of white thinly-parallel-laminated diatomite laying at the base of the Jradzor section. It was dated at 4.29 ± 0.09 Ma based on the magnetostratigraphy and Ar/Ar radioisotopic dating of a tephra layer located at the top of the diatomite package. The skull from Jradzor shows several synapomorphies that allow its assignment to the Soricinae subfamily and Neomyini tribe. Among Neomyini, as far as the cranium anatomy is known, the specimen from Jradzor is most similar to that of and . Both petrosal bones are preserved and are studied thanks to a 3D modelling of their morphology based on a CT-scan. Compared with other eulipotyphlans, the bony labyrinth of from Jradzor shows a morphology typical of soricids. Its anatomy also indicates a high-frequency auditory capability similar to that of modern shrews but cannot confirm an echolocation system neither does it shows any feature that can be related to a specific locomotory adaption or ecological characteristic. The discovery of this cranium inside diatomites, corresponding to a distal lacustrine environment, raises the question of the possible semi-aquatic adaptation of this species (this adaptation being known for other extant species of the family). However, and , the two genera closest to based on cranial anatomy are not semi-aquatic and are clearly distinguished from semi-aquatic shrews. The inner ear morphology is more similar to that of terrestrial shrews despite the general similarities among soricids and suggests an echolocation-based orientation using high frequencies to navigate through low vegetation, which is often essential in high metabolic rate organisms to reduce energy expenditure. We therefore propose a terrestrial locomotion for , consistent with its previously proposed paleoecological model, depicting it was a terrestrial species inhabiting wet or humid environments in close proximity to permanent bodies of water.
The online version contains supplementary material available at 10.1186/s13358-025-00357-6.
我们描述了一个几乎完整的鼩鼱化石颅骨，它被鉴定为来自亚美尼亚Jradzor遗址上新世早期的（佩泰尼，1864年）。产出该标本的沉积单元是一个11米厚的层序，由位于Jradzor剖面底部的白色薄平行层状硅藻土组成。根据位于硅藻土单元顶部的火山灰层的磁性地层学和氩/氩放射性同位素测年，其年代为429±0.09百万年。来自Jradzor的颅骨显示出几个共衍征，使其能够被归入鼩鼱亚科和新鼩鼱族。在新鼩鼱族中，就颅骨解剖结构而言，来自Jradzor的标本与 和 的最为相似。两块岩骨均保存完好，并基于CT扫描对其形态进行三维建模进行了研究。与其他真盲缺目动物相比，来自Jradzor的 的骨迷路显示出鼩鼱科典型的形态。其解剖结构还表明具有与现代鼩鼱相似的高频听觉能力，但既不能证实其回声定位系统，也未显示出任何与特定运动适应或生态特征相关的特征。在对应于远端湖泊环境的硅藻土中发现这个颅骨，引发了该物种可能具有半水生适应性的问题（这种适应性在该科其他现存物种中是已知的）。然而，基于颅骨解剖结构与 最接近的两个属 和 并非半水生，且与半水生的鼩鼱有明显区别。尽管鼩鼱科之间有一般相似性，但其内耳形态更类似于陆生鼩鼱，这表明其使用高频回声定位来在低矮植被中导航，这在高代谢率生物中通常对于减少能量消耗至关重要。因此，我们提出 具有陆地运动方式，这与其先前提出的古生态模型一致，该模型描述它是一种栖息在靠近永久性水体的潮湿或湿润环境中的陆生物种。
在线版本包含可在10.1186/s13358 - 025 - 00357 - 6获取的补充材料。
