Vera Rocío B, Muñoz Cristo O Romano, Krapovickas Verónica
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
Instituto de Estudios Andinos 'Don Pablo Groeber' (IDEAN), Estudios Paleobiológicos en Ambientes Continentales, Universidad de Buenos Aires, Int. Güiraldes 2160, 1428, Ciudad Autónoma de Buenos Aires, Argentina.
Sci Rep. 2025 Jul 2;15(1):23447. doi: 10.1038/s41598-025-06230-3.
Two Late Miocene tracksites in Argentina-Toro Negro and Huayquerías formations-preserve over 300 fossil footprints, offering new ichnological insights into the behavior of extinct South American ungulates. These sites include abundant oval-shaped tracks attributed to proterotheriids, a monodactyl group within Litopterna that evolved horse-like limbs. We describe Okana andina n. igen. n. isp., characterized by elongated, anteriorly narrow tracks lacking lateral digit impressions. Detailed analysis of track morphology, preservation, spatial distribution, and footprint orientation reveals patterns consistent with coordinated group movement. To test this behavioral inference, we evaluated multiple hypotheses for the formation of these high-density surfaces, including non-synchronous accumulation, ephemeral aggregation around localized resources, spatial channeling by environmental barriers, and selective preservation bias. These alternatives were rejected based on the ichnological and sedimentological context, including uniform preservation type, consistent morphology, directional coherence, and analogy with modern gregarious ungulates. The evidence supports near-synchronous movement by multiple individuals, providing the first ichnological record of social behavior in Proterotheriidae and expanding our understanding of group-living in extinct South American native ungulates.
阿根廷晚中新世的两个足迹化石遗址——托罗内格罗组和瓦伊克里亚斯组——保存了300多个化石足迹，为已灭绝的南美有蹄类动物的行为提供了新的遗迹学见解。这些遗址有大量椭圆形足迹，归因于原蹄兽类，这是滑距骨目内的一个单趾类群，演化出了类似马的四肢。我们描述了奥卡纳安第斯足迹属新属新种，其特征是足迹细长、前部狭窄，没有外侧趾印。对足迹形态、保存状况、空间分布和足迹方向的详细分析揭示了与群体协同运动一致的模式。为了验证这一行为推断，我们评估了这些高密度足迹表面形成的多种假说，包括非同步堆积、围绕局部资源的短暂聚集、环境屏障造成的空间通道作用以及选择性保存偏差。基于遗迹学和沉积学背景，包括统一的保存类型、一致的形态、方向连贯性以及与现代群居有蹄类动物的类比，这些假说被否定。证据支持多个个体近乎同步的运动，这提供了原蹄兽科社会行为的首个遗迹学记录，并扩展了我们对已灭绝的南美本土有蹄类动物群居生活的理解。
