New mammal and bird tracks from the Lower Oligocene of the Ebro Basin (NE Spain): implications for the Palaeogene ichnological record

The Ebro Basin (Spain) is one of the few worldwide areas where Palaeogene avian and mammal tracksites have been found. A new unpublished tracksite known as La Sagarreta is here described. The tracksite is located in a sandstone-dominated outcrop from the Early Oligocene Peralta Formation in the northern-central sector of the basin. Six different ichnotaxa have been identified. Four belong to mammals, including perissodactyl (cf. <i>Plagiolophustipus</i> isp), artiodactyl (<i>Megapecoripeda</i> isp. and cf. <i>Pecoripeda</i> isp.) and carnivoramorph tracks (cf. <i>Canipeda</i> isp.), and the other two to avian tracks (<i>Aviadactyla vialovi</i> and <i>Gruipeda dominguensis</i>). La Sagarreta presents a high ichnodiversity with the presence of a medium-sized member likely of the genus <i>Plagiolophus</i> (or relative), one medium- and one small-sized artiodactyl that probably belong to the family Entelodontidae, one medium-size unidentified carnivorous mammal and two types of birds. La Sagarreta tracksite is the most diverse Early Oligocene tracksite of the Ebro Basin and one of the few palaeontologic vertebrate records at the central area of the basin during this age.

埃布罗盆地（西班牙）是全球范围内少数产出古近纪鸟类与哺乳动物足迹化石点的区域之一。本文记述一处名为拉萨加雷塔（La Sagarreta）的未发表新足迹化石点。该足迹点位于盆地中北部的渐新世早期佩拉尔塔组（Peralta Formation）以砂岩为主的露头地层中。现已识别出6个不同的遗迹分类单元（ichnotaxa），其中4个归属哺乳类，包括奇蹄目（cf. *Plagiolophustipus* 未定种）、偶蹄目（*Megapecoripeda* 未定种及cf. *Pecoripeda* 未定种）与食肉形类足迹（cf. *Canipeda* 未定种）；剩余2个归属鸟类足迹，分别为*Aviadactyla vialovi*与*Gruipeda dominguensis*。拉萨加雷塔足迹点的遗迹分类多样性较高，包含1个大概率隶属于*Plagiolophus*属（或其近缘类群）的中型类群、1个中型及1个小型的偶蹄类类群（二者大概率隶属于完齿兽科（Entelodontidae））、1只体型中等的未确认食肉哺乳类，以及2种鸟类。拉萨加雷塔足迹点是埃布罗盆地内渐新世早期遗迹分类多样性最高的足迹化石点，同时也是该时期盆地中部区域少数已发现的古脊椎动物化石记录之一。