A new concentration lagerstätte for marine vertebrates of Tithonian (Uppermost Jurassic) age in southern Coahuila, Mexico

在塞拉Jabalí，戈麦斯村附近Farías，萨尔提略（科阿韦拉）以南约70公里处，我们最近发现了一处海洋爬行动物的遗迹。早梯统时代主要集中在厚度约1.5 m的coquina层。coquina单元存在于La Casita/La Caja组（kimmeridian至Berriasian早期）的下三分之一，几乎完全由由晶石胶结在一起的化石组成。菊石类、双壳类、菱形石类、木类等常见物种，以及丰富多样的海洋脊椎动物群落。到目前为止，我们已经鉴定出了上龙、蛇颈龙、鱼龙、thalattosuchian鳄鱼和两种鱼类。该材料包括孤立的骨骼以及部分和次完整的骨骼。该单元脊椎动物的集中是突出的，可能是由于大陆架边缘附近的上升流条件、海底和底部水的广泛富营养化和缺氧造成的。我们的主要目标是强调这个新的集中矿床的巨大潜力，获取更多的标本，并提出化石组合的分类清单，特别参考地层学和生物地层学。我们进一步打算精确重建导致戈麦斯Farías惊人化石浓度的古环境条件。

In the Sierra de Jabalí, near the village of Gomez Farías, about 70 km south of Saltillo (Coahuila), we recently discovered a locality where remnants of marine reptiles of ?Early Tithonian age are concentrated in coquina layers with a thickness of about 1.5 m. The coquina unit is present in the lower third of the La Casita/La Caja Formation (Kimmeridgian to early Berriasian) and almost entirely consists of fossils cemented together by spar cement. Ammonoids, ostreid bivalves, belemnites and wood occur frequently, as well as an abundant and diverse assemblage of marine vertebrates. So far, we identified pliosaurs, plesiosaurs, ichthyosaurs, thalattosuchian crocodilians and two species of fishes. The material comprises isolated bones as well as partial and sub-complete skeletons. The concentration of vertebrates in this unit is outstanding and may have resulted from upwelling conditions near the shelf edge, widespread eutrophication and anoxia in seafloor and bottom water. It is our main objective to highlight the enormous potential of this new concentration deposit, secure further specimens and present a taxonomic inventory of the fossil assemblage with special reference to taphonomy and biostratigraphy. We further intend to precisely reconstruct the palaeoenvironmental conditions that led to the remarkable fossil concentration at Gomez Farías.