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

在Saltillo(Coahuila)以南约70公里的Gomez Farías村附近的Sierra de Jabalías，我们最近发现了一个地方，在那里，早期提顿纪海生爬行动物的残留物集中在约1.5米厚的coquina层中。coquina单位存在于La Casita/La Caja组(基默里期至贝里亚斯早期)的下部三分之一，几乎全部由由晶石水泥胶结在一起的化石组成。菊科动物、双壳类贝壳类、贝壳类和木材类以及丰富多样的海洋脊椎动物群落经常出现。到目前为止，我们发现了上龙、蛇颈龙、鱼龙、海龙、鳄鱼和两种鱼类。这种材料包括孤立的骨骼以及部分和半完整的骨骼。这一单元脊椎动物的密度很高，可能是由于陆架边缘附近的上升流条件、广泛的富营养化以及海底和底层水的缺氧造成的。我们的主要目标是突出这一新的集中区的巨大潜力，保护更多的标本，并提供化石组合的分类清单，特别是参考挖掘学和生物地层学。我们还打算精确地重建导致戈麦斯-法里亚斯化石集中的古环境条件。

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.