Microvertebrate Fossils

 

The Hayden Quarry at Ghost Ranch, NM, is recognized for its high diversity and abundance of large archosaur fossils including early dinosaurs like Tawa and crocodylian relatives such as phytosaurs and aetosaurs. However, the age of the Hayden Quarry (~ 215 mya) also places it in a prime position to preserve tiny, delicate fossils of early representatives of today’s dominant terrestrial vertebrates including mammals, amphibians, and squamates. Additionally, the uncommon depositional setting of the site, including fluvial transport via a network of small river channels and burned wood associated with terrestrial forest fires, increased the preservation potential of rarer small reptiles such as drepanosaurs  and many fish groups that were diversifying quickly during this time. To put together a more comprehensive picture biodiversity present at Hayden 215 mya and better understand the ecology of the site, we have bulk sampled multiple microvertebrate layers and are in the process of screenwashing, sorting, and identifying the recovered fossils. Preliminary work already has greatly expanded our knowledge of the taxa present at Hayden, particularly for fish and small reptiles, and is beginning to change perspectives about groups once considered to be rare, enigmatic, and of lower diversity. Excavation of both macro- and micro- vertebrate fossils at Hayden is ongoing, and field and lab opportunities for students are a key aspect of the project.