Recent findings from the Naashoibito Member in New Mexico are changing our understanding of dinosaur ecosystems. Previously thought to date back nearly a million years before the mass extinction, new argon dating shows that these layers are much more recent—only a few hundred thousand years prior to the extinction event. This aligns with magnetic field reversals, indicating that these ecosystems thrived alongside those in Hell Creek.
The fossils discovered in Naashoibito reveal a unique environment known as the “Alamo Wash local fauna.” These species are surprisingly different from those found just south in Wyoming, even though they are only about 1,500 kilometers apart. Researchers suggest that two distinct dinosaur bioprovinces existed during the late Cretaceous; there were notable ecological differences between the northern and southern regions.
Interestingly, mammalian fossils suggest a shared community across these areas at the time of extinction. This raises questions about temperature as a key factor in driving these ecological distinctions. Unlike dinosaurs, mammals seem better at regulating their body temperatures, which may have allowed them to adapt more easily to changing conditions.
This research indicates that dinosaurs were quite diverse and thriving in New Mexico right up until the end of the Cretaceous period. However, this raises an important question: if volcanic eruptions in the Deccan Traps had a widespread impact on global ecosystems, how could dinosaurs still be doing so well in some areas?
Despite these insights, our knowledge is still limited to North American ecosystems. There is evidence of dinosaurs in Europe and South America during the late Cretaceous, but dating those fossils is problematic, leaving important gaps in our understanding.
Experts highlight the significance of these findings, stating that they offer clues about how ecosystems can vary even in relatively small distances. This research may change our understanding of dinosaur extinction and survival across different regions.
Staying curious about our planet’s past will help us piece together the intricate puzzle of ecosystems during this critical period.
For more detailed research findings, check out the study in *Science* [here](http://dx.doi.org/10.1126/science.adw3282).
